Regional Anesthesia Is Associated with Improved Survival and Decreased Recurrence in Ovarian Cancer Patients

Abstract 1

Regional Anesthesia is Associated with Improved Survival and Decreased Recurrence in Ovarian Cancer Patients

Presenting Author: Gildasio S. De Oliveira, Jr., M.D. Presenting Author’s City, State: - Chicago, Il

Introduction: The deleterious effects of surgery and anesthesia in cancer patients have been postulated for a long time. It has been demonstrated in animals that surgery and anesthesia may promote metastasis and accelerate the progression of several tumor types. Stress response, opioids and volatile anesthetic drugs can cause perioperative immune suppression and promote a negative effect on the outcome of cancer patients. Regional Anesthesia can blunt the stress response, decreased the use of volatile anesthetics and the consumption of opioids which can lead to a favorable outcome in those patients.

Methods: We performed a retrospective analysis of patients undergoing primary cytoreductive surgery to evaluate if the presence of epidural anesthesia and/or analgesia would have a positive impact on cancer recurrence and survival. Data extracted from patient's medical records included age, height ,weight, medical history , cancer staging, cancer grading, cell type, surgical duration, blood loss during the procedure , preoperative CA125, surgeon performing the operation, presence of perioperative transfusion, number of units transfused and the presence of epidural anesthesia and analgesia . Baseline data was analyzed using independent sample t test, Mann-Whitney U test, Pearson's Chi square or Fisher's exact test as appropriate. Time to event data was analyzed using Kaplan-Meier curves and log-rank test. Cox regression multivariate analysis was used to adjust for possible confounding factors.

Results: We studied 182 patients that were divided into patients who receive perioperative epidural (55 patients) and the ones who did not receive perioperative epidural(127 patients).Groups had no difference among baseline characteristics except for the number of units transfused which was higher in the non- epidural group; 1[0-2] vs. the epidural group ;0[0-1] p=0.03. The epidural group had an increase time to recurrence (p=0.008, log-rank test) and increased survival (p=0.01, log-rank test) when compared to the non-epidural group. When adjusting for confounding factors ( Age ,ASA, CA125, stage, grade, surgical duration, transfusion and number of units transfused) the epidural was still found to be a predictor for less recurrence(p=0.009) and higher survival(p=0.01) ,estimated hazard rate of 0.54[034-0.85] and 0.50[0.28- 0.89] respectively.

Discussion: We demonstrated in this retrospective analysis that the perioperative use of epidural anesthesia and analgesia is associated with decreased recurrence and increased survival in ovarian cancer patients. This positive association is possibly due to a better preservation of the immune system function with the use of epidural.

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Abstract 2

A Multicenter, Randomized, Triple-Masked, Placebo-Controlled Trial of The Effect of Ambulatory Continuous Femoral Nerve Blocks on Discharge- Readiness Following Total Knee Arthroplasty In Patients on General Orthopaedic Wards

Presenting Author: Brian M. Ilfeld, M.D., M.S. Presenting Author’s City, State: - La Jolla, CA Co-Authors: Vanessa J. Loland, M.D. - University of California San Diego - San Diego, CA John F. Donovan, M.D. - Alta Bates Summit Medical Center - Oakland, CA Linda T. Le, M.D. - University of Florida - Gainesville, FL Edward R. Mariano, M.D., MAS - University of California San Diego - San Diego, CA

Background: A previous investigation reported a 4-day ambulatory continuous femoral nerve block (cFNB) decreased the time required to reach 3 important discharge criteria by 53% compared with an overnight, hospital-only cFNB following total knee arthroplasty (TKA, p<0.001). However, a major limitation of that study was the artificial research environment: (1) all subjects convalesced in a specialized, stand-alone clinical research center often with a single nurse per patient; (2) a single anesthesiologist cared for all subjects; and (3) the 3 physical therapists involved in the study were specially trained to optimize the study protocol, including ambulation distances.1 Consequently, it is problematic generalizing results from this single trial to the more than half-million patients who undergo TKA each year in the U.S. We therefore designed this prospective clinical trial to retest the hypothesis that an extended ambulatory cFNB shortens the time until 3 specific, predefined readiness-for-discharge criteria are met following TKA; and to allow inference of the results to the general population by using standard orthopaedic hospital wards in multiple centers with a wide range of healthcare providers.

Methods: Preoperatively, all patients received a cFNB with perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomized to either continue perineural ropivacaine (n=39) or switch to saline (n=38). The primary endpoint was the time to attain three discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation â‰¥ 30 meters). Patients were discharged with their cFNB and a portable infusion pump, and catheters were removed on postoperative day 4.

Results: Patients given 4 days of perineural ropivacaine attained all 3 criteria in a median (25th-75th %iles) of 47 (29-69) h, compared with 62 (45-79) h for those of the control group receiving ropivacaine only until the morning following surgery (Estimated ratio=0.80, 95%CI: 0.66-1.00; p=0.028; Fig. 1). Compared with subjects receiving saline, patients randomized to ropivacaine met the discharge criterion for analgesia in 20 (0-38) vs. 38 (15-64) h (p=0.009; Figs. 2-3); for intravenous opioid independence in 21 (0-37) vs. 33 (11-50) h (p=0.061); and ambulation in 40 (25-68) vs. 45 (25-66) h (P=0.780). There were 4 falls in 3 patients receiving ropivacaine, versus 0 in controls (p=0.240).

Conclusions: In the previous study using the artificial environment of a stand-alone clinical research center,1 subjects with a 4-day cFNB met three discharge criteria in 25 (21-47) h, compared with 71 (46- 89) h for those of the control group with an overnight, hospital-only infusion. Providing the extended cFNB thus resulted in a far greater decrease in time until discharge readiness (46 h, or 53%; p<0.001) than found for subjects of the current study (15 h, or 20%; p=0.028). That the benefit was greater in a highly- controlled environment is not surprising. Our current results reflect a country-wide diversity of practice that is probably more representative of what clinicians can generally expect from an extended, ambulatory cFNB.

References: 1. Ilfeld et al. Anesthesiology 2008; 108: 703-13 2. Kurtz et al. JBJS 2005; 87: 1487-97

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Abstract 3

Perioperative Pulmonary Circulatory Changes During Bilateral Total Hip Arthroplasty

Presenting Author: Matthew C. Rade, B.A. Presenting Author’s City, State: - New York, NY Co-Authors: George Go, B.S. - Hospital for Special Surgery - New York, NY Yan Ma, Ph.D. - Hospital for Special Surgery - New York, NY Nigel E. Sharrock, M.B., Ch.B. - Hospital for Special Surgery - New York, NY Stavros G. Memtsoudis, M.D., Ph.D. - Hospital for Special Surgery - New York, NY

Background: The transient and rarely clinically relevant effect of bone and cement embolization during unilateral joint arthroplasty is a known phenomenon. However, available studies do not address events surrounding bilateral total hip arthroplasties, during which embolic load is presumably doubled. To elucidate events surrounding this increasingly utilized procedure and assess the effect on the pulmonary hemodynamics in the intra- and postoperative period, we studied 24 subjects undergoing cemented bilateral total hip arthroplasty during the same anesthetic session.

Materials and Methods: Twenty four patients without previous pulmonary history undergoing cemented bilateral total hip arthroplasty under controlled epidural hypotension were enrolled. Pulmonary artery catheters were inserted and hemodynamic variables were recorded at baseline, 5 minutes after the implantation of each hip joint, 1 hour and 1 day postoperatively. Mixed venous blood gases and complete blood counts were analyzed at every time point.

Results: An increase in pulmonary vascular resistance was observed after the second but not the first hip implantation when compared to values at incision. Pulmonary vascular resistance remained elevated 1 hour postoperatively (Figure 1). Pulmonary artery pressures were significantly elevated on post operative day 1 compared to baseline values. The white blood cell count increased in response to the second hip implantation but not the first compared to incision (P<0.003).

Conclusion: The embolization of material during bilateral total hip arthroplasty is associated with prolonged increases in pulmonary artery pressures and vascular resistance, particularly after the second side. The performance of bilateral procedures should be cautiously considered in patients with diseases suggesting decreased right ventricular reserve.

Abstract 4

Intrathecal Clonidine Decreases Propofol Sedation Requirements During Spinal Anaesthesia In Infants

Presenting Author: Rajeev Subramanyam, D.N.B., M.D., M.N.A.M.S. Presenting Author’s City, State: - Chandigarh, Karnataka Co-Authors: Yatindra Batra Kumar, M.D., M.N.A.M.S., F.A.M.S. - Postgraduate Institute of Medical Education and Re - Chandigarh, Chandigarh Rakesh S. V., M.B.B.S. - Postgraduate Institute of Medical Education and Re - Chandigarh, Chandigarh Nidhi Panda B., M.D. - Postgraduate Institute of Medical Education and Re - Chandigarh, Chandigarh Lokesh V. C., M.D. - Postgraduate Institute of Medical Education and Re - Chandigarh, Chandigarh

Background: Propofol is a popular agent for providing procedural sedation in paediatric population during lumbar puncture and spinal anaesthesia. Adjuvants like clonidine and fentanyl are administered intrathecally to prolong the duration of spinal anaesthesia and to provide post - operative analgesia in infants. We studied the propofol requirement after intrathecal administration of clonidine or fentanyl in infants undergoing lower abdominal surgeries.

Methods: Institutional review committee approval and parents written informed consent was obtained. 65 ASA I infants undergoing elective lower abdominal surgery under spinal anaesthesia were enrolled in this prospective randomised double blinded study (Figure 1). A bolus of 2-3 mg/kg of propofol bolus was administered for lumbar puncture. Sedation was assessed using a six point sedation score (0 to 5) and a five point reactivity score (0 to 4) based on a behavioural score. After achieving a sedation and reactivity score of 3 - 4, the infants were positioned laterally in knee chest position. Lumbar puncture was performed and test drug was administered based on random assignment into one of the four groups. Bupivacine was administered according to body weight (<5kg = 0.5 mg/kg; 5â€“10 kg = 0.4 mg/kg). Group B received intrathecal bupivacaine alone. Group BC received 1Î1⁄4g/kg of intrathecal clonidine with bupivacaine, group BF received 1Î1⁄4g/kg of fentanyl with bupivacaine and patients in group BCF received 1Î1⁄4g/kg each of clonidine and fentanyl with bupivacaine. Further intraoperative sedation was maintained with propofol infusion at 25-50Î1⁄4g/kg/min. The propofol dose requirements in each of the groups were measured. Sedation and reactivity scores were noted. Analysis was performed with multiple ANOVA with Bonferroni correction as appropriate. Nominal data was analyzed with chi-square. P<0.05 was considered statistically significant.

Results: The mean Â± SD infusion requirement of propofol decreased from 35.5 Â± 4.5 in group B to 33.4 Â± 5.4 Âµg/kg/min in group BF and further decreased significantly to 16.7 Â± 6.2 Âµg/kg/min (P<0.05) and 14.8 Â± 4.9 Âµg/kg/min (P<0.05) in group BC and BCF respectively (Figure 2). There were no statistically significant differences between BC and BCF groups. The mean sedation and reactivity scores were significantly higher in groups BC and BCF (P<0.05) as compared to groups B and BF (Figure 3).

Conclusion: Our study show that the dose requirement of propofol sedation reduces with intrathecal adjuvants. The reduction was significant with the addition of clonidine and clonidine â€“ fentanyl combination as opposed to bupivacaine alone or with fentanyl. There was no significant difference in propofol infusion requirement with the use of bupivacaine alone or with fentanyl.

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Abstract 5

Does Patient Perception of Pain Control Affects Patientâ€™S Satisfaction Across Various Units in a Tertiary Teaching Hospital?

Presenting Author: Artemus Flagg, M.D. Presenting Author’s City, State: - Baltimore, MD Co-Authors: Ashlea Barrett, project manager Service - Johns Hopkins University - Baltimore, MD Kanupria Kumar, M.D. - Johns Hopkins University - Baltimore, MD Shawn Sumida, M.D. - Johns Hopkins University - Baltimore, MD Marie Hanna, M.D. - Johns Hopkins University - Baltimore, MD

Introduction: Patientsâ€™ reports of satisfaction are receiving greater attention as a result of the rise in pay-for-performance and the public release of data from the Hospitals Consumer Assessments of Healthcare Providers and Systems (HCAHPS) survey. Some US News articles published in October 2009 highlight the facts that Patients surveyed give some of America's best hospitals a poor satisfaction scores. Among those surveys are questions on pain management during their hospitalization.

This article examines the relationship between patient's perception of pain control during their hospitalization and their overall satisfaction. It also examines the variable difference in pain control reports among different services and different floor units in the same hospital.

Methods: This project is exempt from the Johns Hopkins IRB. We used the hospital already existing HCAHPS survey for Patients discharged between January 1, 2008 and June 30, 2009(18 month). We analyze the two pain related questions in the survey, questions asking patients how well their pain was controlled and how often hospital staff did everything they could to help controlling their pain. We used t- tests to compare pain control measures to overall satisfaction by inpatient adult service line, surgical service line and surgical nursing unit line. We examined relationships between each pain control question and the proportion of patients who give their overall hospital experience high scores (9 or 10).

Result: A Chi-Squared analysis performed to determine if there was a significant difference in the results (% always) show significant difference by service line in both questions less than 0.05 (figure1). A correlation of r=0.7105 and r=0.6367 was found between the 2 pain questions and patientâ€™s satisfaction question especially with the question concerning staff doing everything to control patientâ€™s pain(Table 2)

Discussion: The results showed that patients are more likely to rate their overall experience high (9 or 10) if they perceive that their care providers did everything they could to help control the pain rather than the pain actually being well controlled.

When looking at the entire hospital and more specifically surgical patients, staff doing everything they could to help with pain was more strongly correlated to overall satisfaction than the actual pain being controlled (Table 2). For the entire hospital, the correlations were stronger when looking at the results by service line as compared to nursing unit, however when limiting the results to surgical patients the correlations are stronger by nursing unit (0.7105 by unit and 0.6484 by service line).

Correlations of actual pain control to overall satisfaction are moderate for the surgical patients (0.6367 by unit and 0.6091 by service line), but not very strong for the hospitalâ€™s aggregate results (0.4198 by unit and 0.5290 by service line).

Conclusion: Patient perception of pain control is directly related to patients overall satisfaction scores. These data will encourage different hospital units and especially surgical units to effectively address pain management and work in changing the culture towards better pain control.

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Abstract 6

Localization of the Superior Cervical Ganglion: Anatomical Landmarks to Facilitate its Targeted Blockade

Presenting Author: Siamak Rahman, M.D. Presenting Author’s City, State: - Los Angeles, CA Co-Authors: Jonathan J. Wisco, Ph.D. - 1David Geffen School of Medicine at UCLA - Los Angeles, CA M. Elena Stark, M.D., Ph.D. - 1David Geffen School of Medicine at UCLA - Los Angeles, CA

Background: Cerebral vasospasm is the leading cause of death and disability in patients with aneurysmal subarachnoid hemorrhage. Stellate ganglion block is one of the recommended treatments for cerebral vasospasm, but it is associated with potential complications of transient unilateral diaphragmatic paralysis, transient unilateral vocal cord paralysis and hoarseness of voice, brachial plexus block, intrathecal or intravascular injection, and pneumothorax. Superior cervical ganglion block is an alternative therapy, but the ganglion is difficult to locate.

Methods: We dissected the superior cervical ganglion in 60 embalmed (from 30 subjects) and six unembalmed (from three subjects) cadaveric specimens and localized its relationship to the common carotid artery bifurcation, greater horn of they hyoid bone, superior margin of the cricoid cartilage and surrounding fascias of the parapharyngeal space.

Results: Quantified for the first time, the superior cervical ganglion was consistently found between the carotid artery bifurcation and greater horn of the hyoid. More precisely, the ganglion was located, with 95% confidence, 1.09 â€“ 1.96 cm superior to, and 0.69 â€“ 1.92 cm inferior to the carotid artery bifurcation; and 1.01 â€“ 1.78 cm superior to, and 1.03 â€“ 1.91 cm inferior to the greater horn of the hyoid bone. Height, weight and gender (but not age or side) each predicted the distance of the superior cervical ganglion to the carotid artery bifurcation after controlling for other independent variables. Third, the alar fascia thickens and compartmentalizes the ganglion against the outside of the carotid sheath.

Conclusions: We recommend that ultrasound or CT guided injection of 2.5 cc or less anesthetic in the parapharyngeal space at the level of, or superior to the common carotid artery bifurcation will precisely target the superior cervical ganglion for blockade. If imaging is unavailable, the greater horn of the hyoid bone is also a reliable landmark to locate the superior cervical ganglion. We provide a chart to localize the inferior pole of the superior cervical ganglion relative to the carotid artery bifurcation, taking into account height, weight and gender.

Abstract 7

A Phase 2 Open-Label Functionality, Safety, and Efficacy Study of the Sufentanil NanoTabâ„¢ PCA System in Patients Following Elective Unilateral Knee Replacement Surgery

Presenting Author: David Griffin, M.D. Presenting Author’s City, State: - Vero Beach, FL Co-Authors: Roman Skowronski, M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. – Redwood City, CA Pamela Palmer M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. - Redwood City, CA

Methods: This multicenter, open-label study enrolled 30 patients (mean age 65.7; range 51-78) following elective unilateral knee replacement surgery. Nineteen patients (63.3%) were at least 65 years old. Patients self-administered 15 mcg doses of Sufentanil NanoTabs sublingually as needed using the handheld Sufentanil NanoTab PCA System with a minimal re-dosing interval of 20 minutes. The primary efficacy endpoint was device functionality assessed as the proportion of patients who successfully completed the study without any type of System failure.

Results: All enrolled patients (100%) completed the study without System failures or dosing errors of any kind, which included over 375 dispensed NanoTabs. Twenty-five patients (83.3%) reported the two highest scores on the 5-point Likert scale of overall patientâ€™s satisfaction with the System. All 30 enrolled patients indicated that they could handle the system easily and their user instructions were clear. All 30 enrolled patients indicated that the dosing tone was sufficiently loud and that the time required for dosing was just right. Twenty-seven patients (90%) indicated that the size and the shape of the dosing tip was just right. The majority of patients indicated that the other system features (weight, size, shape, and dose button function) were acceptable. The mean pain intensity difference (PID) scores increased from 0.3 at 15 minutes to 2.4 at 3 hours. After 3 hours, the mean PID were variable and ranged from 1.3 to 2.0. Nineteen (63.3%) and 24 patients (80%) responded very good or excellent on the patient global evaluation of pain relief and global evaluation of tolerability, respectively. The most common related adverse events (AEs) were vomiting (6 patients, 20.0%) and nausea (5 patients, 16.7%). All events were mild or moderate in severity; no severe AEs were reported during the study. There were no serious AEs (SAEs) during the study drug treatment or 12-hours after the end-of-treatment. One patient discontinued study drug due to an AE of moderate anxiety that was judged as not related to study drug. There were no reports of oral mucosa irritation.

Conclusions: The results of this Phase 2 study confirm the functionality, safety and efficacy of the Sufentanil NanoTab PCA System in management of acute moderate-to-severe post-operative pain following knee replacement surgery. Future Phase 3 studies of the Sufentanil NanoTab PCA System will further delineate the safety and efficacy of this PCSA system.

Abstract 8

A Phase 2 Multicenter, Randomized, Placebo-Controlled Study to Evaluate the Clinical Efficacy, Safety, and Tolerability of Sublingual Sufentanil NanoTabâ„¢ in Patients Following Elective Unilateral Knee Replacement Surgery

Presenting Author: Harold Minkowitz, M.D. Presenting Author’s City, State: - Houston, TX Co-Authors: Roman Skowronski, M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. – Redwood City, CA Pamela Palmer, M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. - Redwood City, CA

Introduction: Intravenous patient-controlled analgesia (IV PCA) with morphine is the standard of care in many hospitals for the management of acute post-operative pain. However, IV PCA is associated with several limitations, including, the risk of PCA pump programming errors, reduced patient mobility secondary to the requisite IV line, and increased risk of analgesic gaps due to infiltrated and dislodged IV catheters or pump malfunction. Furthermore, while morphine is the most commonly used analgesic in this treatment modality, it can produce many undesirable side effects due to accumulation of active metabolites, especially in elderly and renally impaired patients. The Sufentanil NanoTab PCA System is a novel patient-controlled sublingual analgesia (PCSA) product candidate with a pre-programmed patient lock-out feature that is designed for use in hospital settings to provide effective, titratable, patient- controlled analgesia and reduce the risk of programming errors. The Sufentanil NanoTab PCA System also avoids the IV-related limitations of IV PCA by being designed to provide convenient and safe patient self-administration of Sufentanil NanoTabs sublingually for oral transmucosal absorption. The active drug, sufentanil, is a high therapeutic index opioid approved for intravenous and epidural administration. Although the analgesic efficacy of sufentanil has been well established, its use has been limited due to its short IV plasma half-time. In the NanoTab oral transmucosal dosage form, sufentanil demonstrates a therapeutically appropriate pharmacokinetic profile for post-operative PCA usage and has the potential for improved patient tolerability over IV PCA morphine. The primary objective of this study was to evaluate the efficacy, safety and tolerability of Sublingual Sufentanil NanoTabs in patients following knee replacement surgery.

Methods: A total of 101 patients following elective unilateral knee replacement were randomized to receive placebo, 5 mcg, 10 mcg or 15 mcg doses of Sufentanil NanoTabs for post-operative pain after stabilization of pain levels in the post-operative care unit. Study drug was nurse administered sublingually as needed to treat pain at the patient's request, with a minimum re-dosing interval of 20 minutes. Patients were allowed to drop out of the study at any time. The primary efficacy endpoint was Sum of the Pain Intensity Difference SPID-12 (a cumulative measure of the difference in pain intensity over the 12- hour study compared to baseline).

Results: Only the patients receiving 15 mcg Sufentanil NanoTabs experienced a significant reduction in pain intensity compared to placebo for the primary endpoint SPID-12 using the three alternative imputation Methods (last-LOCF, p=0.018, baseline-BOCF, p=0.007, and worst-WOCF, p=0.015 observation carried forward). Furthermore, the only the 15 mcg dose met a key secondary endpoint, lower percentage of patient dropouts due to inadequate analgesia compared to placebo (p=0.006). No significant differences were observed among treatment groups for the overall incidence of adverse events with mild to moderate nausea and vomiting being the most common. There were no serious adverse events related to study drug.

Conclusions: This Phase 2 study demonstrates analgesic efficacy, safety and tolerability of the Sublingual Sufentanil NanoTab in management of acute moderate-to-severe post-operative pain following knee replacement surgery. Future Phase 3 studies of the Sufentanil NanoTab PCA System will further delineate the safety and efficacy of this PCSA system.

Abstract 9

Presenting Author: Neil Singla, M.D. Presenting Author’s City, State: - Pasadena, CA Co-Authors: Roman Skowronski, M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. – Redwood City, CA Pamela Palmer, M.D., Ph.D. - AcelRx Pharmaceuticals, Inc. - Redwood City, CA

Methods: A total of 88 patients following major lower and upper abdominal surgery were randomized to receive placebo, 10 mcg or 15 mcg doses of Sufentanil NanoTabs for post-operative pain after stabilization of pain levels in the post-operative care unit. Study drug was nurse administered sublingually as needed to treat pain at the patient's request, with a minimum re-dosing interval of 20 minutes. Patients were allowed to drop out of the study at any time. The primary efficacy endpoint was Sum of the Pain Intensity Difference SPID-12 (a cumulative measure of the difference in pain intensity over the 12- hour study compared to baseline).

Results: Patients receiving 10 mcg or 15 mcg of Sufentanil NanoTabs experienced a significant reduction in pain intensity compared to placebo for the primary endpoint SPID-12 using the three alternative imputation methods (last-LOCF, p<0.001 (10 and 15 mcg), baseline-BOCF, p=0.004 (10 mcg) and p<0.001 (15 mcg), and worst-WOCF, p<0.001 (10 and 15 mcg) observation carried forward). Furthermore, both the 10 mcg and 15 mcg dose met a key secondary endpoint, lower percentage of patient dropouts due to inadequate analgesia compared to placebo (p<0.001). There were no significant differences among treatment groups for the overall incidence of adverse events, or any specific adverse event with the exception of pruritus, which was more frequent in 15 mcg group than in the other groups. There were no serious adverse events related to study drug.

Conclusions: This Phase 2 study demonstrates analgesic efficacy, safety and tolerability of the Sublingual Sufentanil NanoTab in management of acute moderate-to-severe post-operative pain following major abdominal surgery. Future Phase 3 studies of the Sufentanil NanoTab PCA System will further delineate the safety and efficacy of this PCSA system.

Abstract 10

Comparison of Chronaxie and Rheobase Values in Awake and Anesthetized Patients

Presenting Author: Ban C H Tsui MSc M.D. FRCPC Presenting Author’s City, State: - Edmonton, Alberta Co-Authors: Pratamaporn Chanthong M.D. - University of Alberta - Edmonton, Alberta Tariq Al-Zahrani MBBS - University of Alberta - Edmonton, Alberta Jason Lee M.D. - University of Alberta - Edmonton, Alberta Adam Dryden BSc - University of Alberta - Edmonton, Alberta

Introduction: A century ago Weiss (1) mathematically described electrical stimulation of peripheral nerves using the concepts of rheobase (Ir) and chronaxie (C), which have traditionally been plotted using the strength-duration curve (Fig 1). (2) Nerve blocks to facilitate post-operative analgesia are performed on both conscious and anesthetized patients, and while several factors alter chronaxie and rheobase values (3)(4), little is known about whether there are effects from general anesthesia. Our objective was to directly compare chronaxie and rheobase values in awake and anesthetized patients using a novel experimental model.

Methods: With Ethics Board approval (University of Alberta, Edmonton) and informed consent, those adult patients undergoing elective surgery under general anesthesia were prospectively enrolled. Patients with known anatomical variations or tissue disease of the wrist were excluded. Prior to surgery, 2 standard ECG electrodes were attached â€“ the negative to the medial side of the wrist, the positive to the forearm along the course of the ulnar nerve. With a nerve stimulator (Multistim Switch, Pajunk, Germany) set at an initial pulse width of 0.1 ms, the current (mA) was gradually increased until finger movement was seen (5). This threshold mA was recorded and the procedure was repeated with pulse widths of 0.2, 0.3, 0.5 and 1 ms. Within 10 min of induction of general anesthesia, the above procedure was repeated. From linear regression analysis of the results in both the awake and anesthetized states, the chronaxie (C=b/a) and rheobase (Ir=b) values were calculated and the goodness-of-fit (r squared values) of the values to the equation Q = I(t) = Ir(t + C) was determined (Figs 1 & 2). Chronaxie and rheobase values before and after induction of general anaesthesia were compared using two-tailed, paired Studentâ€™s t-tests. P < 0.05 was considered significant. Data is presented as mean Â± standard deviation.

Results: Data were obtained from 30 patients with no exclusions or withdrawals. Linear regression analysis resulted in average r squared values of 0.986Â±0.023 and 0.985Â±0.025, for awake and anesthetized patients respectively. The chronaxie values pre and post anaesthesia were similar at 0.32Â±0.17 and 0.29Â±0.13 ms, respectively (P=0.20; Fig 3), but the rheobase increased from 0.91Â±0.37 to 1.11Â±0.53 mA (P=0.02; Fig 3).

Conclusion: In this study, the minimum current required to depolarize a nerve (i.e. rheobase) was higher while the patients were under general anesthesia than when awake. While more study is warranted, the commonly relied upon threshold current range of 0.3 - 0.5mA for confirming nerve localization may not reliably safeguard against intraneural needle placement in anesthetized patients.

References: 1) Pacing Clin Electrophysiol 1980; 3: 292-301. 2) J Neurosci Methods 2000; 97: 45-50. 3) Trans Biomed Eng 2004; 51: 176-81. 4) J Physiol 1907; 9: 620-35. 5) Anesthesiology 2004; 100: 1526- 30.

Abstract 11

Determination of the Dynamic Compliance of the Intraneural Space During Intraneural Injection

Presenting Author: Robert M. Raw, M.D. Presenting Author’s City, State: - Iowa City, Iowa Co-Authors: Achir Alalami, M.D. - Univ Iowa - Iowa City, Iowa Chehade Jules-Marie, M.D. - Univ Iowa - Iowa City, Iowa Anderson Corey, M.D. - Univ Iowa - Iowa City, Iowa Boateng Major, M.D. - Uiniv Iowa - Iowa City, Iowa

Background and Objectives: Nerve injury from nerve blocks have previously been attributed to intraneural injection. Studies suggest intraneural injection is common. This study investigates the resistance nerves offer to intraneural injection compared to other tissues and expressed as the dynamic compliance. The stiffness of a container is the ratio of pressure within to the volume of fluid in the container. Compliance is the reciprocal of stiffness. Dynamic compliance is defined in the study.

Pressure measured DURING injection depends on (i) the injection flow rate, (ii) the elasticity of the tissues, (iii) the ability of fluid to dissipate by flow via fascial bound channels or by passage through porous barriers. Tissue ability to dissipate fluid and the rate of injection have opposite influences on pressure. If the flow rate is constant the pressure measured will proportionately reflect the ability of the tissue to dissipate the injected fluids.

DYNAMIC COMPLICANCE (DC) is the tissue ability to dissipate injected fluids. DC is the reciprocal of the ratio of pressure in mmHg to the flow of 5 ml/minute. The pressure is measured 30 seconds after initiation of injection.

Methods: To avoid inserting a second needle into a nerve during injection, injection-line pressure was measured at the proximal end of the needle via a three way stopcock. Fluid injected was 5% Dextrose water. Tissue pressure •is calculated as the increase in pressure observed above the pressure measured during injection into air. This eliminates the influence of the needle's resistance to flow. Anesthetized 30 kg great white pigs were used. Skin, fat and 1 cm of bicep femoris muscle was dissected off leaving the study sciatic nerve under 2 cm of muscle and in a natural physiological anatomical state. Arrow 90mm Stimuquick needles were used. The DC was determined for subcutaneous fat, muscle and intraneural. Ultrasound imaging was used to place the needle intraneural. A needle was considered to be intraneural when it looked and felt intra-neural to the same one researcher inserting the needle. A typical pattern of nerve movement could be seen and felt as the epineurium was penetrated. Minimum stimulating current was also measured at the final position. The ultrasound transducer was removed before injections started.

Results: The average pressure was 90 mmHg injecting into air (n= 4, range 94-83), 223 mmHg (n= 9 range = 350-103) into subcutaneous fat, 273 mmHg (n= 13 range = 352-119) into muscle, and 170 mmHg (n = 22 range = 358 to 95)into nerves. Data inspection suggests there are two subgroups of intraneural injection, one with an average pressure of 134 mm Hg (n=18, range 119-179) and one with an average of 327 (n= 4, range 243-358). The ranges are widely separated. The dynamic compliance were as follows subcutaneous fat = 0.037, muscle = 0.027, nerves over all = 0.062, low pressure intraneural subgroup = 0.112 and high pressure intraneural subgroup = 0.021

Conclusion: Overall intraneural injection reveals a higher dynamic compliance than muscle and subcutaneous fat. It is easier to inject into nerves than into muscle. The intraneural space as studied seems to have one high dynamic compliance space and a different less dynamic compliance space.

Abstract 12

Supraclavicular vs. Interscalene Brachial Plexus Block for Shoulder Surgery

Presenting Author: Christopher A. DiMeo, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Andrew Cameron, M.B., Ch.B. - Hospital for Special Surgery - New York , NY Christopher Cook, D.O. - Hospital for Special Surgery - New York , NY Victor Zayas, M.D. - Hospital for Special Surgery - New York , NY Dorothy Marcello, B.A. - Hospital for Special Surgery - New York , NY

Background: Despite its well documented constellation of side effects (hemidiaphragmatic paresis, Hornerâ€™s syndrome and hoarsenes), interscalene block (ISB) is considered the regional anesthetic of choice for surgery of the shoulder. This study compared the efficacy and side effect profile of an alternative technique, ultrasound guided supraclavicular block (SCB), with ultrasound guided interscalene block (ISB) for ambulatory arthroscopic shoulder procedures, focusing on comparative efficacy and side effect profiles.

Methods: In this double blinded, randomized controlled trial, patients were randomized to receive either ultrasound guided SCB or ultrasound guided ISB for outpatient arthroscopic shoulder surgery. Prior to block placement, patients underwent ultrasound imaging of the hemidiaphragm on the surgical side, digital photography of the pupils and digital voice recordings. After block placement, the aforementioned tests were repeated for later comparison by a blinded third party. In addition, intraoperative block efficacy was recorded.

Results: Both ultrasound guided SCB and ISB provided complete anesthesia 100% of the time without the need for supplementation or conversion to general anesthesia. Mean time to perform ultrasound guided ISB was 5.35 minutes, versus 4.95 minutes for ultrasound guided SCB. The difference in mean time to perform either block was not statistically significant. 21.9% of patients randomized to receive ultrasound guided SCB developed partial or complete Horner's syndrome (miosis and/or ptosis), versus 32% of patients randomized to receive ultrasound guided ISB. Ultrasound images of hemidiaphragmatic movement revealed paradoxical hemidiaphragmatic movement in 76% of ISB patients versus 40.6% of SCB patients. Finally, 56% of ISB patients demonstrated hoarseness, versus 46.7% of SCB patients.

Discussion: Ultrasound guided supraclavicular block is an equally efficacious anesthetic technique for arthroscopic shoulder surgery when compared to ultrasound guided interscalene block. Furthermore, ultrasound guided SCB is associated with a reduction in the rate of hemidiaphragmatic paresis. It is also worth noting that because ultrasound guided SCB is performed in a more caudad position along the course of the brachial plexus, it eliminates the possibility of neuraxial and/or phrenic nerve complications (such as spinal/epidural/subdural anesthesia and persistent phrenic nerve paresis) that have been described in association with interscalene block. Therefore, in light of its equivalent efficacy, reduced side effect profile (hemidiaphragmatic paresis) and diminished potential for catastrophic complications, the authors of this study believe that ultrasound guided SCB should be considered the anesthetic technique of choice for surgery of the shoulder.

Abstract 13

Functional Outcome Following Total Knee Replacement: A Comparison of Continous Femoral Nerve and Opioid Analgesia in the Perioperative Period

Presenting Author: Johnny Lee, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Mark C. Kendall, M.D. - Northwestern University, Feinberg School of Medici – Chicago, Illinois Antoun Nader, M.D. - Northwestern University, Feinberg School of Medici - Chicago, Illinois Robert J. McCarthy, Phar.M.D. - Northwestern University, Feinberg School of Medici - Chicago, Illinois

Introduction: Patients who have undergone a total knee replacement (TKR) frequently experience intense postoperative pain which may delay physical therapy and hospital discharge. We previously reported that continuous femoral catheter analgesia improved range of motion, decreased postoperative pain, and increased completion of physical therapy in the first 72 hr following surgery.1 We now report one year follow-up evaluating functional outcome between patients that received continuous femoral nerve block and those who received oral analgesics at 1 month, 6 months and 1 year following TKR.

Methods: Following IRB approval, written informed consent was obtained by adult patients (>18 y/o) undergoing elective TKR performed by a single orthopedic surgeon. Subjects were randomized into Group 1 (epidural followed by oral analgesia) or Group 2 (epidural followed by continuous femoral analgesia). Epidural anesthesia was discontinued morning of POD1. Femoral nerve catheters were placed preoperatively and analgesia was initiated the morning following surgery with ropivacaine 0.25% 10-15 ml and maintained with 0.1% ropivacaine 5mL/hr. Femoral nerve catheters were removed on POD 2. All patients received oral analgesia as needed. Patients were started on a standardized physical therapy regimen beginning on POD1 after femoral nerve catheter activation. Patients were discharged 72h after surgery and were scheduled to have a follow-up visit with their orthopedic surgeon at 1 month, 6 month and 1 year following surgery. Range of motion and verbal pain scores were compared between groups using the Mann-Whitney U-test.

Results: Sixty-two (43 F/19 M) subjects were studied. Leg extension was increased from preoperative values at all testing intervals, and range of motion increased by the 6th month of follow-up. Thirty-four percent of subjects reported moderate to severe pain persisting at 1 month, but only 1 subject at later intervals. There were no differences in outcomes between the groups.(Table)

Conclusions: Despite earlier ambulation and adherence with physical therapy rehabilitation, our study results are consistent with reports that continuous femoral nerve blocks does not affect the functional status of patients at 6 months or 1 year and does not lead to any differences in knee range of motion.2

References: 1.) ASA 2008; A1239 2.) J. Arthroplasty 2009; 24(2): 204-9.

Abstract 14

Diabetes Mellitus Does Not Increase the Electrical Current Threshold to Elicit Motor Response during Interscalene and Sciatic Nerve Block

Presenting Author: Ali N. Shariat, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Jenna M. Hobeika - St. Luke's Roosevelt Hospital Center - New York, NY Alen A. Hadzic - St. Luke's Roosevelt Hospital Center - New York, NY Catherine F.M. Vandepitte, M.D. - St. Luke's Roosevelt Hospital Center - New York, NY Jeff G. Gadsden, M.D. - St. Luke's Roosevelt Hospital Center - New York, NY

Introduction: During electrical nerve localization, a motor evoked response (MER) with current of 0.2-0.5 mA (0.1 msec) is suggested for successful nerve block.1 Several recent studies and case reports suggested that higher current intensity may be required to elicit an MER in patients with diabetes mellitus (DM) as compared to healthy patients. 2,3 The available studies and case reports on this subject, however, involved only a small number of patients and thus this notion remains largely anecdotal. In this study we compared the minimal current intensity required to elicit MER in a large series of patients with and without DM.

Methods: Following IRB approval, 362 anesthetic records of patients having nerve stimulator-guided sciatic or interscalene block (January, 2001- June, 2006) were reviewed. An equal number of patient records with DM, and age and sex-matched non-diabetic counterparts were randomly selected from our computerized anesthesia record-keeping data base. The demographic, co-existing disease data as well as information on minimum current intensity (mA) to elicit MER, a standard required documentation in our practice, was extracted. Student t-test and multivariate regression analysis to control for potential confounding factors were used to analyze the data.

Results: The minimum current intensity for MER for sciatic block was 0.45±0.3 mA in non-diabetic and 0.48Â±0.3 mA patients with DM (NS). For the interscalene block, the minimum current intensity necessary for MER in the non-diabetic patients was 0.36±0.1 mA versus 0.41±0.3 mA (NS) in patients with DM, respectively. The multivariate regression model found no correlation between the presence of DM and current intensity required to elicit MER. (Table 1)

Discussion: In 362 patients interscalene and sciatic blocks no significant difference in current intensity (mA) was required to elicit MER between non-diabetic patients and patients with DM. Future studies using US needle-nerve distance monitoring are indicated to more accurately determine the needle-nerve relationship and the current threshold (mA) required to elicit MER during electro-localization of major peripheral nerves in patients with DM and other co-existing disease.

Table1. Comparisons of minimum current between diabetic and non-diabetic patients

References 1. Reg Anesth Pain Med 2001; 26: 478-83 2. Anesthesiology 2009; 110: 1235-43 3. Reg Anesth Pain Med 2003; 28: 479-8 4. Anesthesiology 2008; 109: 473-8

Additional File #1: Table1. Comparisons of minimum current between diabetic and non-diabetic patients Sciatic Block (N=156) Interscalene Block (N=206)

Non Diabetes P- Non Diabetes P-value Diabetes (n=51) value Diabetes (n=67) (n=105) (n=139) Age (yr) 46.0 ± 16.5 61.3 ± 12.2 <0.001 53.3 ± 15.0 63.1 ± 12.8 <0.001

BMI 27.4 ± 7.4 28.7 ± 8.1 0.32 28.3 ± 7.4 30.6 ± 10.0 0.11

Midazolam(mg) 4.2 ± 1.7 3.0 ± 1.1 <0.001 3.9 ± 1.7 3.5 ± 1.7 0.11

Gender 34/71 30/21 0.002 67/72 20/47 0.01 (Male/Female) Hypercholesterol/ 8/97 10/41 0.03 14/125 11/56 0.19 Hyperlipidemia (Yes/No) Hypertension 23/82 36/15 0.001 62/77 51/15 <0.001 (Yes/No) Mental Disease 3/98 2/47 0.66 14/124 4/63 0.43 (Yes/No) Neuropathy 0/105 3/48 0.03 1/137 1/66 0.55 (Yes/No) ┼ ┼ Minimum current 0.45 ± 0.32 0.48 ± 0.27 0.54 0.36 ± 0.07 0.41 ± 0.28 0.06 (mA) 0.95* 0.19*

┼ p-value: obtained from simple t-test. * p-value: obtained from Multivariate Regression Analysis with controlling the potential confounders – hypertension.

Abstract 15

Periopeartive Pulmonary Complications in Patients with Sleep Apnea After Lower Extremity Arthroplasty.

Presenting Author: Anna C. Westrick, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Yan Ma, Ph.D. - Hospital for Special Surgery, Weill Medical Colleg - New York, NY Ya-lin Chiu, Ph.D. - Weill Medical College of Cornell University - New York, NY Madhu Mazu, M.D., Ph.D. - Weill Medical College of Cornell University - New York, NY Stavros Memtsoudis, M.D., Ph.D. - Hospital for Special Surgery, Weill Medical Colleg – New York, NY

Background: Although patients with sleep apnea (SA) are considered to be at increased risk for postoperative complications and guidelines for safe management of individuals suffering from the disease have been published (1), evidence supporting increased risk of perioperative morbidity among this patient population is limited. Conclusions are largely derived from a small number of single institutional analyses of relatively limited sample sizes (2,3). Therefore we sought to study perioperative demographics and outcomes of patients with SA after lower extremity arthroplasty, utilizing data collected for the National Inpatient Sample, the largest all-payer database in the United States.

Methods: National Inpatient Sample data for each year between 1998 and 2007 were accessed. Entries for lower extremity joint arthroplasty were included in the sample. Discharges with a diagnosis code for sleep apnea were identified. Demographics were analyzed for patients with and without SA. Pulmonary embolism, respiratory insufficiency after trauma or surgery/Adult Respiratory Distress Syndrome (ARDS), aspiration pneumonia and the need for respiratory intubation and mechanical ventilation were the primary outcomes. Logistic regression models were fitted to elucidate if SA was associated with independently increased odds for the four outcome measures while controlling for age, gender, race, admission type (elective, emergent), overall comorbidity burden and the presence of obesity.

Results: We identified a total of 2,610,441 entries for lower extremity arthroplasties between 1998 and 2007 in the NIS, representing a national estimate of 12,760,565 procedures performed in this time frame in the US. Of those 65,761 (weighted estimate 320,101) (2.52%)), carried a diagnosis of SA. The coding for SA increased steadily over time reaching a prevalence of 5.5% in 2007. Patients with SA tended to be younger, more frequently male and carry a higher average comorbidity burden compared to non-SA individuals. Obesity was approximately 5-times more prevalent among SA patients (6% versus 30.1% (P<0.001)).

Aspiration pneumonias, pulmonary embolism, ARDS and intubation with mechanical ventilation were more frequent in the SA compared to the non-SA group. The adjusted odds for these events attributable to SA were OR 1.32(CI 1.20;1.45), OR 1.32(CI 1.14;1.53), OR 2.47(CI 2.24,2.72), and 5.36 (CI 5.08;5.66), respectively (P<0.001).

Interestingly, obesity was not a risk factor for ARDS and intubation and was associated with lower odds for aspiration pneumonias and the same odds for pulmonary embolism compared to SA.

Conclusion: SA represents an independent risk factor for perioperative pulmonary complications following lower extremity arthroplasty. The risk for adverse events remains increased even when adjusting for obesity. Our results therefore provide further proof that special attention needs to be paid when caring for patients with SA. Further research is warranted to identify interventions that will allow for the decrease of complications in this patient population.

References:

1) Gross JB, et al. Anesthesiology 2006;104:1081-93.

2) Gupta RM, et al. Mayo Clin Proc 2001;76: 897-905.

3) Liao P, et al. Can J Anaesth. 2009 Nov;56(11):819-28.

Abstract 16

Safety Associated with the Removal of Paravertebral Catheters in Trauma Patients Receiving Enoxaparin for Thromboprophylaxis

Presenting Author: Brian T Gierl, M.D. Presenting Author’s City, State: - Pittsburgh, Pennsylvania Co-Authors: Andrea Fanelli, M.D. - University of Pittsburgh Medical Center - Pittsburgh, Pennsylvania Jennifer Horne, B.S. - University of Pittsburgh Medical Center - Pittsburgh, Pennsylvania Louis Alarcon, M.D., F.A.C.S. - University of Pittsburgh Medical Center - Pittsburgh, Pennsylvania Jacques E. Chelly, M.D., Ph.D., M.B.A. - University of Pittsburgh Medical Center - Pittsburgh, Pennsylvania

Abstract Body: It is established that trauma patients are at a very high risk of developing deep venous thrombosis, that pulmonary embolism is the third-leading cause of death in those who survive beyond the first day after trauma(1) and that the prevention of these complications is based on the use of an effective thromboprophylaxis especially enoxaparin 30 mg SC BID.(2) However, the most recent ASRA guidelines based on theoretical considerations recommend interrupting the administration of enoxaparin for the removal of a â€œdeepâ€ perineural catheter.(3) This study was designed to assess the safety of removing paravertebral catheter in patients with multiple rib fractures receiving enoxaparin without interruption.

Methods: The acute interventional perioperative pain IRB approved database was searched for patients with rib fractures who benefited from continuous paravertebral blocks while receiving enoxaparin 30 mg BID between July 1 2008 to July 31 2009. The time of initiation of therapy and its duration were recorded along with any bleeding and/or hematoma associated with the removal of the catheter. In these patients, either one or two paravertebral block catheters (PBCs) (â‰¤4 or >4 ribs fractured on the same side, respectively) were placed after review of the chest radiograph. After positioning of the patients either sitting or in the lateral position, the appropriate thoracic level for the placement of PBC was determined. The spinous processes were identified and the site of Introduction of the needle was marked 2.5 cm lateral to the midline. An 18 G Tuohy needle was introduced in search of the transverse process. The needle was redirected and positioned 1 cm beyond the inferior border of the transverse process. Next, 5 ml of ropivacaine 0.5% was injected through the needle and the PBC threaded 4 cm beyond the tip of the needle. The PBC was secured with a steri-strip and an additional 10 ml of ropivacaine 0.5% was injected through the catheter. Finally, the catheter was covered with a transparent dressing.

Results: Between July 2008 and July 2009, AIPPS was consulted for 236 time for the management of pain caused by rib fractures. AIPPS placed 216 continuous PBCs in 156 patients for 757 catheter-days including 136 PBCs placed in 95 patients who received enoxaparin 30 mg SC BID. The PBCs remained in place for 4.9 Â± 2.5 days range (1 â€“ 11). Following the removal of the PBCs without dosing interruption no major bleeding and/or hematoma were recorded. One patient had insignificant serosanguinous oozing and another developed a local cellulitis.

Discussion: These data support the concept that it is not necessary to withhold enoxaparin thromboprophylaxis prior to the removal of a â€œdeepâ€ perineural catheter. This is also supported by our recent report on 3,588 orthopedic patients who received various types of thromboprophylaxis, including 916 patients who were receiving LMWH without dosing interruption while either a lumbar plexus or a sciatic catheter was being removed.(4)

References 1. Geerts WH et al. N Engl J Med. 1994; 331:1601â€“1606. 2. Geerts WH et al. Chest 2008; 133; 381-453. 3. Horlocker TT et al. Reg Anesth Pain Med. 2010;35(1):64-101. 4. Chelly JE, Schilling D. J Arthroplasty 2008; 23: 350-354.

Abstract 17

Transient Thermal Hyperalgesia after Resolution of Ropivacaine Sciatic Nerve Block in Rat

Presenting Author: Lavinia M. Kolarczyk, M.D. Presenting Author’s City, State: - Pittsburgh, Pennsylvania Co-Authors: Brian A. Williams, M.D., M.B.A. - University of Pittsburgh - Pittsburgh, Pennsylvania Allison E. Garda, (student) - University of Pittsburgh - Pittsburgh, Pennsylvania Gerald F. Gebhart, Ph.D. - University of Pittsburgh - Pittsburgh, Pennsylvania

Introduction: When the local anesthetic effects of a peripheral nerve block resolve, patients can develop significant â€œrebound pain. Mechanisms for the development of rebound pain remain unknown, but it has been observed that the longer the duration of peripheral nerve block, the less incidence of rebound pain (1). In order to understand this phenomenon, we studied the effect of ropivacaine on thermal and tactile sensitivity after rat sciatic nerve block resolves, in vivo.

Methods: The left sciatic nerves in male Sprague-Dawley rats were exposed surgically, and no surgical insults applied to the hindpaw or distal lower extremity. Treatment groups received a 200 mcL perineural subfascial injection of: (i) ropivacaine (0.5%, n=14), (ii) ropivacaine (0.5%) with clonidine (0.5 mcg/kg) and buprenorphine (2 mcg/kg; n=15, R-C-B), (iii) ropivacaine (0.5%) with clonidine, buprenorphine, and dexamethasone (20 mcg/kg; n=13, R-C-B-D), (iv) or saline vehicle (n=11). Nociceptive testing using tactile (von Frey filaments) and thermal (hindpaw withdrawal from heat stimulus) stimuli was performed at 1, 3, 5, and 7 hrs after injection. Tactile and thermal nociceptive testing was repeated before euthanasia at 12-14 days after injection. All nociceptive data were non-parametric in distribution; Friedman, Kruskal-Wallis, Wilcoxon Signed Ranks, and Mann Whitney U tests were employed. P<0.05 was considered to be statistically significant.

Results: All ropivacaine-treated rats were anesthetic to thermal and mechanical stimuli at 1 hr after injection (P<0.001 for each when compared to saline vehicle). Thermal response latencies in treatment groups receiving ropivacaine (median response latencies 4.9 â€“ 6.5 sec) were significantly hyperalgesic 3 hr after injection when compared to saline vehicle (median 8.3 sec, P=0.019). Withdrawal responses to tactile stimuli after ropivacaine treatment did not show hyperalgesic responses at any time after nerve block resolution. All responses to thermal and tactile stimuli returned to baseline by 7 hrs. There were no differences among treatment groups in thermal or tactile nociceptive responses at 12-14 days.

Discussion: Ropivacaine sciatic nerve blocks in rat led initially to thermal and tactile anesthesia, followed by transient rebound thermal hyperalgesia. The addition of clonidine, buprenorphine, and dexamethasone did not attenuate thermal hyperalgesia. While the role of sensory nerve fiber type in response to local anesthetics has been studied (2), it is not fully understood. Our findings appear to be the first report of thermal hyperalgesia after ropivacaine local anesthetic nerve block resolves; fiber specificity cannot be determined from this study. Whether local anesthetics other than ropivacaine produce similar transient rebound thermal hyperalgesia (or distinct transient allodynia) upon nerve block resolution requires further study. Other injectable preservative-free perineural additives (e.g., dexmedetomidine, tramadol, minocycline, ziconotide) should be tested to evaluate whether rebound thermal hyperalgesia (induced by ropivacaine) can be attenuated.

References: (1) Williams BA et al., Reg Anesth Pain Med 2007; 32:186-92 (2) Gokin AP et al., Anesthesiology 2001; 95:1441-54

Abstract 18

Effect of Type of Anesthesia on Hospital Cost and Long Term Mortality After Hip Fracture Repair in Elderly Patients

Presenting Author: James Heyman, M.D. Presenting Author’s City, State: - Gainesville, Florida Co-Authors: Linda Le-Wendling, M.D. - University of Florida College of Medicine – Gainesville, FL Azra Bihorac, M.D. - University of Florida College of Medicine - Gainesville, FL Andre Boezaart, M.D., Ph.D. - University of Florida College of Medicine - Gainesville, FL Stephen Lucas, M.D. - University of Florida College of Medicine - Gainesville, FL

Introduction: Hip fractures are a significant cause of morbidity and mortality in the elderly with 20% mortality in the first year and significant disability and complications. While some studies have shown a reduction in short term mortality and morbidity when a neuraxial technique is used as the sole anesthetic, a Cochrane review showed only a difference in immediate post-operative neurocognitive function. Data on long term mortality is minimal and is inconclusive with regards to the benefits of regional anesthesia.

Objective: We studied the effect of use of regional anesthesia (RA) versus general anesthesia (GA) on hospital cost and long term mortality and morbidity after hip fracture repair in elderly patients.

Methods: This is retrospective cohort study of 314 elderly patients (age 65 years or greater) who underwent operative treatment (percutaneous pinning, open reduction internal fixation, or bipolar hip arthroplasty) for low-impact hip fracture at the University of Florida between 2006 and 2008. These patients either underwent RA (spinal anesthetic with conscious sedation) versus GA (inhalational or intravenous anesthetic) for their intraoperative anesthetic. Patient survival was determined through a search of the National Social Security Death Index. Survival differences between anesthesia groups were analyzed using the covariates-adjusted log-rank tests. Long-term survival was analyzed with a risk- adjusted Cox proportional hazards regression model.

Results: Patients who underwent regional anesthesia (n=73) were older, more likely to receive regional analgesia and were less likely to require intensive care unit (ICU) hospitalization and mechanical ventilation. The median cost for hospitalization was on average $1200 less for RA than for GA but the difference was not statistically significant. In-hospital mortality for both groups was similarly low (4% for GA and 3% for RA). However, survival rates decreased dramatically at comparable rates in both groups following discharge: at two years, survival rate was 63% for GA patients and 58% for RA patients while at 3 years, it further dropped to 54% for GA patients and 56% for RA patients (Figure 1). In the risk-adjusted model, long-term mortality was associated with an increase in age (adjusted hazard ratio (AHR) of 1.03 (95% confidence interval [CI], 1.00 to 1.06), an increase in the number of billed diagnoses (AHR 1.08, 95%CI 1.04-1.12) and chronic pulmonary disease (AHR 1.85, 95%CI 0.97-3.50 ) (p<0.001).

Conclusion: Use of regional anesthesia is associated with a small benefit in cost of hospitalization and no difference in hospital and long-term mortality up to 3 years after discharge. However, the survival rate after surgery drops dramatically from 97% at 6 months to 54% at the 3 years following hospital discharge.

Additional File #1: Figure 1. Long-term survival of patients after hip surgery (follow-up time range 0.03 to 42 months).

Additional File #2:

General anesthesia Regional anesthesia P (n=241) (n=73)

Age 81 (7) 83 (8) 0.008 Females (No, %) 171 (71%) 58 (79%) 0.17 Use of regional analgesia (No, %) 64 (27%) 64 (88%) <0.001 Cardiac condition on admission (No, %) 20 (8%) 9 (12%) 0.35 COPD (No, %) 15 (6%) 6 (8%) 0.59 Dementia (No, %) 17 (7%) 2 (3%) 0.26

Need for Mechanical ventilation (No, %) 18 (6%) 1 (1%) 0.08

Readmission (No, %) 48 (21%) 16 (23%) 0.74

Time elapsed to readmission (median, IQR) 3 (6, 17) 6 (8, 14) 0.81

Reason for readmission (No, %) 0.84 Wound/surgery related issues 15 (33%) 3 (19%) Pneumonia 8 (17%) 4 (25%) GI 7 (15%) 2 (13%) Cardiac 6 (13%) 3 (19%)

Pulmonary embolism 4 (9%) 0

Hospital length of stay, days 5 (4, 7) 5 (4, 7) 0.31 (median, IQR)

Patients requiring ICU (No, %) 20 (12%) 1 (1%) 0.16 Total Cost, $ (median, IQR) 15,770 ( 12,514, 14,537 (12,246, 0.27 20,682) 18,934)

Primary payer Medicare 234 (97%) 72 (99%) 0.68 Number of billed procedures (median, IQR) 1 (1, 2) 1 (1, 1) 0.14 Number of billed diagnoses (median, IQR) 8 (11, 15) 11 (8, 16) 0.71 Day of surgery (median, IQR) 1 (0, 2) 1 (0, 1) 0.19 In-hospital mortality (No, %) 9 (4%) 2 (3%) 0.76

Disposition at discharge 0.55

Home (n, %) 29 (12%) 6 (8%) In-patient rehabilitation (n, %) 48 (20%) 14 (19%) Nursing home (n, %) 131 (54%) 48 (66%) Adjusted cumulative survival* 0.233 6-months survival 79% 73%

12-months survival 75% 63%

24-months survival 63% 58% 36-months survival 54% 56% Incidence mortality rate (per 100 patients- 21 31 year)

Additional File #3: Table 2. Cox regression model for long-term mortality ((Model p<0.001).

Adjusted Hazard Ratio 95% Confidence Interval P Age (per year) 1.03 1.00-1.06 0.03 Gender (reference Male) 0.92 0.61-1.40 0.92 Type of anesthesia (reference general) 0.92 0.53-1.58 0.75 Use of regional analgesia (reference intravenous) 1.18 0.73-1.92 0.49 Cardiac condition on 1.02 admission (reference No) 0.55-1.91 0.94 Chronic pulmonary disease (reference No) 1.85 0.97-3.50 0.06 Dementia (reference No) 1.26 0.62-2.51 0.52 Need for Mechanical 0.51 ventilation (reference No) 0.19-1.34 0.17 Readmission (reference No) 1.39 0.91-2.15 0.13 Hospital length of stay (per day) 1.03 0.98-1.07 0.29 Primary payer (reference Medicare) 2.26 0.91-5.67 0.08 Number of billed diagnoses (per one) 1.08 1.04-1.12 <.0001 Disposition at discharge (reference Home) In-patient rehabilitation 0.88 0.96 Nursing home 0.98 0.42-1.85 0.73

Abstract 19

Incidence of Meningitis or Epidural Abscesses in Patients Undergoing Neuraxial Block for Removal of Infected Prosthesis in Hips and Knees

Presenting Author: Karina Gritsenko M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Dorothy Marcello BA - Hospital for Special Surgery - New York, NY Kethy Jules-Elysee M.D. - Hospital for Special Surgery - New York, NY Gregory A Liguori M.D. - Hospital for Special Surgery - New York, NY

Introduction: The presence of localized infection or systemic sepsis is considered by some to be a relative contraindication to spinal or epidural anesthesia. Fear of seeding the CNS with systemic bacteria is the primary rationale for this belief. No current data exists to determine if there is indeed a correlation between neuraxial anesthesia and the development of meningitis or epidural abscesses. We designed a retrospective chart review to assess the correlation between the development of CNS infections and performance of neuraxial anesthesia in patients presenting for removal of infected joint prosthesis.

Methods: Retrospective chart review on 708 medical records of patients admitted for removal of total hip and total knee prostheses over a 12 year period. Significant medical history (diabetes, prior MI, CRI, rheumatoid arthritis and hypertension), antibiotic use up to 6 months prior to admission, signs and symptoms of a pre-operative infection (i.e. fever defined as a temperature greater than 37.5Â° C, chills, hypotension defined as a systolic BP <100 mmHg), an elevated WBC count defined as greater than 10.7 cells per nano liter and the results of cultures taken during admission were documented.

Results: 242 patients were excluded from analysis when: lack of prosthesis removal (53/242); absence of neuraxial anesthesia (101/242); aseptic (78/242); transferred to another institution shortly after their surgery, making it impossible to determine if they developed meningitis or epidural abscesses (9/236). Ultimately, 466 patients were included. Mean age of patients was 65.7 years and mean length of hospital stay was 21 days. The profile of these patients is outline in Tables 1-3. Of note, 232 patients (49.8%) had joint pus expressed intraoperatively and 195 patients (41.8%) had positive Gram stains. 407 patients (87.3%) had positive joint cultures. We defined neuraxial infectious complications as the diagnosis of meningitis or epidural abscess in the inpatient postoperative period. No patients undergoing removal of total joint prostheses under neuraxial anesthesia developed a neuraxial infectious complication (95% CI 0.64%). Postoperative issues also documented included hematoma (1/466), back pain (2/466) and headaches (1/466).

Discussion: Our findings suggest that the incidence of CNS infections following neuraxial anesthesia in patients with infected hip and knee prostheses is exceedingly low, at least within 21 days of administration of neuraxial blockade. Also, preoperative use of antibiotics in 50.4% of the patients may have been protective. Potential limitations to our review include: patientsâ€™ verbal disclosure was often the only proof of antibiotic use; and the unavailability of the decision process by which the anesthesiologist chose GA over regional anesthesia, which may have presented a possible selection bias of our included patients.

References 1.Wedel and Horlocker. Regional Anesthesia in the Febrile or Infected Patient. Reg Anesth Pain Med 2006;31(4):324-333 2. Agarwal and Kishore. Complications and Controversies of Regional Anaesthesia: a review. Indian Journal of Anaesthesia 2009;53(5):545-553

Additional File #1:

Table 1: Profile of Patients upon admission

PATIENT PROFILE: UPON ADMISSION N % Fever 74 15.9

Chills 34 7.3

Hypotension (systolic BP <100 mmHg) 8 1.7 High WBC (>10.7 cells/nL) 92 19.7 Pre-admission antibiotic use 235 50.4

Additional File #2:

Table 2: Intraoperative Findings and Types of Anesthesia Administered

PATIENT PROFILE: INTRAOPERATIVE N %

Negative Gram Stain 75 16.1 Preadmission antibiotic use, negative gram stain 42 56.0 Positive Gram Stain 195 41.8 Joint pus 232 49.8

Type of Anesthesia

*CSE 302 64.8 Epidural 56 12.0 Spinal 87 18.7

GA combined with neuroaxial block 17 3.6 *CSE: combined spinal/epidural

Additional File #3: Table 3: Results of Joint Cultures

PATIENT PROFILE: POSTOPERATIVE N % Patients with negative joint cultures 51 10.9

Preop antibiotic use 43 84.3

15.7 No preop antibiotic use* 8 Patients with positive joint cultures 407 87.3 Preop antibiotic use 186 45.7 WBC on gram stain 171 42.0 Organism on gram stain 29 7.1 WBC and organism 37 9.1 Positive blood cultures 19 4.0 *WBC on gram stain verified infection

Abstract 20

Risk of Postoperative Hypoxemia in Ambulatory Orthopedic Surgery Patients with Diagnosis of Obstructive Sleep Apnea

Presenting Author: Spencer S. Liu, M.D. Presenting Author’s City, State: - New York, New York Co-Authors: Mary F. Chisholm, M.D. - Hospital for Special Surgery - New York, New York Raymond S. John, B.A. - Hospital for Special Surgery - New York, New York Justin Ngeow, B.A. - Hospital for Special Surgery - New York, New York Yan Ma, Ph.D. - Weill Medical College of Cornell University - New York, New York

Background and Objectives: It is unclear whether it is safe to discharge patients with a diagnosis of Obstructive Sleep Apnea (OSA) to home immediately after ambulatory surgical procedures. Practice guidelines are based on consensus, and there are minimal data on postoperative respiratory monitoring. Our OSA patients undergoing ambulatory-type orthopedic procedures are monitored overnight in the PACU, thus we reviewed patient records to determine incidence of complications.

Methods: Two hundred and six charts of patients with preoperative diagnosis of OSA based on ICD-9 codes were reviewed for outcomes including episodes of hypoxemia (defined as mild SpO2 <95% and severe <90%). Univariate analysis followed by logistic regression and propensity analysis was performed to determine independent risk factors for hypoxemia and association with adverse outcomes.

Results: The majority of patients had regional anesthesia (95%). Other selected perioperative characteristics are displayed in Table 1. Thirty four percent of patients had hypoxemia (31% mild and 3% severe) in the PACU. Initial risk factors for hypoxemia identified by univariate analysis were BMIâ‰¥35, increased age, history of COPD, upper extremity procedure, and use of peripheral nerve block. Independent risk factors identified by logistic regression were history of COPD (OR 3.64 with 95% CI 1.03-12.88) and upper extremity procedure (2.53, 1.36-4.68). Adverse events were infrequent. Only adjustment in oxygen flow was statistically associated with hypoxemia (37% with hypoxemia vs. 16%), which remained significant after adjustment for underlying risk factors with propensity analysis (OR 3.62, 1.79-7.35). Unplanned hospital admission after the required PACU stay was not increased by hypoxemia (11% vs 16%). Table 2 displays details of adverse events and reasons for hospital admission.

Conclusions: Patients with a diagnosis of OSA have a substantial postoperative incidence of hypoxemia after regional anesthesia for ambulatory orthopedic surgery. However, serious adverse outcomes were rare and not associated with hypoxemia, thus it appears to be reasonable to discharge these patients home after surgery.

Additional File #1: Table 1: Selected perioperative characteristics

Characteristic No hypoxemia Any hypoxemia Mild Severe (n=135) (n= 71) (SpO2 < 95%) (SpO2 < 90%) (n=64) (n=7) Age *(yrs, mean/SD) 55 ± 11 58 ± 12 58 ± 12 58 ± 14 Gender (M/F, %) 79%/21% 77%/23% 78%/22% 71%/29% BMI (mean/SD)* 32 ± 6 35 ± 7 34 ± 7 37 ± 8 ASA Class (1/2/3/4, %) 1/61/37/1 1/47/52/0 1/47/52/0 0/57/43/0 Past Medical History CPAP at home (%) 53% 54% 55% 43% COPD (%)* 3% 11% 13% 0% Physical exam Airway Class (%) 24/12/47/16/1 18/14/45/23/0 17/14/49/20/0 29/14/14/43/0 NA/1/2/3/4 Procedure* Knee arthroscopy (%) 25% 18% 17% 29% Knee ACL Repair (%) 3% 3% 3% 0% Hand/Forearm (%) 12% 20% 21% 14% Shoulder Scope (%) 33% 47% 50% 0% Foot/Ankle (%) 12% 7% 6% 14% Other upper extremity (%) 4% 4% 3% 14% Other lower extremity (%) 11% 1% 0% 14% Anesthesia* General only (%) 6% 4% 5% 0% General + regional (%) 3% 3% 3% 0% Regional 91 93% 92% 100% Postoperative Analgesia Oral Opioids (%) 85% 92% 92% 86% NSAIDs (%) 36% 39% 39% 43% IV Opioids (%) 24% 32% 36% 0% * = Identified as potential risk factor by univariate analysis. Upper extremity vs lower extremity. Regional vs General.

Additional File #2: Table 2: Adverse outcomes. * = Hypoxemia is significantly different (p<0.05) from No hypoxemia.

Outcome Percent of No Hypoxemia Mild Severe patients with hypoxemia (N=71) (SpO2<90%) (SpO2<95%) adverse (N=135) (N=64) (N=7) outcome (N=206) CPAP at home + 35 33 41 44 14 subsequent routine PACU use (%) Emergent CPAP (%) 0 0 0 0 0 Change in oxygen 23 16 37 33 71 delivery (%)* Incidence of postoperative 35 33 41 41 43 hypertension (%) Need treatment for 4 4 4 3 14 hypertension (%) Need for postoperative 15 16 11 9 29 hospital admission from PACU (%) Reasons for hospital admission Physical Therapy (%) 37 45 13 17 0 Intravenous antibiotics 10 9 13 0 50 (%) Pain Control (%) 13 14 13 17 0 Infectious Complication 23 18 38 33 50 (%) Radiation therapy (%) 4 0 13 17 0 Other (%) 13 14 13 17 0

Abstract 21

Postoperative Hemodynamic Instability after Simultaneous Bilateral Total Knee Arthroplasty

Presenting Author: Christopher M. Reidy, M.D. Presenting Author’s City, State: - Lebanon, NH Co-Authors: Michael L. Beach, M.D., Ph.D. - Dartmouth-Hitchcock Medical Center – Lebanon, NH John D. Gallagher, M.D. - Dartmouth-Hitchcock Medical Center - Lebanon, NH Brian D. Sites, M.D. - Dartmouth-Hitchcock Medical Center - Lebanon, NH

Background: Bilateral total knee arthroplasty (BTKA) is a commonly performed surgical procedure that has been associated with increased morbidity and mortality when compared to unilateral TKA (1). At our institution BTKA is performed simultaneously by two surgical teams during a single anesthetic. Our quality assurance program identified multiple cases of profound postoperative hypotension and bradycardia. We sought to characterize the incidence of postoperative hemodynamic instability after simultaneous BTKA and identify associated risk factors to better inform perioperative management.

Methods: This study involved a retrospective chart review of 312 consecutive patients undergoing simultaneous BTKA between 2007 and 2009 at Dartmouth-Hitchcock Medical Center. All BTKA procedures were performed under either spinal or general anesthesia, with bilateral femoral nerve blocks for postoperative analgesia. Information collected included demographics, comorbidities, anesthetic techniques, fluid administration, blood loss, and postoperative hemodynamic events. A clinically concerning hypotensive event in the postoperative period was defined as a systolic blood pressure of less than 85 mmHg and/or the need for vasoactive medications. Bradycardia was defined as a heart rate of less than 50.

Results: The incidence of hypotensive events in the post anesthesia care unit (PACU) was 17% (95% confidence interval (CI): 13-22%). 20% of all patients exhibited a greater than 40% reduction from preoperative baseline systolic blood pressure (95% CI: 15-24%). The incidence of bradycardia in the PACU was 19% (95% CI: 15-23%). The incidence of simultaneous hypotension and bradycardia was 7% (95% CI: 4-10%). 10% of the patients required emergent treatment with vasopressors or vagolytics (95% CI 7:-13%).

The performance of BTKA under spinal anesthesia was an independent risk factor (odds ratio = 4.45, p < .01) for the development of postoperative hypotension (21%) compared with general anesthesia (5.7%). Comparison of the patients who received spinal versus general anesthesia revealed no significant differences. Spinal anesthesia continued to predict hypotension even in multivariate modeling that controlled for patient age, BMI, comorbidities, and post-operative bleeding. The average volume of blood loss on postoperative day 0 was 1.8 +/- 0.9 liters.

Conclusion: Hypotension and bradycardia are common after simultaneous BTKA. Many cases of hypotension are severe and require emergent pharmacologic treatment. Performance of the operation under spinal anesthesia is a significant risk factor for the development of postoperative hypotension compared to general anesthesia. We hypothesize that this may result from the loss of a compensatory, sympathetic response to hypovolemia in the postoperative period in those patients receiving spinal anesthesia. Following the completion of this investigation, our institution has standardized an approach to BTKA that consists of general anesthesia, invasive blood pressure monitoring, standardized fluid replacement, and extended PACU monitoring.

Reference 1) Memtsoudis S, et al. Perioperative Outcomes after Unilateral and Bilateral Total Knee Arthroplasty. Anesthesiology. 2009;111:1206-16.

Additional File #1:

The effect of spinal anesthesia and other variables on the development of PACU hypotension by logistic regression modeling Odds Ratio 95% CI p-value Model A* Spinal anesthesia 4.45 (1.71 , 11.59) <0.01 Model B** Spinal anesthesia 4.92 (1.69 , 14.34) <0.01 Postoperative bleeding 1.40 (1.00,1.95) .047 Model C*** Spinal anesthesia 4.90 (1.65 , 14.62) <0.01 ASA I II 1.08 (0.19 , 6.21) .93 III 1.27 (0.19 , 8.61) .8 IV 1.00 (1.00 , 1.00) Age (years) 1.00 (0.96 , 1.04) .89 BMI 0.98 (0.92 , 1.03) .42 CAD 0.45 (0.08 , 2.42) .35 Hypertension 0.70 (0.33 , 1.51) .37 Volume infused in OR 0.87 (0.69 , 1.09) .21 Postoperative bleeding 1.35 (0.96,1.91) .087

*Model A (unadjusted) includes only anesthetic technique. **Model B (adjusted) incorporates postoperative bleeding. ***Model C (adjusted) adds patient demographics as well as volume infused in the operating room. PACU = post anesthesia care unit, CI = confidence interval, ASA = American Society of Anesthesiologist health classification, BMI = body mass index, CAD = coronary artery disease, OR = operating room.

Abstract 22

Non-IgE Mediated Reaction to Ester and Amide Local Anesthetics

Presenting Author: Bret M. Bahn, M.D. Presenting Author’s City, State: - Ann Arbor, Michigan Co-Authors: Alan Baptist, M.D., M.P.H. - University of Michigan - Ann Arbor, MI Chad M. Brummett, M.D. - University of Michigan - Ann Arbor, MI

Introduction: Despite being widely used drugs, allergic reactions to local anesthetics (LA) are rare. Less than 1% of all adverse reactions to local anesthetics are due to an allergic mechanism(1). Allergic reactions may be caused by delayed-type hypersensitivity reactions and also immediate type reactions(2). LA toxicity may cause convulsions, hypotension, bradycardia, and cardiac arrest resembling allergic reaction(2).

Case Report: A 44 year-old woman presented for evaluation of allergic reactions to a lidocaine/prilocaine with epinephrine mixture for two separate dental procedures. Reactions included tachycardia, hypertension(200/100), and tremors without dyspnea as documented at the dentistâ€™s office. The symptoms resolved without intervention and were followed by 2-3 days of fatigue.

Skin testing and intradermal testing were performed with preservative-free prilocaine resulting in no reaction. Approximately 3 minutes after subcutaneous injection of 0.5 ml of 4% prilocaine without epinephrine, the patient developed visible tremors and a splotchy rash with erythema over face and upper chest without hives. She became hypertensive (200/100) and tachycardic (105), with no dyspnea or angioedema. Her symptoms subsided after diphenhydramine and 45 minutes of rest.

She was seen again by the allergist and tested with preservative-free 1% procaine without epinepherine. Skin and intradermal testing were again negative. She was then given a blinded injection of 0.5 ml of normal saline, resulting in no reaction. After 10 minutes she was given a 0.5 ml challenge of procaine. Within 2 minutes of subcutaneous injection with procaine without epinephrine, she became flushed over her face and chest along with visible tremors and hypertensive(189/101). Symptoms resolved after 15 minutes and an oral dose of diphenhydramine. She denied any pruritis, dyspnea, or hives.

On her third visit with the allergist, skin and intradermal testing was not performed, as previous testing had yielded no reaction. The patient was blinded to the nature of the solutions given to her subcutaneously. First, 0.5 ml normal saline was injected and she was observed for 20 minutes with no reaction. Then, within the first few minutes after receiving 0.02 ml 0.5% bupivacaine without epinephrine, she began feeling her heart race and had visible tremors. Facial and upper chest flushing was again noted and patientâ€™s blood pressure was 207/99 with a heart rate of 145. Patient was given diphenhydramine 3 minutes into the this 12 minute reaction.

Discussion: Regional anesthesiologists are frequently faced with patients complaining of allergic reactions during dental procedures. Tachycardia due to epinephrine is commonly the culprit. Amide allergies are very rare. It is unlikely that these reactions are IgE mediated due to lack of hives, angioedema, hypotension, and respiratory complaints. Non-IgE mediated allergic reactions are also rare. LA toxicity is also unlikely with such a small dose of LA. The etiology and recommendations for future management are unclear.

(1) Stoelting, R.K. Pharmacology & Physiology in Anesthetic Practice. 4th Ed. Philadelphia,PA; 2006:188- 9 (2) Thyssen, JP. Hypersensitivity to local anesthetics. Contact Dermatitis. 2008;59(2):69-78

Abstract 23

Incidence of Hypotensive/Bradycardic Events During Elective Outpatient Shoulder Arthroscopy in the Sitting Position After Interscalene Peripheral Nerve Block: A 10 Year Retrospective Analysis

Presenting Author: Patrick A. Armstrong, M.D. Presenting Author’s City, State: - Durham, NC Co-Authors: Steve Melton, M.D. - Duke University Medical Center - Durham, NC William D. White, M.P.H. - Duke University Medical Center - Durham, NC Stephen M. Klein, M.D. - Duke University Medical Center - Durham, NC

Introduction: Sudden, severe hypotensive and/or bradycardic events (HBE) have been reported in 13- 28% of patients undergoing shoulder arthroscopy in the sitting position after interscalene block.1-3 In contrast to these studies, this phenomenon does not appear to be as prevalent when interviewing clinicians and does not seem to deter the use of interscalene blocks in patients in the sitting position. In an effort to better define the incidence of HBE in a large population we present a retrospective analysis of HBE in the sitting position after interscalene peripheral nerve block.

Materials and Methods: After IRB approval, the anesthesia perioperative database was searched for all patients who underwent outpatient shoulder arthroscopy in the sitting position with interscalene nerve block from September 1999 to September 2009. Cases with an emergent ASA classification were excluded. Intraoperative data was analyzed to identify HBE, defined as: decrease in heart rate (HR) of > 30 beats per minute (BPM) in < 5 minutes or any decrease < 50 BPM, and/or systolic blood pressure (SBP) decrease of > 30 mmHg in < 5 minutes or any decrease < 90 mmHg, that was treated with atropine, ephedrine, glycopyrolate, or epinephrine. The HBE and no-HBE cases were compared with Wilcoxon tests for numeric measures and Chi-squared tests for categorical characteristics. P-Values of <0.05 were considered statistically significant.

Results: There were 3,875 subjects that met the inclusion criteria; 9 ASA â€œEâ€ cases were excluded. Of these, 5.78% (CI 5.08-6.58%) met the criteria for a HBE. The HBE patients were significantly more likely to be older (mean age of 57 versus 46, p<0.0001) and have a higher ASA classification (p<0.0001). There was no significant difference in terms of gender, body mass index, or the inclusion of epinephrine in the surgical irrigation fluid. (See Table 1)

Discussion and Conclusion: This study demonstrates a significantly lower incidence of HBE than previously reported in patients undergoing shoulder arthroscopy with interscalene block in the sitting position. There was a correlation between HBE and patients of increased age and/or higher ASA class. The proposed mechanism of these events is the Bezold-Jarisch Reflex, which is triggered by venous pooling and a high catecholamine state. Given that less sedated patients may have increased vagal tone and endogenous catecholamines we postulate that our practice of heavy sedation may be one factor in the very low incidence of HBE at our institution.

References: 1. D'Alessio JG, Weller RS, Rosenblum M. Activation of the Bezold-Jarisch reflex in the sitting position for shoulder arthroscopy using interscalene block. Anesth Analg 1995;80:1158-62. 2. Liguori GA, Kahn RL, Gordon J, Gordon MA, Urban MK. The use of metoprolol and glycopyrrolate to prevent hypotensive/bradycardic events during shoulder arthroscopy in the sitting position under interscalene block. Anesth Analg 1998;87:1320-5. 3. Kahn RL, Hargett MJ. Beta-adrenergic blockers and vasovagal episodes during shoulder surgery in the sitting position under interscalene block. Anesth Analg 1999;88:378-81.

Additional File #1: Figure 1. Patient Characteristics (Mean + SD) HBE No HBE (n=3639) p-Value (n=224) Age 46 + 16.2 57 + 13.2 <0.0001 Gender (Male) 62% 57% 0.9 87.5 + 86.8 + 20.4 0.6 Weight (kg) 20.8 BMI 28.7 + 6 29.4 + 6.2 0.07 ASA Class I and II 78% 65% <0.0001 III and IV 22% 35%

Epinephrine 12% 16% 0.1 in Irrigant

Abstract 24

Incidence of Nerve Injury in 158 Patients Who Received Femoral Nerve Block During Residual Neuraxial Block After Total Knee Replacement: A Retrospective Chart Review.

Presenting Author: Victor Pascua, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Fanny Wong, MS2 - SUNY Downstate Medical Center - Oakland Gardens, NY Yimar Berrios, M.D. - SUNY Downstate Medical Center - Brooklyn, NY Dennis Dimaculangan, M.D. - SUNY Downstate Medical Center - Brooklyn, NY

Background: The risk of nerve injury associated with peripheral nerve blocks (PNB) performed after plexus or neuraxial blockade (NAB) is unclear. Nevertheless, PNB placement during partial plexus or NAB continues to be practiced in different settings. An unpublished survey among American Society of Regional Anesthesiologists (ASRA) members revealed that 20% of respondents performed lower extremity PNB during residual NAB(1). The ASRA practice advisory states that, â€œdata are limited with regards to the risk, if any, of performing peripheral nerve blocks in the setting of an incomplete proximal peripheral or plexus block, or an unresolved neuraxial blockâ€ (2). No large randomized prospective or retrospective studies have been done to evaluate the risk of nerve injury in adults, in the setting of lower extremity PNBs performed during complete or partial NAB.

Methods: We conducted a retrospective chart review of all patients who underwent total knee replacement at SUNY-DMC from August 2004 to December 2009 to determine the incidence of nerve injury in patients who received femoral nerve block (FNB) during residual NAB.

Results: Out of 199 charts reviewed, 158 were identified to be those of patients who received NAB for surgical anesthesia followed by a FNB for postoperative acute pain management. Of the 158, two patients were found to have postoperative nerve injury.

Discussion: We found an incidence rate of 1.27% (2/158) for nerve injury. One sustained a transient obturator nerve sensory deficit and the other suffered a foot drop. Considering that foot drop cannot be associated with injury from a FNB, our calculated incidence rate for nerve injury that can be possibly associated with FNB is actually lower at 0.63 % (1/158). The retrospective nature as well as our small sample size limit us in making a statistical comparison with existing incidence rates for nerve injury after PNBs or FNBs. Large randomized prospective studies are needed to obtain a reliable comparison.

References: 1. Le, M. The Practice of Femoral and Sciatic Nerve Blocks: An ASRA based Survey. Poster presented at: 46th Western Anesthesia Residents Conference; 2008 Apr 25-27; Seattle, WA. 2. Neal, J. ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine. RAPM, 2008.

Additional File #1: Age 64.6 ± 8.7 years Gender Female 143 (91%) Height 64.2 ± 2.77 inches Male 15 (9%) Weight 192.7 ± 38.1 ASA II 94 (60%) pounds BMI 32.9 ± 6.7 kg/m² III 59 (38%) Average Time elapsed from NAB to FNB 369.0 ± 114.6 min placement

Additional File #2: Risk Factor *Nerve Mean ± SD Risk Factor Nerve Frequency Deficit Deficit NAB Type and Dose: (-) 14.2 ± 3.4 mg Nerve Localization bupivacaine Technique: (+) 15 mg Nerve Stimulation (-) 126 bupivacaine Tourniquet Time: (-) 77.9 ± 24.8 (+) 2 minutes (+) 78 ± 15.6 Ultrasound Guided (-) 21 minutes (+) 0 Local Anesthetic Type & Type & Size of Initial FNB Dose: Needle: Bupivacaine (-) 64.4 ± 47.4 mg 18g 3" Insulated (-) 130 Tuohy (Used for CFNB) Ropivacaine (-) 69.5 ± 55.5 mg (+) 2 Lidocaine (-) 101.5 ± 67.9 mg 22g 2' Stimplex (-) 23 (Used for SFNB) Bupivacaine (+) 25 mg (+) 0 Lidocaine (+) 100 mg

CFNB = continuous femoral nerve block; SFNB = single shot femoral nerve Two out of 158 patients were found to have postoperative neurological deficits. Negative refers to data pertaining to these 2 patients. Positive refers to the remaining 156 patients without neurological deficit.

Abstract 25

Effects of Interscalene Block on the Diaphragm

Presenting Author: Kethy Jules-Elysee, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Shane Reid, B.A. - Hospital for Special Surgery - New York, NY Christopher Edmonds, M.D. - Hospital for Special Surgery - New York, NY Richard Kahn, M.D. - Hospital for Special Surgery - New York, NY Michael Urban, M.D. - Hospital for Special Surgery - New York, NY

Background: Previous studies have shown that Ipsilateral hemidiaphragmatic paralysis occurs in 100% of patients undergoing interscalene block (ISB) (Urmey 1991). This has been shown to resolve upon the resolution of the anesthetic block. However, persistent diaphragmatic paralysis (DP) has been reported post-interscalene block (Bashein 1985, Robaux 2001). These events are thought to be infrequent. However, over the past few years, several cases of persistent DP after interscalene block were observed, some of which were accidentally discovered per routine chest X-ray or CT scan. As these cases were asymptomatic, it could be possible that persistent DP goes undetected. We sought to study the frequency of which persistent DP after interscalene block occurs.

Materials and Methods: After IRB approval and informed consent, patients undergoing ISB for shoulder arthroscopy in an ambulatory setting were enrolled. Vital capacity (VC) and inspiratory force (NIF) were recorded. Three trials were taken with the two closest measurements being averaged and documented. Measurements were collected at baseline (prior to surgery), post-surgery (2 to 3.5 hours after block administration) and post-surgical follow-up visit (7 to 14 days after the surgical procedure). A decrease in vital capacity of greater than 20% from baseline was considered abnormal.

All patients received 0 to 5 mg of midazolam for anxiolysis. ISB was performed with either paresthesia technique or a nerve stimulator. Local anesthetic (LA) consisted of Mepivacaine 1.5% with 1:300,000 epinephrine and NaCO3 (1meq/10ml) with the anesthesiologistâ€™s discretion to additionally use bupivacaine for a total of 60 mL of LA. The presence or lack thereof parasthesia was recorded. All diaphragmatic twitches, if observed were recorded. Following block placement, all patients were positioned in the â€œbeach chairâ€ position for surgery.

Results: A total of 98 patients were enrolled. Of those, two patients were observed to have persistent diaphragmatic paralysis with an incidence of 2%, 95% CI 7.1%. The mean difference in vital capacity measured more than 1 week postoperatively between those presenting with DP and those without were a 28.25% decrease and a 6.88% increase over baseline, respectively. One patient with DP presented asymptomatically, while the other patient presented with shortness of breath. It is also of note the symptomatic DP patient did experience diaphragmatic stimulation while the anesthetic block was being performed. Nine other patients were also noted to have DP stimulation, but had no consequences.

Conclusion: Persistent DP paralysis post ISB may be more common than originally thought. At times, it may be asymptomatic and go unnoticed. This possibility needs to be taken into consideration whenever an ISB is performed either by paresthesia or nerve stimulator technique.

Additional File #1:

Anesthetic Technique Patient Population N Avg Age ASA Avg BMI Paresthesia Nerve Stimulator *DP Paralysis 2 47.5 2 28.7 1 1 No DP Paralysis 96 47.8 2 26.5 30 56 * DP Paralysis defined as greater than 20% decrease in VC by final follow up

Additional File #2: FVC % Change NIF % Change Patient Population N from Baseline from Baseline **Diaphragmatic Stimulation *DP Paralysis 2 -28.2 -38.7 1 No DP Paralysis 96 6.9 10.7 9 ** noted at the time of block administration

Abstract 26

Anomalous Brachial Plexus Anatomy Resulting from Thyromegaly

Presenting Author: Eric K. Shepard, M.D. Presenting Author’s City, State: - Baltimore, Maryland Co-Authors: Timothy E. Scott, M.R.C.P., F.R.C.A. - Kernan Orthopaedic and Rehabilitation Hospital - Baltimore, Maryland

Introduction: We describe a cohort of five patients presenting for elective upper limb surgery, who upon ultrasound examination in preparation for interscalene blocks, demonstrated significantly altered cervical and brachial plexus anatomy due to thyromegaly

Setting: Kernan Orthopaedics and Rehabilitation, an orthopaedic specialty hospital affiliated with the University of Maryland Medical System.

Patient Demographics: All cases were identified during the period of March 2008 through December 2009. There were four females and one male. Two of the patients had known hypothyroidism and were taking thyroid hormone supplementation. The other three patients had no prior history of thyroid disease. The age range was 54 to 72 with four females and one male. In all patients marked thyromegaly resulted in posterior displacement of the great vessels and the brachial plexus. All 5 underwent successful ultrasound guided interscalene blocks. In all 5 cases an attempt at an interscalene block based strictly on external anatomic landmarks would likely have resulted in vascular puncture and a failed block.

Discussion: Thyroid abnormalities occur frequently as an incidental finding in patients undergoing carotid duplex ultrasonography with a reported incidence of between 9.4% and 30%. Subclinical thyroid disease is a common disorder found in up to 8.5% of the adult US population rising to 20% in females over the age of 60. Goiters occur in approximately 15% of the population and are found four times more frequently in females than males. Despite its high incidence, a search of the anesthesia literature reveals no articles describing the influence of thyromegaly on the brachial plexus, and its consequences when performing interscalene blocks.

Conclusion: Patients with thyroid disease may have distorted anatomy significantly increasing their risk of complications resulting from attempts at blind interscalene or supraclavicular brachial plexus blockade. We recommend that such blocks be undertaken in such patients with ultrasound guidance. Further ultrasound evaluation of patients with thyroid disease should be considered for further study.

Additional File #1: Figure 1: With the ultrasound probe placed posterior to the sternocleidomastoid, in the usual anatomic position for an interscalene block, the great vessels are seen in the center of the screen.

Additional File #2:

Figure 2: The enlarged Rt. Lobe of the thyroid is seen displacing the carotid artery posteriorly. The sternocleidomastoid (SCM) terminates over the carotid, instead of its usual position over the anterior scalene muscle.

Additional File #3:

Figure 3: The enlarged thyroid is can be seen displacing the great vessels and anterior scalene muscle (ASM) posterior to their usual positions.

Abstract 27

Complications and Side Effects of the Combined Suprascapular and Axillary Nerve Block: A Case Series of 230.

Presenting Author: Darcy J Price MB ChB, FANZCA Presenting Author’s City, State: - Auckland, Auckland

Abstract Body: The combined suprascapular and axillary nerve block (CSANB) was designed as an alternative to interscalene brachial plexus block (ISB) for pain relief following shoulder surgery (1,2). The technique involves blocking the two major nerves supplying the shoulder joint, thus minimizing both the side effects and potential complications of the traditional interscalene technique. The author has now collated a case series of 230. The indications for the technique have been recorded in Table 1.

The adverse effects if the technique can be divided into three categories: insertion complications, side effects and long term complications. Both insertion complications and side effects were assessed and recorded by the author during block insertion, and 1 to 2 hours following surgery respectively. Long term complications of interest were neurological in nature, related to either a deficit or neuropathic-type pain. While follow-up was not standardized, 198 of the 230 cases involved the same surgeon who was aware that the technique had been used. The complications and side effects are listed in Table 2.

Only one insertion complication was noted, a presumed intravascular injection. There were no neurological complications bought to the attention of the author by any of the surgical teams following up the patients. Side effects following the technique were limited to three cases of concurrent radial nerve blockade associated with the axillary nerve block. The cause of this was local anaesthetic tracking proximally to the posterior cord.

Conclusion: This case series of 230 CSANB reported on adverse events associated with the technique. Insertion complications were rare, and side effects mild and very infrequent. The rate of long term complication also appears to be area also, but would need a bigger case series with more standardized follow-up to determine the true incidence.

References: 1. Price DJ. The shoulder block: a new alternative to interscalene brachial plexus blockade for the control of postoperative shoulder pain. Anaesthesia Intensive Care 2007;35:575-81 2. Price DJ. Axillary (circumflex) nerve block used in association with suprascapular nerve block for the control of pain following total shoulder joint replacement. RAPM 2008;33:280-1

Additional File #1: Table 1.

Indication Procedure Number Comment Preoperative Minor sub-acromial 101 Intra-articular 95 Major sub-acromial 19 10 x ISB not indicated 9 x scheduled for minor bur RCR required TSJR 2

Postoperative PACU 8 ISB/ISC failure On ward 4 2 x severe pain when single shot block wore off 1x ISC pulled out 1x ISC failure

Other Chronic pain diagnostic block 1

Total 230

Additional File #2: Table 2.

Complications Event Number Comment Incidence On insertion Intravascular 1 Tachycardia during suprascapular NB 0.4%

Postoperative Neurological Nil 0% reported

Side effects Postoperative Concurrent radial nerve 3 All female, 15ml 0.75% ropivacaine to 1.3% block axillary nerve

Abstract 28

An Updated Meta-Analysis of Ultrasound-Guided Nerve Blocks Presenting Author: Harold Gelfand M.D.

Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: Maggie Lesley, B.S. - Johns Hopkins University - Baltimore, M.D. Phebe Ko, B.S. - Johns Hopkins University - Baltimore, M.D. Calvin Eng, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Ultrasound-guided peripheral nerve blocks may offer greater accuracy and safety in regional anesthesia of the upper and lower extremities, whereas conventional â€˜landmark-basedâ€™ approaches have varying success rates. Although prior systematic reviews and meta-analyses of randomized controlled trials on this topic have been published, none has examined the efficacy of ultrasound on specific nerve blocks. We have undertaken a systematic review and meta-analysis to examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. The National Library of Medicineâ€™s PubMed database was searched for all articles containing text words related to ultrasound nerve blocks. Only randomized controlled trials assessing the success rate of peripheral nerve blocks were included for analysis and only articles in the English language were considered. Data on pertinent study characteristics and the primary outcome were extracted from accepted articles. Studies were excluded from analysis if they reported no comparative information on the magnitude of the treatment effect. Overall success rate of peripheral nerve blocks with and without ultrasound guidance were compared. Meta-analysis was performed using the Review Manager 4.2.7 (The Cochrane Collaboration, 2004). A random effects model was used.

Results: Our literature search yielded 791 abstracts of which a total of 16 met all inclusion criteria. There were 528 subjects in the 8 randomized trials used for this meta-analysis. Pooled estimates (relative risk) were made for the success rate of ultrasound guidance on peripheral nerve blocks compared to all Methods of control. Ultrasound guidance (vs. all non-ultrasound) was associated with a significant increase in the success rate of nerve blocks (RR= 1.12 [95% CI: 1.06 to 1.18, p < 0.001]), and ultrasound guidance was associated with an increase in the success rate as compared only to blocks using nerve stimulators (RR= 1.09 [95% CI: 1.04 to 1.15, p < 0.001]). For specific blocks, ultrasound guidance (vs. all non-ultrasound) was associated with a significant increase in successful brachial plexus nerve block (RR= 1.09 [95% CI: 1.02 to 1.17, p = 0.008]) and popliteal nerve block (RR= 1.22 [95% CI: 1.08 to 1.39, p = 0.002]) but not infraclavicular nerve block (RR= 1.25 [95% CI: 0.88 to 1.76, p = 0.22]) or axillary nerve block (RR= 1.12 [95% CI: 0.97 to 1.22, p = 0.17]).

Conclusions: Ultrasound-guided (vs. non-ultrasound) peripheral nerve block is associated with increased overall success rate; however, the benefits of ultrasound for individual nerve blocks is not clear.

Abstract 29

Comparison of Two Techniques of Us-Guided Popliteal Block

Presenting Author: Genevieve Germain, M.D. resident Presenting Author’s City, State: - Quebec, Quebec Co-Authors: Nicolas Dion, M.D. - Hopital de l'Enfant-Jesus - Quebec, Quebec Simon Levesque, M.D. - Hopital de l'Enfant-Jesus - Quebec, Quebec Pierre C. Nicole, M.D. - Hopital de l'Enfant-Jesus - Quebec, Quebec Alexis F. Turgeon, M.D., MSc (Epid) - Hopital de l'Enfant-Jesus -Quebec, Quebec

Background: With the Introduction of ultrasound, the sciatic popliteal block can be performed above or below the sciatic nerve division. To assess the hypothesis that an injection below the division hastens the onset of anesthesia, we compared the success rate of ultrasound-guided sciatic popliteal block (USGPB) performed above or below the sciatic nerve division.

Methods: Following REB approval and informed consent, patients undergoing foot or ankle surgery were enrolled in this prospective randomized controlled study. In group A (above the division), 25mL of ropivacaine 0.75% were injected on the sciatic nerve before the division while in group B (below the division), 15mL of ropivacaine 0.75% were injected on the tibial nerve and another 10mL of ropivacaine 0.75% on the common peroneal nerve. Certified anesthesiologists performed the USGPB using an in- plane technique with a linear ultrasound probe (5-12 mHz) positioned in the popliteal crease. The sensory and motor blocks were evaluated every 5 minutes up to 30 minutes by an investigator unaware of the technique. The primary endpoint was the rate of complete sensory block (anesthesia to cold in tibial, superficial peroneal, deep peroneal and sural nerves territories) and motor block (absence of plantar flexion and extension of the first toe) at 30 minutes. Secondary endpoints were the rate of sensory and motor blocks at each evaluation time, the need for complementary anesthesia, procedure time and incidence of complications at 24 hours and at 1 month. Based on data from a recent study (1), 51 patients per group were required to detect an increase in the success rate from 65% in group A to 90% in group B, accepting Î² error of 20% and Î± error of 5%. Statistical analyses were performed using the Student t test for continuous data, the Fisher exact test for success rate at a definite period and a hierarchical logistic regression modeling for the success rate on the entire observation period of 30 minutes (ProcGlimmix, SAS v9.2). A p<0.05 was considered significant.

Results: Both groups of 51 patients were comparable. The rate of complete motor and sensory block at 30 min was higher in group B (24% [CI95%:14-37]) as compared to group A (8% [CI95%:3-19]), but not in a significant manner (p=0.05). Overall, the rate of complete motor block between 0 and 30 minutes was comparable between groups (p=0.08), but the rate of complete sensory block was significantly higher (p<0.0001) in Group B as compared to Group A (fig 1). The number of patients who underwent surgery without the need for complementary anesthesia was significantly higher in Group B (96% [CI95%:87-99] vs. 51% [CI95%:38-64])(p<0.0001). There was no statistically significant difference in the duration of procedures or the incidence of complications.

Conclusion: Our results did not confirm the hypothesis that the rate of complete block at 30 min is improved when performing USGPB below instead of above the division of the sciatic nerve. However, because we observed a clear trend toward a higher rate of motor block, an enhanced rate of complete sensory block and a decreased need for complementary anesthesia, an injection below the division should be favoured in clinic when performing USGPB using a long acting local anesthetic.

REF: 1. Anesth Analg 2008;106:1553-8

Additional File #1:

Abstract 30

Circumferential Local Anesthetic Spread Speeds the Onset of Ultrasound Guided Sciatic Nerve Block at the Popliteal Fossa

Presenting Author: Simon J. Parrington, M.B.B.S., F.R.C.A. Presenting Author’s City, State: - Chertsey , Surrey Co-Authors: Richard Brull, M.D., F.R.C.P.C. - Toronto Western Hospital - Toronto , Ontario Anahi Perlas, M.D., F.R.C.P.C. - Toronto Western Hospital - Toronto, Ontario Alan Macfarlane, M.B.B.S., M.R.C.P., F.R.C.A. - Glasgow Royal Infirmary – Glasgow, Glasgow City David Xu, M.B.B.S. - Toronto Western Hospital - Toronto, Ontario

Introduction: Ultrasound guided techniques can increase the success rates of peripheral nerve blockade, as well as potentially reduce onset and procedure time when compared with the use of peripheral nerve stimulator techniques. The proposed mechanism of the increased success and rapid onset when ultrasound is used is the ability to accurately place local anesthetic solution around the target nerve.

Sciatic nerve block has been shown to reduce postoperative pain and opiod requirements as well as improve patient satisfaction after outpatient foot and ankle surgery.1 However a slow onset time may be a limitation to the widespread adoption of popliteal sciatic nerve blockade in the peri-operative environment.2

Our hypothesis was that using ultrasound to ensure that the popliteal nerve is circumferentially surrounded by local anesthetic will reduce the time for the local anesthetic to diffuse perineurally and speed the onset of anesthesia compared to a single location injection under ultrasound guidance.

Methods: Following institutional ethics approval and informed consent 30 adult patients undergoing elective foot and ankle surgery were randomly assigned to one of two groups; Ultrasound guidance with circumferential spread (USC) and Ultrasound guidance with single location injection (USS).

Using a standardised technique the sciatic nerve was identified just above its bifurcation and 15 mL of 2% lidocaine containing 1:200,000 epinephrine plus 15 mL of 0.5% bupivacaine (total volume = 30 mL) was injected using an out of plane approach with needle repositioning to achieve circumferential spread in group USC. The primary outcome measure was onset time of sensory and motor blockade. Secondary outcomes included block procedure time, pain associated with block placement. Tests of significance included t-tests for parametric variables, the Mann Whitney ANOVA of ranks for non-parametric data and the Chi-squared test for frequency count data.

Results: Interim data was analyzed on an intention-to-treat basis, using SPSS 10.0 for Windows. Patient characteristics were similar between groups.The mean onset time was significantly shorter in group USC than group USS 23.4 +/-11.6 min vs 36.6 +/- 13.0 min respectively ( p=< 0.05), block procedure time, and VAS for the procedure did not differ significantly between the groups (Table 1). Complications were minor and transient and did not differ between the groups at two weeks post operatively.

Discussion: Ensuring circumferential spread of local anesthetic around the popliteal nerve speeds the onset of surgical anesthesia and may be of clinical benefit potentially reducing operating room time particularly where there is no block room or anesthetic induction room, where a predictable rapid onset block is desirable.

References

1.Ilfeld BM, Morey TE, Wang RD, Enneking FK: Continuous popliteal sciatic nerve block for postoperative

pain control at home: a randomized, double-blinded, placebo-controlled study. Anesthesiology 2002; 97: 959-65.

2. Perlas A, Brull R, Chan VW, McCartney CJ, Nuica A, Abbas S: Ultrasound guidance improves the success of sciatic nerve block at the popliteal fossa. Reg Anesth Pain Med 2008; 33: 259-65

Additional File #1:

Popliteal block procedural data USC Circumferential USS Single p value injection n=16 injection n=14 Onset time (min) 23.4 (+/- 11.6) 36.6 (+/- 13.4) 0.01 (+/- SD) Procedure time (min) 8.0 (+/- 3.3) 6.6 (+/- 1.8) 0.17 +/- SD Visual analog score for procedure 3.4 (+/- 2.0) 2.5 (+/- 1.4) 0.28 VAS (0-10)

Abstract 31

Augmented Reality Guidance System. Novel Method of Needle Navigation for Ultrasound Guided Peripheral Nerve Blocks

Presenting Author: Maxim Rachinsky, M.D. Presenting Author’s City, State: - London, Ontario Co-Authors: Chris Wedlake, Ph.D. - Robarts Research Institute - London, Ontario Daniel Bainbridge, M.D. - The University of Western Ontario - London, Ontario Kevin Armstrong, M.D. - The University of Western Ontario - London, Ontario Terri Peters, Ph.D. - Robarts Research Institute - London, Ontario

Background: Confident needle tracking is important for safe and successful performance of peripheral nerve blocks. Current practice is to use ultrasound guidance (US) for needle visualization. However, inability to predict precise trajectory of needle advancement leads to necessity of constant movements of US probe for the needle tip tracking which sacrifices target visualization and vice versa. We have designed the system which contains a fusion of real-time two dimensional US with a magnetic tracking system (MTS) (Aurora MTS, NDI, Waterloo, ON, Canada). This platform consists of a magnetic field generator and position sensors which attached to a needle and US probe and original software. The position of the tracked needle can now be displayed, as a virtual representation, in a real time image along with the US image itself, all in real time. Currently, the MTS uses a sensor located at the needle tip. To simplify the Introduction of this system into clinics, we have evaluated attaching the sensor at the needle hub.

Purpose of the study: 1. To assess augmented reality guided system for peripheral nerve block compare to US alone. 2. To determine whether it is sufficient to place a tracking sensor on the hub rather than embedded in the tip of the needle.

Material and Methods: Five experienced anaesthesiologists and five novices performed simulated nerve block deliveries in a polyvinyl alcohol (PVA) phantom. The phantom was designed from two lexan plates which rigidly held plastic tubes that represented the brachial plexus nerves(medial, lateral and posterior), axillary artery and axillary vein that are present when performing an infraclavicular block . Each participant was required to place the needle at the medial, lateral and posterior cord using three Guidance Systems (GS). I. GSUS where the users were restricted to using the US machine monitor (Figure 1,a), II. GSTip where US plus virtual representations with the needle is tracked by the tip and III. GSHub where US plus virtual representations with the needle is tracked by the hub (Figure 1,b).

Results: Both novices and experienced anaesthesiologists were able to achieve substantially better accuracy with fewer attempts and less intersection with critical structures, where the needle was tracked by either the tip or the hub (see Table 1). Accuracy in reaching the target area and number of successful attempts were improved among both novices and anaesthetists with the GStip (see Table 2).

With the use of the system, the novices were able to increase their ability to be in the target area of the nerve almost as often as the experienced anaesthesiologists.

Conclusions: Augmented Reality Guidance System has shown superior performance in hands of both novices and experienced anaesthesiologists. GSHub and GSTip tracking showed comparable results.

Additional File #1: Table 1. Intersections with critical structures and the number of insertions to reach their final placement for Anesthetists when targeting with the needle in-plane. N=30

Guidance Method Critical Hits Insertions / for % Attempt Anaesthesiologists GSUS 16.7% 1.77 GSTip 10.0% 1.43

GSHub 6.7% 1.37

Table 2. Accuracy in reaching the target area of the nerve, the number of successful targeting attempts when targeting with the needle in-plane. N=30

Guidance Method RMS % successfully (mm) targeted GS 4.11 43.3% Novices US GSTip 0.78 63.3% GS 1.34 66.7% Anaesthesiologists US GSTip 0.68 66.7%

Additional File #2:

(a) GSUS

(b) GSTip and GSHub

Figure 1. (a) Traditional US only image of phantom (b) Tracked US of phantom with needle showing trajectory and relation to US plane.

Abstract 32

Ultrasound Guided Tap Blocks for Post-Cesarean Section Pain Relief: A Pilot Study

Presenting Author: Marcos Silva, M.D. Presenting Author’s City, State: - London, Ontario Co-Authors: Indu Singh, F.R.C.P.C. - University of Western Ontario - London, Ontario Sarah Rehou, B.Sc. - University of Wester Ontario - London, Ontario

Purpose: Pain management after cesarean section (CS) can be challenging. Multimodal analgesia improves pain after CS. Transversus abdominis plane (TAP) blocks have been shown to be effective for pain relief after abdominal surgeries. A pilot study was carried out to assess the feasibility and efficacy of bilateral ultrasound guided (USG) TAP blocks for post CS pain relief at 24h in term parturients.

Methods: After REB approval, we carried out a prospective study of two non-randomized cohorts of 10 patients each. Informed consent was obtained from each patient. Adult women with an ASA score of 1-3, at term gestation with singleton fetuses having elective CS under spinal anesthesia were included.. All women received spinal bupivacaine 0.75% (10-12 mg), fentanyl (10-15 mcg) and epidural morphine (100 â€“ 150 mcg) and standard postoperative multimodal analgesia, NSAIDs, acetaminophen and codeine). The patients in the TAP block group received USG bilateral TAP blocks with ropivacaine 0.5%, 3 mg/kg, with a max. dose of 60 ml or 300 mg total at the end of the CS. Block levels were assessed 4 hours after spinal placement. Pain scores (NRS, with rest & movement) in both groups were recorded at 24h.

Results: Baseline characteristics including age, BMI, parity, and previous CS were similar between groups. The pain scores in the TAP block group vs. the control group at 24h at rest were 0.8 (1.03) vs. 3.3 (1.4) (p value = 0.0003). The pain scores in the TAP block group vs. the control group at 24h with movement were 2.9(1.2) vs. 6.1 (0.9), (p value= 0.0001). The total codeine consumption at 24h was less in the TAP block group compared to the control group: 102 mg (40.5) vs. 147 mg (45.7) respectively (p value = 0.031). The time for the first request of codeine was longer in the TAP block group compared with the control group: 17.8 h (1.5) vs.16.2h (1.9), (p value= 0.007). The TAP blocks were easily carried out with no complications and in an average time of 12 minutes. Average sensory block levels to ice at 4h were T10.

Conclusion: In this pilot study, bilateral USG TAP blocks were feasible and effective for post CS pain relief in term parturients. A randomized clinical trial is planned.

Abstract 33

Reduced Volume for Triple Injection Ultrasound Guided Supraclavicular Block Results in Significantly Less Motor Block While Providing Adequate Surgical Anesthesia

Presenting Author: Joni Maga, M.D. Presenting Author’s City, State: - Miami, FL Co-Authors: Andres Missair, M.D. - U. Miami - Miami, FL Maria Suarez, M.D. - U. Miami - Miami, FL Daniel Fernandez-Soto, M.D. - U. Miami - Miami, FL Ralf Gebhard, M.D. - U. Miami - Miami, FL

Introduction: There remains great academic debate regarding the optimal number of injections and the required volume to perform effective and safe supraclavicular blocks. While Duggan et al. (1) report that a local anesthetic volume of 42ml is necessary to achieve 95% block success with multiple injections, Renes et al. (2) recently achieved 100% success rate with 20ml using a double injection technique. This prospective randomized clinical trial was designed to evaluate whether a reduced volume of local anesthetic (15ml vs. 30ml) will result in similar block characteristics when a triple injection technique for supraclavicular is utilized.

Methods: After approval by the Institutional Review Board and written informed consent was obtained, a total of 30 patients scheduled to undergo ultrasound-guided supraclavicular nerve blocks for elective forearm and/or hand surgery were enrolled in the study. Patients were randomly assigned to either receive a supraclavicular nerve block with 30mL (Group High) or 15mL (Group Low) of 1.5% mepivacaine. A triple injection technique was employed in both groups. A blinded observer assessed all patients for degree of sensory and motor blocks at 5, 10, 15, 20, and 30 minutes post-injection in 5 different nerve territories. Patient and surgeon satisfaction with the technique and incidence of complication were also recorded. Demographic data were recorded as mean Â± standard deviation and degree of motor and sensory block as percentages. Data were analyzed using student's t-test for normal distributed data and Fisher exact test when indicated.

Results: Twenty-nine patients qualified for statistical analysis. Groups were similar in regards to demographics. Block success rate was 87% in Group High vs. 86% in Group Low. Complete motor block defined as motor block in all 5 nerve territories at 30 minutes was present in 83% of patients in Group High and in 65% in Group Low (p < 0.05). Surgeon and patient satisfaction were high and did not differ between groups. No block related complications were observed in either group.

Discussion: Our data indicate that a volume of 15ml of 1.5% mepivacaine results in similar quality of surgical anesthesia as a volume of 30ml of the same local anesthetic solution, when a triple injection technique with ultrasound guidance is utilized. At the same time, motor function was significantly more preserved in patients receiving the lower volume. Future research should evaluate whether, reducing the local anesthetic volume may also result in lower complication rate associated with supraclavicular nerve blocks.

References: 1. Duggan E et al., Reg Anesth Pain Med 2009;34: 215-218 2. Renes SH et al., Reg Anesth Pain Med 2009;34: 595-599

Abstract 34

Single vs. Double Injections for Ultrasound Guided Supraclavicular Block

Presenting Author: Simon Lévesque, M.D. Presenting Author’s City, State: - Quebec, Qc Co-Authors: Mélanie Roy, M.D. - Université Laval - Quebec, Qc Marie-Josée Nadeau, M.D. - CHAUQ, Université Laval - Québec, Qc Dion Nicolas, M.D. - CHAUQ, Université Laval - Québec, Qc Coté Dany, M.D. - CHAUQ, Université Laval - Québec, Qc

Background: Ultrasound guided supraclavicular block (USGSB) using one or multiple injections of local anesthetics have been described1. Despite the fact that multiple injections are thought to provide faster onset of analgesia, there is no consensus on whether more than one injection should be used for USGSB1. To assess this hypothesis, we conducted a prospective randomized controlled study to compare the success rate of USGSB performed with single or double injections.

Methods: Adult patients undergoing hand, wrist or elbow surgery were enrolled in this study following provision of informed consent. In group S, 30 mL of mepivacaine 1.5% were injected at the junction of the subclavian artery and the first rib. In group D, 15 mL of the same solution were injected at the site described above, and 15 mL were injected in the nerve bundle of the brachial plexus. All USGSB were performed by certified anesthesiologists using an in-plane technique with a linear ultrasound probe (5-10 mHz) positioned parallel to the clavicle and adjusted to give a transverse view of the subclavian artery. The sensory block was evaluated every 3 minutes up to 30 minutes by an investigator blinded to the technique. Primary endpoint was the success rate of sensory block defined as anesthesia to cold in the ulnar, radial, medial and musculocutaneous nerves territories at 15 minutes. Secondary endpoints were the success rate of sensory and motor blocks at each evaluation time, procedure time, need for complementary anesthesia, complications, and incidence of temporary ipsilateral diaphragmatic paralysis evaluated by spirometry and echography2. A follow-up phone call was made at 24 h and 1 month. Statistical analyses were conducted using the Student t test for continuous data and the Fisher exact test for proportions. A sample size of 102 patients was required to detect an increase in success rate of sensory block from 65% (data from local experience) in group S to 90% in group D, accepting Î± and Î² error of 5% and 20% respectively. A p<0.05 was considered significant. The study was approved by our hospital REB.

Results: The two groups of 51 patients were comparable. The rate of complete sensory block at 15 minutes was comparable between groups: 49% (CI95% 36-62%) in group S versus 53% (CI95% 40-66%) in group D (p=0.8). The rate of sensory and motor blocks was comparable between groups for each time intervals up to 30 minutes. The procedure time was shorter in group S (179Â±104 sec vs. 275Â±137 sec, p<0.01). General anesthesia was required for five patients in group S as opposed to one in group D (p=0.20). The incidence of temporary diaphragmatic paralysis was 18% (CI95% 10-30%) in group S and 29% (CI95%19-43%) in group D (p=0.24). No complication was reported at follow-up.

Conclusion: These results did not confirm our hypothesis that the success rate of sensory block at 15 minutes of USGSB using a double injection technique is superior to a single injection technique. Thus, both techniques appear to be a reasonable choice to perform USGSB.

REF: 1 Tran QH et al., Reg Anesth Pain Med 2009 2. Riazi S et al., Br J Anaesth 2008

Abstract 35

Learning Curves for Brachial Plexus Ultrasound Imaging by Anesthesia Residents Using the Cusum Method

Presenting Author: Lei Li M.D. Presenting Author’s City, State: - Brooklyn, NY Co-Authors: Ian Neugeborn, M.D. - SUNY Downstate Medical Center - Brooklyn, NY Jason Jacobs, M.D. - SUNY Downstate Medical Center - Brooklyn, NY Obinna Efobi, M.D. - SUNY Downstate Medical Center - Brooklyn, NY Dennis Dimaculangan, M.D. - SUNY Downstate Medical Center - Brooklyn, NY

Introduction: Learning curves for ultrasound (US) guided peripheral nerve blocks have been studied in simulated settings (de Oliveira Filho, Anesth Analg 2008), but no study has delineated learning curves on human subjects or real patients that can be used as bases for credentialing. In this study, we attempt to establish the learning curves for US imaging of the brachial plexus among anesthesia residents at the SUNY Downstate anesthesia training program.

Methods: Inexperienced anesthesia residents were asked to participate as subjects in the study. They were randomly assigned to four groups based on brachial plexus imaging approaches: Interscalene (IS), Supraclavicular (SC), Infraclavicular (IC), and Axillary (AX). Subjects were asked to generate and print out an ideal US image of the brachial plexus according to their assigned approach, on adult volunteer models, and identify the brachial plexus and associated structures. Feedback about the performance was given only after the completion of an attempt. Each attempt was timed and independently assessed and scored by an expert attending anesthesiologist based on criteria that focus on the quality of the image and the correct identification of the brachial plexus and surrounding sonoanatomical landmarks (Table 1). Subjects were not allowed to do more than one attempt in a day. Successive attempts were plotted in a cumulative summation (CUSUM) curve for each subject.

Results: A total of 186 imaging attempts on volunteer models have been completed by forty six subjects. Eleven subjects have completed at least 6 attempts, 3 each in the IS, IC and AX group, 2 in the SC group. CUSUM curves on these subjects indicated that no one has reached proficiency yet in their assigned approach (Fig. 1). We calculated success rates based on a number of factors, such as approaches, subjects' level of training, and volunteer models' sex, weight, height and BMI (body mass index). We found that the AX approach had the lowest success rate of 8.82%, which was significantly lower than the IS (44.19%), SC (53.06%), and IC (45%) approaches (p<0.001 Ï‡2 test, Fig. 2A). The success rate of attempts on volunteer models with BMIs greater than 30 was 20%. This was significantly lower than on those models with BMIs less than 30 (46.48% for BMI between 25 and 30; 41.11% for BMI < 25. p<0.05, Ï‡2 test, Fig. 2B). No significant difference was observed in success rates based on other factors.

Discussion and Conclusion: Our current study is being conducted on human volunteers instead of simulation phantoms. This allows us to examine inherent patient factors that may affect the ease or difficulty of US imaging of the brachial plexus such as BMI. We found that obesity (BMI > 30) complicated ultrasound imaging of the brachial plexus. Our preliminary data suggests that the AX approach is the most difficult to obtain a success rating based on our scoring criteria. We observed that this was most often due to the failure to identify the musculocutaneous nerve. The results show that subjects in general improved their success rate with increasing number of attempts. However, no one has reached proficiency as yet due to limited trials. Continued data collection is needed to complete the learning curves for each individual subject.

Additional File #1:

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Abstract 36

Postoperative Pain Control in Children Undergoing Laparoscopic Appendectomy: Comparison of Ultrasound- guided Peripheral Nerve Blocks to Local Anesthetic Infiltration Analgesia

Presenting Author: Lisa Sohn, M.D. Presenting Author’s City, State: - Chicago, IL Co-Authors: Polina Voronov, M.D. - Chldren's Memorial Hospital - Chicago, IL Amod Sawardekar, M.D. - Chldren's Memorial Hospital - Chicago, IL Narasimhan Jagannathan, M.D. - Chldren's Memorial Hospital - Chicago, IL Santhanam Suresh, M.D. - Chldren's Memorial Hospital - Chicago, IL

Introduction: The aim of this study was to compare the use of ultrasound-guided (US) rectus sheath and ilioinguinal nerve blocks in children undergoing laparoscopic appendectomies in comparison to the traditional infiltration of local anesthetic solution.

Methods: After IRB approval and informed consent and assent, 70 ASA I and II children ages 6-16 years old, scheduled for laparoscopic appendectomies, were prospectively randomized into two groups; (i) Group A, received local infiltration (0.25% bupivacaine) by the surgeon at each port site; (ii) Group B received bilateral US-guided rectus sheath and ilioinguinal nerve blocks. A blinded observer documented pain scores and rescue medications in the PACU and the first 48 hours after surgery. Other side effects of narcotics such as itching, nausea, vomiting, and drowsiness were also recorded.

Statistical analysis Method: Descriptive statistics were used to summarize continuous variables by treatment groups. Frequencies and proportions were calculated for categorical variables for each group. Chi-square test or Fisher exact test was applied for comparison of categorical variables between the two groups. Wilcoxon Rank Sum test or two-sample t-test were applied for continuous variables depending on if the data distribution was normal or not. The mixed linear model was used to analyze vital measurements over time. Statistical software SAS 9.2 was used for statistical analysis.

Results: A total of 70 patients were enrolled. Five patients were excluded from the study, four due to incomplete data collection and one for a change in surgical procedure after incision was made. The treatment groups consisted of 46% were girls and 54% were boys. The mean age for the two groups was 10 years (range of 5 to 16 years). The age of subjects between the two groups was not significantly different (p=0.36). The height was not significantly different either (p=0.64) between the two groups. The weight was marginally significant between the two groups (p=0.06). The total frequency of rescue pain medications administered to patients was significantly higher in group A (control) than in group B (p=0.04). There were no differences for adverse outcomes between the two treatment groups.

Conclusions: Rectus sheath blocks have been shown to be effective in controlling pain during and after umbilical hernia repairs, as have ilioinguinal nerve blocks for groin surgery in pediatric patients.(1) The combination of these blocks was performed on patients in the peripheral nerve block group (group B) with US-assistance to provide analgesia to the dermatomal regions involved with port sites in laparoscopic appendectomies. This study validates the use of US-guided rectus sheath blocks and ilioinguinal nerve blocks in children undergoing laparoscopic appendectomies when compared to standard infiltration analgesia. We hope that this study will encourage anesthesiologists to perform these blocks in children undergoing laparoscopic appendectomies.

1. Tsui B, Suresh S. Ultrasound imaging for regional anesthesia in infants, children, and adolescents: a review of current literature and its application in the practice of extremity and trunk blocks. Anesthesiology;112:473-92, 2010.

Abstract 37

Prepuncture Ultrasound Imaging to Predict Transverse Process and Lumbar Plexus Depth for Psoas Compartment Block and Perineural Catheter Insertion: A Prospective, Observational Study

Background: All widely-used psoas compartment block/catheter techniques have a common limitation: external landmarks do not accurately predict lumbar plexus depth, leaving practitioners to â€œguessâ€ at what depth to stop advancing the placement needle when neither transverse process nor lumbar plexus is intercepted. Ultrasound may be used to visualize the transverse process and estimate its depth prior to needle insertion . Therefore, we assessed the accuracy of ultrasound in estimating transverse process depth prior to needle insertion and prediction of actual needle-to-plexus intercept depth.

Methods: Prior to needle insertion, ultrasound was used to estimate the depth of the transverse process lying directly anterior to the intercrestal line. A linear array transducer (HFL38, SonoSite MicroMaxx, Bothell, WA) providing a frequency of 6-13 MHz was placed in the sagittal plane at the intercrestalâ€“midline intersection, rendering an image of the spinous processes (Fig. 1). The transducer was then moved directly lateral towards the operative side to identify the hyperechoic transverse processes (Fig. 2). If a transverse process was not directly anterior to the intercrestal line, then the process immediately caudad to the line was imaged. Following this measurement, the transducer was removed, an insulated needle (Contiplex, B. Braun Medical Inc., Bethlehem, PA) connected to a nerve stimulator inserted in the parasagittal plane, and the depth of both the transverse process (if contacted) and lumbar plexus noted. A perineural catheter was subsequently inserted and 15 mL of mepivacaine 2% with epinephrine (5 Âµg/mL) injected via the catheter using a technique described previously . Patients with a successful nerve block were subsequently included in a randomized, controlled study involving postoperative perineural local anesthetic infusion dose/concentration, the results of which have been published previously .

Results: Of 53 enrolled subjects, in 50 cases (94%) the transverse processes were identified by ultrasound at a median (interquartile; range) depth of 5.0 (4.5-5.5; 3.5-7.5) cm. In 27 subjects (54%), a transverse process was positioned directly anterior to the intercrestal line, and in all of these subjects the transverse process was intercepted with the block needle a median of 0.5 cm (0.0-1.0; 0.0-1.0) within the predicted depth. In all 50 subjects in whom the transverse processes were identified by ultrasound, the actual lumbar plexus depth measured with the needle was a median of 7.5 (7.0-8.5; 5.0-9.5) cm; and the plexus depth was a median of 2.5 (2.0-3.0; 0.2-4.0) cm past the estimated transverse process depth by ultrasound.

Conclusions: For psoas compartment blocks/catheters, prepuncture ultrasound imaging accurately predicts transverse process depth to within 1 cm, and if the lumbar plexus is estimated to be within 3 cm of the transverse process, ultrasound allows prediction of maximum lumbar plexus depth to within 1 cm. This information and use of prepuncture ultrasound screening has the potential to greatly decrease the risks of psoas compartment block needle and catheter misplacement.

References: 1. Kirchmair et al. Anesthesiology 2004; 101: 445-50 2. Ilfeld et al. Anesthesiology 2010; In Press

Additional File #1: Table 1. Patient data n mean (SD) median (range) Sex (female / male) 27 / 26 Age (yr) 53 (15) 52 (21-83) Height (cm) 172 (11) 170 (150-193) Weight (kg) 79 (17) 80 (36-113) Body mass index (kg/m2) 27 (5) 26 (15-37)

Additional File #2:

Additional File #3:

Abstract 38

Ultrasound and Spinal Anesthesia in Obstetric Patients

Presenting Author: Steven T. Fogel, M.D. Presenting Author’s City, State: - Columbia, Missouri Co-Authors: Wendy B. Becker, M.D. - University of Missouri - Columbia, Missouri Wade Davis, Ph.D. - University of Missouri - Columbia, Missouri Ge Bin, M.A. - University of Missouri - Collumbia, Missouri

Introduction: Recently, there has been interest in the use of ultrasound (US) for the performance of neuraxial analgesia/anesthesia both in the obstetric and non obstetric patient populations. Grau et al. have shown that pre-procedural ultrasound can improve the learning curve of obstetric epidural anesthesia.1 Arzola et al. have studied the agreement between ultrasound measured depth and actual needle depth of the epidural space in parturients requesting epidural analgesia.2 Chin et al examined the agreement of US measured depth and needle depth in spinal anesthesia (SA) in orthopedic patients. Good to excellent correlation and accuracy were found in these studies. Thus far, among obstetric patients there have been few or no reports of the agreement between US measured depth (UD) and actual needle depth (ND)during SA. We are seeking to determine the correlation and accuracy of these two measures for SA in the obstetric patient population and wish to report our preliminary results.

Methods: This IRB approved study is being conducted as part of an IRB approved database project for ultrasound use in neuraxial anesthesia/analgesia in obstetric patients. Thus far 29 patients have been examined. Patients presenting for cesarean delivery or post partum tubal ligation had a pre-procedural US examination of the spine. Prior to US examination, patientsâ€™ landmarks were graded as prominent, palpable, barely palpable and non palpable. The level of needle placement was determined by a method described by Carvalho.4 Both oblique para sagittal and transverse views of the intrathecal (IT) space were obtained with a Sonosite Turbo-M Model US machine utilizing a curvilinear 5 MHz probe. UD was obtained utilizing an internal caliper. Depth was measured from the skin to the estimated middle of the IT space. ND was measured with a 90 mm ruler upon obtaining CSF. The number of attempts was recorded as well as estimated probe and needle angles. All US exams were performed by a single examiner (STF). SA was performed by anesthesia residents and/or an attending physician (STF). Data were analyzed using the following statistical tests: Altman-Bland analysis, Pearson product-moment correlation and Linâ€™s concordance correlation.

Results: Results are shown in the table and figs 1 and 2. Two patients were not included in the data analysis as the needle depth was greater than the length of the 9 cm spinal needle that was used requiring significant skin depression. Of note, among patients whose spinal landmarks were considered barely palpable or non-palpable, 90% (9 of 10) required only 1 or 2 separate needle punctures.

Discussion: Thus far, our results seem to approximate those published for epidural analgesia. While our data show that US underestimated ND with a mean bias of -0.29 cm (-0.13, -0.45) [mean, 95% CI], Chin et al. demonstrated that US over estimated the IT space by 0.21 cm. Our method of measurement, however, was different from theirs. In patients whose spinal landmarks were not easily identified, US seemed to be of significant assistance.

1. Can J Anesth 2003; 50: 1047-50 2. Anesth Analg 2007; 104: 1188-92 3. Can J Anesth 2009; 50: 643- 50 4. Anesthesiol Clin 2008; 26: 145-58

Additional File #1: Concordance correlation Mean difference (95%CI)) Pearson correlation coefficient (95% CI) TUD vs OUD 0.33 (0.48, 0.17) 0.9149 0.8522 (0.7185, 0.9191) TUD vs ND -0.29 (-0.13, -0.45) 0.9237 0.8897 (0.7821, 0.9414) OUD vs ND -0.58 (-0.39, 0.78) 0.8694 0.7116 (0.4806, 0.8455) TUD: transverse US measurement, OUD: Oblique parasagittal US measurement, ND: needle depth.

Abstract 39

An Ultrasound Review of Failed TAP Blocks to Establish Anesthetic Locality

Presenting Author: James Whelan, M.D. Presenting Author’s City, State: - San Antonio, TX Co-Authors: Jonathan Rogers, M.D. - SAUSHEC - San Antonio, TX Lisa Rogers, M.D. - SAUSHEC - San Antonio, TX

Introduction: With the popularity of TAP blocks becoming common practice via ultrasound guidance, different aspects of the block are starting to be examined. The use of TAP blocks at our facility is a common practice-its use ranging from large abdominal cases, inguinal hernia repair and even laparoscopic surgery. With both residents and staff performing the blocks, an examination of failed TAP blocks was evaluated for potential locations of local in areas besides between the internal oblique and transverses abdominis. Seventeen patients that experienced failed TAP blocks were evaluated by a fellowship trained regionalist utilizing an ultrasound for determining location of local anesthetic and verifying if a trend was present.

Material and Methods: Seventeen patients were examined after physical exam showed no loss of sensation in the T8-T12 dermatomes within 30 minutes of the TAP blocks. The patients ranged from ASA one to three with different body types and having multiple different procedure planned. The evaluation was done using a Sonosite MicroMaxx ultrasound with a HFL38 probe. All patients received 30 ml of 0.5 % Ropivacaine using a 100mm 21 ga needle. The evaluation was completed by a fellowship trained regionalist, and was categorized with local in 5 possible locations resulting in the failure of the TAP block. These areas were, External oblique, internal oblique, space between external and internal oblique, transverses abdominis muscle or peritoneal/bowel.

Results: Of the 17 patients examined, it was determined that 12 failed blocks had local anesthetic placed within the internal oblique muscle, 3 showed local anesthetic in the transverses abdominis muscle, and 2 showed no volume located so presumed intraperitoneal placement or redistribution within a muscle layer.

Discussion: The internal oblique proved to be the most common location of local anesthetic for a failed TAP block. Multiple reasons can be used to explain the inability to place local in the proper layer, with the most common being the inability to see the needle tip on ultrasound. Inexperience with sonography can significantly contribute to the failure of this block, along with large body habitus or small abdominal musculature. Low resolution ultrasound also has a part in the inability to obtain good definition on muscle layers, with new technology making the TAP much easier and safer to perform. Teaching TAP blocks to staff and residents can be improved by utilizing high resolution ultrasound with the proper probe, demonstrating proper needle orientation and advancement, and most importantly, proper identification of the applied anatomy in regards to the muscles and layers in-between. With the modifications noted above, and proper identification of needle tip on ultrasound, the failure rate of TAP blocks can be reduced.

Abstract 40

Ultrasound Evidence of Intrafascicular Injection

Presenting Author: Robert M. Raw, M.D. Presenting Author’s City, State: - Iowa City, Iowa Co-Authors: Achir Alalami, M.D. - Univ. Iowa - Iowa City, Iowa Jared Lake, M.D. - Univ. Iowa - Iowa City, Iowa Corey Anderson, M.D. - Univ. Iowa - Iowa City, Iowa Major Boateng, M.D. - Univ. Iowa - Iowa City, Iowa

Introduction: Nerve injection pressure data was being collected on anesthetized pigs during which an unanticipated interesting observation was with ultrasound imaging. Case Presentation: Arrow 90 mm Arrow Stimuquick needles were placed into porcine sciatic nerves under ultrasound guidance, and pressure measurements taken during injection of fluids. Sonographic resolution was optimized by first removing the skin, fat and half the muscle mass above the nerve. Electro nerve stimulation confirmed the target was a nerve. Injections were made without ultrasound imaging to avoid transducer weight effects on pressure measurements. This studyâ€™s pressure data is the subject of another presentation. One nerveâ€™s pressure measurement of 350 mmHg exceeded double that of any preceding nerve measurement. In curiosity the nerve was re-examined image B was obtained. A different injection was made on another nerve obtaining more usual pressures and it was also scanned afterwards producing ultrasound image A. Ultrasound re- examination had not been done before in this study. In the images solid white arrows indicate the sciatic nerve, broken white arrows indicate injection fluid surrounding the nerves. The black arrow indicates the possible fascicle. Image A shows the â€œnormal pressureâ€ sciatic nerve with bright hyperechoic (white) spots within it, and homogenous hypoechoic (dark) fluid surrounding the nerve. The bright spots within the nerve are possibly bubbles from the intraneural injection. The nerve epineurium seemingly retained the bubbles but permitted escape of injected fluid. The large bubbles were likely augmented by a change in syringe preceding that injection. In image B where the very high pressure was measured some of the injected fluid is seems contained within a structure within the sciatic nerve indicated by the black arrow.

Discussion: Recent sonographic data suggest intraneural nerve block injection may be common and documented clinical intraneural injections have been without harm. Common opinion suggests the escape of injury was because the injections were interfascicular but that an intrafascicular injection will likely be harmful. Intrafascicular injection in research is hard to achieve and is likely a rare clinical event. Image B here is believed to be the first recorded ultrasound image of an intrafascicular injection.

References: 1. Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiol-06;105(4):779-83 2. Chan VW. An ultrasonographic and histologic study of intraneural injection and electrical stimulation in pigs. Anes & Anal-07;104(5):1281-4

Abstract 41

Medial to Lateral vs. Lateral to Medial Approach to US-Guided Supraclavicular Block: A Prospective Randomised Controlled Trial.

Presenting Author: Vandana Vaishnav, F.C.A.R.C.S.I., M.B.B.S., D.A. Presenting Author’s City, State: - Oakville, Ontario Co-Authors: Vincent Chan, M.D., F.R.C.P.C. - Toronto Western Hospital - Toronto, Ontario Danielle Shreves, M.D. - Toronto Western Hospital - Toronto, Ontario Anahi Perlas, M.D., F.R.C.P.C. - Toronto Western Hospital - Toronto, Ontario Richard Brull, M.D., F.R.C.P.C. - Toronto Western Hospital - Toronto, Ontario

Introduction: As we move into the centenary of the Supraclavicular Block (SCB), first demonstrated by Kulenkampff in 1911, we are still left to deal with unique challenges posed by the block. The Ulnar nerve still remains the â€˜Achilles Heelâ€™ for supraclavicular block and is most commonly spared nerve with this block .The ulnar nerve fibres (C8,T1) lie most close to subclavian artery over the first rib (â€˜corner pocketâ€™) and the nerve fibres are deep seated among brachial plexus fibres. As we master the technique of US guided SCB, two approaches have evolved over a period of time at the Toronto Western Hospital. These are namely, â€˜medial to lateralâ€™ approach and â€˜lateral to medialâ€™ approach for the SCB.The aim of this study is to evaluate the applicability of â€˜medial to lateralâ€™ approach vs â€˜lateral to medialâ€™ approach to access deeper C8,T1 fibres and translate it into the success of the ulnar nerve block at 30 minutes.

Methods: After the Institutional Ethical Board approval, patients scheduled for upper limb surgery (excluding shoulder) are randomised into two groups by computer generated table. The allocation concealment is maintained and all observations are recorded by a blinded observer. The procedure is carried out in the â€˜block roomâ€™. The US probe is placed in supraclavicular fossa in a coronal oblique plane in the neck. 30 ml of 50:50 mix of bupivacaine and lidocaine with 1: 200 000 epinephrine is injected at the â€˜corner pocketâ€™. Hydrodissection but not needle withdrawl is allowed.

Medial Approach: Block needle is advanced from the medial edge of the probe, under US beam, in medial to lateral direction, passing over the subclavian artery, and then taking a steep angle, pushing the subclavian artery medially and aiming towards the corner pocket.

Lateral Approach: Block needle is advanced from the lateral edge of the probe in lateral to medial direction along the long axis of probe under the US beam. The needle has to manoeuvre around brachial plexus fibres to reach the â€˜corner pocketâ€™ in front of the subclavian artery.

Results: 25 patients analysed for â€˜Medial' gp and 28 patients in â€˜Lateral'gp. The characteristics of patients do not differ in terms of age, gender, BMI, ASA status and type of surgery. The groups are not statistically different for ulnar nerve block success at 30 mins., Similarly, access to the â€˜corner pocketâ€™, block performance time, onset of sensory-motor block for each nerve and overall block success is not significant. Only finding close to significance is 'ease of perormance' which favours 'lateral' gp.1 pt had hemiperesis.

Conclusion: The study do not provide evidence for superiority of medial or lateral approach, for a successful ulnar nerve block. Results indicate, lateral approach may be easier to perform. The study is not powered to comment on safety profile of the 2 approaches.

Ref 1.Soares LG, Brull R, Lai J, Chan VW. Eight ball, corner pocket: the optimal needle position for ultrasound-guided supraclavicular block. Reg Anesth Pain Med 2007;32:94-95 2.Perlas A, Lobo G, Lo N, Brull R, Chan V, Karkhanis R. US guided SCB: Outcome of 510 cosecutive cases.RAPM 2009;34: 171-6

Additional File #1: ‘MEDIAL to LATERAL’ vs ‘LATERAL to MEDIAL’ APPROACH TO US-GUIDED SUPRACLAVICULAR BLOCK: A PROSPECTIVE RANDOMISED CONTROLLED TRIAL

PATIENT PROFILE GROUPS MEDIAL TO LATERAL TO P VALUE LATERAL MEDIAL (25) (28) AGE : MEAN (SD) 45.16 (16.26) 45.82 (16.43) 0.88 GENDER (M/F) 12/13 11/17 0.52 ASA (I/II/III) 13/10/2 14/13/1 0.74

BMI : MEAN (SD) 27.24 (5.38) 26.34 (5.29) 0.60 SURGERY SITE (HAND- 23/2/0 27/0/1 0.20 WRIST/FOREARM/ELBOW)

BLOCK CHARACTERISTICS MEDIAL TO LATERAL TO P VALUE LATERAL MEDIAL ULNAR BLOCK YES 23 23 0.42 SUCCESS @ 30 MINS NO 2 5

BLOCK PERFORMANCE TIME IN MINS : 11.44 (4.62) 11.32 (4.99) 0.92 MEAN (SD) EASE OF BLOCK EASY 9 19 0.05 PERFORMANCE MOD. DIFFICULT 14 7 VERY DIFFICULT 1 1 ‘CORNER POCKET’ YES 22 26 0.34 INJECTION NO 3 1 OVERALL BLOCK YES 21 22 0.61 SUCCESS @ 30 MINS NO 4 6 VAS PAIN SCORE DURING PROCEDURE 1.66 (1.50) 2.93(2.48) 0.26 MEAN (SD) OVERALL PATIENT SATISFACTION 9.60(0.70) 9.39(1.62) 0.53 SCORE: MEAN (SD)

SENSORY BLOCK ONSET: AV TIME IN MINS 12.20 (7.22) 13.75(6.75) 0.42 (SD)

MOTOR BLOCK ONSET : AV TIME IN MINS 9.20 (6.06) 8.04 (4.58) 0.43 (SD)

Additional File #2: ‘Medial to Lateral’ Approach

‘Lateral To Medial’ Approach

SUPRACLAVICULAR SCAN

Additional File #3: 3021910124205chart.doc Click here to view

FIRST RIB

PLEURA

SUBCLAVIAN ARTERY

CORNER POCKET

BRACHAIL PLEXUS NERVES

Abstract 42

Peripheral Nerve Injury After Total Hip Arthroplasty

Presenting Author: Hans P. Sviggum, M.D. Presenting Author’s City, State: - Rochester, MN Co-Authors: Adam K. Jacob, M.D. - Mayo Clinic College of Medicine - Rochester, MN Carlos B. Mantilla, M.D., Ph.D. - Mayo Clinic College of Medicine - Rochester, MN James R. Hebl, M.D. - Mayo Clinic College of Medicine - Rochester, MN

Introduction: Regional anesthesia (RA) techniques have been shown to improve outcomes after total hip arthroplasty (THA). One of the most debilitating complications following THA is postoperative nerve injury (PNI). Retrospective reviews have estimated the incidence of PNI following THA to range from 0.2% to 3%.(1-3) However, the overall incidence of neurologic complications after RA has been estimated between 0.03% and 3%, depending on the type of RA (e.g. neuraxial vs. peripheral nerve blockade).(4) The objective of this large-scale, single institution, retrospective cohort study was to test the hypothesis that the use of RA during elective THA does not increase the risk of PNI.

Methods: All patients aged â‰¥ 18 years that underwent elective THA surgery at Mayo Clinic from January 1, 1988 to July 1, 2007 were identified by retrospective query from the Mayo Clinic Total Joint Registry. Data including patient demographics, type of procedure, surgeon, type of anesthesia, use of peripheral nerve blockade (PNB), and postoperative details (including neurologic complications) were collected. The primary outcome variable was the presence of new PNI documented within 3 months of the procedural date. Cases of PNI were confirmed by manual chart review. The frequency of PNI was summarized using point estimates along with 95% confidence intervals (CI) calculated using the Poisson approximation. Age, sex, type of procedure (unilateral primary, unilateral revision, and bilateral primary), type of anesthesia (general, neuraxial, and combined general/neuraxial), and use of PNB were evaluated as potential risk factors for PNI using multiple logistic regressions.

Results: A total of 12,998 patients underwent elective THA during the study period and were included for review. After chart review, 93 cases met our criteria of PNI. The overall incidence of PNI was 0.72% (95% CI 0.58% to 0.88%) across all THA procedures. From a multivariable analysis, use of RA during elective THA was not associated with an increased risk of PNI. PNI was not associated with use of lower extreminty PNB (OR=0.64; 95% CI 0.35 to 1.18) nor type of anesthesia (OR=0.70; 95% CI 0.43 to 1.11 for neuraxial vs. general and OR=0.96; 95% CI 0.30 to 3.08 for combined vs. general). The risk of PNI was increased with revision surgery (OR=1.63; 95% CI 1.05 to 2.52; p 0.028) and with female gender (OR=1.65; 95% CI 1.08 to 2.53; p 0.022).

Discussion: The incidence of PNI (0.72%) is consistent with that reported previously for patients undergoing THA or RA. The risk of PNI after THA was unchanged by the use of any type of RA (neuraxial or PNB). The risk of PNI was increased in females and those undergoing revision surgeries. These results support the hypothesis that RA provides substantial outcome benefits to patients undergoing THA without increasing the risk of neurologic injury.

References: 1. Schmalzried T et al. (1997) Clin Orthop Relat Res 344:188-206, 2. Dehart M et al. (1999) J Am Acad Ortho Surg 7(2):101-11, 3. Farrell C et al. (2005) J Bone J Surg Am 87A(12):2619-25, 4. Brull R et al. (2007) Anesth Analg 104: 965-74.

Abstract 43

The Use of Regional Anesthesia in the Aftermath of the Haiti Earthquake

Presenting Author: Eric K. Shepard, M.D. Presenting Author’s City, State: - Baltimore, Maryland Co-Authors: Emilene Drager, C.R.N.A. - R Adams Cowley Shock Trauma Center - Baltimore, Maryland Tracy Wood, C.R.N.A. - R Adams Cowley Shock Trauma Center - Baltimore, Maryland

Background: On January 12, 2010 a magnitude 7.0 catastrophic earthquake struck Haiti resulting in over 250,000 deaths, and massive numbers of injuries. In the immediate aftermath, an estimated 10,000 emergency amputations were performed. With most of Port-Au-Prince hospitals heavily damaged, Haitian and foreign relief teams have been working with very limited resources in trying to help survivors. Our team has made extensive use of regional anesthesia to manage our patientâ€™s surgery and postoperative pain.

Setting: Hospital Francois De Salle is a Catholic hospital in downtown Port-Au-Prince. The earthquake destroyed more than half the hospital. Approximately 120 patients, families, and staff were killed in the quake. The operating rooms and supporting areas were also destroyed. The hospital reopened several days after the earthquake, with most of the medical staff coming from relief agencies. Makeshift operating rooms, no ventilators, no recovery facilities, and postoperative care provided mostly by families in outdoor tent wards, made perioperative management especially challenging.

Patient Data: In our first five days from February 5 â€“ 10, our team performed 41 surgeries on 39 patients. The majority of procedures were orthopaedic and soft tissue/wound related. The most common procedures performed were (in descending order) adjustment of external fixation devices, application of external fixation devices, open reductions and internal fixations, and wound debridements. Our operating room was a large multipurpose room converted to hold two OR tables and anesthesia machines. There was no high pressure oxygen for ventilators. The room was relatively open to the environment, with other non-OR functions being performed in the back of the room. There was no PACU, and patients who needed recovery had to remain on the OR table until stable to return to their tented wards. Postoperative pain control was usually limited to NSAIDs and acetaminophen, as oral narcotics are not used in Haiti. The absence of overnight nursing staff precluded the use of intravenous narcotics. Regional anesthesia accompanied by light or no sedation was utilized by our team in order to both eliminate the need for recovery, and provide postoperative pain relief. Of the first 41 cases performed by our team, there were 2 GAs (one peds and one failed spinal), 3 spinals, 11 MACs, and 26 regional anesthetics. A total of 37 peripheral nerve blocks were performed, the most common being popliteal (10), femoral (10) and supraclavicular (9). Two supraclavicular catheters were placed in patients having repeated procedures. All blocks except sciatic and spinal were placed under ultrasound guidance. There were no block failures among the peripheral nerve block patients.

Discussion: In the aftermath of a natural disaster, the provision of medical care is often very challenging due to the lack of equipment, physical plant, and personnel. In our experience, in the aftermath of the Haiti earthquake, we found the use of regional anesthesia to greatly facilitate surgical management, patient flow, and postoperative pain control. Medical relief agencies may want to consider the inclusion of regional anesthesiologists when designing their deployment teams.

Abstract 44

Selective Tibial Nerve Block Provides Effective Pain Control Without Footdrop in Patients Having Total Knee Arthroplasty.

Presenting Author: Sanjay K. Sinha, M.D. Presenting Author’s City, State: - Hartford, CT Co-Authors: Jonathan H. Abrams, M.D. - St.Francis Hospital and Medical Center - Hartford, CT Sivasenthil Arumugam, M.D. - St.Francis Hospital and Medical Center - Hartford, CT John D'Alessio, M.D. - St.Francis Hospital and Medical Center - Hartford, CT Robert S. Weller, M.D. - Wake Forest University School of Medicine - Winston-Salem, NC

Introduction: Previous studies have shown that the addition of sciatic nerve(n) block to femoral n block provides superior analgesia in patients having total knee arthroplasty (TKA) (1). However, sciatic n block including the common peroneal component generally results in paresis or paralysis of dorsiflexion (footdrop). Peroneal n injury is a rare but well documented risk after TKA, usually manifesting as a postoperative footdrop with an incidence of 0.3%-10% (2). Since a potential delay in diagnosing peroneal n palsy due to surgery in patients with sciatic n block exists, surgeons may request no pre-operative sciatic n block for analgesia in their TKA patients. This prospective, randomized, observer-blinded study was designed to determine if placing a selective tibial n block in the popliteal fossa will avoid foot drop, but still provide post-operative analgesia comparable to patients who receive sciatic n block.

Methods: Patients scheduled for primary TKA gave written consent to participate in this IRB- approved study. Patients with pre-existing valgus deformity, flexion contracture, neuropathy or diabetes were excluded. Patients were randomized by sealed envelopes to receive either a sciatic n block (SN group) or selective tibial n block (TN group). All patients were premedicated as per our multimodal analgesia regimen (Table 1). An ultrasound guided continuous femoral n block was placed with 15ml of ropivacaine 0.5%. Patients randomized to SN group received an ultrasound-guided sciatic n block just proximal to the bifurcation of the sciatic n while patients in the TN group received a tibial n block below the bifurcation and close to the popliteal crease. Sufficient ropivacaine 0.5% was injected to encircle the target nerve, up to 20ml. General anesthesia was supplemented with fentanyl or hydromorphone if needed. In the PACU, sensorimotor function was tested by blinded PACU nurses including dorsiflexion, plantarflexion, and sensation to cold (alcohol swab) on the planter aspect and dorsum of foot using a three point scale (0=normal, 1=decreased and 2=absent). Foot drop was defined as the inability to dorsiflex the foot against gravity. Standard analgesia protocol was continued post surgery(Table 1). Pain scores and narcotic consumption in PACU and 24 hours after PACU discharge were tracked.

Results: This data describes the results of 53 patients recruited to this study to date. There were no differences in the demographic variables. A higher volume of ropivacaine (15.2 vs 9.5ml) was injected in the SN group (Table 2). No patient in the TN group, while 80% of patients in SN group demonstrated footdrop(p<0.001)(Figure 1). Pain scores and narcotic consumption after surgery were similar between groups.

Discussion: Preliminary results suggests that selective tibial n block provides equivalent analgesia in conjunction with femoral n block without causing footdrop. The ability to monitor peroneal n function after surgery is a distinct advantage of selective tibial n block over sciatic n block.

References 1.Cook, P:The Journal of Arthroplasty.2003;18:583-586 2.Nercessian, O: The Journal of Arthroplasty.2005;20:10

Additional File #1:

Table 1. Multimodal Analgesia Regimen Pre-medication Celecoxib 200mg Pregablin 50m

Post-surgery Oxycodone time-release (OxyContin®) 10mg every 12 hours Celecoxib 200mg every 12 hours Pregablin 50mg every 12 hours Acetaminophen 975mg every 6 hours Ropivacaine 0.2% infusion at 6ml/h via Femoral nerve catheter for 2 days

Break-through pain (prn) Oxycodone 5mg for mild pain Oxycodone10mg for moderate pain I.V. Hydromorphone 0.5mg to 1.0mg for severe pain

Additional File #2: Table 2. Patient Demographics , Pain scores and Narcotic Consumption

Tibial Nerve (TN) Sciatic Nerve (SN) Significance Group Mean(SD) Group Mean(SD) “p” value Number of patients 28 25 Age (years) 66.9(8.9) 64.6(9.7) 0.375 Sex (F/M) 13/15 17/8 0.166 Height (cm) 170.6(11.9) 165.5(12.0) 0.131 Weight (kg) 90.6(19.8) 82.7(22.7) 0.184

Block site-Distance from 1.6(1.2) 9.0(3.3) <0.001 popliteal crease(cm) Volume of ropivacaine(ml) 9.5(1.6) 15.2(1.0) <0.001

Intra-op Fentanyl(mcg) 73.2(50) 64(53) 0.554 Intra-op 0.7(0.7) 0.5(0.6) 0.262 Hydromorphone(mg)

PACU Admission Pain 2.7(3.5) 2.1(3.1) 0.518 Score PACU Discharge Pain score 0.9(1.4) 0.6(1.0) 0.885 PACU – i.v. 0.3(0.5) 0.2(0.4) 0.306 Hydromorphone(mg)

Floor pain -6 hours 1.5(2.0) 0.8(1.6) 0.134 Floor pain -12 hours 1.4(1.8) 0.6(1.1) 0.069 Floor pain -18 hours 1.4(2.1) 1.6(2.4) 0.702 Floor pain – 24 hours 1.9(2.2) 1.6(1.7) 0.502

Floor- Oral Oxycodone(mg) 11.8(10.3) 9.0(8.5) 0.287 Floor –Intravenous 0.1(0.4) 0.4(0.9) 0.242 Hydrocodone(mg)

Additional File #3: Figure 1. Dorsiflexion and Peroneal Sensation in PACU. (SN =sciatic nerve group, TN = tibial nerve group

Abstract 45

Bevel Direction of Epidural Needles Reliably Predicts Direction of Catheter Placement and Contrast Spread in Human Cadavers: Results of a Pilot Study

Presenting Author: Andrew G. Kaufman, M.D. Presenting Author’s City, State: - Newark, New Jersey Co-Authors: Naum Shaparin, M.D. - UM.D.NJ - New Jersey Medical School - Newark, New Jersey Faraz Chaudhry, M.D. - UM.D.NJ - New Jersey Medical School - Newark, New Jersey

Backround: Sacral nerve root coverage during lumbar epidural anesthesia has been shown to be more effective when the epidural catheter is threaded caudad rather then cephalad. However, the reliability with which catheter direction can be predicted based on bevel direction in the epidural space is not clear. In addition, the reliability of caudal fluid spread once the catheter is placed in the caudal direction is also unclear. In this study the direction of the catheter placement and subsequent direction of fluid flow based on bevel direction were evaluated in human cadavers with the use of radiographic imaging and radiographic contrast.

Methods: After obtaining approval from our Institutional Ethics Committee, eight human cadavers were obtained from the medical school anatomy laboratory. The cadavers were turned prone and remained in the prone position for the duration of the study. The epidural spaces were accessed using 18 guage Tuohy needles with the needles directed perpendicular to the skin using the loss of resistence to air technique. Prior to that, the cadavers were randomized into two groups, Group I had the bevel turned cephelad and Group II had the bevel turned caudad during access of the epidural space. Once the Tuohy needle was in the epidural space an epidural catheter was threaded 4cm. After catheter placement, radiopaque contrast was injected and the direction of catheter placement as well as the direction of the contrast spread was imaged and recorded.

Results: In group I, three of the four cadavers had the catheter in the cephalad direction with the contrast spread primarily cephelad. Due to technical difficulties we were unable to access the epidural space on the fourth cadaver. In group II, the epidural catheter was directed caudad in all four cadavers. The radiopaque contrast was visualized spreading primarily in the caudad direction in 3 cadavers and equally cephelad and caudad in the remaining cadaver.

Conclusion: Orientation of the needle bevel reliably predicts the direction of the catheter placement and to a significant extent the direction of fluid flow in the epidural space.

References: 1) Chou,W-Y, Hsu, C-J., Cheng, J-T. Anesthetic effect of epidural anesthesia with cephalad or caudad catherization for ankle surgery or hemmorrhoidectomy. Acta Anaesthsiol. Scandia. 2005;49 406-410

2) Park WY, Poon KC, et.al. Direction of the needle bevel and epidural spread. Anesthesiology 1982; 57:327-8.

Abstract 46

Air vs. Saline and Analgesic Efficacy for Labor

Presenting Author: Jamie Wingate, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: E. David Bravos, M.D. - Johns Hopkins University - Baltimore, M.D. Calvin Eng, M.D. - Johns Hopkins University - Baltimore, M.D. Kanupriya Kumar, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Air and saline are commonly used for the loss-of-resistance during identification of the epidural space. However, the overall analgesic efficacy of air versus saline for use during the loss-of- resistance during identification of the epidural space is unclear. We have performed a meta-analysis to further examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. Systematic literature searches of the National Library of Medicineâ€™s PubMed and EMBASE databases were conducted using terms related to air, saline, epidural, and loss of resistance. Only randomized controlled trials comparing air with saline or local anesthetic were included for analysis. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles. There was no restriction on language for inclusion. Meta-analysis was performed using the Review Manager 4.2.10 (The Cochrane Collaboration, 2004). A random effects model was used.

Results: The literature search yielded 6 articles which met all inclusion criteria. There were a total of 185 subjects for the air group and 188 for the saline group. We were able to obtain pooled estimates for unblocked segments, need for additional medications, and replaced catheters. We found use of air was associated with an increased risk for unblocked segments [Relative risk (RR): 2.12 (1.07, 4.21] but there was no difference with regard to replaced catheters [odds ratio (OR): 0.68 (0.25, 1.87)] or additional medication [OR: 1.59 (0.78, 3.24)].

Conclusions: Our pooled analysis examining the analgesic efficacy of air versus saline/local anesthetic for loss-of-resistance for abdominal surgery during identification of the epidural space revealed that use of air results in decreased analgesia in one parameter (unblocked segments) but not others (additional medications, replaced catheters). The results should be interpreted with caution and certainly further examination with larger RCT is warranted as the overall number of subjects is relatively small.

Abstract 47

P2Y12 Assay of the Residual Antiplatelet Activity of Clopidogrel

Presenting Author: Honorio T. Benzon, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Benzon A. Hubert, M.D. - Northwestern University - Chicago, Illinois Kendall C. Mark, M.D. - Northwestern University - Chicago, Illinois

Introduction: ASRA recommends the discontinuation of clopidogrel for 7 days before a neuraxial injection (1). We investigated the residual antiplatelet activity of clopidogrel with the PFA II test and the new point-of care P2Y12 assay.

Methods: The study was approved by our IRB and informed consent was obtained from every patient. Patients scheduled to have their clopidogrel discontinued before a neuraxial injection had their blood drawn for the PFA II and P2Y12 assays at the following times: a) baseline; b) 3 days; c) 5 days; and d) 7 days after discontinuation of the clopidogrel. The PFA II was determined by the platelet function analyzer (PFA) II (Dade Behring, Inc., Deerfield, Illinois) while the P2Y12 values were determined by the P2Y12 assay (VerifyNowR, Accumetrics, San Diego, CA).

Results: Three patients completed the study. The % inhibition in all the patients was less than 10% at the 7th day of discontinuation of clopidogrel (table). The PFA II was prolonged in one of the patients at the seventh day (normal: 58-171 seconds).

Table. Results of P2Y12 Assay and PFA II After Discontinuation of Clopidogrel Patient Baseline 3rd Day 5th Day 7th Day 1 P2Y12 (PRU) 287 276 340 354 % Inhibition 18% 26% 16% 0% PFAII (sec) 78 69 103 71 2 P2Y12 (PRU) 94 173 67 211 % Inhibition 58% 27% 13% 6% PFAII (sec) >300 115 81 83 3 P2Y12 (PRU) 251 312 333 323 % Inhibition 24% 15% 9% 0% PFAII (sec) 194 229 294 255

PRU: Platelet Reaction Units

Discussion: The P2Y12 assay is more sensitive than the PFAII as a test for residual antiplatelet activity of clopidogrel (2). We showed that at 5 days after discontinuation of clopidogrel the percent platelet inhibition was less than 10% , a % inhibition that is considered as a â€œnon-responderâ€ (3). The CURE trial showed that perioperative bleeding is less at 5 days after clopidogrel is stopped (4). Based on the CURE trial, it has been postulated that 5 days of discontinuation maybe adequate (5). Other studies showed that 7 days of discontinuation of clopidogrel may not be necessary. There is a case report of a safe removal of an epidural catheter in a patient 24 hours after the stoppage of clopidogrel (6), a report of an uneventful caudal steroid injection 5 days after discontinuation of clopidogrel (7), and a report of an uneventful spinal anesthesia 5 days after discontinuation of the clopidogrel (8). Based on a study in volunteers (9), the newly released Nordic anticoagulation guidelines stated that 5 days is adequate (10). Our initial results, in the clinical setting, show that 5 days maybe adequate. The performance of neuraxial injections on the earliest day that is considered safe after discontinuation of clopidogrel balances the risk of spinal hematoma against the development of myocardial infarction or stroke.

References: 1. Horlocker TT. Reg Anesth Pain Med 2010;35:64-101 2. Panicia R. Thromb Haemost 2007;5:1839-47 3. Muller I. Thromb Haemost 2003;89:783-7 4. Fox KAA. Circulation 2004;110:1202-8 5. Lecompte T. Can J Anaesth 2006;53:S103-12 6. Bergman L. Reg Anesth Pain Med 2007;32:354-7 7. Broad L. Br J Anaesth 2007;98:19-22 8. Benzon HT. Reg Anesth Pain Med 2010;35:115 9. Weber A. Br J Clin Pharmacol 2001 ;52 :333-6 10. Breivik. Acta Anaesthesiol Scand 2010;54:16-41

Abstract 48

Intrathecal Analgesia for Refractory Pain

Presenting Author: Mohammed Alhujairi, M.D., F.R.C.P.C. Presenting Author’s City, State: - Verdun, Quebec Co-Authors: Gerard Huni, M.D.CM - McGill University - Montreal , Qc David Bracco, M.D. - McGill University - Montreal , Qc Juan Francisco Asenjo, M.D. - McGill University - Montreal , Qc

Introduction: The WHO ladder for pain management in cancer is the corner stone in treating this symptom in oncology patients. Between 10 and 15% of them will experience significant side effects or will not achieve comfort with WHO-level III and coadjuvants. Interventional measures are required in this case to alleviate this group or to control their intolerable side effects. Intrathecal pain techniques are part of the armamentarium to conquer pain control. We report here our experience with intrathecal analgesia over the last five years.

Method: The charts from all patients that received prolonged intrathecal analgesia over the last five years (June 2004 to December 2009) were reviewed and the data was collected. Demographic and medical information pertinent to the implant of an intrathecal device was examined. We focused our interest in pain control, decrease in opioid requirements and their side effect, quality of life and complications of intrathecal catheter placement or its infusion solution, immediately post implant, 2-4 weeks, 6-8 weeks and 20-24 weeks after the procedure

Results: Between 2004 and 2009, 2173 pain procedures were done by a senior author, of those procedures 51 cases had an intrathecal catheter or pump placed. 49 cases were related to advanced cancer, one for a phantom limb pain and another for failed back surgery syndrome All catheters were successfully implanted without complications related to the procedure. No catheter/reservoir related complication was recorded during the period in use. In the first 24 hours intrathecal therapy improved pain scores by 5 to 10 points (VAS 0-10) in 76% of the patients. At 6-8 weeks follow-up, 40% had total pain relief and an additional 52% had 5 points or more improvement. Only one patient out of 51 did not improve following intrathecal analgesic administration. In all other patients the pain decreased from 7 to 10 before the intervention to 5 or less at 6-8 weeks or last follow-up. 46% of patients had a quality of life improvement of 100% and another 48% of patients improved by 50% or more at 2-4 weeks. At 2-4 weeks the opioid requirement decreased by a median of 80%. At 2-4 weeks, 82% were opioid side-effects free. Side effects of intrathecal medication were transient lasting 1 to 3 days. Only one patient exhibit an unclear lower limb weakness, lasting 3 months possibly due to a combination of disease related deconditioning and local anesthetic effect

Discussion: Refractory pain in palliative patients can be well controlled with intrathecal medication. This route significantly improved quality of life, decreased narcotic consumption and itâ€™s related side effects. Intrathecal medication side effects were uncommon and transient in this series.

Since the advent of implantable IT drug delivery systems over 25 years ago, numerous advances have been made with regard to system technology,pharmacology, and patient selection. Whereas strong evidence exists for the use of IT therapy for cancer pain, the evidence supporting long-term efficacy in noncancer pain is less convincing. However, in carefully selected patients

The results presented here are encouraging and the palliative care team in our institution have been very interested and supportive of collaborating with us.

Additional File #1: Parameter Median (interquartiles)

Age (years) 63 (31 - 89)

Sex 35 M / 16 F

Pain type Neuropathic: 47% Somatic: 20% Mixed: 33%

Location of pain Back: 39% Ribs/chest wall: 28% Pelvis/hip: 10% Lower limb: 10% Upper limb: 6% Abdomen: 6%

Catheter tip location (Fluoroscopy) Median T8 (IQ T7 – T10)

Type of intervention Portacath 68.5% Catheter 27.5% Pump 4%

Intrathecal medication (total exceed 100%, most Local anesthetics: 61% patients received combination) Opioids: 96% Baclofen: 24% Clonidine: 2%

VAS post catheter Pre-insertion: 9 (7 - 10) Immediate: 2 (0 - 4) 2-4 weeks: 1 (0 - 2) 6-8 weeks: 1(0 - 2) 20-24 weeks: 1 (0 – 2)

VAS improvement Immediate: 6 (0 - 10) 2-4 weeks: 8 6-8 weeks: 9 20-24 weeks: 7

Narcotic requirement decrease Immediate: -60% (30 – 80%) 2-4 weeks: -70% (-40 - -100%) 6-8 weeks: -100% (-50% - -100%) 20-24 weeks: -100% (-90 - -100%)

Duration of infusion [days] Cancer patients (n=49): 30 (4 - 382) Non cancer patients (n=2): 835 - 1967

Side effects of intrathecal medication Lower limb weakness/numbness: 9 Decrease in level of consciousness: 3 Decrease in respiratory rate: 1 Urinary retention: 1 Nausea: 1

Abstract 49

Continuous L2 Paravertebral Block vs. Continuous Lumbar Plexus Block for Postoperative Analgesia after Total Hip Arthroplasty: A Blinded Interim Analysis

Presenting Author: Richa Wardhan, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Antonio Bonilla, M.D. - UPMC - Pittsburgh, PA Sylvia Wilson, M.D. - UPMC - Pittsburgh, PA Bruce Ben-David, M.D. - UPMC - Pittsburgh, PA Chelly E. Jacques, M.D., Ph.D., M.B.A. - UPMC - Pittsburgh, PA

Background: Lumbar plexus block has long been an accepted technique for pain management after THR. It provides effective analgesia for total hip arthroplasty, reducing intra- and postoperative opioid requirements. (Stevens, et al., 2000).And while mostly favorable postoperative analgesia has been demonstrated over intravenous opiods, these blocks may not produce effective postoperative analgesia or may lead to excessive motor blockade(Chudinov, et al., 1999). Motor blockade is deleterious following hip surgery as it will inhibit progress with postoperative physical therapy and ambulation and may predispose to patient falls. Recently the use of a L2 paravertebral block has been described as an effective postoperative analgesic technique in the case of hip arthroscopy (Lee, et al., 2008). The purpose of this study is to prospectively compare these two approaches to blockade of the lumbar plexus with respect to the associated morphine consumption and motor blockade.

Method: After approval by the Institutional Review Board, 16, ASA I-III patients aged 18-75 years, with BMI less than 40, meeting inclusion criteria were recruited and randomized to one of the two study groups on the day of surgery. These patients were scheduled to undergo elective primary hip replacement surgery all by one orthopedic surgeon at UPMC-Shadyside Hospital in Pittsburgh, PA The study groups are defined as: a. Group I: L2 Paravertebral approach group (n=7) b. Group II: Posterior Lumbar Plexus approach (n=9).

The nerve blocks were performed as indicated. Continuous catheters were placed in both the groups. Adequate block was tested after 20 minutes. The anesthetic regimen for both groups was identical using spinal anesthesia.In the recovery room, bupivacaine 0.0625% was started at 10 ml/h. The patients in both groups were also be given access to PCA Morphine (1 mg bolus, 8 minutes lock out, no basal infusion, 6 mg one hour limit) once verbal pain score is < 4.. PCA morphine was continued for 24 hours.

Once on the floor, additional pain relief was available via nurse-administered 5 ml boluses of bupivacaine 0.0625% via catheter pump given no more than hourly. In addition, nurse-administered intravenous bolus of Morphine 3 every 30 min as needed up to 2 doses while the patient has a PCA was ordered. Morphine consumption, pain scores TUG test along with motor/sensory examination were recorded 24hours after completion of surgery. The timed get up and go test is a measurement of mobility, For the test, the person is asked to stand up from a standard chair and walk a distance of approximately 10 feet (measure as 3 meters), turn around and walk back to the chair and sit down again. The time taken to complete the task are noted.

Result: No significant differences were detected between the lumbar plexus and L2 paravertebral groups in 24-h pain scores during PT (visual analogue scale, 5.8 Â± 2.77 mm vs. 5.6 Â± 3.05 mm ( P >0.05 ). Mean morphine usage in the lumbar plexus group was 28.1 Â± 17.32 mg compared with 26.2Â± 19.80 mg in the L2 Paravertebral group (P >0.05).Mobility as assessed by the TUG(timed up and go) test performed by physical therapy was similar between groups(78.9 Â± 27.73 vs 92.2 Â± 18.24 sec).

Discussion: Combined L1, L2 single shot paravertebral blocks were performed and evaluated by Lee et al in hip arthroscopy patients to facilitate pain control and mitigate hip flexor/quadriceps weakness, commonly observed with a lumbar plexus block.In this study we are attempting to compare these two techniques by using continuous L2 paravertebral and lumbar plexus block in total hip replacements.

Conclusion: This study demonstrates that L2 Paravertebral and lumbar plexus blocks provide a similar postoperative analgesia in patients undergoing THR. L2 paravertebrals were associated with less motor weakness when compared to the Lumbar plexus group.

Capdevila, X., Macaire, P., Dadure, C., Choquet, O., Biboulet, P., Ryckwaert, Y. and D'Athis, F., (2002). 'Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation'. Anesth Analg, 94 (6):1606-1613,

Chudinov, A., Berkenstadt, H., Salai, M., Cahana, A. and Perel, A., (1999). 'Continuous psoas compartment block for anesthesia and perioperative analgesia in patients with hip fractures'. Reg Anesth Pain Med, 24 (6):563-568.

Lee, E.M., Murphy, K.P. and Ben-David, B., (2008). 'Postoperative analgesia for hip arthroscopy: combined L1 and L2 paravertebral blocks'. J Clin Anesth, 20 (6):462-465.

Marino J, Russo J, Herenstein R, Kenny M, Chelly JE. Continuous psoas compartment block vs. continuous femoral block or PCA for total hip arthroplasty. J Bone Joint Surg Am. 2009 ;91:29-37 Mannion, S., O'Callaghan, S., Walsh, M., Murphy, D.B. and Shorten, G.D., (2005). 'In with the new, out with the old? Comparison of two approaches for psoas compartment block'. Anesth Analg, 101 (1):259- 264

Stevens, R.D., Van Gessel, E., Flory, N., Fournier, R. and Gamulin, Z., (2000). 'Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty'. Anesthesiology, 93 (1):115-121.

Abstract 50

The Analgesic Efficacy of Transversus Abdominis Plane Blocks in Ileostomy Takedowns

Presenting Author: Kristopher M. Schroeder, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Corey A. Amlong, B.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Jocelyn Blake, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI Seungbong Han, M.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Melanie J. Donnelly, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI

Introduction: Transversus abdominis plane (TAP) blocks have shown promise in reducing post-operative pain in multiple surgeries involving abdominal incisions. This regional technique involves injecting local anesthetic into a potential space between the internal oblique and transversus abdominis muscles, thus blocking the sensory afferents from T10-L1 to the anterior abdominal wall. TAP blocks are relatively simple to perform and have been rare reports of morbidity associated with them, making them an ideal analgesic adjunct for patients undergoing procedures involving abdominal incisions that do not warrant an epidural.

Methods: Following IRB approval, the charts of 69 consecutive adult patients undergoing ileostomy takedown between November 2008 and December 2009 were reviewed. Thirty-one of these patients received a preoperative ultrasound-guided TAP block and 38 received no TAP block. Following intravenous sedation with midazolam and fentanyl, TAP blocks were performed on the same side as the ileostomy under ultrasound guidance. A 100 mm, 21 gauge needle was inserted using an â€œin plane approachâ€ between the internal oblique and transversus abdominis muscles and 20-30 mL of 0.25% Bupivicaine with 1:400 mcg epinephrine was injected. Patients then received a general anesthetic for the surgical procedure. All but one patient received a PCA upon admission to the floor postoperatively. Statistical analysis was a multiple regression analysis based on the generalized linear model with gamma distribution assumption that adjusted for intraoperative subcutaneous bupivicaine use.

Results: Similar demographics were noted between the two groups. (Table 1) Patients receiving TAP blocks were less likely than the control group to have their wounds infiltrated with local anesthetic intraoperatively (19% v 68%, p < 0.001). Opioid consumption in the post-anesthesia care unit (PACU) was significantly lower in patients who received a TAP block than in those who did not (6.83mg v 13.21mg, adjusted p = 0.003). Furthermore, patients who received TAP blocks had lower mean postoperative numerical pain scores both in the PACU (3.4 v 4.5, adjusted p = 0.015) and for the first 24 hours after surgery (2.9 v 3.8, adjusted p = 0.019) as well as lower initial pain scores on arriving to the PACU (2.3 v 4.3, adjusted p = 0.013). 24-hour postoperative opioid consumption was also lower in the group receiving TAP blocks (59.7 mg v 104 mg, adjusted p = 0.01). Our analysis yielded no statistical difference in the amount of time patients spent in the PACU or the duration of the patientâ€™s hospital stay. (Table 2)

Discussion: Here we present for the first time evidence that TAP blocks show analgesic efficacy in patients undergoing ileostomy takedowns. TAP blocks are an ideal analgesic adjunct for these patients who are not good candidates for epidurals. While the present study is obviously limited by its retrospective nature, it opens the door for further study of this promising regional block in patients who receive reversal of their ileostomy. We plan to further investigate the analgesic efficacy in these patients with a prospective, double-blinded randomized control trial in the future.

Additional File #1: Patient Characteristics Median, Mean (SD) P-Value* Age 50, 46.6 (15.2) 44, 43.8 (16.8) 0.375 BMI 24.1, 27.2 (6.8) 23.5, 26.2 (7.6) 0.323 Pre-op Baseline Pain Score 0, 0.3 (1.1) 0, 0.3 (1.2) 0.847 (VRS 0-10)

Count(%) P-Value** Sex Male 14 (54.8) 20 (52.6) 0.95 Female 17 (45.2) 18 (47.4)

ASA Score 1 1 (3.2) 3 (7.9) 0.86 2 23 (74.2) 27 (71.1) 3 7 (22.6) 7 (18.4) 4 0 (0) 1 (2.6)

Intraoperative SQ Bupivicaine Administration Yes 6 (19.4) 26 (68.4) < 0.001 No 25 (80.6) 12 (31.6)

Wilcoxon Rank Sum Test ** Fisher's Exact Test

Additional File #2: Outcome Data Opioid Administration Control TAP n=31 n=38 P-Value Univariate Adjusted Median, Mean (SD) Test* ** Intraoperative IV 27.7, 26.3 Morphine 16.7, 19.2 (9.1) (9.6) 0.003 0.002 Equivalents (mg)

Intraoperative IV 27.7, 26.3 Morphine Equiv 23.3, 23.8 (9.6) (9.6) 0.429 0.224 including opioids administered during block placement (mg)

Total PACU IV 6.7, 6.8 (6.8) 11.3, 13.2 0.017 0.003

Morphine (11.2) Equivalents (mg)

50.7, Total 24-hour Post-op 104.0 IV 48, 59.7 (61.3) (146.1) 0.198 0.01 Morphine Equivalents (mg)

Numerical Patient- Reported Pain Scores Control TAP n=31 n=38 P-Value Univariate Adjust Median, Mean (SD) Test* ed** Immediate PACU Pain 4, 4.3 Score (0-10) 0, 2.3 (2.8) (3.3) 0.012 0.013

Peak PACU Pain Score (0-10) 6, 5.1 (3.1) 6, 6 (2.7) 0.308 0.028

Mean PACU Pain Score 4.3, 4.5 (0-10) 3.7, 3.4 (2.2) (2.3) 0.098 0.015

3.6, 3.8 Mean 24-hour Post-op 2.7, 2.9 (1.8) (1.7) 0.021 0.019 Pain Score (0-10)

Outcome variables compared using Wilcoxon rank sum test **Adjusted model with outcome variables adjusted for amount of intraoperative local anesthetic administered by surgeon

Abstract 51

Combination Electrochemical Therapy (CET) to Treat Patients with Diabetic Neuropathy

Presenting Author: Cynthia R. Cernak, D.P.M. Presenting Author’s City, State: - Kenosha , WI Co-Authors: Robert H. Odell, Jr. M.D., Ph.D. - New Vision Pain Mamnagement - Las Vegas, NV Elizabeth Marriott, M.D. - Aurora Healthcare System - Milwaukee, WI Briana Silvani, R.NSC.T, R.EDT - SE Wisconsin Surgical Suites, S.C. - Kenosha, WI

Background: Diabetic Peripheral Neuropathy (DPN) is a major cause of morbidity in patients with diabetes. Available treatment options offer limited efficacy and potential side effects.This growing problem requires new approaches.

Electronic signal treatment (EST) utilizes computer controlled, exogenously delivered specific parameter electroanalgesia using both varied amplitudes and frequencies of electronic signals. EST is delivered with local anesthetic injections, termed combination electrochemical treatment (CET). CET is effective to treat neuropathic pain related to DPN.

CET suppresses axonal pain signals both electrically and chemically, decreases peripheral sensitization to break the pain cycle, facilitates and optimizes normal metabolic and reparative processes, suppresses edema,reduces inflammation,improves circulation, decreases central sensitization by altered gene expression in dorsal horn neurons and supports the immune system.

Objective: To evaluate safety and efficacy of CET in DPN patients

Methods: 32 DPN patients were enrolled in an open-label trial that combined peripheral nerve injections using 0.25% marcaine with patented programmed electroanalgesia described above. Patients received 4 weeks of therapy,each week containing three 25 minute sessions of electroanalgesia with 2 of 3 weekly sessions including nerve blocks.

Results: 19 males and 13 females were enrolled with a mean age of 69.4. Patients complained of sensory pain including numbness, tingling, RLS and burning pain that limited daily activities. 24 of 32 patients evaluated reported a mean reduction of symptoms from baseline of 49%. 8 patients (25%) reported no relief.Post-treatment quality of life benefits included improved pain-free sleeping, balance, walking and enhanced ability to exercise.Pre and post Nerve Conduction Velocity (NCV) exams were given to a subset of 10 patients.These case studies document improvement of NCV studies after 4 weeks of CET.Some patients demonstrated recordable motor nerve conduction amplitudes.No patients suffered any adverse effects.

Discussion: Pre and post treatment NCV has shown measurable objective improvement,findings which the authors believe offer substantive proof of the potential for this technology.While more data is needed the CET protocol appears to treat the underlying causes of DPN and positively aids in the reversal of sensory and motor pathophysiology.

Most neurologists agree that the main pathophysiology of nerve damage due to diabetes includes axonal nerve damage.CET seeks not only to relieve patient discomfort due to the painful neuropathy, but also to help restore nerve function.In some patients there was recordable improvement in the amplitude of motor nerve conductions,indicating improvement of axonal function,thus improvement in motor function and decreased neurological morbidity. CET is safe,with risk limited to the local anesthetic injections,with no risk from the electrical signals.

Conclusion: DPN patients showed marked symptom and motor function improvement with this safe technology.Patient follow-up will be provided to better understand the long-term effects of CET on sensory and motor function.The outcomes discovered are exciting since there are limited treatment alternatives.

Abstract 52

A New Approach to Interscalene Blockade of the Brachial Plexus

Presenting Author: Aric S. Jorgenson, M.D. Presenting Author’s City, State: - Charlottesville, VA Co-Authors: Paul H. Ting, M.D. - University of Virginia - Charlottesville, VA David C. Scalzo, M.D. - University of Virginia - Charlottesville, VA Antonakakis G. John, M.D. - University of Virginia - Charlottesville, VA Zhiyi Zuo, M.D. - University of Virginia - Charlottesville, VA

Abstract Body: The interscalene approach to the brachial plexus is one of the most frequently utilized regional anesthetic techniques in our armamentarium. Commonly employed ultrasound-guided approaches call for the block needle to penetrate the fascia of the middle scalene muscle in order to enter the fascial plane between the anterior and middle scalene muscles, defined on surface anatomy as the â€œinterscalene groove.â€ This places the needle in extremely close proximity to the plexus and is associated with a risk of paresthesia. We have developed a technique in which the block needle is moved from posterior to anterior and positioned within the substance of the middle scalene muscle, without attempting to penetrate the muscle fascia. The needle tip is positioned approximately two thirds of the way through the muscle, where local anesthetic is administered.

Methods: In this preliminary study, we randomized 22 patients undergoing outpatient shoulder surgery to receive either 15 ml of 0.5% ropivacaine deposited via the traditional method between the middle and anterior scalene muscles at the level of the presumed C5 and C6 nerve roots, or 15 ml 0.5% ropivacaine into the substance of the middle scalene muscle. Time to first pain was collected, as well as total morphine equivalents required during the first 24 hours after discharge. Additionally, motor and sensory exam information was collected before the procedure and 60 minutes after arrival in PACU. Lastly, diaphragmatic function was evaluated via ultrasound and pulmonary function tests to determine whether this technique resulted in less diaphragmatic paralysis than the conventional approach.

Results: Time to first pain was 595 minutes in the study group and 656 minutes in the control group (p=0.27), Difference in 24 hour morphine equivalent use was also not significant between control and study groups (17.35 and 17.76 respectively), There was no difference in diaphragmatic function. One patient in each group had diaphragmatic sparing. There were no differences in sensory or motor exam detected between groups. No paresthesias were noted in the intervention arm, while one occurred in the control arm.

Conclusion: Deposition of local anesthetic into the middle scalene muscle results in effective interscalene blockade for postoperative analgesia. Though a trend towards decreased duration of action was noted, this decrease is not likely clinically significant. Given the intention to maintain distance between the needle and the brachial plexus, this technique may offer a lower likelihood of paresthesia and the possibility of an improved safety profile.

Abstract 53

The Utility of Lumbar Paravertebral Nerve Blocks in Guiding Surgical Management of Chronic Pain Following Open Inguinal Hernia Repair

Presenting Author: Luke Stoltzfus, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Kristopher Schroeder, M.D. - University of Wisconsin - Madison, WI

Introduction: Peripheral nerve blocks are commonly performed to aid in the diagnosis of post-operative pain syndromes. Inguinodynia (groin pain) is a common complication of open inguinal hernia repair due to injury or entrapment of the Ilioinguinal or Genitofemoral nerve or neuroma formation. Standard Ilioinguinal nerve blocks may not be feasible diagnostic tools in many of these cases due to transection and displacement of the involved nerve away from the anatomical landmarks required to perform the block. In these situations, paravertebral nerve blocks can be performed to help identify the involved nerve and guide treatment decisions.

Case Presentation: A 22-year-old male with a history of a right ventral hernia repair and Ilioinguinal nerve transection presented to our institution with a history of chronic right groin pain and testicular pain refractory to conservative management. The patient underwent exploration of his right inguinal region with neurolysis of the Ilioinguinal nerve. Approximately eight centimeters of the Ilioinguinal nerve was then mobilized, tunneled superiorly and buried within the external oblique muscle in the right lower quadrant. The patient reported minimal pain relief from this procedure. The following month, he was readmitted with persistent right groin pain and he underwent a repeat exploration of his inguinal hernia repair site with transection of the Genitofemoral nerve. He noted complete resolution of his right groin pain following this procedure.

Approximately six months later, the patient returned with complaints of progressive, â€œburningâ€ right lower quadrant pain. Non-neurologic sources of right lower quadrant pain were ruled out and he was readmitted to the surgical service for pain management. The acute pain service was consulted for assistance in identifying the responsible nerve branch. On exam, the patient had a two-by-two centimeter area of tenderness located three centimeters lateral and inferior to the umbilicus in the T11-T12 nerve distribution. This corresponded to where the distal portion of the Ilioinguinal nerve was buried within the external oblique muscle. A right L1 paravertebral nerve block was performed and lead to complete resolution of the patientâ€™s right lower quadrant pain, suggesting that the tunneled Ilioinguinal nerve was the source of the patientâ€™s ongoing pain. The patient was scheduled for neurolysis of the Ilioinguinal nerve.

Discussion: This case illustrates the complexities of diagnosing and treating chronic pain following open inguinal hernia repairs. Both the Ilioinguinal and Genitofemoral nerves can be injured and history and exam are often unreliable in identifying the causative nerve, which complicates surgical treatment decisions. Regional blockade of these nerves at their origin, such as with L1 or L2 paravertebral blocks, can help identify the nerve that is involved and direct surgical therapy. Alternatively, one could perform a diagnostic Ilioinguinal nerve block using anatomical landmarks. However, in this case, the Ilioinguinal nerve had been transected and displaced away from its usual landmarks, such that a L1 paravertebral block was the best diagnostic choice.

Abstract 54

A Prospective Randomized Controlled Double Blind Volunteer Study Comparing Two Saphenous Nerve Blockade Techniques

Presenting Author: Rachel Rome, M.D. Presenting Author’s City, State: - Charlottesville, VA Co-Authors: Paul Ting, M.D. - University of Virginia - Charlottesville, VA David Scalzo, M.D. - University of Virginia - Charlottesville, VA Zhiyi Zuo, M.D., Ph.D. - University of Virginia - Charlottesville, VA

Background: As the largest sensory branch of the femoral nerve, the saphenous nerve innervates the skin overlying the medial, anteromedial, and posteromedial aspects of the lower extremities. In order to provide surgical anesthesia to the lower medial leg, multiple techniques have been described to block signal transduction along the saphenous nerve. The abundance of approaches and techniques reflect the inconsistency of results and complications that can occur with each. Ultrasound guided saphenous nerve blockades were first described to enhance the identification of the saphenous vein and nerve to make accurate infiltration of local anesthetic possible. Saphenous nerve blocks assisted by ultrasound guidance hold the promise of improved success and decreased technical difficulty, but no controlled trials have been performed to date comparing these approaches with more traditional ones. We hypothesized that the ultrasound guided transsartorial approach would be superior to the traditional approach in providing a dependable saphenous nerve block with a greater extent of conduction blockade and a faster time to onset.

Methods: We performed a randomized controlled double-blind trial comparing two saphenous nerve blockade techniques: Traditional transsartorial approach and ultrasound guided transsartorial approach. Both blocks were performed on each volunteer, allowing each to serve as their own control. Primary outcome measures include success rate and extent of conduction blockade for each technique. Secondary outcome measures included time to onset of sensory blockade, time to perform nerve block, time to complete sensory blockade, duration of blockade, patient satisfaction, and complications encountered.

Results: An interim analysis was performed after the first 19 subjects were enrolled. The median age of the subjects was 30.7 (range 24-40). The success rate for the ultrasound guided transsartorial approach was 77.7% compared to 55.5% for the traditional transsartorial approach (P = 0.290). Of the successful blocks in each respective group, the time to onset was faster in the ultrasound transsartorial group (15.2 minutes for pinprick sensation, 13.1 minutes for temperature sensation) when compared to the traditional approach (18.3 minutes for pinprick sensation, 16.9 minutes for temperature sensation) (P =0.052). There were no differences between the two approaches in regards to time to achieve complete sensory blockade, duration of blockade, or patient satisfaction. The only side effect encountered was tenderness at the injection site on one volunteer after a traditional transsartorial block. This complication resolved within 24 hours.

Conclusion: This interim analysis suggests that ultrasound guided transsartorial approach provides a higher success rate with a faster onset time when compared to traditional transsartorial approach. No differences were detected in time to achieve complete sensory blockade, the duration of blockade, or patient satisfaction when comparing these two approaches. In the appropriate patient population, an ultrasound guided transsartorial approach may be more efficacious than a traditional transsartorial approach.

Abstract 55

Effect of Infusion Strategies for Continuous Interscalene Block on Postoperative Analgesia

Presenting Author: Vijay Patel M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Daquan Xu MB, MPH - St. Luke's Roosevelt Hospital Center - New York, NY Kishor Gandhi M.D. - St. Luke's Roosevelt Hospital Center - New York, NY Thomas Maliakal M.D. - St. Luke's Roosevelt Hospital Center - New York, NY Jeff Gadsden M.D. - St. Luke's Roosevelt Hospital Center - New York, NY

Introduction: The analgesic benefits of continuous interscalene block have been demonstrated in several studies (1-4). Modern ambulatory infusion pumps allow for a wide range of both basal infusion and bolus settings. However, the optimal infusion strategies for delivery of local anesthetic remains inadequately studied. In this pilot study, we compared three infusion settings in patients having arthroscopic shoulder surgery.

Methods: Continuous nerve block catheters were inserted preoperatively in the interscalene brachial plexus under ultrasound guidance. All patients received a 20 ml bolus of 0.5% ropivacaine via interscalene catheter for intraoperative anesthesia. Following the surgery, patients were transferred to the PACU where adequacy of the catheter placement was re-assessed by visualizing the spread of a bolus of 2-3 ml of normal saline on ultrasound. Prior to discharge from the hospital the interscalene catheter was connected to a disposable electronic continuous nerve block pump (StrykerÂ® PainPump2 BlockAid â€“ Stryker Corp., Kalamazoo, MI) filled with 400ml of 0.2% ropivacaine. The patients were then randomized to receive 1 of 3 infusion regimens. The Infusion only (I) group received a constant infusion at a rate of 10 ml/hr only with no option for a bolus. The Infusion+Bolus group (I+B) received an infusion of 5ml/hr, plus the option of a 5ml bolus timed to lockout at 60 minutes. Finally, the Bolus (B) only group was allowed to self-administer a 10 ml bolus every 60 minutes. Data on maximal/minimal pain scores (NRS-11), PO opioid consumption, total local anesthetic consumption and overall satisfaction with analgesia were collected on POD 1 and 2.

Results: Preliminary results obtained from a sample of 16 patients showed the I+B group had the fewest number of patients experiencing severe pain (0 patients had a NRS-11 >7/10 on POD 1 & 2) and greatest number of patients with minimal pain intensity (only 1 patient reported a NRS-11>2/10 on POD 1). Patients in I+B group also had the lowest need for PO analgesics on both POD 1 and 2. Patient satisfaction was also the highest in the I+B group. The total consumption of the local anesthetic was lowest in the B group (284.7 ml Â± 97.4ml vs I+B group 373.2mL Â±25.2 vs B 389.6mL Â± 42.9).

Discussion: In the setting of our study, our preliminary data suggest that the combination of the basal infusion and hourly bolus of local anesthetics for continuous interscalene block after shoulder arthroscopy results in better analgesia and higher patient satisfaction then infusion or bolus only infusion strategies.

Table1. Results of the continuous interscalene blocks with three different pump settings

References: 1. Anesth Analg 2008;106:991â€“6 2. Best Pract Res Clin Anaesthesiol 2002;16:295-310 3. Anesthesiology 2006;105:999â€“1007 4. RAPM 2010;35:28-33

Additional File #1:

Table1. Results of the continuous interscalene blocks with three different pump settings Infusion only (I) Infusion+ Bolus Bolus only (B) (n=5) (I+B) (n=5) (n=6) Age (yrs) 54.4 ± 11.4 51.0 ± 9.0 60.2 ± 19.4

Gender (female/male) 3/2 2/4 3/2

Worst Pain Intensity On Day1 3/2 0/6 4/1 (Sever Pain ≥ 7 / No Sever Pain ≤ 6) On Day2 1/4 0/6 2/3

Least Pain On Day1 4/1 1/5 4/1 (Pain ≥ 2 / No Pain ≤1) On Day2 4/1 0/6 3/2

Narcotics (Tablets) On Day1 4/1 2/4 3/2 (took>3tabs QD / took<3 tabs QD) On Day2 3/2 0/6 4/1

0.2%Ropivicaine Consumption (mL) On Day1 193.7 ± 42.2 163.8 ± 38.0 128.1 ± 65.2

On Day2 389.6 ± 42.9 373.2 ± 25.2 284.7 ± 97.4

Preference On Day1 3/0/2 1/0/5 0/3/2 (Both /Oral drug /Catheter) On Day2 1/2/2 2/1/3 0/4/1

Satisfaction (scale ≥ 7 / ≤ 6) on Day 2 4/1 5/1 3/2

Inconvenience to Carry the Pump (Yes/No) 2/3 3/3 2/3

Adverse Events related to Continuous Block 1 leaky case None None

Abstract 56

A New Approach to the Suprascapular Nerve Block

Presenting Author: Yvonne A. Cuffy, M.D. Presenting Author’s City, State: - Albany, NY Co-Authors: Jean-Pierre P. Ouanes, D.O. - Albany Medical Center - Albany, NY Leon J. Martino, Ph.D. - Albany Medical Center - Albany, NY Walter H. Folger, M.D., Ph.D. - Albany Medical Center - Albany, NY

Background: The Suprascapular nerve block was first described by Wertheim and Rovenstine in 1941 as a means of alleviating chronic shoulder pain. Â¹ The suprascapular nerve arises from the fifth and sixth cervical nerves and provides motor innervations to the supraspinatus and infraspinatus muscles. Â² It provides sensory innervation to 70% of the shoulder joint. The suprascapular nerve is typically anesthetized during an interscalene nerve block. However, interscalene blocks have been associated with blockade of the phrenic and recurrent laryngeal nerves, vertebral artery injection, and inadvertent subarachnoid or epidural anesthesiaÂ³. The suprascapular nerve block provides a safer alternative for patients that cannot tolerate the possible complications of an interscalene block. It provides excellent post op analgesia for relief of shoulder pain. Patients have a shorter hospital stay and a reduced opoid intake postoperatively. Â³

Purpose: 1) Pain relief for shoulder surgery for the patient with severe COPD because the loss of one side of the diaphragm by anesthesia of the phrenic nerve cannot be tolerated from an interscalene or supraclavicular block. 2) Augmentation of an incomplete interscalene/supraclavicular block with posterior shoulder pain.

Methods: 30 milliters of embalming latex solution was injected around the suprascapular nerve from an anterior landmark approach. A 20 gauge insulated block needle was inserted in a groove between the trapezius and posterior to the clavical. The needle was directed anteriorly and inferior to the clavicle. After the latex hardened we dissected a fresh cadaver from infraclavicular and supraclavicular directions without resection of the clavicle. Skin and subcutaneous tissue were removed above the neck and chest fascia. The space below the fascia was bluntly dissected. Below the clavicle the pectoralis major and pectoralis minor muscle were divided revealing the brachial plexus sheath lying on the rib cage. Above the clavicle, the investing layer of deep cervical fascia was entered anterior to the trapezius muscle and lateral to the middle/posterior scalene muscles (Fig 1). The supraclavicular nerve was identified by its origin from the upper trunk of the brachial plexus crossing the superior axillary space to the scapula (Fig 2).

Results: The suprascapular nerve was the in the superior portion of the axillary space. This space was filled with only adipose tissue. The suprascapular nerve crossed the axillary space just below the investing layer of deep cervical fascia. This could be identified by a fascial â€œpopâ€ with a blunt, coated needle used for continuous catheter placement. The nerve ran parallel to the dorsal caudad edge of the clavicle. Puncture sites for the approaches can be anterior to the clavicle through the clavipectoral fascia or central between the trapezius muscle and the clavicle.

Conclusions: 1) The approach is easy and safe as it is directed away from the ribcage. 2) It is suitable for long acting single shot or continuous catheter placement. 3) This is an alternative modality for pain relief in the presence of COPD or augmenting incomplete blocks.

References: 1. Wertheim, HM, Rovenstine, EA. Suprascapular Nerve Block. Anesthesiology 1941; 2: 541-5

2. Moore KL and Dalley AF: Clinically Oriented Anatomy. Lippincott Williams &Wilkins, Baltimore, 2006.

3. Ritchie, ED, Tong D, Chung, F, Norris, AN, Miniaci, A, Vairavanathan, SD. Suprascapular Nerve Block for Postoperative Pain Relief in Arthroscopic Shoulder Surgery : A New Modality? Anesthesia & Analgesia 1997: 84:1306-12.

4. Netter FH: Atlas of Human Anatomy. ICON Learning Systems, Teterboro, 2004.

Abstract 57

Safety and Efficacy of Ambulatory Continuous Lumbar Plexus Blocks: A Retrospective Analysis of 281 Cases

Presenting Author: Zachary Nye, D.O. Presenting Author’s City, State: - Portland, OR Co-Authors: Michael Aziz, M.D. - Oregon Health and Science University - Portland, OR Matthew S. Abrahams, M.D. - Oregon Health and Science University - Portland, OR Andrea Herzka, M.D. - Oregon Health and Science University - Portland, OR Jean-Louis Horn, M.D. - Oregon Health and Science University - Portland, OR

Background: Continuous-catheter based peripheral nerve blocks are currently considered the â€œgold standardâ€ for management of acute pain following major surgery of the extremities. Numerous studies have demonstrated the advantages of discharging patients home with perineural catheters for postoperative pain control, though no large series have been published for ambulatory continuous lumbar plexus blocks (CLPBâ€™s).

Methods: We performed a retrospective review of all patients discharged home from our institution with a CLPB for pain control following arthroscopic hip surgery from January 2004 to July 2009. During that time, 281 patients had a CLPB placed for post operative pain control. We reviewed the medical records of these patients in order to analyze the efficacy of the blocks (quality of analgesia, patient satisfaction), as well as the incidence of side effects and adverse events (impaired ambulation, suspected systemic local anesthetic toxicity, potential epidural spread, possible neurologic injury).

Results: Of these 281 patients, 214 were discharged with the CLPB in place. Of these patients, 179 (84%) were contacted by phone for follow-up with our Acute Pain service (APS). Of these, 89% reported good or excellent pain control, and 97% reported being satisfied or very satisfied with the block. 37% of patients reported side effects, predominantly nausea and sedation likely related to the use of oral opioid analgesics. 6% of patients reported symptoms potentially related to systemic local anesthetic toxicity, such as tinnitus (3%), metallic taste (2%) and agitation (0.6%). 10% of patients reported some degree of sensory or motor deficit. The majority of these were minor and resolved spontaneously, though three patients (1%) experienced persistent symptoms. Two patients experienced falls, and one patient was readmitted for likely epidural spread from the CLPB. One patient was admitted for surgical evacuation of a thigh hematoma.

Conclusions: Ambulatory CLPB is effective for acute pain relief following hip arthroscopy. The incidence of side effects and complications directly related to the CLPB is low. Keys to successful ambulatory CLPBâ€™s include appropriate patient selection and education, as well as mechanisms for routine follow-up and urgent management of problems potentially related to the block. Randomized controlled trials may clarify the benefits of ambulatory CLPBâ€™s. Use of ambulatory CLPBâ€™s for other types of surgery, such as hip arthroplasty, requires further investigation.

Abstract 58

Thoracic Epidural Hematoma Following Lumbar Epidural Steroid Injection: Is our Present Practice Safer Than Before?

Presenting Author: Harsha Shanthanna, M.D. Presenting Author’s City, State: - Hamilton, Ontario Co-Authors: Joseph Park, M.D. - McMaster University - Hamilton, Ontario Mehran Midia, M.D. - McMaster University - Hamilton, Ontario

Abstract Body: This case report describes a complication of thoracic epidural hematoma following lumbar epidural steroid injection. The patient was a 65 year old, male who had chronic right sided lumbar radicular pain and low back pain since 2002. He was diagnosed to have moderate to severe spinal stenosis at multiple levels. He had previously undergone more than 10 epidural steroid injections over the last 3 years and reported significant pain relief and improvement in functions following each epidural. His medical history also included atrial fibrillation for which he was on warfarin, and non insulin dependent diabetes. Interlaminar lumbar epidural under fluoroscopic guidance was performed with a 20 G Tuohy epidural needle at L3-4 level. Warfarin was stopped 4 days prior to the procedure and the INR was 1.2. It was a difficult but atraumatic epidural. About 20 mins after the epidural he complained of severe back pain and difficulty to stand. A neurological assessment showed no change from the pre-epidural status, except a sense of weakness in his trunk and legs. The patient had persistent pain despite 20 mg of IV Morphine. An emergent MRI done in the next 3 hours revealed a localized thoracic epidural hematoma at T10-T12, in addition to severe spinal stenosis. The hematoma was moderate in extent and extended 1/3rd into the spinal canal. Neurological consultation was sought and patient was admitted; his severe pain treated with IV PCA. The neurosurgical team decided for a conservative management and observation as there were no focal neurological signs. The patient was discharged the next day and followed up with an MRI a week later, which showed a resolving hematoma. This case was unusual for two reasons; A) patient had epidural hematoma despite adhering to anticoagulation guidelines, B) it is very rare to develop a localized hematoma so distant from the site of epidural injection. Most guidelines regarding anticoagulation and neuraxial blockade have been based on regional anesthesia practice. There have been only a handful of case reports of epidural hematoma in pain practice. Although spinal stenosis has been mentioned as a possible contributor in complications related to neuraxial techniques, it is unknown as to how it can increase the chances of hematoma formation or does it only increase the chances of a â€˜hematoma being detectedâ€™. Considering the above factors we came out with a possible â€˜pressure hypothesisâ€™ which might explain the occurrence of a distant but induced hematoma during injection caused by â€˜give way of pressureâ€™ in a weakened vessel wall at a distant site. In view of the complexity of patients in pain practice and with the increasing frequency of epidurals, there is a greater need for 'guidelines which are inclusive of other factors which might significantly tilt the balance, apart from anticoagulation therapy. This would be helpful in putting the risks and benefits in proper perspective to the patient, 'for a problem which is so rare but tragic'. There is also need of a registry to record, and audit these rare case reports as the problem is beyond the scope of a controlled study.

Kreppel. Spinal hematoma: a metaanalysis.Neurosurg Rev 2003;26:1-49 Horlocker T. Neuraxial blockade & spinal stenosis: Ane & Anal 2010 Jan;110(1):2

Abstract 59

Performance Characteristics of the Opioid Related Symptom Distress Scale after Orthopedic Surgery

Presenting Author: Jacques T. YaDeau, M.D., Ph.D. Presenting Author’s City, State: - New York, New York Co-Authors: Matthew C. Rade, B.A. - Hospital for Special Surgery - New York, New York Spencer S. Liu, M.D. - Hospital for Special Surgery - New York, New York Michael A. Gordon, M.D. - Hospital for Special Surgery - New York, New York Gregory A. Liguori, M.D. - Hospital for Special Surgery - New York, New York

Abstract Body: The Opioid Related Symptom Distress Scale (OR-SDS) has been validated for outpatient surgery under general anesthesia (Apfelbaum et al. Anesth Analg 2004). It quantifies 12 opioid-related side effects (Table 3); each symptom is assessed for frequency, severity, and bothersomeness. The symptom-specific score is the average of the three symptom distress dimensions. The overall composite score is the mean of the 12 symptom-specific scores. This study examined performance characteristics of the OR-SDS after orthopedic surgery.

Methods: Patients gave informed written consent for this Institutional Review Board-approved study. OR- SDS was administered to 4 groups of patients (50 patients/group). Outpatient hand surgery patients received a brachial plexus block; anterior cruciate ligament reconstruction (allograft) surgery (ACL) patients received a spinal or combined spinal-epidural (CSE); total knee arthroplasty (TKA) patients received a CSE, a bupivacaine femoral nerve block, patient-controlled epidural analgesia (bupivacaine/hydromorphone) until POD-2, and a non-steroidal anti-inflammatory; posterior spine fusion, 1-2 levels (PSF) patients received a general anesthetic and intravenous hydromorphone PCA. The scale was administered on POD-1 (all patients), and POD-3 (TKA and PSF). All patients received postoperative oral opioids. Pain was assessed via oral numerical rating score (NRS). Total opioid consumption was converted to oral morphine equivalents.

Results: Table 1 presents demographics, pain scores, and opioid usage. Table 2 presents OR-SDS scores.

Discussion: Pain scores fell within a 3-5 range, despite markedly different surgeries. Opioid use varied widely, ranging from 34 mg oral morphine equivalent (hand) to 217 mg (PSF) by end of POD-1. Using multivariable linear regression, a statistically significant correlation was shown between the overall composite SDS scores and opioid intake recorded on POD1 in hand, PSF and TKA patients.

Hand patients received a regional anesthetic, had a low opioid intake, and had a low burden of opioid- related symptoms. Composite scores (0.52 and 0.51) for ACL and TKA patients were equivalent despite increased invasiveness of TKA surgery, presumably due to aggressive regional analgesia received by TKA patients (femoral nerve block + epidural PCA). PSF patients had higher OR-SDS scores (0.94) to accompany the markedly higher opioid use. We indicate which symptoms had a median score > 0 (i.e., at least half the patients experienced the symptom). Number of qualifying symptoms ranged from 0 (hand) to 5 (PSF). We also report symptoms with a third quartile score > 1, i.e., symptoms for which at least 25% of the patients reported scores above 1. On POD-1 these symptoms included nausea, difficulty concentrating, drowsiness, feeling dizzy, itchiness, dry mouth, fatigue and headache for PSF patients, but only drowsiness and dry mouth for hand patients. For inpatients, the pattern of symptoms on POD-3 was similar to POD-1.

As a research tool, the OR-SDS scale quantifies which symptoms are problematic. Much patient distress arises from symptoms other than nausea, indicating avenues for future research. The OR-SDS scale is an effective tool in measuring opioid-related side effects in an orthopedic setting.

Additional File #1: Table 1. Demographic Information, Pain Scores, and Opioid Usage

Hand ACL TKA Spine Age, yr (Mean ± SD) 50 ± 16 42 ± 10 64 ± 10 58 ± 14 BMI (Mean ± SD) 26 ± 6.3 25 ± 3.6 33 ± 7.8 28 ± 6.3 Completion rate (%) 71% 69% 82% 75% NRS POD1 (Mean ± SD) 3.9 ± 2.9 4.2 ± 2.0 3.3 ± 2.4 4.7 ± 2.5 NRS POD3 (Mean ± SD) NA NA 4.1 ± 2.1 4.3 ± 2.1 Opiate Use, POD0-1 Oral/Subcutaneous, mg (Mean ± SD) 34 ± 25 60 ± 31 42 ± 34 52 ± 53 via PCEA/PCA*, mg (Mean ± SD) NA NA 39 ± 25 165 ± 125 Total, mg (Mean ± SD) 34 ± 25 60 ± 31 83 ± 47 217 ± 166 Opiate Use, POD2-3 Oral/Subcutaneous, mg (Mean ± SD) NA NA 101 ± 56 148 ± 139 via PCEA/PCA*, mg (Mean ± SD) NA NA 8 ± 36 40 ± 67 Total, mg (Mean ± SD) NA NA 109 ± 64 188 ± 163 Opiate Use Cumulative, POD0-3 oral/subcutaneous, mg (Mean ± SD) NA NA 143 ± 82 200 ± 174 via PCEA/PCA*, mg (Mean ± SD) NA NA 47 ± 58 205 ± 173 Total, mg (Mean ± SD) NA NA 192 ± 103 405 ± 298

*Please note: TKA patients received PCEA while Spine patients received PCA

Additional File #2: Table 2. Opiod Related Symptom Distress Scale Overall Composite and Factor Scores

Hand ACL TKA Spine OR-SDS POD1 composite, Median 0.19 (0.06:0.50) 0.52(0.33:0.93) 0.51 (0.27:0.97) 0.94 (0.70:1.18) (25%:75%) frequency 0.33 (0.08:0.65) 0.75 (0.35:1.08) 0.63 (0.25:1.08) 1.08 (0.83:1.40) severity 0.21 (0.08:0.65) 0.46 (0.33:0.90) 0.54 (0.27:1.08) 0.92 (0.69:1.23) bothersomeness 0.13 (0.02:0.27) 0.37 (0.20:0.73) 0.37 (0.13:0.92) 0.80 (0.47:1.00) OR-SDS dimensions (median) (Median Score >0) POD-1 Nausea, Median - - - 1.53 Drowsiness - 1.40 - 1.93 Feeling Dizzy - - 0.93 0.47 Dry Mouth - 1.30 1.60 3.27 Fatigue - - - 1.77 OR-SDS dimensions (3rd quartile) (3rd Quartile Score >1) POD-1 Nausea, 3rd Quartile - 2.38 2.18 2.68 Difficulty Concentrating - - - 1.35 Drowsiness 1.60 1.93 1.60 2.60 Feeling Dizzy - 1.58 1.87 1.68 Itchiness - 1.20 2.22 1.27 Dry Mouth 1.52 2.18 2.32 4.00 Fatigue - 1.27 1.68 2.27 Headache - - - 1.33 OR-SDS POD3 composite, Median NA NA 0.61 (0.34:1.26) 0.74 (0.53:1.08) (25%:75%) frequency NA NA 0.88 (0.42:1.40) 1.04 (0.69:1.33) severity NA NA 0.54 (0.33:1.08) 0.58 (0.42:0.92) bothersomeness NA NA 0.43 (0.20:0.93) 0.53 (0.33:0.85) OR-SDS dimensions (Median Score >0) POD-1 Drowsiness, Median NA NA - 1.60 Dry Mouth NA NA 1.60 1.87 Fatigue NA NA 0.17 0.47 OR-SDS dimensions (3rd Quartile Score >1) POD-3 Nausea, 3rd Quartile NA NA - 1.60 Constipation NA NA 1.93 1.93 Difficulty Concentrating NA NA 1.95 1.33 Drowsiness NA NA 2.27 2.32 Feeling Dizzy NA NA 1.55 1.60 Itchiness NA NA 1.02 1.02 Dry Mouth NA NA 2.55 2.80 Fatigue NA NA 2.02 2.48 Headache NA NA - 1.53

Additional File #3: Table 3. The Opioid Related Symptom Distress Scale

In the last 24 hours, have you If yes, how frequently did it occur? If yes, how severe? And how bothersome was experienced any of the following: the experience? Did Not Rarely Occasionally Frequently Almost Slightly Moderately Severe Very Not A Some Quite Very Experience Constantly At Little what A Bit Much All Bit

Nausea 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Vomiting 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Constipation 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Difficulty Passing 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Urine┼

Difficulty 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Concentrating

Drowsiness/Difficulty 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Staying Awake

Feeling Lightheaded 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 or Dizzy

Feeling Confused 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Feelings of General 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Fatigue or Weakness

Itchiness 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Dry Mouth 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4 Headache 0 1 2 3 4 1 2 3 4 0.8 1.6 2.4 3.2 4

┼Please note: "Difficulty Passing Urine" was not asked to patients that had a urinary catheter at time of interview.

Abstract 60

Medial Forefoot Block for Analgesia After Foot Surgery

Presenting Author: Andrew Coe, M.B.B.S., F.R.C.A. Presenting Author’s City, State: - Kingston-upon Hull, North Humberside Co-Authors: Packianathaswamy Balaji, M.B.B.S., M.D., D.N.B., F.R.C.A. - Hull and East Yorkshire Hospitals NHS Trust - Kingston-upon Hull, North Humberside Ian Williams, M.B.B.S., F.R.C.A. - Hull and East Yorkshire Hospitals NHS Trust - Kingston-upon Hull, North Humberside Mamta Pandya, M.B.B.S., M.D. - Hull and East Yorkshire Hospitals NHS Trust - Kingston-upon Hull, North Humberside Jai Sivapraksham, M.B.B.S., D.A., F.R.C.A. - Hull and East Yorkshire Hospitals NHS Trust - Kingston- upon Hull, North Humberside

Background: In this prospective, randomised, double blind study, we tested the hypothesis that a new medial forefoot block (MFB) was superior to a landmark-guided ankle block (AB) for postoperative analgesia following forefoot surgery. The MFB comprised a nerve stimulator directed common peroneal block at the fibular head, a nerve stimulator directed posterior tibial block at maleolar level, and a landmark directed distal saphenous block.

Methods: Patients presenting for medial forefoot surgery were randomised. All patients were given a standardised GA. Group MFB (n=36) were then given the new block with 25-30 mls 0.5% levobupivacaine. Group AB (n=36) received a standardised, landmark ankle block with 25-30mls 0.5% levobupivacaine. The time taken to perform each block was recorded. The extent of sensory block was also recorded. The requirement for analgesia in the recovery area, and amount of morphine required (we used PCA morphine) in the first 24 h after surgery, were also recorded.

Results: We defined inadequate block as a requirement for IV opioids in recovery together with normal sensation to cold or â€œneurotipâ€. Nine(Ankle Block)AB patients and one (Medial Foot Block)MFB patient had inadequate blocks (P less than 0.01). Group MFB had more marked sensory blocks when compared with AB group (P less than 0.001). Group MFB had longer lasting blocks when compared with AB group(P less than 0.01). The mean time taken to perform the Medial Foot Block was 4.5 minutes longer than for the Ankle Block(P less than 0.001).

Conclusion: We could conclude from our study that Medial Foot Block is superior and provided prolonged and satisfactory analgesia when compared to the standard landmark - guided Ankle block for foot surgeries but the time taken to start the surgical procedure was slightly delayed by 4-5 minutes in Medial Foot Block as we took around 5 minutes more time to perform Medial Foot Block when compared to Ankle Block.

Additional File #1:

Table 1. Patient, local anaesthetic block and surgical characteristics. Values are mean (range). F, female: M, male; n, number. ______

Group AB Group MFB (n=35) (n=35) ______

Patients

Gender (M/F) 5/30 4/31 Age(yr) 58(43 -80) 60(22-84) Weight (kg) 70 (51-100) 69 (53-107)

Surgery

Procedure Metatarsal osteotomy 21 22 Fusion of first MTPJ 13 12 Other medial forefoot 1 1 Duration (mins) 70(25-180) 64* (25-120)

Local block

Time taken to perform(mins) 10.6(6-20) 14.1** (8-33) Inadequate block 9 1*** Block score 3.7 (0-8) 6.7@ (2-8) Duration of successful blocks(hrs) 8.3(2-19) 13@@ (2-20) (who required IV morphine) n=15 n=20

* p=0.43 (student‟s unpaired “t” test) ** p<0.001(student‟s unpaired “t” test) *** p=0.01-0.02 (chi squared test with Yates‟s correction) @p<0.001 (student‟s unpaired “t” test) @@p=0.01-0.02 (student‟s unpaired “t” test)

______

Table 2 Opioid requirements. Values are mean(range). ______

Group AB Group MFB (n=35) (n=35)

______

Perioperative fentanyl (mcg) nil nil

24 hr morphine total (mg) 11.1(0-42) 10.7 (0-45) (recovery plus PCA)

24 hr morphine total per kg (mg/kg) 0.16(0-0.7) 0.15* (0-0.52)

Working block, but no opioids 5of 26 patients 9** of 34 patients required

* p=0.1 (student‟s unpaired “t” test) ** p>0.5 (chi squared test)

______

Abstract 61

Comparison of Anesthesia-Controlled Time for Carpal Tunnel Release Cases Performed Under Intraoperative Intravenous Regional Anesthesia Versus Preoperative Ultrasound-Guided Peripheral Nerve Blocks

Presenting Author: Megan K. Lehr, M.D. Presenting Author’s City, State: - San Diego, California Co-Authors: Brian M. Ilfeld, M.D., M.S. - UCSD - San Diego, California Vanessa J. Loland, M.D. - UCSD - San Diego, California Michael L. Bishop, M.D. - UCSD - San Diego, California Edward R. Mariano, M.D., MAS - UCSD - San Diego, California

Background: The use of intravenous regional anesthesia (IVRA) performed in the operating room is indicated for minor extremity procedures such as carpal tunnel release. Peripheral nerve blocks (PNB) performed outside of the operating room are known to decrease the anesthesia-controlled time compared to general anesthesia for major upper extremity surgery. The effects of preoperative PNB on anesthesia- controlled time for minor surgical procedures, if any, is currently unknown. We hypothesize that, for carpal tunnel release, performing preoperative ultrasound-guided PNB (including individual median and ulnar nerve blocks) in an induction area decreases anesthesia-controlled time as compared to IVRA in the operating room.

Methods: After IRB approval, we reviewed upper extremity surgical case data from a tertiary care university hospital outpatient surgery center for the prior year. Unilateral carpal tunnel release cases were identified by anesthetic technique: 1) preoperative ultrasound-guided PNB performed outside of the operating room or 2) IVRA administered in the operating room. Cases involving surgical procedures in addition to unilateral carpal tunnel release and/or requiring general anesthesia were excluded. Demographic and procedural data were examined. Since the anesthesia-controlled time data were not normally distributed, differences in anesthesia-controlled time were analyzed using the Mann-Whitney U test; and p<0.05 was considered statistically significant.

Results: Ninety-two cases met the criteria for analysis (40 PNB and 52 IVRA). Median [10th-90th percentiles] anesthesia-controlled time was shorter for patients who received ultrasound-guided PNB than for patients who received IVRA (11.0 [6.0-18.0] vs. 13.0 [8.3-20.7], respectively; p=0.01). Ultrasound- guided PNB procedures took a median of 5.0 [10.0-28.0] min to perform.

Conclusions: Ultrasound-guided PNB performed preoperatively in an induction area by a dedicated regional team significantly reduces anesthesia-controlled time as compared to IVRA performed in the operating room for carpal tunnel release. Although statistically-significant, the clinical significance of these results has yet to be determined.

Figure 1. Ultrasound image of the median nerve in the distal forearm; FCR = flexor carpi radialis; MN = median nerve.

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Abstract 62

Epidural Blood Patch Reverses Neurological Deterioration

Presenting Author: Andrea Toufexis Esch, D.O. Presenting Author’s City, State: - Gainesville, FL Co-Authors: Stephen Lucas, M.D. - UF - Gainesville, FL

Introduction: Intracranial hypotension is a diagnosis that is typically characterized by postural headache, photophobia, nausea and vomiting, cranial nerve six palsy, and radiating neck pain that is not relieved with common analgesics. Symptoms are attributed to leakage of cerebral spinal fluid (CSF) from inadvertent dural puncture such as during epidural procedures or from intentional disruption of dura mater as in cases of diagnostic lumbar puncture or craniotomy. Diagnosis is often made clinically, however advances in MRI provides objective evidence of thickened dura, engorged venous sinuses, subdural fluid collection, and caudally displaced brain. Conservative treatment typically includes bed rest, increase fluid consumption, and caffeine. Aggressive therapy typically involves epidural blood patch after infectious causes and coagulation status have been evaluated. Cases have described spontaneous intracranial hypotension following craniotomy resulting in encephalopathy and coma. There have been few reports of epidural blood patch alleviating these severe symptoms in the neurosurgical literature, but to our knowledge there have been no reports on epidural blood patch alleviating intracranial hypotension in the regional anesthesia literature.

Case Presentation: A 57 year old female who sustained blunt trauma to her head, brief loss of consciousness and subsequent subdural hematoma presented to our neurosurgical service 9 months after the trauma occurred. In the interim she had been treated non-operatively for headaches at an outside hospital with oral analgesics and seizure prophylaxis. Meningitis had been excluded by diagnostic lumbar punctures on many occasions for recurrent headaches and low-grade fevers. She presented to our hospital with worsening headaches accompanied by nausea, vomiting, hearing and visual disturbances. A CT scan demonstrated a subacute on chronic subdural hematoma and also signs notable for intracranial hypotension. She quickly developed increased somnolence, suffered a seizure and became unarousable. She underwent craniotomy for evacuation of subdural hematoma and remained in poor neurologic condition postoperatively in the neurosurgical intensive care unit (NSICU). Three days later a MRI demonstrated reaccumulation of the hematoma and she was taken back to the operating room for craniotomy for hematoma evacuation however she remained in a coma and ventilator dependent in the NSICU. Repeat MRI demonstrated persistent intracranial hypotension and no reaccumulation of hematoma and sagging of central brain. The acute pain service was consulted to evaluate her for blood patch placement for intracranial hypotension that was attributed to either diagnostic lumbar punctures or to recent craniotomies. At this time she did have a temperature of 37.8 and was receiving antibiotics for a urinary tract infection. She also had developed a deep vein thrombosis in her left arm which required anticoagulation. We elected to wait until she was afebrile for 24 hours and for leukocytosis to trend towards normal prior to placement of blood patch. We also interrupted her anticoagulation so that a hematoma would form. Under sterile conditions, we injected 20 mls of blood in the L4-L5 interspace with the patient in lateral decubitus position. She recovered in supine position and in the ensuing hours, the patient regained neurological function and on the next day she was bright and awake and following commands. She was weaned from the ventilator and extubated and was discharged home three days later. Her primary team reevaluated her upper extremity prior to discharge and felt that she did not need to reinitiate anticoagulation.

Discussion: This patient had a complicated clinical presentation and treatment course that may have contributed to her headaches. Initially after the blunt trauma occurred, subdural hematoma may have been responsible for her headache but after numerous lumbar punctures to evaluate for meningitis she may have then developed a headache from continuous cerebrospinal leakage. After two neurosurgical procedures, she may have developed post-craniotomy intracranial hypotension syndrome. Irrespective of the cause of intracranial hypotension, we applaud our neurosurgical colleagues for considering an epidural blood patch in this patient who was in a coma, unable to communicate the typical complaints associated with CSF leak.

Conclusion: This was the first time that we have seen the effect of severe intracranial hypotension and the ability of a blood patch to reverse such symptoms so quickly and dramatically. Although the usual presentation that an anesthesiologist is exposed to for intracranial hypotension is headache; a patient who is severely decompensated may present with persistent altered mental status, coma and ventilator dependence. The evaluation in this patient for appropriateness of placement of a blood patch was complicated by an essentially non-responsive patient in terms of detecting paresthesias, a urinary tract infection and risk of introducing infected blood into the epidural space, interruption of anticoagulation and the logistics of positioning a mechanically ventilated patient for safe epidural access. After weighing the risks and benefits and obtaining informed consent from the patient's husband, we are pleased with the results that we were able to offer this patient.

Abstract 63

A Short Structured Regional Anesthesia Course Given in Egypt Improves Knowledge of Perioperative Pain Management Among Anesthesia Trainees

Presenting Author: Joseph Hung, M.D. Presenting Author’s City, State: - Baltimore, MD Co-Authors: Magda AboOllo, M.D. - Research Institute-Alexandria University - Alexandria, Egypt Sherif Abdel Hamid, M.D. - Research Institute-Alexandria University - Alexandria, Egypt Mona Shawki, M.D. - industrial medicine and occupational health Alexan - Alexandria, Egypt Marie Hanna, M.D. - Johns Hopkins - Baltimore, MD

Introduction: Adequate perioperative pain management leads to early ambulation, shorter hospital stay, lower costs and increased patient satisfaction. The demand for regional anesthesia in perioperative pain management has increased worldwide over the last two decades, making regional anesthesia education a critical requirement. It is important to include third world countries with regards to regional anesthesia education.

The purpose of this study is to evaluate knowledge gain after a structured interactive regional anesthesia course in perioperative pain management given to a small group of anesthesia physicians in Egypt.

Methods: A structured course in regional anesthesia and pain management was given by a US trained regional anesthesiologist at an academic hospital in Alexandria, Egypt. The course consisted of 4 hours of interactive lectures on pain management with an overview on how to build and maintain an acute pain service. Lectures were followed by 3 hours of hands-on workshops on regional anesthesia for the upper and lower extremities in addition to neuraxial techniques. The breakdown of the teaching group included 10 anesthesia residents (8 third year residents and 2 second year residents), 7 pain fellows, and 3 junior faculty members. Immediately prior to the course, participants took a twenty-five multiple choice question (MCQ) pretests and also took a pretest OSCE (objective structured clinical examination). After completing the course, study participants completed an identical MCQ posttest and an identical posttest OSCE. Pre and post test results were statistically analyzed for comparison.

Results: Pre and post test results (scored as percentage correct) for both the written MCQ and OSCE were compared using paired t-test for dependent samples. Results show overall statistical improvement in both MCQ post test scores (p < 0.0001) and OSCE scores (p < 0.0001) regardless of training level table1 and table 2 respectively. There was a statistical improvement (p <= 0.05) between both MCQ pre and post test scores in the third year resident and fellow groups. There was also a statistical improvement (p<=0.05) between pre and post test OSCE scores in the same groups (third year resident and fellow). Although there were improvements in posttest results for both second year residents (OSCE and MCQ) and junior faculty members (MCQ only), these improvements were not statically significant. However, these groups had only two and three members respectively (in comparison to seven and eight members in the other two groups).

Conclusion: These results confirm that a structured hand on course in regional anesthesia is beneficial for teaching anesthesia trainees in an international setting. Following up on retained knowledge and long term improvement in clinical practice is a logical next step. Based on these results, outreach regional anesthesia teaching efforts should continue internationally with a focus on future educators in this field. These efforts will support expansion of regional anesthesia and pain management education in third world countries.

Key Words: Education, Regional anesthesia, Pain management, OSCE.

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Abstract 64

The Accuracy of Preoperative Landmark Assessment on Low Thoracic Epidural Catheter Placement

Presenting Author: Nita Khandelwal, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Mark C. Kendall, M.D. - Northwestern University, Feinberg School of Medici - Chicago, Illinois Antoun Nader, M.D. - Northwestern University, Feinberg School of Medici - Chicago, Illinois Robert McCarthy, Phar.M.D. - Northwestern University, Feinberg School of Medici - Chicago, Illinois

Introduction: Previous studies have demonstrated a poor correlation between the intended intervertebral space and the actual interspace for lumbar epidural placement when using anatomical landmarks.1 The greater prominence of the spinous processes in the thoracic spine suggests that better agreement might occur between the intended intervertebral space and the actual puncture level. The purpose of this study was to evaluate the accuracy of preoperative placement of low thoracic epidural catheters with the actual catheter insertion point using fluoroscopic imaging.

Methods: Following IRB approval, written informed consent was obtained by 20 ASA I-III female patients (>18 y/o) undergoing uterine artery embolization, all receiving low thoracic epidural analgesia for postoperative pain relief. All thoracic epidural catheters were intended to be placed at the T10-11 vertebral interspace. Patientâ€™s physical landmarks were used to determine the point of needle entry. The location of the catheter entry point was confirmed using fluoroscopic imaging with contrast. Data was compared using the Wilcoxon signed rank test.

Results: Our results show that the procedural insertion point of the thoracic epidural catheter differed by the intended space by 1 level in 55% of the cases, 2 levels in 20% of cases, and 3 levels in 25% cases. Nonetheless, contrast spread covered the intended interspace in 60% of the cases, extended above in 10% and below in 30% of cases.

Discussion: Similar to the findings in lumbar epidural placement, landmark based guides are frequently inaccurate when thoracic catheters are placed despite the more prominent spinous processes.2 Nonetheless, in the majority of these cases contrast studies suggest that anesthetic would reach the intended sensory dermatome levels. If low volume/dose specific dermatome coverage is desired our study suggests that imaging modalities should be used.

References: 1. Masui 2009 58(6) 692-699. 2. Acta Anaesthesiol Scand 2006 50(3) 368-373.

Abstract 65

Water Cooled Radiofrequency: A Neuroablative Modality with the Ability to Render Lasting and Distinctive Nerve Block

Presenting Author: Khalid Malik, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Kiran Chekka, M.D. - Northwestern University Feinberg School of Medicin - Chicago, Illinois Honorio Benzon, M.D. - Northwestern University Feinberg School of Medicin - Chicago, Illinois

Introduction: Water-cooled radiofrequency (WC-RF) ablation is an FDA approved minimally invasive neuroablative technique used for nociceptive blockade. The basic principle of WC-RF application is similar to the conventional thermal radiofrequency (CT-RF) application.1 However, in contrast to CT-RF the volume of the tissue heated and the resultant thermal lesion is substantially larger with WC-RF application.2 The larger area of neural destruction increases the probability of successful denervation of a pain generator with numerous and/or variable afferent nociceptive innervation. WC-RF is currently used exclusively for the treatment of discogenic pain and sacroiliac joint dysfunction. However, due to its ability to precisely deliver thermal energy to larger tissue volumes, WC-RF may be effective when more traditional forms of neuroablation have failed. Here we report the successful use of novel application of WC-RF.

Method: The patient is a 52 year old female with a history of craniotomy for ruptured intracranial aneurysm. She reported persistent pain in the left parietal area, at the site of her prior surgery. The patient reported severe pain, rating 8-9/10 on NRS, which precluded her from performing her daily activities. A series of local anesthetic and steroid injections of the painful area provided only few days of pain relief. Six months after the initial presentation, pulsed RF3 was applied locally at the painful area and the patient reported no pain relief after the procedure. Almost two years after the initial presentation, WC- RF was applied locally at the painful; the electrode temperature was raised to 40Â°C and the total lesioning time was 150 seconds.

Results: At 3-week, 3 and 6 month follow-up visits, the patient reported significant pain relief with pain scores reduced to 1-2/10 on NRS. The patient had resumed her daily activities and she was satisfied with the overall results of her treatment.

Discussion: A logical explanation for this patientâ€™s persistent pain was possible neuritis and /or neuroma formation at the site of surgery. The patient did not respond to pulsed RF and we decided against alcohol or phenol injection because of the possibility of neuritis. The patient responded to water- cooled RF. WC-RF is applied by using a special electrode that is actively cooled by the continuous flow of water at ambient temperature. The active cooling prevents the electrode from acquiring the high temperatures from the surrounding tissue, which allows the continued flow of the RF current. Consequently, the volume of the tissue is heated is extended, and the thermal lesion eventually created is significantly larger. The success of the WC-RF use in this case is likely due to the larger thermal lesions created although other factors may be involved. The current evidence does not favor preferential interruption of small nociceptive fibers during thermal RF lesioning, the existing evidence does not rule out such preferential lesioning at temperatures between 40Â°C to 45Â°C.4 The ability of WC-RF to maintain temperatures of larger tissue volumes in a narrow desired range, may allow such selective blockade of the nociceptive pathways. It is plausible that this mechanism of pain relief was at play in the pain relief experienced by this patient. Prospective studies on this modality in patients with neuromas are recommended.

References: 1. Malik K, Benzon HT. (2008) Anesthesiology;109:527-42. 2. Pilcher TA, Sabford AL, Saul JP, Haemmerich D. (2006) Pacing Clin Electrophysiol;29:1368â€“1374. 3. Malik K, Benzon HT. (2007) Anaesth Intensive Care:35:863-873. 4. Smith HP, McWorther JM, Challa VR. (1981) J Neurosurg;55:246-53.

Abstract 66

The Perioperative Effect of Obesity on Peripheral Nerve Blockade: An analysis of 530 Interscalene Blocks

Presenting Author: Kristopher M. Schroeder, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Meghan Furlong, B.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Christopher Schmidt, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI Seungbong Han, M.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Becker Aimee, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI

Introduction: Anesthetic implications for the obese are well known and anesthetic care for these patients can be challenging. Previous studies have demonstrated that when using nerve stimulation, increased Body Mass Index (BMI) is an independent risk factor for block failure. A small study then demonstrated that when using ultrasound guidance for Interscalene nerve block placement, increasing BMI no longer impacts block success rates. We attempted to more closely investigate the relationship between increasing BMI and various perioperative parameters.

Methods: We retrospectively reviewed the charts of 529 patients who had shoulder surgery with preoperative ultrasound guided interscalene nerve block placement. After dividing patients into those of low or normal weight (BMI<25), those who were overweight (BMI 25-30), and those who were obese (BMI>30), a multiple regression and logistic regression analysis was applied to determine how BMI, sex, ASA score, age, and preoperative opioid use influenced a variety of clinical variables including time required for the block placement, opioids required to place the block, intraoperative fentanyl use, intraoperative hydromorphone use, postoperative hydromorphone use, immediate postoperative pain score, peak postoperative pain score, and nausea. We also evaluated how the total volume of local anesthetic used for the block influenced these postoperative variables.

Results: BMI had a highly significant impact on the time required for block placement. Intraoperative fentanyl administration was significantly increased with increasing BMI. Intraoperative hydromorphone use was not affected by increasing BMI. Postoperative hydromorphone, postoperative oral opioid administration and total postoperative intravenous morphine equivalent administration was increased with increasing BMI. Immediate postoperative pain score was not affected by BMI but peak postoperative pain was increased with increasing BMI. Postoperative nausea occurred much more frequently in the obese population. Volume of local anesthetic injected appeared to have no impact on the quality of the block.

Discussion: In this retrospective review of patients undergoing shoulder surgery with preoperative placement of an ultrasound guided interscalene nerve block, increased BMI was highly significant for increased time required to place the block, increased perioperative opioid consumption, and increased postoperative nausea. This larger patient set demonstrates that ultrasound guided IS blocks can be effectively used for postoperative pain control in patients of increased BMI but that pain control may not be as complete and may result in adverse outcomes such as increased PONV.

Additional File #1: 1020910162441ASRA_Interscalene_T.doc Click here to view

Abstract 67

Infraclavicular Nerve Block: An Ultrasonographic Anatomical Study

Presenting Author: Tristan T. Lai, M.D. Presenting Author’s City, State: - Lackland AFB, TX Co-Authors: Jonathan M. Rogers, M.D. - Wilford Hall Medical Center - Lackland AFB, TX Lisa A. Rogers, M.D. - Wilford Hall Medical Center - Lackland AFB, TX

Introduction: Since the growing popularity ultrasonography for performing the infraclavicular nerve block, several techniques have been developed to optimize visualization of the brachial plexus and maximizing success. To date, there has been no dedicated anatomical study focusing specifically on the change in location of the brachial plexus based on arm position when performing the infraclavicular nerve block.

Materials and Methods: Our study consisted of 73 healthy volunteers (42 males and 31 females), who gave their permission to be imaged under ultrasound. Using a Sonosite MicroMaxx portable ultrasound and a 13-6MHz 38mm broadband linear array probe, the brachial plexus was imaged via the infraclavicular approach. Ultrasound images were taken with the arm initially adducted and then with the arm abducted to 90 degrees and the elbow bent. Measurements were made from the most distal end of the axillary artery to the skin in both positions. These values were recorded and the difference between the two positions was calculated. Using statistical analyses, the differences were averaged and compared. Special attention was also paid to the location of the pectoral vessels in both positions when seen.

Discussion: Our study revealed a trend in difference not only with arm position, but also according to gender. With the arm abducted, the distance from axillary artery to the skin was closer only in the males as compared to the females. In fact, with the females, the axillary artery was deeper with the arm abducted as compared to adducted. The reason can be hypothesized that males, in general, have larger pectoralis major muscles and with the arm adducted, it contracts this muscle group thus increasing the distance of the artery, and subsequently the nerve sheath, to the skin. With the arm abducted, the pectoralis major is relaxed or stretched and thus brings the neurovascular sheath closer to the surface. In the females, the pectoralis major muscles were not as bulky and thus made little difference with the arm adducted. However, the pectoralis minor muscle groups were more developed and thus with the arm abducted, these muscles were contracted adding bulk to the muscle and interesting increases the distance of the neurovascular sheath to the skin. Additionally, it was noted in both groups that with the arm adducted, the pectoral vessels, if seen, were in the direct trajectory of the needle if a nerve block were to be performed. However, with the arm abducted, the pectoral vessels are displaced medially allowing a clear path to performing the nerve block. With the vessels displaced, there is minimal chance of accidental intravascular injection.

Thus with the information obtained from this anatomical study, we conclude that the infraclavicular nerve block should be performed with the arm abducted in males and adducted in females.

Abstract 68

Combined Intrathecal / Epidural Analgesia for Pain Management after Pediatric Spinal Fusions for Scoliosis

Presenting Author: Lynn Wang, M.D. Presenting Author’s City, State: - Loma Linda, CA Co-Authors: Charles Lee, M.D. - LLUMC - Loma Linda, CA Shyam Kishan, M.D. - LLUMC - Loma Linda, CA Michelle Schlunt, M.D. - LLUMC - Loma Linda, CA

Introduction: Several Methods have been reported for postoperative pain management following posterior spinal fusion in pediatric patients with idiopathic scoliosis. Recent studies have described the use of thoracic epidural catheter infusions, intrathecal analgesia, or intravenous patient-controlled analgesia (PCA). At our institution, pediatric patients undergoing posterior spinal fusion for scoliosis routinely receive a combination of intrathecal opioid and continuous epidural catheter infusion for postoperative pain control which may offer a more comprehensive method of managing postoperative pain. To our knowledge, a combined intrathecal / epidural technique for patients undergoing these surgeries has not been reported.

Method: Following IRB approval, we retrospectively analyzed 35 patients who received combined intrathecal opioid and continuous epidural catheter infusion between 2006 and 2009 and ranged in age from 7 to 17 years old. 34 patients received 10 mcg/kg of intrathecal morphine intraoperatively near the beginning of surgery and one patient received 2 mcg/kg of intrathecal hydromorphone due to morphine allergy. All patients received a high thoracic epidural catheter placed intraoperatively under direct vision by the surgeon prior to wound closure and were managed postoperatively by the Acute Pain Service. The medical record was reviewed for gender, age, magnitude of spine curvature, postoperative visual analog pain scores, time to return of PO intake, respiratory depression, pruritis, length of stay, ambulation, and time to return of bowel sounds.

Results: The study group consisted of 20 female (57%) and 15 male (43%) patients with a mean age of 13 years. The means for curvature of the spine in degrees and levels fused were 69 and 12.7, respectively. On postoperative day one, 22 patients (63%) had VAS pain scores between 0-4, 7 patients had VAS scores above 4, and 6 patients were unable to self report. 21 patients (60%) experienced some form of nausea and/or vomiting while 10 patients (28%) reported pruritis. All patients responded effectively to treatment for their symptoms. In the first 48 hours postoperatively, 5 patients (14%) were noted to have respiratory rates less than 10 breaths/minute, one of which required a short duration of resuscitation with oxygen via bag mask. The mean time was 3.5 days for duration of epidural catheter, 1.6 days for return of bowel sounds, 1.5 days for return to PO intake, 2.2 days for time to ambulation, and mean length of stay was 5 days postoperatively. There were no significant intraoperative somatosensory or motor evoked potentials changes or permanent neurologic injury recorded.

Discussion: Combined intrathecal / epidural analgesia appears to provide a safe and effective method of postoperative pain management for patients undergoing posterior spinal fusion for scoliosis. Compared to previous studies using intrathecal, epidural, or intravenous analgesia (1-5), pain scores, time to ambulation, PO intake and length of stay appear to be less using a combined technique. The incidence of side effects was comparable.

Abstract 69

Epidural Blood Patch for Postdural Puncture Headache Due to Intrathecal Catheter Placement in a Patient with History of Pseudotumor Cerebri

Presenting Author: Jay N. Parekh, D.O. Presenting Author’s City, State: - Philadelphia, Pa Co-Authors: Dajie Wang, M.D. - Jefferson - Philadelphia, Pa Eileen Manabat, M.D. - Jefferson - Philadelphia, Pa

Introduction: Post dural puncture headaches (PDPH) are a well known complication status post any breach of the dura. Idiopathic intracranial hypertension can present with headache similar to low pressure spinal headache. We report a case of a quadriplegic patient with a history of idiopathic intracranial hypertension that developed spasticity and had an intrathecal catheter and baclofen pump placed. The patient subsequently developed headaches and treated successfully with an epidural blood patch.

Case Report: 46 year old quadriplegic female presenting with a headache. Her headache began a day after intrathecal catheter and baclofen pump placement for spasiticity. Twenty years prior, she was diagnosed with idiopathic intracranial hypertension which manifested with similar headaches. She was treated successfully with a lumbar peritoneal (LP) shunt. She developed intractable lower extremity spasticity, after her accident which rendered her quadriplegic. She was deemed to be a good candidate for an intrathecal baclofen trial. A nuclear cisternograph was performed and the LP shunt was determined to be nonfunctional. The patient had a successful trial and subsequently had an intrathecal catheter and baclofen pump placed. An 18 gauge needle was used to access the spinal space. One day after placement, the patient started complaining of bilateral, frontal headache radiating to her occipital region and neck. The headache was constant, aching, that worsened with sitting or head movement. Conservative management provided no relief. Three weeks later, an epidural blood patch was performed under fluoroscopic guidance. To avoid baclofen catheter damage, the epidural space was entered at the L4-L5 level and 8 ml of venous blood was injected until the patient complained of pressure sensation in her head. The patient was followed up immediately, one day, and three weeks post-op. She stated all three times that her headache had completely resolved.

Discussion: Our patient had a BMI of 21, was 46 years old, female, and 18 gauge needle was used, all risk factors for a PDPH. It maybe plausible that the patient had become tolerant of higher CSF pressures throughout her life, secondary to her pseudotumor, and the CSF leak that occurred during the placement of the catheter may have allowed enough CSF to leak resulting in a headache. This may have not been the case or she may have recovered sooner had she been used to normal CSF pressures. Another consideration was were headaches an exacerbation of her idiopathic intracranial hypertension, however this was low on our differential as she had not had any symptoms for 20 years, her headaches were positional, and she had just had a procedure that invaded the dura. In summary, we present a case of a patient who developed post dural puncture headaches after the placement of a intrathecal catheter and baclofen pump. We were successfully able to treat our patient with an epidural blood patch. An interesting observation in our patient was that what used to be a potential treatment in our patient (lumbar puncture and CSF drainage) for her idiopathic intracranial hypertension, had now led to her headache.

Abstract 70

TAP Block in Penetrating Trauma

Presenting Author: David Mosteller, M.D. Presenting Author’s City, State: - San Antonio, Texas Co-Authors: Robert M. Frohm, M.D. - WHMC - San Antonio, Texas Capra Jason, M.D. - WHMC - San Antonio, Texas Jonathan Rogers, M.D. - WHMC - San Antonio, Texas

Background: Transversus Abdomenis Plane Blocks have been described as a treatment modality for pain after many abdominal procedures. Here we detail the case of a patient who presented with a penatrating trauma injury and the use of this technique as his primary method of pain control.

Case Report: A 22 year old average size, intoxicated, hispanic male presented throught the ED with a rightlower quadrant gun shot wound with an entry wound anteriorly near the T11 dermatome and an exit wound posteriorly. He was taken emergently to the OR for exploratory laparotomy. Due to the emergent nature of the case and the unpredictability of potential coagulopathy if he had severe bleeding and required transfusion, he was not an optimal candidate for placement of an epidural preoperatively. An incision from xiphoid process to pubic was made after prep and drape in the steril fashion. Through this incision a thourough examination of his abdomen was performed and he was found to have a solitary small bowel injury which was repaired primarily. At that point the surgeon made the decision that primary closure was the best option. After completion of the surgical procedure, bilateral transversus abdominus plane blocks were performed. With the patient in supine position the ultrasound was used to obtain optimal view of the abdominal musculature (clearly demonstrationg all three muscle layers) just beneath the costal margins in the midlclavicular line. The probe was oriented transverse in the anterior-posterior plane to achieve this. At this point in standard sterile fashion a 21 gauge 100mm needle was advanced in-plane from anterior to posterior through the external and internal oblique muscles to enter the plane between the internal oblique and transversus abdominis muscles. With the needle tip in this position, 30ml of 0.5% Ropivacaine were administered. This entire procedure was then repeated on the contralateral side for a total dose of 60ml of 0.% Ropivacaine. On follow up visit, six hours after the block the patient was found to have complete coverage of the incision site and reported his pain at 0/10. He reported the pain relief to be adequate for a period of approximately 24 hours.

Conclusion: For patients such as this one, where this is concern of developing coagulopathy and the urgency of the case may preclude placement of an epidural, ultrasound guided transversus abdominis plane blocks provide a safe alternative.

Abstract 71 Meta-analysis of the Efficacy of Transversus Abdominis Plane Block after Abdominal Surgery

Presenting Author: Grace Kong, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: E. David Bravos, M.D. - Johns Hopkins University - Baltimore, M.D. Calvin Eng, M.D. - Johns Hopkins University - Baltimore, M.D. Vineesh Mathur, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Transversus abdominis plane (TAP) block has been advocated as a means for providing analgesia after abdominal surgery including Cesarean section. However, the overall analgesic efficacy of TAP blocks is unclear. We have performed a meta-analysis to further examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. Systematic literature searches of the National Library of Medicineâ€™s PubMed and EMBASE databases were conducted using terms related to transversus abdominis plane blocks. Only randomized controlled trials comparing TAP block with local anesthetic to control (either saline block or no block) were included for analysis. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles. There was no restriction on language for inclusion. Meta-analysis was performed using the Review Manager 4.2.10 (The Cochrane Collaboration, 2004). A random effects model was used.

Results: The literature searches yielded 110 abstracts of which 7 met all inclusion criteria. There were a total of 185 subjects for the TAP block group and 188 for the control group. We were able to obtain pooled estimates for VAS pain at 12 hours (all procedures), VAS pain at 24 hours (Cesarean section only), postoperative nausea and vomiting (all procedures), and sedation (all procedures). We were unable to obtain pooled estimate for other parameters (VAS pain at 6 and 24 hours for all procedures, morphine consumption at 24 hours) due to excessive heterogeneity. We found no significant differences in any of the pooled estimates for VAS pain at 12 hours (all procedures) [weighted mean differences (WM.D.): - 0.63 (-1.31, 0.05)], VAS pain at 24 hours (Cesarean section only) [WM.D.: -0.33 (-1.00, 0.35)], postoperative nausea and vomiting (all procedures) [Odds ratio (OR): 0.35 (0.11, 1.14)], and sedation (all procedures) [OR: 0.37 (0.08, 1.80)].

Conclusions: Our pooled analysis examining the analgesic efficacy of TAP block for abdominal surgery did not reveal any differences (versus control) with regard to VAS pain at 12 hours (all procedures), VAS pain at 24 hours (Cesarean section only), postoperative nausea and vomiting (all procedures), and sedation (all procedures). The â€œnegativeâ€ results should be interpreted with caution and certainly further examination with larger RCT is warranted as the overall number of subjects is relatively small.

Abstract 72

Continuous Tibial Nerve Block for Hallux Valgus Surgery

Presenting Author: Marie-Claude, Paquet R4 Presenting Author’s City, State: - Québec, Québec Co-Authors: Natalie T. Albert, M.D. - CHUQ-CHUL - Québec,Québec Maxime Côté M.D. - CHUQ-CHUL - Québec, Québec

Introduction: Hallux valgus correction (HV) is a recognized cause of moderate to severe post-operative pain. A continuous posterior tibial block has been shown to be effective for pain control following foot surgery but no randomized study has yet proven its superiority over a simple ankle block. The objective of this study is to determine the sparing effect of a continuous posterior tibial block on post-operative narcotic consumption (0-24h). Secondary objectives are post-operative pain intensity scores (VAS 0-100) and quality of life evaluation as determined by a validated questionnaire (SF-8).

Method: After obtaining institutional approval and informed consent, 43 consecutive patients scheduled to undergo HV osteotomy surgery were prospectively enrolled in this double-blind randomized controlled trial. Patients were excluded if they presented any of the following criteria: diabetes with or without neuropathy, peripheral neuropathy, narcodependancy, renal or hepatic insufficiency, local infection at puncture site or contraindication to any of the study medications. Under light sedation, a peripheral nerve catheter was inserted along the tibial nerve at the distal third of the leg. Five ml bupivacaine 0,5% and five ml lidocaine 2% with epinephrine 5Âµg/ml was injected through the catheter. The ankle block was completed using 8 ml of the same mixture without epinephrine on the saphenous nerve and the deep and superficial peroneal nerves. All patients were operated under regional anesthesia only. After surgery, an infusion pump administering either 5mL/h of 0,2% ropivacaine (Study group) or 0,9% salin (control group) was assigned randomly by an independent investigational pharmacist. Post-operative analgesia was strictly controlled and consisted of regular doses of acetaminophen and naproxen. If patients scored higher than 40/100 on the VAS pain score they were advised to take 1mg hydromorphone p.o. Narcotic consumption and the VAS scores were evaluated at 24, 48 and 72h by a daily telephone questionnaire. Quality of life was evaluated by a standardized (SF-8) questionnaire. Based on a previous study, it was established that 42 patients were necessary to obtain 80% power with a 5% Type 1 error to detect a 40% reduction of narcotic consumption at 24h. Significance was established at p â‰¤ 0,05. Statistical analyses were conducted with the Savage test and with the Student-t test.

Results: Sixty-four patients were approached during the study period. Twenty patients presented at least one exclusion criteria and one refused to participate. Demographic and anesthetic values were comparable in both groups. Median consumption of narcotics (hydromorphone mg) is detailed in the Table below.Pain scores at 24, 48 and 72h and quality of life at 24h and 4 weeks were comparable in both groups.

Conclusion: When combined with a regular regimen of acetaminophen and naproxen, a continuous posterior tibial block does not significantly reduce narcotics consumption after hallux valgus with osteotomy surgery.

Richman JM et al, Anesth Analg 2006; 102: 248-257 Singelyn FJ et al, Anesth Analg 1997 :84 :383-386 Larrabure P et al, Can J Anesth 2005: 52 (3); 276-280 White PF et al, Anesth Analg 2003;97:1303-1309

Additional File #1:

Time Groups p Value (hours) Ropivacaine Placebo (n=21) (n=22) mg mg (IQ 25-75%) (IQ 25-75%) 0-24 1 (1-4) 2,5 (0-5) 0,19 0-48 2 (2-5) 3,5 (0-8) 0,68 0-72 32 (2-6) 3,5 (0-9) 0,63

Abstract 73

Ultrasound Guided Supraclavicular Catheter as Anesthetic Technique to Facilitate Serial Wound Debridments

Presenting Author: Jeffrey I. Frohock, M.D. Presenting Author’s City, State: - Miami , FL Co-Authors: Andres Missair, M.D. - University of Miami - Miami, FL Ralf Gebhard, M.D. - University of Miami - Miami, FL

Introduction: Continuous peripheral nerve block catheters are frequently utilized to provide perioperative pain control for major orthopedic surgery and to facilitate rehabilitation (1). Certain clinical scenarios such as patients suffering from necrotizing fasciitis may require multiple consecutive surgical interventions. We present a case of necrotizing fasciitis in which a supraclavicular nerve block catheter as the primary anesthetic technique allowed for multiple surgical interventions over a prolonged time period.

Case Report: A 52yo patient presented to our hospital for treatment of necrotizing fasciitis to the right upper extremity. The extremity was severely infected and necrotic upon presentation, and limb salvage strategy would require multiple debridements, antibiotic placements, and dressing changes. The surgical team consulted the Regional Anesthesia/Acute Pain Service and the decision was made to place a continuous supraclavicular nerve block catheter. Under sterile conditions and ultrasound guidance, a supraclavicular catheter was placed using a 5cm, 18g Tuohy needle and a 20g multi-orifice catheter. The catheter was advanced to 8cm at the skin. Ultrasound visualization confirmed catheter tip position at the medial-inferior corner within the brachial plexus sheath. An initial bolus of 15ml of 0.5% ropivacaine in 5ml increments with intermittent negative aspiration was injected via the touhy needle. This was performed postoperative of the first wound debridement to ensure the patient was not progressing into sepsis. A continuous infusion of 0.2% ropivacaine at 8ml/hr was initiated. Upon returning to the operating room for further debridement, surgical anesthesia was reestablished by injecting 20cc of 1.5% mepivacaine through the catheter in the same fashion as described above. The supraclavicular catheter remained in place for 16 days and was successfully utilized as primary anesthetic technique for 6 consecutive surgeries, which resulted in salvage of the patientâ€™s limb.

Discussion: The use of continuous nerve block catheters to facilitate multiple consecutive surgeries has been previously described by the US military (2). Due to the lack of general anesthesia capability or based on patientâ€™s physical status, regional anesthesia techniques present an interesting alternative and may be a favorable choice to provide surgical anesthesia. However, since catheter duration is linked to likelihood of infection (3), careful follow-ups and daily inspection of catheter site are warranted. The supraclavicular approach under ultrasound guidance seems to be particularly efficient in providing dense surgical anesthesia for the upper extremity and consequently should be considered in a clinical setting as encountered by us.

Conclusion: Based on our case presentation, a supraclavicular nerve block catheter can be utilized to successfully establish surgical anesthesia for multiple consecutive procedures involving the upper extremity. This concept may present an interesting alternative to general anesthesia, especially in patients with severe co-existing morbidities.

Ref: 1)Grossi P et al. Curr Opin Anaesthesiol 2003; 493-501 2)Buckenmaier CC et al. Reg Anesth Pain Med 2005; 30: 202-5 3)Capdevila X et al. Anesthesiology 2005; 1035-45

Abstract 74

5 mg Dexamathasone Added to Levobupivacaine Improves Postoperative Analgesia in Ultrasound Guided Interscalene Brachial Plexus Blockade for Arthroscopic Shoulder Surgery

Presenting Author: Youn-Jin Kim. M.D., Ph.D. Presenting Author’s City, State: - Seoul, Yangcheon-gu Co-Authors: Jong-In Han, M.D., Ph.D. - Ewha Womans University, School of Medicine – Seoul, Yangcheon-gu Hee-Jung Baik, M.D., Ph.D. - Ewha Womans University, School of Medicine – Seoul, Yangcheon-gu Guie-Yong Lee, M.D., Ph.D. - Ewha Womans University, School of Medicine – Seoul, Yangcheon-gu

Background: The purpose of this study is to evaluate the effect of the addition of 5 mg dexamethasone to 10 ml of 5 mg/ml levobupivacaine on postoperative analgesic effects of ultrasound guided interscalene brachial plexus block for arthroscopic shoulder surgery under general anesthesia.

Method: In 45 patients scheduled for arthroscopic shoulder surgery underwent general anesthesia, ISBPB was preoperatively performed with 10 ml of 5mg/ml levobupivacaine under the guidance of ultrasound and nerve stimulator. Patients were randomly allocated to receive same volume of normal saline (Group I), 5 mg of dexamethasone (Group II), or 1: 400,000 epinephrine (Group III) as an adjuvant to the mixture. A blind observer recorded verbal numerical rating scale (VNRS) at 0, 1, 6, 12, 24, 48h after operation, total analgesic consumption, sleep quality, complication, and patients` satisfaction.

Results: All patients had successful interscalene brachial plexus blocks and excellent analgesic effects less than 4 of VNRS up to discharge time. VNRS in Group II at 12h and 48h was statistically much lower than in Group I and III. There were no differences in total analgesic consumption, sleep quality, complications, and patients` satisfaction.

Conclusions: We conclude that the addition of 5 mg of dexamethasone to 10 ml of 5 mg/ml levobupivacaine in intersclane brachial plexus block showed improvement of postoperative analgesia for arthroscopic shoulder operation without specific complication.

Abstract 75

Neurolytic Blocks as Adjuncts in the Management of Advanced Cancer Pain

Presenting Author: Gerard E. Huni, M.D.C.M. Presenting Author’s City, State: - Montreal, Quebec Co-Authors: Mohammed Al-Hujairi, M.D. - McGill University Health Center - Montreal, Quebec Juan-Francisco Asenjo, M.D. - McGill University health Center - Montreal, Quebec David Bracco, M.D. - McGill University Health Center - Montreal, Quebec

Design: Retrospective chart review.

Objective: To analyse experience with neurolytic blocks as adjuncts in the management of pain due to advanced cancer. Analysis of the procedureâ€™s impact on pain scores, opiate use and opiate side effects was also done.

Background: The majority of the patients diagnosed with cancer will suffer from pain. A small proportion of cancer patients will require advanced strategies as adjuncts to control their pain. Some of these strategies call upon neurolytic blocks. These involve injecting percutaneously a nerve-destroying agent (phenol or alcohol) in and around peripheral nerves or sympathetic ganglia.

Method: A retrospective chart review studied the relation of the procedure with pain levels, opiate dose, opiate toxicity and survival. The computerized operative record was used to select charts. Data was collected about the procedure, patient demographics, disease, and survival. In addition, pain level, adjunct analgesic medications, opiate use, opiate side effects, procedure related complications and quality of life parameters were examined. Information was taken from time periods immediately prior, two weeks after and six to eight weeks after the procedure. Statistical analysis was used to interpret the data and Wilcoxon test of the median was performed on certain parameters.

Results: In five years, 2173 individual procedures were performed by a single operator (JFA). Of these procedures, selecting the term neurolysis isolated 53 charts. Twenty-eight patients were retained as those having had a procedure to control pain due to advanced cancer. Seventeen splanchnic blocks, 5 celiac plexus blocks, 4 superior hypogastric block, 2 intercostal nerve blocks using either phenol (16) or alcohol (11). Patients suffered pain due to mainly pancreatic cancer and all were considered palliative. Sixteen patients were male and the average age was 58.9 years (range 36 â€“ 83). Five patients suffered immediate complications, but only one case had a prolonged complication lasting beyond two weeks (diarrhea). The procedures were done an average time of 86 days (range 23 â€“ 240) before death. The mean decrease in pain scores (VAS) was 3 points (1 â€“ 5). This 40% average reduction is statistically significant (p=0.001). Symptoms of opioid toxicity were charted as being present in 29% of patients prior to the procedure, 11% within two weeks following and 29% at 6 to 8 weeks after the procedure (charted as somnolence, hallucinations, myoclonous or delirium). Opioid maintenance dose decreased at the two- week mark in 40% of cases, a 16.7% reduction (p=0.06).

Conclusion: This study serves as a survey of local practice and it helps to learn from our experience. A significant reduction in VAS score and a trend in reducing opioid dose and toxicity are consistent with established practice and the literature: a select group of patients suffering from cancer pain benefit from neurolytic blocks to alleviate the burden of pain and medication side effects. This chart review helps contribute to build with better knowledge a prospective study of future cases in our institution.

Additional File #1:

ETIOLOGY

ESOPHAGEAL, 1 LUNG, 3 PENILE, 2

PROSTATE, 1

CHOLANGIO, 3 BLADDER, 2

GASTRIC, 1

COLON, 1

CERVICAL, 1

PANCREAS, 14

Additional File #2:

Abstract 76

Paravertebral Blockade for Postoperative Pain Control in a Patient with Superficial Epidural Site Infection and Staph Aureus Bacteremia

Presenting Author: Brian F.S. Allen, M.D. Presenting Author’s City, State: - Nashville, TN Co-Authors: Sripada Ramprasad, M.D. - Vanderbilt University - Nashville, TN

Introduction: We present a case of a patient with inadequately treated bacteremia and thoracic epidural site infection who underwent thoracotomy for decortication of purulent hemopneumothorax. Postoperative pain was managed with paravertebral blockade due to infectious contraindications to epidural placement.

Case Report: A 66 year-old male with left-sided rib and scapular fractures following a 6-foot fall was admitted for SOB, pulmonary contusion, and left hemopneumothorax. While being managed with tube thoracostomy and thoracic epidural analgesia, he became febrile without elevated WBC. Blood cultures grew gram-positive cocci and Unasyn and Vancomycin were started with concerns for pneumonia. When speciation revealed MSSA, antibiotics were changed to Nafcillin. He was transferred to our facility for further management. Upon arrival 12 days post trauma, he had a 7 day-old indwelling epidural catheter surrounded by erythema and purulent drainage. He was neurologically intact without back pain, elevated white count, or fever. Epidural catheter was removed and catheter tip cultures grew MRSA. Vancomycin was restarted. Surgical decortication of purulent left hemopneumothorax was performed. Postoperatively, the patient was tachypneic, "splinting", hypoxic despite 40% O2 by facemask, and with VAS pain score of 10. After weighing infectious risks of regional anesthesia vs. likelihood of reintubation, left-sided single- shot paravertebral blocks with 8 ml of ropivacaine 0.5% at T2, T4, T6, and T8 were performed followed by stabilization of vital signs, diminished O2 requirements, improved respiratory pattern, and pain score decreased from 10 to 2. On post-operative day 2 (POD 2), MRI ruled out epidural abscess and patient was offered but refused paravertebral or epidural catheter placement. He was discharged POD 5 on Nafcillin.

Discussion: This case presents several challenges including assessing likelihood of neuraxial infection and selecting appropriate regional blockade. It also demonstrates the effectiveness of single-shot paravertebral blocks as a postoperative rescue technique.

Clear guidance for replacing an epidural after removal for infectious reasons is lacking. ASRA guidelines recommend against neuraxial anesthesia in untreated active infection (1). MRI may be useful in determining when epidural replacement is safe (2). Though our patientâ€™s symptoms alone would not warrant MRI evaluation for abscess, MRI may help evaluate the safety of epidural replacement in this case. The normal MRI on POD 2 enabled us to comfortably offer him epidural replacement. Case reports of paravertebral abscess after regional block are rare and involve steroid injections or immune compromise (3). Paravertebral block should thus be deemed lower risk for epidural abscess than epidural or spinal anesthesia and should be considered in patients with infectious contraindication to epidural that would benefit greatly from regional blockade (4).

References: 1. Neal JM. Reg Anesth Pain Med. 2008;33:404-415 2. Du Pen SL. Anesthesiology. 1990;73:905-909 3. Puehler W. Pain. 2005;113:427-9 4. Wedel DJ. Reg Anesth Pain Med. 2006;31:324-333

Abstract 77

A Retrospective Review of Epidural vs. Intravenous Analgesia for Hepatic Resection

Presenting Author: Rahul Guha, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Melanie Donnelly, M.D. - University of Wisconsin-Madison - Madison, Wisconsin Seungbong Han, M.S. - University of Wisconsin-Madison - Madison, Wisconsin Rebecca Nause-Osthoff, M.D. - University of Michigan-Ann Arbor - Ann Arbor, Michigan Kristopher Schroeder, M.D. - University of Wisconsin-Madison - Madison, Wisconsin

Introduction: Hepatic resection is typically performed for tumors of the liver and can be associated with a large amount of blood loss. Epidural Analgesia (EA) is one of the tools available to accomplish a decreased intraoperative central venous pressure with resulting decrease in blood loss. Perioperative epidural placement has been shown with other abdominal procedures to result in improved postoperative pain control, earlier return of postoperative bowel function, and a decreased incidence of postoperative pulmonary complications. There has been no research which specifically addresses the benefit of postoperative continuous epidural infusions for hepatic resection patients.

Methods: Following IRB approval, the charts of 102 adult patients who had undergone hepatic resection over a sixteen month period were reviewed. Each patientâ€™s baseline characteristics were recorded including age, sex, body mass index, ASA score, preoperative opioid use, and baseline INR. Our primary question evaluated whether patients undergoing hepatic resection who received EA had improved outcomes compared to those who received intravenous Patient Controlled Analgesia (PCA). The outcomes evaluated were time in the operating room, time in the PACU, total hospital time, time until diet initiated, estimated blood loss, need for transfusion during surgery, immediate and peak PACU pain scores, pain scores on postoperative days 0-5, and postoperative INR.

Results: The groups were similar with regard to age, height, weight, BMI, baseline INR and preoperative opioid consumption (table 1). There were more males in the EA group compared to the PCA group and ASA scores were generally higher in the PCA group. EA for hepatic resection resulted in statistically significant lower pain scores over postoperative days 0 to 5 when compared to the PCA group (p < 0.001), as well as lower immediate (p = 0.013) and peak (p=0.007) PACU pain scores. The EA group had lower total hospital time following surgery, decreased estimated blood loss, and decreased need for transfusion in the OR but these were not statistically significant. The groups had similar results with regards to OR time and time until diet initiation. Postoperative INR was similar between the two groups.

Discussion: Prior studies have shown perioperative epidural infusions result in improved pain control and earlier return of postoperative bowel function for general abdominal procedures. Our study demonstrated improved pain control with EA following hepatic resection both in the PACU and for the first five days following surgery. In addition, there may be some benefit with regard to total hospital time and estimated blood loss.

References: Matot, I., Scheinin, O., Eid, A., Jurim, O. Epidural Anesthesia and Analgesia in Liver Resection. Anesth Analg. 95: 1179-81. 2002.

Borromeo, C.J., Stix, M.S., Lally, A., Pomfret, E.A. Epidural Catheter and Increased Porthrombin Time After Right Lobe Hepatectomy for Living Donor Transplantation. Anesth Analg. 91:1139-41. 2000.

Pratt, W., Steinbrook, R.A., Maithel, S.K., Callery, M.P., Vollmer, C.M. Epidural Analgesia in Pancreaticoduodenectomy is Not Superior to Intravenous Analgesia. Anesthesiology. 105: A1632. 2006.

Additional File #1: Table 1 – Baseline patient characteristics

Epidural Variable (n=69) PCA (n=33) Age (years) 60.1 61.2 Height (inches) 66.9 68.3 Weight (kg) 85.6 90.9 BMI (kg/m2) 29.7 30.1 Baseline INR 1.1 1.1 EBL (mL) 689.2 927.3 Preoperative Opioid use (%) 6 (8.7) 2 (6.1) Male (%) 32 (46.4) 19 (57.6) Prophylactic vitamin K use (%) 9 (13) 4 (12) Need for transfusion in OR (%) 9 (13) 9 (27)

ASA 1 (%) 1 (1.5) 0 (0) 2 (%) 37 (54) 8 (24) 3 (%) 30 (44) 24 (73) 4 (%) 0 (0) 1 (3)

Additional File #2: Table 2 - Results

Epidural Variable (n=69) PCA (n=33) p-value Total Hospital Time (days) 7.63 9.96 0.656 EBL (mL) 689.2 927.3 0.239 time until Diet Initiation (hours) 47.73 47.79 0.837 OR Time (Hours) 5.13 5.41 0.455 PACU Time (hours) 2.7 2.68 0.987 Immediate PACU Pain Score 3.6 5.9 0.013 Peak PACU Pain Score 4.9 7.4 0.007 Need for transfusion in OR (%) 9 (13) 9 (27) 0.27

Average pain score at rest < 0.001 Day 0 2.84 4.95 Day 1 2.39 4.47 Day 2 2.68 3.14 Day 3 1.99 2.73 Day 4 2.47 3.1 Day 5 2.83 2.76 Average pain score in activity < 0.001 Day 0 3.31 5.44 Day 1 3.72 5.95 Day 2 4.03 4.56 Day 3 2.87 3.94 Day 4 2.57 4.33 Day 5 3.47 4.75 Peak pain score at rest < 0.001 Day 0 3.98 6.77 Day 1 4.4 6.06 Day 2 4.14 4.29 Day 3 3.37 3.9 Day 4 3.36 4.42 Day 5 3.98 3.5 Peak pain score in activity < 0.001 Day 0 3.71 5.6 Day 1 4.65 6.88 Day 2 4.39 5.47 Day 3 3.62 4.09 Day 4 2.79 4.71 Day 5 4.56 4.75

Abstract 78

Rate of Implementation of a Universal Protocol for Peripheral Nerve Block Site Identification

Presenting Author: Jeffrey Truitt, M.D. Presenting Author’s City, State: - Philadelphia, PA Co-Authors: Ali Ekbatani, D.O., M.B.A. - Thomas Jefferson University - Philadelphia, PA Kishor Gandhi, M.D., M.P.H. - Thomas Jefferson University - Philadelphia, PA Eugene Viscusi, M.D. - Thomas Jefferson University - Philadelphia, PA

Introduction: In spite of the best intentions of healthcare professionals, wrong sided procedures continue to occur. A Universal Protocol (UP) has been implemented for all surgical procedures with laterality and has been proposed for peripheral nerve blocks. A Universal Protocol for peripheral nerve blocks was implemented at our institution to help prevent wrong-sided blocks. Incorporation and compliance with a new policy takes time to be fully integrated into everyday practice. The purpose of this study was to determine the rate of compliance by anesthesiologists and holding area nurses with the Universal Protocol after its initiation.

Methods: Following IRB approval, a retrospective chart review of patients undergoing preoperative peripheral nerve blocks at our institution was performed. We reviewed approximately 5-15 charts per week, comprised of all the patients receiving interscalene blocks for shoulder surgery and femoral/popliteal blocks for foot and ankle surgery. Our Universal Protocol requires patient identification and site marking (ensuring correct laterality) followed by the anesthesiologist signing, dating, and timing the Universal Protocol/Site Identification form in the chart with a holding area nurse witnessing. The chart was reviewed to determine compliance with the Universal Protocol checklist. The Universal Protocol was implemented at week 1.

Results: The following is the weekly breakdown of patients receiving peripheral nerve blocks and the documentation of the new Universal Protocol policy:

PLEASE SEE ATTACHED TABLE

Discussion: While prudent practice dictates site and laterality verification, our chart review prior to implementation of the UP (week 0) demonstrated no consistent method of site identification for peripheral nerve blocks. The poor compliance numbers in week 1 were expected and likely due to lack of familiarity with the specifics of the new procedure. Compliance with the Universal Protocol was relatively consistent from weeks 2 through week 5 and decreased weeks 6 through 9. A decrease in compliance (weeks 6-9) was unexpected. Possible reasons for lower levels of compliance after week 5 could include complacency and lack of disciplinary consequences in not adhering to the new protocol.

Conclusion: Implementation of a policy does not ensure compliance. When instituting an important procedure for patient safety, it is advisable to monitor performance until compliance is satisfactory and to perform periodic reviews. Factors facilitating an improvement in compliance may include feedback to the staff regarding performance numbers and ultimately disciplinary consequences to not adhering with the new policy. Compliance with a Site Identification Protocol may reduce the incidence of wrong-sided peripheral blocks.

Additional File #1:

Universal Universal Percent Time Patients Protocol Protocol Completed Completed Not Completed

week 0 6 0 6 0% (pre-UP) week 1 11 2 9 18% (Initiation of UP) week 2 6 5 1 83% week 3 13 10 3 77% week 4 15 12 3 80% week 5 14 11 3 79% week 6 13 7 6 54% week 7 14 11 3 79% week 8 5 2 3 40% week 9 12 8 4 67% * red denotes less than 70% compliance

Abstract 79

Alteration of Ultrasound Guided Continuous Peripheral Nerve Block Techniques Seen in Combat Injuries with Subcutaneous Air

Presenting Author: Matthew S. Fisher, D.O. Presenting Author’s City, State: - Lackland AFB, Texas Co-Authors: Jonathan Rogers, M.D. - Wilford Hall Medical Center - Lackland AFB, Texas

Introduction: Improvements in body armor has increased the ability of soldiers to survive severe combat injuries. A soldier exposed to an IED (improvised explosive device) or RPG (rocket propelled grenade) usually presents with fragmental trauma to head, neck, and upper extremities. These injuries are unique to combat zones and typically require tracheotomies and placement of external fixators or amputations. Common practice in the military is to place CPNB (continuous peripheral nerve block) and over several years, thousands of CPNBs have been placed with certain trends noticed. These patients are good candidates for CPNB, but the presence of subcutaneous air above the clavicle makes catheter placement difficult due to poor ultrasound imaging.1 In addition, traumatic upper extremity wounds make ultrasound imaging for catheter placement the only option available to these patients. Three cases presented represent a sample of the alterations done to facilitate ultrasound guided placement of CPNB complicated by combat injuries.

Case Report: Case 1: A 22 year old soldier injured by an IED explosion, sustained facial injuries and a mid-humerus amputation. He presented with mandible wired closed, tracheostomy, and stump pain of 10/10. Placement of a supraclavicular catheter was planned, but the patient had significant subcutaneous air above the clavicle that prevented ultrasound imaging. The plan was changed to placement of an infraclavicular catheter by ultrasound guidance, and pain decreased to 2/10. Case 2: A 27 year old tank commander injured when an RPG struck his tank turret, sustained neck and facial burns, and forearm fractures. He presented with tracheostomy, external fixator, and burns to arm and upper chest with arm pain of 10/10. Placement of a supraclavicular catheter was planned, though subcutaneous emphysema above and burns below the clavicle obscured imaging. The plan was altered to placement of an axillary catheter using ultrasound, and pain decreased to 3/10. Case 3: A 25 year old infantry soldier injured when his vehicle ran over an IED, sustained neck and facial injuries along with a traumatic forearm amputation. He presented with tracheostomy, mandible wired closed, and arm pain 10/10. Placement of a supraclavicular catheter was planned, but subcutaneous air above the clavicle hindered ultrasound imaging. The plan was changed to placement of an infraclavicular catheter under ultrasound guidance, and pain decreased to 2/10.

Discussion: Regional anesthesia is essential in treating extremity injuries unique to combat environments and sometimes modified techniques need to be employed. The inability of patients to communicate and lack of nerve twitch makes ultrasound imaging invaluable and the only option available for placement of CPNB. Although the knowledge that subcutaneous air is a poor medium for sound transmission has been well established2, understanding brachial plexus anatomy and ultrasound imaging allows for alternative approaches and options. In addition, proficiency in doing upper extremity nerve blocks is a valuable asset when treating these combat injuries.

References: 1. Regional Anesthesia and Pain Medicine Vol. 33, Pg 419, 2008 2. Regional Anesthesia and Pain Medicine Vol. 32, Pg 353, 2007

Abstract 80

A Novel Nerve Block: Axillary Nerve Block

Presenting Author: Jean-Pierre P. Ouanes, D.O. Presenting Author’s City, State: - Albany, NY Co-Authors: Yvonne A. Cuffy, M.D. - Albany Medical Center - Albany, NY Leon J. Martino, Ph.D. - Albany Medical Center - Albany, NY Walter H. Folger, M.D., Ph.D. - Albany Medical Center - Albany, NY

Background: The axillary nerve provides motor innervation to the deltoid and teres minor muscles. It also provides sensory innervation to the glenohumeral (shoulder) joint and skin of the superior lateral arm over the inferior part of the deltoid.Â¹ The axillary nerve block may be beneficial to relieve pain from shoulder surgery for the patient with severe COPD. These patients cannot tolerate the loss of one side of the diaphragm by phrenic nerve block from an interscalene or supraclavicular block. It also is used for augmentation of an incomplete interscalene or supraclavicular block with anterior shoulder pain. Purpose: To provide relief for post-operative anterior shoulder pain for patients with COPD or incomplete blocks.

Methods: 20 milliliters of embalming latex solution was injected next to the axillary nerve using an anterior landmark approach. With one hand the space between the lateral and long heads of the triceps brachii muscle was palpated and a finger remaining there to mark that location. In the axillae a 20 gauge insulated block needle was inserted in a groove medial to the coracobrachialis muscle and superior to the insertion of the latissimus dorsi muscle. The direction of the needle was towards the palpating finger of the other hand. Following a fascial "pop" between the latissimus dorsi and subscapularis muscle 20 mL of the latex solution was injectedÂ². After the latex hardened, we dissected a fresh cadaver from an infraclavicular and supraclavicular approach without resection of the clavicle. The puncture site was identified as superior to latissimus dorsi muscle and medial to the brachial plexus sheath (Fig 1). The axillary nerve was located in the axillary space outside the brachial plexus sheath. The axillary nerve was identified by its tracing it back to posterior cord of the brachial plexus. It coursed superficially to the subscapularis muscle and into the quadrangular space (Fig 2). Next the anterior deltoid and pectoralis major muscles were separated to expose the terminal branches of the axillary nerve (Fig 3).

Results: The axillary nerve was in the inferior portion of the axillary space. The axillary space was filled with only adipose tissue. The nerve crossed the axillary space just above the tendon of the latissimus dorsi muscle through the axillary fascia.Â² This could be identified by a fascial â€œpopâ€ with a blunt, insulated block needle. The quadrangular space does not have to be entered dorsally to anesthetize the nerve.

Conclusions: 1) This approach is not technically difficulty. 2) It is suitable for long-acting single shot or continuous catheter placement. 3) This is an alternative modality for pain relief in the presence of COPD or augmenting incomplete blocks of the anterior shoulder.

Reference: 1. Moore, KL and Dalley AF: Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore 2006 2. Netter FH: Atlas of Human Anatomy. ICON Learning Systems, Teterboro, 2004.

Abstract 81

Symptomatic Post-Laminectomy Cerebrospinal Fluid Leak

Presenting Author: Steven R. Clendenen, M.D. Presenting Author’s City, State: - Jacksonville, Florida Co-Authors: Christopher B. Robards, M.D. - Mayo Clinic Florida - Jacksonville, Florida Bruce J. Leone, M.D. - Mayo Clinic Florida - Jacksonville, Florida Stephen Pirris, M.D. - Mayo Clinic Florida - Jacksonville, Florida Eric W. Nottmeier, M.D. - Mayo Clinic Florida - Jacksonville, Florida

Background: A persistent cerebrospinal fluid leak after spinal surgery is associated with meningitis or pneumocephalus, and early active intervention is recommended with surgical exploration, lumbar subarachnoid drain and less common treatment including epidural blood patch. The Introduction of high- resolution ultrasound spine imaging enables real-time advancement of a Tuohy needle towards the dura and the precise injection of blood to cover the dural defect. We tested the effectiveness of ultrasound- guided epidural blood patch in the treatment of a symptomatic cerebrospinal fluid leak after spinal surgery.

Methods: In two patients following lumbar spine surgeries with instrumentation and incidental dural tears treated with primary closure and muscle flaps developed severe symptomatic headaches with failed conservative therapy underwent ultrasound guided epidural blood patch. Precise needle advancement to the dura was observed with ultrasound guidance with real-time three dimensional ultrasound scanning used to view expansion of blood over the dura.

Results: We present two cases of the successful treatment of dural leaks following laminectomies using ultrasound-guided blood patches. The Introduction of high-resolution 3-dimensional ultrasound allows real time assessment of injectate spread and confirms flow of blood over the dura. A repeat 3- dimensional ultrasound scan, 30 hours after the blood patch, demonstrated a volume increase of cerebrospinal fluid in the spinal canal in one of the cases. Discussions: The epidural blood patch is commonly used for treatment of a headache caused by CSF leak associated with a needle puncture. In this scenario, the blood is injected through a needle placed by an anesthesiologist guided by tactile feedback between the intact ligament of flavum and the dura (epidural space).

In contrast, the wound closure of laminectomies involves closure of the paraspinal muscle fascia, subcutaneous layer, and the skin with elimination of the ligament of flavum and dura interface with disruption of tissue layers commonly used to guide epidural needle placement. Real-time ultrasound allowed accurate positioning of the epidural blood patch in the absence of landmarks, while obtaining adequate visualization to avoid surgical implants, allowing safe and effective treatment of the dural tear after lumbar laminectomy with fusion.

Conclusion: Further investigations are needed to determine the efficacy of epidural blood patches serving as an intermediate step between the conservative initial measures and openly invasive operative measures.

Abstract 82

Granulomatous Conduit for Intrathecal Infusion of Morphine and Bupivicaine: A Case Report

Presenting Author: David M. Webb, M.D. Presenting Author’s City, State: - Augusta, Georgia Co-Authors: John R. Schneider, M.D. - Medical College of Georgia - Augusta, Georgia Robert M. Lober, M.D., Ph.D. - Standford University Medical Center - Stanford, California John R. Vender, M.D. - Medical College of Georgia - Augusta, Georgia

Abstract: Intrathecal Drug Delivery Systems (IT-DDS) have gained widespread acceptance as a therapeutic alternative to high dose parenteral opioids for unremitting chronic pain. Due to the increased use of IT-DDS there have been reports of complications associated with its use. One specific complication noted is granuloma formation, mainly at the distal tip of the catheter.

There have been many proposed etiological factors that influence the formation of IT-DDS granulomas, including infection, reaction to catheter material, and trauma at the site of implantation. The most widely accepted etiology is that of the use of morphine as an intrathecal medication with the formation of granulomas directly related to the dose dependent increase in morphine.

We present a unique case in which a 38yo female with unremitting GI pain and IT-DDS placement developed a granuloma at the hub of the catheter. After a short period of pump failure initially due to unknown reasons, the patient returned to clinic and stated she had adequate analgesia again. Eventually a decision was made to replace the pump due to concerns of battery depletion. Upon explantation, it was discovered that the leakage site had been encapsulated by drug concretion and granuloma formation. It was clear that the granuloma formation formed a sealed conduit that re-established drug flow between the pump and catheter.

After an extensive literature search we found multiple journal articles and case studies reporting granuloma formations with the placement of IT-DDS, but we believe this to be the first publication of granuloma formation and subsequent sealed conduit formation resulting in re-established flow of intrathecal delivery of drug with adequate analgesia.

References 1. North RB, Cutchis PN, Epstein JA, Long DM: Spinal cord compression complicating subarachnoid infusion of morphine:Case report and laboratory experience. Neurosurgery 29:778-784,1991 2. Deer TR: A prospective analysis of intrathecal granuloma in chronic pain patients: A review of the literature and report of a surveillance study. Pain Physician 7:225-228, 2004 3. Schuchard M: Catheter granuloma formation complicating lumbar subarachnoid infusion therapy:survey results. Neuromodulation, 1998 4. Cabbell KL, Taren JA, Sagher O: Spinal cord compression by catheter granulomas in high-dose intrathecal morphine therapy:case report.Neurosurgery 42: 1176-80, 1998 5. Albright AL, Barry MJ, Fasick P, Barron W, Shultz B:Continuous intrathecal baclofen infusion for symptomatic generalized dystonia. Neurosurgery 38: 934-8, 1996 6. Blount,JP, Remley KB, Yue SK, Erickson DL:Intrathecal granuloma complicating chronic spinal infusion of morphine:report of three cases.J Neurosurg 84: 272-6, 1996 7. Coffey RJ,BurchielK:Inflammatory mass lesions associated with intrathecal drug infusion catheters:Report and observations on 41 patients.Neurosurgery 50:78-87,2002 8. Miele VJ,Price KO,Bloomfield S, Hogg J, Bailes JE: A review of intrathecal morphine therapy related granulomas. Eur J Pain 10:251-261, 2006

Abstract 83

Patient Education Handouts for Regional Anesthesia: Help or Hindrance?

Presenting Author: Jennifer W. Lee, M.D. Presenting Author’s City, State: - Stanford, CA Co-Authors: Lindsey Vokach-Brodsky, M.B., Ch.B., F.F.A.R.C.S.I. - Stanford University Medical Center - Stanford, CA

Background: The majority of patients having forearm and hand surgery at the Stanford Hospital and Clinics Outpatient Surgery Center receive regional anesthesia as the primary anesthetic. The purpose of the project was to determine a patientâ€™s prior knowledge and anxiety regarding anesthesia. In addition, the Introduction of pre-operative patient education handouts was attempted to serve as an aid and supplement to the anesthesiologist. The study looked at quality assessment and improvement for a system that is already in place in order to help determine a potentially better way to educate patients about regional anesthesia.

Methods: In the pre-operative area, 25 patients who were scheduled for a regional anesthesia technique were asked generic questions about regional anesthesia and interest in receiving additional patient education. As part of clinical care, they were also asked to rank their anxiety level and communicate any concerns about anesthesia. Preliminary patient education handouts about regional anesthesia were prepared. They were then distributed to a congruent patient population of 25 upon arrival and check-in at the surgery center. The same questions were posed to these patients, as well as whether or not they had read the handout in the waiting area.

Results: Of all 50 patients, 25 (50%) had heard of â€˜regional anesthesiaâ€™ or a â€˜nerve block,â€™ while the other 25 (50%) had not. Of the patients who did not receive a patient education handout, 14 (56%) thought it would have been helpful if they had received one, while 11 (44%) did not think they would benefit from one. Of the patients who did receive a handout, 19 (76%) read the information prior to receiving the peripheral nerve block. An independent t-test was performed comparing the anxiety scores of the two patient groups. The mean anxiety score, on a scale of 0-10, for group 1 (no handout) was 3.4 (SD, 3.0), while the mean anxiety score for group 2 (handout) was 3.7 (SD 2.3). There is not a statistically significant difference between the two groups (p= 0.68).

Conclusions: Patient education handouts about regional anesthesia can be informative and helpful to patients and their families. Though the handouts may not alleviate anxiety about anesthesia, they may have additional benefits post-operatively as written reminders about expectations and advantages of receiving a peripheral nerve block. The findings of the study serve as an important step in encouraging pre-operative education about regional anesthesia for patients.

Additional File #1: 1. Prior to your arrival today, had you heard of a „regional anesthesia‟ or a „nerve block‟? Yes No

2. If yes, how so? a. Prior surgery, had block before b. Family member, friend c. Internet d. Surgeon e. Other- please specify:

3. On a scale of 0-10, how anxious are you about anesthesia?

4. Which of the following is your #1 concern regarding anesthesia? a. Post-operative pain control b. Preventing nausea/vomiting c. Avoiding a general anesthesia and its side effects d. Anxiety/discomfort during nerve block e. Potential complications of nerve block

5. Do you think it would have been helpful to receive a patient education handout about nerve blocks? Yes No

Patient explanations:

6. Did you receive a patient education handout about peripheral nerve blocks? Yes No

7. Did you read it? Yes No

Additional File #2: Patient Education: Regional Anesthesia for Forearm and Hand Surgery Your anesthesiologist, in consultation with the surgeon, will determine the best type of anesthesia for you. Your anesthesiologist will take your desires into consideration whenever possible. 1. What are the types of anesthesia? a. General anesthesia is the loss of consciousness, pain sensation, and protective airway responses. b. Regional anesthesia, more specifically, a peripheral nerve block, is the preferred form of anesthesia for forearm and hand surgery.

2. What is regional anesthesia? Regional anesthesia is the loss of sensation of a particular part of the body; in your case, the arm. The anesthesiologist places numbing medication near a cluster of nerves to numb only the area of your body that requires surgery. The cluster of nerves, known as the „brachial plexus,‟ run over your collar bone, then dive beneath the collar bone, and disperse around the underarm area. The nerves may be blocked at any point mentioned above.

3. If I receive a peripheral nerve block, will I be asleep or awake for the surgery? You may remain awake, or you may be given a sedative. You do not see or feel the actual surgery take place. You will be in a semi-conscious state that allows you to be comfortable. Sedation can be light, moderate, or deep.

4. How is the peripheral nerve block performed? An ultrasound machine is used to locate your nerves of interest as you are lying in bed in the preoperative area. You will be given sedation and oxygen to keep you relaxed during the block. Your vital signs will be continuously monitored. Your skin will be cleaned with an antiseptic solution. A small, special needle is then placed near the cluster of nerves that need to be numbed. Local anesthetic is used to bathe the nerves and numb the arm.

5. What are the benefits of a peripheral nerve block? Frequently, there is less nausea and vomiting. The use of nerve blocks is associated with reduced use of narcotics for post-operative pain due to improved post-operative pain control. Patients often avoid general anesthesia and its associated side effects, and have a faster postoperative recovery and discharge time.

6. What are the risks of a peripheral nerve block? Like any medical procedure, there are risks associated with regional anesthesia. Risks include: bleeding, infection, bruising, local anesthetic toxicity, and nerve injury.

7. How common is nerve injury? Nerve injury after a regional block is a rare occurrence, which can occur anywhere in 0.5-1% of the population. Of those affected, greater than 95% resolve over 4 weeks, and over 99% resolve within 1 year. If you experience any new symptoms after the block has worn off, such as tingling, numbness, or loss of strength, you should seek medical attention.

8. How long will the block last? Depending on the medication used, blocks generally last anywhere from 8-10 hours. As the block wears off, a feeling of „pins and needles‟ may be experienced. It is very important to take your oral pain medicine approximately 6 hours after the block, then every 4-6 hours afterwards.

9. Are there any special precautions I need to take? Altered sensation and movement of the affected limb can be unsafe. Be sure to protect your arm. Do not attempt to perform any tasks with it.

10. Will an anesthesiologist check up on me afterwards? Yes, someone from the regional anesthesia team will see you in the recovery room. An anesthesiologist will also give you a phone call the day after surgery to follow-up with your care and to answer any questions or concerns.

Abstract 84

Continuous Thoracic Paravertebral Nerve Block in a working Anesthesia Resident â€“ When Opioids are not an Option.

Presenting Author: Anthony Plunkett, M.D. Presenting Author’s City, State: - Washington, DC Co-Authors: Michael Buckley, DO - Walter Reed Army Medical Center - Washington, DC Chester Buckenmaier, III, M.D. - Walter Reed Army Medical Center - Washington, DC Hisani Edwards RN - Walter Reed Army Medical Center - Washington, DC

Abstract Body: Multiple unilateral rib fractures can cause significant pain and morbidity. Treatment has classically been conservative, with an emphasis on pain control to prevent subsequent morbidity. Delayed morbidity for patients with rib fractures is often a result of hypoventilation leading to atelectasis, pneumonia, and respiratory failure. Many options exist for providing analgesia including: systemic analgesics such as opioids or non-steroidal anti-inflammatory drugs and transcutaneous electrical nerve. Additionally, regional analgesic techniques such as intercostal nerve block, epidural analgesia, intrathecal opioids, interpleural analgesia and thoracic paravertebral block have been used effectively. Continuous nerve block catheters are often maintained while inpatient and patients are discharged with oral analgesics. However, in many institutions, this dynamic is changing and patients are being managed effectively with outpatient catheters. The functional limitations related to pain or cognitive impairment as a consequence of opioid use often precludes patients from returning to work in a timely manner.

A 45 year old male presented with fractured right posterior/lateral ribs 6 though 9 status post a bicycle accident two days prior. He had been prescribed acetaminophen/oxycodone (325/5 mg) and was still experiencing 9/10 pain (zero = no pain, 10 = worst pain imagined). The patient was an anesthesiology resident and was unable to perform his clinical duties due to severe pain and limited functionality. He was unable to extend his residency training for professional and personal reasons to recover on conventional conservative treatment with rest and opioid medications. Single paravertebral nerve blocks were performed at right thoracic levels 6-9. At the T7 level a 17 gauge Tuohy needle was used to thread an indwelling catheter with approximately 4 centimeters of catheter in the paravertebral space. An infusion of0.125% bupivicaine was set at a basal hourly rate of 5mL/hr with a bolus demand of 8mL every 30 minutes for a maximum of 21mL/hr (approximately 0.25 mL/kg/hr).

He performed non clinical duties for the first week and on post injury day 8 returned to work performing clinical duties. On post injury days 7, 11, and 15, the patient attempted to wean the infusion but was unable to work at the increased level of pain. On post injury day 18 he was able to discontinue the catheter and there were no associated complications. Our Acute Pain Service contacted the patient daily, as well as had a video teleconference enabling assessment of the site for any signs of infection.

We report a unique case of a patient with multiple rib fractures who was not able to be absent from work or be exposed to potential side effects of opioids. The use of a continuous thoracic paravertebral nerve in an outpatient setting allowed a faster return to function with no adverse events.

Abstract 85

Analgesic Efficacy of Intravenous Naloxone for the Treatment of Posotperative Pruritus

Presenting Author: Harold Gelfand, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: Mark Bicket, B.S. - Johns Hopkins University - Baltimore, M.D. Vineesh Mathur, M.D. - Johns Hopkins University - Baltimore, M.D. Kanupriya Kumar, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Pruritus may be a significant problem for parturients in the postoperative period. There are many options for the treatment of pruritus, including intravenous naloxone. However, it is not clear whether the use of intravenous (IV) naloxone may also affect analgesia or other opioid-related side effects. We have performed a systematic review to further examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. Systematic literature searches of the National Library of Medicine's PubMed and EMBASE databases were conducted using terms related to postoperative use of IV naloxone. Only randomized controlled trials comparing IV naloxone used either as a continuous infusion or part of an IV PCA regimen were considered. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles. There was no restriction on language for inclusion. Meta-analysis was performed using the Review Manager 4.2.10 (The Cochrane Collaboration, 2004). A random effects model was used.

Results: The literature searches yielded 8 articles which met all inclusion criteria. There were a total of 424 subjects in the naloxone group and 376 in the saline group. We found use of naloxone was associated with a decreased risk for pruritus [odds ratio (OR): 0.41 (95% CI: 0.21, 0.79)] and postoperative nausea, but there was no difference with regard to risk of postoperative emesis [OR = 0.97 (95% CI: 0.70, 1.33)], opioid consumption [OR = 0.29 (95% CI: -3.54, 4.13)], sedation [OR = 0.82 (95% CI: 0.38, 1.74)], or urinary retention [OR = 0.44 (95% CI: 0.18, 1.04)]. Use of IV naloxone did not appear to be associated with increased VAS pain scores at 24 hours postoperatively [WM.D. = -0.21 (95% CI: - 0.59, 0.16)].

Conclusions: Our pooled analysis examining the analgesic efficacy of IV naloxone (either as a continuous infusion or IV PCA) revealed that naloxone was associated with a decrease in pruritus and nausea without any increase in pain scores. When compare to controls, the use of IV naloxone was not associated with any changes in opioid consumption or the risk of sedation, urinary retention, or emesis. The results should be interpreted with caution and certainly further examination with larger RCT is warranted as the overall number of subjects is relatively small.

Abstract 86

Survey of Skin Preparation Technique During Neuraxial Procedures

Presenting Author: Shawn Sumida, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: Christopher Grunseich, M.D. - Georgetown University - Washington, DC Vineesh Mathur, M.D. - Johns Hopkins University - Baltimore, M.D. Calvin Eng, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Assess the current practices and beliefs of a group of practitioners using skin cleanser solutions before neuraxial procedures such as lumbar puncture, spinal anesthesia or combined spinal and epidural anesthesia. There is controversy surrounding the negative effects of chlorhexidine on the spinal cord. The ideal skin preparation for neuraxial techniques is one which prevents infection with no measurable toxicity. Whereas previous studies have shown chlorhexidine to be a superior antiseptic compared to iodine based compounds, intrathecal neurotoxicity has not been studied. Furthermore, there is no FDA approved antiseptic solution for neuraxial techniques. The impact on clinical decision making has not been studied.

Methods: An anonymized, IRB approved survey was distributed to clinical care providers from the Department of Anesthesiology and Critical Care Medicine at the Johns Hopkins Hospital-Broadway performing neuraxial techniques. The survey asked respondents various questions pertaining to practices and perceptions of skin preparation compounds.

Results: A total of 151 respondents completed the survey; 60 residents, 64 attendings, and 27 CRNAs. Iodine-based solutions were preferred by 68% of all respondents. Most respondents polled (61%) believed that neither solution was a better antiseptic; 66% believed that neither was more toxic, and 14% and 19% believed that iodine or chlorhexidine respectively was more toxic.

Conclusions: The study shows that most respondents are not using the cleaning solution which has been shown in the literature to have superior bactericidal activity. While a number of practitioners believe that either iodine or chlorhexidine is toxic, evidence for chlorhexidine induced toxicity specifically during neuraxial technique is not available. Further studies are needed to more adequately evaluate for potential toxicity associated with the application of these skin cleansers.

Abstract 87

Local Anesthetic Dilution for Peripheral Nerve Blocks: Comparative Evaluation of Saline with 5% Dextrose

Presenting Author: Shalini Dhir, M.D. Presenting Author’s City, State: - London, ON Co-Authors: Mario Francispragasam, M.D. - University of Western Ontario - London, ON Amir Bouzari, M.D. - University of Western Ontario - London, ON Luminita Tureanu, F.R.C.P.C. - University of Western Ontario - London, ON Sugantha Ganapathy, F.R.C.P.C. - University of Western Ontario - London, ON

Introduction: High perineural sodium concentration is known to antagonize the analgesic effect of local anesthetic (LA) due to competitive sodium channel blockade. Therefore LA diluted with normal saline (NS) may alter onset/regression of blockade (Kanai 2006). Five percent dextrose (D5W) is painless on injection and is not known to cause any long-term sequelae in animals or humans when injected around neurological tissue (Tsui 2005).

The hypothesis of this study is that dilution of LA with D5W reduces the onset time of peripheral nerve block. The objective was to prospectively compare and evaluate the onset and duration of action of LA drug when diluted with D5W or NS in patients scheduled for upper limb surgery under regional block.

Methods: In this double blind trial, following REB approval, 550 patients scheduled for upper limb surgery under axillary brachial plexus block were randomized into two groups. All blocks were done under ultrasound guidance with 0.5% ropivacaine. Group 1 received ropivacaine diluted with D5W and group 2 received ropivacaine diluted with NS. Motor and sensory block was tested every 5 minutes for the next 30 minutes. Postoperatively, a telephonic interview was conducted after 24 hours and 7 days to document side effects, patient satisfaction and time of block resolution. Any nerve deficits were followed up until completely resolved.

Parametric data was analysed by studentâ€™s t test and non-parametric data was analysed by ANOVA. The mean time for onset of complete sensory block was 9.6 (Â±6.8) min in D5W group vs. 12.9 (Â±6.2) min in NS group and this was highly significant (p<0.003). Time of onset of motor block was similar between the two groups (table). The time taken for block recession was not different between the groups. One patient developed tingling of the lips during the block procedure that could be attributed to possible LA toxicity. Six patients had sensory deficit and one had sensory as well as motor deficit. However, forty- seven patients had non-specific neurological symptoms with no actual deficits (no difference between groups). All patients made full recovery.

Discussion: Influence of dilution agent on the outcome of peripheral regional block is currently unknown. In this randomized controlled double blind study, we determined that D5W is a safe and effective diluent for LA and reduces the time of onset of regional block, which may have implications in improving the efficiency of operating room time utilization.

References: Kanai A, Hoka S. Anesth Analg 2006; 102: 1851-5. Tsui BCH, Kropelin B. Anesth Analg 2005; 100: 1837-39.

Additional File #1: Sensory block Motor block (min) (min) Group NS 9.6 (±6.8) 12.9 (±6.1) Group D5W 12.9 (±6.2) 13.9 (±6.3) p value <0.003 NS Abstract 88

Utilizing a Heads Up Display (HUD) Unit Can Improve Hand-Eye Coordination When Performing Ultrasound Guided Regional Anesthesia

Presenting Author: Rajnish Gupta, M.D. Presenting Author’s City, State: - Nashville, TN Co-Authors: Robert D. Todd, M.D. - Vanderbilt University - Nashville, TN

Abstract Body: With the increased utilization of ultrasound, there is a need to recognize its challenges and develop means to teach safe, effective use of this technology for regional anesthesia. The most common sources of error for the novice user during UGRA are problems of ergonomics and hand-eye coordination. During an in-plane approach for a block, novice users often allow their ultrasound probe to drift and slide away from the needle or rotate relative to the axis of the needle. Visualizing the needle tip by keeping the ultrasound beam in the same longitudinal plane as the needle is a particularly challenging portion of these procedures. Inexperienced providers commonly advance the needle even when the tip is not well visualized or allow the ultrasound probe to move unintentionally when they are focused elsewhere. Inaccurate needle tip visualization can lead to failed blocks or, more importantly, accidental placement of the needle inside a nerve, inside a blood vessel, or cause a pneumothorax.

We present a novel approach to ultrasound imaging during regional anesthesia utilizing a heads up display (HUD) unit, the Vuzix Wrap 920. A HUD unit allows the user to effectively maintain visualization of their hands and block area while simultaneously keeping the ultrasound image in their field of view. This ergonomic improvement should help the user avoid ultrasound probe drift and enhance their ability to keep the needle in line with the ultrasound beam. Ultrasound guided regional anesthesia is often performed in less than ideal environments with reduced working space and significant amounts of ambient light causing glare on the ultrasound screen. The HUD unit would allow the user to view excellent ultrasound images without requiring the ultrasound machine to be positioned directly in front of them. A secondary benefit of using the headset is that ambient light is reduced, thereby improving the contrast of the ultrasound image and making it easier to identify small structures. The userâ€™s ability to monitor the orientation of the ultrasound probe and needle while focusing on the ultrasound image of the block being performed, can lead to decreased unintentional movements and complications while improving the nerve block success rate.

Although we noticed many advantages to using the HUD headset unit, there were disadvantages as well. This is one additional piece of equipment to purchase, maintain, and handle during a procedure. The additional wire from the headset can often get in the way of performing a block or get in the prepped sterile field. If the user wears glasses, this particular headset is uncomfortable and unstable to wear. If the ocular distance on the headset is not adjusted properly, a double image can result that can be confusing and distracting. If an instructor wants to point out a structure on the ultrasound image, the user wearing the headset canâ€™t follow along.

As with any new technology, there is clearly a learning curve with this device when looking at the ultrasound image and the userâ€™s hands at the same time. However, we feel the HUD unit provides a more efficient ultrasound imaging environment and will help improve success rates and reduce complications when performing the advanced techniques of UGRA.

Abstract 89

Impact of Increased Body Mass Index on Ultrasound Guided Femoral Nerve Blocks for Anterior Cruciate Ligament Reconstruction Surgery

Presenting Author: Kristopher M. Schroeder, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Rohan K. Jain, B.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Luke D. Stoltzfus, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI Seungbong Han, M.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Melanie J. Donnelly, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI

Introduction: The femoral nerve block (FNB) has been shown to provide effective analgesia for those patients undergoing ACL reconstruction surgery. However, administration of regional anesthesia presents obvious technical challenges in the obese population. A large scale study demonstrated that when using the nerve stimulation technique, higher body mass index (BMI) was associated with significantly higher block failure and complication rates for all types of blocks. However, the effect of BMI on the efficacy of ultrasound (US) guided FNB has not been studied. This 22 month retrospective study was done to investigate the relationship between increasing BMI and various perioperative parameters for US guided FNB placement in ACL reconstruction surgeries.

Methods: Following IRB approval, the charts of 211 patients who underwent ACL reconstruction surgery with postoperative US guided FNB placement from 1/15/08 - 10/9/09 were reviewed. A multiple regression and logistic regression analysis was used to determine how BMI, when adjusted for age, sex, ASA score, and type of graft used in the ACL reconstruction influenced a variety of clinical variables.

Results: BMI significantly impacted the amount of opioids used intraoperatively and the total amount of opioids used in PACU Phase I. However, BMI did not affect the amount of opioids required after the block was placed in PACU Phase I or II. BMI did not impact the time required for block placement, the amount of time spent in PACU Phase I, the amount of time spent in PACU Phase I after the block had been placed, nor the amount of time spent in PACU Phase II. Peak postoperative pain was greater with increased BMI (p=0.024). However, this typically occurred before the patient received the block and this difference disappeared after the patients entered PACU Phase II. Finally, BMI was not associated with meaningful differences in the amount of nausea experienced in PACU Phase I or II.

Discussion: In this retrospective review of patients having undergone ACL reconstruction with postoperative placement of an US guided FNB, we found that increased BMI did not appear to have any significant impact on the time required for block placement or the amount of time spent in PACU Phase I or II. Similarly, when receiving US guided FNB, BMI did not significantly impact the amount of pain reported by the patient following block placement or in PACU Phase II. Additionally, block placement was associated with equal rates of postoperative nausea regardless of BMI. Importantly, while the obese group did require significantly more total opioids in PACU Phase I, there was no difference in PACU Phase I opioid consumption after the block was placed. Taken together, the data suggests that US guided FNBs provide effective analgesia in patients of increased BMI. As the obesity epidemic continues to worsen, we may rely even more on US guidance to continue to ensure high block success rates and patient satisfaction. Nielsen et al. Anesthesiology 2005 vol:102 iss:1 pg:181 -187

Additional File #1:

TABLE 1: BASELINE PATIENT CHARACTERISTICS Table 1 shows the baseline patient characteristics, stratified by BMI group, about sample mean and standard deviation for age and ASA. For the discrete variable of sex, it shows the number of patients for each category.

POSTOPERATIVE BLOCK BMI <25 BMI 25-29.99 BMI ≥30 COMBINED Age 28.7 ± 10.3 32.6 ± 9.2 33.8 ± 10.5 31.0 ± 10.1 ASA 1.3 ± 0.4 1.4 ± 0.5 1.8 ± 0.6 1.4 ± 0.5 Female 48 20 18 86 Male 49 54 21 125

TABLE 2: OUTCOME VARIABLES

The various outcome variables were modeled employing a generalized linear fit. Based on the histogram of continuous variables, we chose gamma or normal distribution depending on its shape. For immediate postoperative pain score, peak postoperative pain, and phase II time, we assumed normal distribution (denoted by n) while utilizing Gamma distribution for the others. Our models were adjusted for Age, Sex, ASA, BMI and surgery type. The p-value shown corresponds to the Wald test.

PERIOPERATIVE PARAMETERS (Mean+-SD) BMI BMI BMI P-value <25 25-29.99 ≥30 PACU PHASE I PERIOPERATIVE PARAMETERS Immediate Postoperative Pain (0-10) 4.3 ± 2.7 4.9 ± 2.5 5.6 ± 3.2 0.746 Peak Postoperative Pain (0-10) 5.6 ± 1.9 5.3 ± 2.3 6.6 ± 2.5 0.024 Phase I Time (min) 59.8 ± 23.0 62.6 ± 23.7 63.9 ± 21.5 0.210 Phase I Time After Block (min) 24.9 ± 16.4 33.2 ± 28.9 33.1 ± 19.6 0.210 Total Phase I IV Morhpine Equivalent (mg) 5.7 ± 5.0 6.0 ± 5.5 9.3 ± 9.2 0.008 Post Block Phase One IV Morphine Equivalent (mg) 1.8 ± 3.6 2.4 ± 4.0 3.0 ± 4.1 0.277 Total Phase I IV Morhpine Equivalent (mg) 5.7 ± 5.0 6.0 ± 5.5 9.3 ± 9.2 0.008 Phase I Time (min) 59.8 ± 23.0 62.6 ± 23.7 63.9 ± 21.5 0.210 Phase I Nausea 10 (85.6%) 6 (8.1%) 2 (5.3%) 0.842 PACU PHASE II PERIOPERATIVE PARAMETERS Phase II Peak Pain (0-10) 2.8 ± 1.4 2.8 ± 1.4 2.9 ± 2.01 0.387 Phase II Mean Pain (0-10) 2.8 ± 1.4 2.8 ± 1.4 2.9 ± 2.0 0.652 Phase II IV Morphine Equivalent (mg) 1.7 ± 1.6 2.0 ± 1.9 2.0 ± 2.1 0.156 Phase II Nausea 14 (14.4%) 8 (11.3%) 3 (8.6%) 0.449

Abstract 90

Epidural Injection of Platelet-Rich Plasma (PRP) for Treatment of Dural Tears â€“ a Novel Intervention

Presenting Author: Krishna Boddu, M.B.B.S., M.D., D.N.B., F.A.N.Z.C.A. Presenting Author’s City, State: - Houston, Texas Co-Authors: Suparna Saha, M.D. - University of Texas Medical Branch - Galviston, Texas Eldor L. Brish, M.D. - M.D. Anderson Cancer Center - Houston, Texas Rohini Boddu, Medical Student Observer - Royal College of Surgeons in Ireland - Houston, Texas

Background: Platelet-rich plasma (PRP) therapy has been gaining prominence in its applications for bone and soft tissue healing. Our institution is the first to apply this technique to dural tears by injecting autologous platelets epidurally along with thrombin into a patient with spontaneous dural leaks.

Case Report: A patient with chronic low pressure headache secondary to chronic CSF leak was administered platelet rich plasma and thrombin instead of conventional blood patch . This intervention resulted in resolution of her symptoms for several months.

Conclusion: PRP plus Thrombin therapy is a new and quite useful technique to the field of Anesthesia and Pain Medicine. Its clinical applications in dural tears merit further exploration.

Introduction: Platelet-rich plasma (PRP) has been gaining popularity in its relatively new-found clinical applications in soft tissue and bony injuries. Historically, PRP was mainly applied in the intraoperative arena, such as in the use of platelet derived products (fibrin sealants, platelet gels, etc) (Mishra). PRP has recently been used as an injectate in chronic tendinopathies and acute ligamentous injuries (Eppley). Current clinical applications of PRP include use by oral and maxillofacial surgeons, otolaryngologists, plastic surgeons, orthopedic surgeons, and general surgeons to aid in soft and hard tissue healing (Eppley). PRP contains growth factors and bioactive proteins that influence the healing of tendon, ligament, muscle, and bone. (Eppley, Foster, Alsousou) Platelet alpha granules are rich in growth factors that play an essential role in tissue healing, such as TGF-beta, VEGF, and PDGF (Alsousou). PRP, with a platelet concentration of at least 1,000,000 platelets/microL in 5mL of plasma is associated with an enhancement of healing (Foster). This corresponds to a platelet count 5 times higher than that of blood, which is normally 150,000/ microL to 350,000/ microL, with an approximate mean of 200,000/ microL (Alsousou). This concentration of PRP has been shown to contain a 3-5 fold increase in growth factor concentrations (Foster). A great deal of literature has been published documenting the healing abilities of PRP in tendon injuries(Eppley). As dura mater is composed of dense connective tissue similar to tendons, our insititution attempted to repair damage to the dura via an autologous platelet injection epidurally (DeFranco).

Case Report: The patient is an 18 year old Caucasian female with a past medical history significant for CSF Leak Syndrome and Intracranial Hypotension with history of chronic headaches since she was 11 years old.. Her past medical history also includes inflammatory bowel disease, peripheral neuropathy, and an underlying connective tissue disorder. The patient has had multiple admissions in the past for worsening headache. This admission, the patient presented with a 1 day history of 10/10 headache, not improving despite her home Dilaudid PCA pump (1.5 mg/hr basal, 1 mg q10 mins prn demand) and Oxycodone 60 mg PO q8 hours. This was the second episode over a period of 2 months. The patient has also had decreased PO intake for 2 days secondary to nausea. The patient was admitted for pain control of worsening headache, and plans were made to administer a platelet patch. The patient had already had over 30 epidural blood patches placed in the past (6 years. As such, the innovative technique of a platelet patch was attempted. The patient was brought to the OR and given general endotracheal anesthesia Bilateral L1 laminectomy, bilateral L2 laminotomies, and bilateral T12 laminotomies were first performed by the neurosurgeon. Following this and in collaboration with the chronic pain service, an arterial line catheter was guided under fluoroscopic guidance to about the T1 level in the epidural space cephelad. Contrast was then injected to confirm the location. The area was then irrigated extensively with saline solution to remove as much contrast as possible. Plasma enriched with platelets (PRP) and a combination of thrombin was injected slowly in the epidural space, starting at T1 and working all the way down to the T12 area. A total of 80ml of platelet concentrate along with thrombin was injected. The patient then underwent a dural graft at the end of the procedure to the dural biopsy site.

The patient remained in the hospital for 10 days post-operatively under Acute Pain Medicine team. She complained of pressure in her back for the first three post platelet patch days. During her hospital course, the patient maintained normal oxygenation on room air and was hemodynamically stable. She developed no neurological deficits. Pain was reasonably controlled (the patient could tolerate to be weaned off of all IV pain medications and reported no further headache). In addition, the patientâ€™s mobility improved during the hospital course. The patientâ€™s medications upon discharge included Oxymorphone ER 35mg PO q8hrs, and Hydromorphone 4mg tab, 2.5 tab PO q 4 hours PRN breakthrough pain. The patientâ€™s headaches remained controlled for 4 months at which time further occurrences of spontaneous dural leaks caused a worsening of symptoms leading to another hospital admission.

Discussion: PRP is used in various surgical fields to enhance bone and soft-tissue healing by placing supraphysiologic concentrations of autologous platelets at the site of tissue damage (Alsousou). The number of basic science studies, animal, and human investigations of PRP has risen sharply in recent years (Mishra). However, there remains a significant amount of basic science study and clinical evaluation that is required to define the optimal concentration of PRP, the optimal timing of the injection after an acute injury, and the optimal physiologic environment (Foster).

Currently, there is one major theory behind the healing properties of PRP in soft tissue and bony injuries (Foster). Connective tissues, such as tendon, ligament, and muscle, heal through 3 phases: inflammation, proliferation, and remodeling. During each of these three phases of wound healing, various cytokines play a role. Cytokines bind to transmembrane receptors on local and circulating cells, thereby inducing conformational changes in these transmembrane proteins and initiating a complex signal cascade within the cell, with the end point being the a modulation in gene expression within the nucleus of the cell. Cytokine binding influences the expression of proteins that regulate, among many things, extracellular matrix production and cellular differentiation and proliferation. Tendons have shown enhanced gene expression of type 1 and type 3 collagen after being cultured in PRP in vitro (Schnabel LV, Mohammed HO, Miller BJ. Platelet-rich plasma (PRP) enhances anabolic gene expression in flexor digitorum superficialis tendons (Foster).

When administering PRP to a patient, there are a few considerations to take into factor. Because PRP is prepared from autologous blood it is inherently safe, and any concerns regarding transmission of diseases such as HIV, hepatitis, of Creutzfield-Jacob disease, or immunogenic reactions that exist with preparations of allograft or xenograft, are eliminated (Alsousou). Also, it is important that NSAIDs not be used in the first 2 weeks after injection as they may inhibit the prostaglandin pathway and may inhibit the beneficial effects stimulated by the PRP injection. While there is no current clinical evidence in humans for this practice, the effect of PRP depends on the inflammatory healing cascade which theoretically could be inhibited by NSAIDs (Foster). In the case of our patient, relief from headaches secondary to intracranial hypotension was obtained for a substantial period of time (4 months) due to repair of the dura from the injection of PRP epidurally. Because the patient has an underlying connective tissue disorder, it was expected that she would continue to develop tears in her dura and that her headaches would return. In a normal patient who does not suffer from spontaneous dural tears, PRP injection could be considered to repair a possible iatrogenic dural tear, such as in situations of post-dural puncture headache.

Conclusion: PRP has many clinical applications in medicine, and its usage has been reported for the first time by anesthesiologists in this paper. While the case presented of a patient with spontaneous dural leaks is rare, the epidural application of PRP to other situations in which dural tears are encountered by anesthesiologists, for example, in the treatment of post-dural puncture headaches, is a circumstance that merits further investigation.

References: Mishra A, Woodall J, Vieira A. Treatment of Tendon and Muscle using platelet-rich plasma. Clin Sports Med 2009; 28(1):113-125.

Alsosou J, Thompson M, Hulley P, Noble A, Willett K. The biology of platelet-rich plasma and its application in trauma and orthopaedic surgery. J Bone Joint Surg 2009; 91-B:987-96.

Foster TE, Puskas BL, Mandelbaum BR, Gerhardt MB, Rodeo SA. Platelet-Rich Plasma: From Basic Science to Clinical Applications. Am J Sports Med 2009; 37:2259-2272.

Eppley BL, Woodell JE, Higgins J. Platelet Quantification and Growth Factor Analysis from Platelet-Rich Plasma: Implications for Wound Healing. Plast Reconstr Surg 2004; 114:1502-1508

Schnabel LV, Mohammed HO, Miller BJ. Platelet-rich plasma (PRP) enhances anabolic gene expression in flexor digitorum superficialis tendons. J Orthop Res 2007;25(2):230-240.

Michael J. DeFranco, M.D., Kathleen Derwin, PhD and Joseph P. Iannotti, M.D., PhD. New Therapies in Tendon Reconstruction. J Am Acad Orthop Surg, Vol 12, No 5, September/October 2004, 298-304.

Abstract 91

Ultrasound Assessment of Neurovascular Relationships in the Posterior Triangle of the Neck

Presenting Author: Steven Orebaugh L., M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Wallis T. Muhly, M.D. - UPMC Anesthesiology Residency - Pittsburgh, PA

Introduction: Vessels within the posterior triangle of the neck may influence the spread of local anesthetic (1) and, if found in close proximity to the brachial plexus, may increase the risk of vascular trauma or intravascular injection during brachial plexus blocks (2). We utilized ultrasonography to document the presence and location of these vascular structures at the sites of interscalene and supraclavicular block.

Methods: Following Institutional Review Board approval, we obtained consent for a pre-block scan from 50 ASA class 1-3 patients who were undergoing interscalene block. Age, gender, height, weight, and side of procedure were recorded. Prior to the block, the supraclavicular and interscalene regions were evaluated and any arteries or veins in close association with the brachial plexus were documented. The diameter, depth, position and anatomical course of the vascular structures were recorded and a hard copy was captured for further analysis.

Results: Patient demographics are presented in Table 1 and anatomic characteristics of vessels are outlined in Table 2. An arterial branch, traced to the subclavian artery was evident in the supraclavicular area in 43/50 (86%) patients. Of these, 77% were seen to branch directly from the 3rd portion of the artery. A branch from the subclavian vein, coursing laterally across the supraclavicular region was evident in 28/50 (56%) of patients studied. Within the interscalene region, an artery was identified coursing from medial to lateral across the interscalene groove in 45/50 (90%) of patients. This vessel could be traced to the SCA in 22/45 (49%) of cases. Finally, a small vein coursing medial to lateral within the interscalene region was noted in 23/50 (46%) of cases and 35% of these were traced back to the SCV.

Discussion: Small arteries and veins frequently lie close to the brachial plexus and if not appreciated, are at risk of vascular trauma or intravascular injection. Our data confirms that these vessels may be interspersed with the roots or trunks of the plexus at either site (1,3) and reinforces the importance of a brief pre-block scan to characterize structures surrounding the target nerve (4).

References: 1. Abrahams MS, Panzer O, Atchabahian A, Horn J-L, Brown A. Limitation of local anesthetic spread during ultrasound-guided interscalene block. Reg Anesth Pain Med 2008;33:357-359.

2. Orebaugh SL, Williams BA, Kentor ML. Ultrasound guidance with nerve stimulation reduces the time necessary for resident peripheral nerve blockade. Reg Anesth Pain Med 2007;32:448-454.

3. Sites BD, Brull R, Chan VWS, Spence BC, Gallagher J, Beach ML, Sites VR, Abbas S, Hartman GS. Artifacts and pitfall errors associated with ultrasound-guided regional anesthesia. Reg Anesth Pain Med 2007;32:419-433.

4. Manickam BP, Perlas A, Chan VWS, Brull R. The role of a preprocedural systematic sonographic survey in ultrasound-guided regional anesthesia. Reg Anesth Pain Med 2008;33:566-570.

Additional File #1: TABLE 1: Patient Demographics

Gender Male 54% Female 46% Age (years) 49 ± 14* Height (in) 67 ± 4* Weight (lb) 182 ± 44* Side of Interscalene Block Left 42% Right 58% * mean ± standard deviation

Additional File #2: TABLE 2: Vascular structures, dimensions and depths within the supraclavicular and interscalene region

Vessel of Interest Incidence (%) Depth (cm)* Diameter (cm)* Supraclavicular Region Arterial branch 43/50 (86%) 1.7 ± 0.5 0.3 ± 0.1 Venous branch 28/50 (56%) 1.6 ± 0.5 0.3 ± 0.1 Interscalene Region Arterial branch 45/50 (90%) 1.1 ± 0.5 0.2 ± 0.1 Venous branch 23/50 (46%) 1.1 ± 0.6 0.3 ± 0.1 * mean ± standard deviation

Abstract 92

Posterior Knee Pain Control Improvement Following Total Knee Arthroplasty with Scheduled Nurse-Delivered Sciatic Nerve Catheter Boluses

Presenting Author: Anna M. Clendenen, R.N. Presenting Author’s City, State: - Jacksonville, FL Co-Authors: Karen R. Christopher-Smith, R.N. - Mayo Clinic - Jacksonville, Florida Bonnie L. Howe, R.N. - Mayo Clinic - Jacksonville, Florida Beth L. Ladlie, M.D. - Mayo Clinic - Jacksonville, Florida Steven R. Clendenen, M.D. - Mayo Clinic - Jacksonville, Florida

Background: Literature supports peripheral nerve catheters as a superior form of pain control for total knee arthroplasties (TKA) with fewer complications when compared to IV patient-controlled analgesia (PCA)(1). Femoral nerve blocks, including continuous femoral nerve blocks, are considered a valuable component of peripheral nerve analgesia while varying importance has been placed on the addition of sciatic nerve blocks. Sciatic nerve blocks that are given prior to surgery may last 12 to 24 hours, resulting in posterior knee pain with regression of sensory block. Since the timing of surgery and uptake of local anesthetics is different for each patient, it may be difficult to anticipate sensory block regression. At our institution, we previously utilized a continuous femoral nerve catheter infusion with a PCA dose for anterior knee pain. A sciatic bolus of 6 ml 0.2% ropivacaine was ordered every four hours as needed (PRN) for posterior knee pain. During rounds on the first postoperative day, we noticed that patients frequently complained of posterior knee pain. In many cases the PRN boluses were under utilized or not used at all. With the purpose of improving analgesia, we added scheduled sciatic boluses at 8 pm, 12 am, and 4 am beginning the day of surgery. The visual analogue scale (VAS) was recorded and compared to patients who received PRN boluses only.

Methods: All TKA patients received a continuous femoral nerve infusion of 0.2% ropivacaine at 8 ml/hr with a PCA option of an additional 8 ml every hour. TKA patients with sciatic blocks were changed to the protocol including the three scheduled boluses. After accumulating 40 patients, we then compared their VAS scores to 40 patients prior to the protocol change (who received only PRN sciatic nerve block boluses). The continuous femoral nerve infusion of 0.2% ropivacaine at 8 ml/hr with a PCA option of an additional 8 ml every hour remained unchanged. VAS was recorded and compared for each patient during the first 48 hours postoperatively while the peripheral nerve catheters were in place.

Results: Medical records were reviewed for 40 patients who received scheduled and PRN sciatic boluses and 40 patients who received only PRN boluses. Along with demographic information, the primary endpoint recorded was the VAS. The patients in the scheduled bolus group consistently had better pain scores than those in the PRN only group on both postoperative days. For anterior knee pain on postoperative day 1, the VAS was 2.1 for PRN boluses versus 1.4 for those who also received scheduled sciatic boluses. For anterior knee pain on postoperative day 2, the VAS was 2.1 versus 1.2, respectively. For posterior knee pain on postoperative day 1, the VAS was 4.5 for PRN boluses versus 1.3 for the scheduled sciatic boluses. For posterior knee pain on postoperative day 2, the VAS was 3.9 versus 2.2, respectively. Total local anesthetic dose was similar for both groups despite the three scheduled sciatic nerve boluses in one group.

Conclusions: When using continuous femoral and sciatic nerve block for TKA, scheduled sciatic nerve boluses are an effective addition to postoperative analgesia.

References: 1. Raimer C, Priem K, Wiese AA, et al. Acta Orthop 2007; 78:193-200.

Abstract 93

Transversus Abdominis Plane Block in a Canadian Lynx

Presenting Author: Carrie Schroeder, D.V.M. Presenting Author’s City, State: - Madison, WI Co-Authors: Rebecca A. Johnson, D.V.M., Ph.D., D.A.C.V.A. - University of Wisconsin School of Veterinary Medic - Madison, WI Kristopher M. Schroeder, M.D. - University of Wisconsin School of Medicine and Pub – Madison, WI

Case Description: A Canadian lynx (Lynx canadensis) presented with a history of vomiting, diarrhea, and anorexia. The animal was extremely fractious; anesthesia was induced with isoflurane administered in 100% oxygen in a plastic bag surrounding the crate and maintained on isoflurane throughout the procedure. Abdominal radiographs suggested a gastric foreign body; an abdominal exploration was elected and a fentanyl infusion was started (5-15 mcg/kg/hour IV). The animal was positioned in a supine position and the abdominal layers were imaged with a 13-6 MHz linear array probe. A 22G Tuohy needle attached to an extension set primed with bupivacaine solution was passed through the external and internal oblique muscle layers perpendicular to the skin. The needle was inserted directly adjacent to the ultrasound probe using an out of plane approach 3 cm lateral to the midline. When the fascial plane between the internal abdominal oblique and transversus abdominis muscles was reached, negative aspiration revealed no evidence of vascular puncture and a test dose of 1 ml 0.125% bupivacaine was injected to confirm placement. The local anesthetic solution was immediately visualized in the proper fascial plane and an additional 4 ml of the solution were injected. The procedure was repeated in an identical manner on the right side of the abdomen. No appreciable changes in cardiovascular or respiratory parameters were seen following the block. Intra-operative anesthesia was largely uneventful with minimal variations from normal anesthetized values. Based on the absent response to surgical stimulation, analgesia appeared to be sufficient from the TAP block and fentanyl was slowly reduced and discontinued upon closure of the abdomen. At this point, buprenorphine (0.03 mg/kg IV) and acepromazine (0.04 mg/kg SC) were administered immediately prior to extubation to provide mild postoperative sedation for transport to the ownerÃ¢â‚¬â„¢s residence. The animal recovered very smoothly and appeared comfortable post-operatively. The TAP block produced no overt complications and may have played a role in this non-eventful recovery. Approximately 10-12 hours following the TAP block, the owner reported a bout of aggression. We propose that this timepoint may have corresponded to the termination of analgesia provided by the bupivacaine.

Discussion: The post-operative management of zoo and exotic animal species presents significant challenges, including provision of post-surgical analgesia. The prolonged analgesia offered by human regional anesthetic techniques may be beneficial for animals that are not easily handled in the postoperative period. Due to the aggressive nature of the species and the limited opportunities for adequate post-operative pain control, the authors elected to perform the TAP block in this animal. Although there were many confounding factors, this novel regional anesthetic technique appears to have potential in the field of exotic animal medicine to provide acceptable, moderate duration analgesia where repeated doses of shorter-duration analgesics may be impractical. Further studies are needed in veterinary species to verify the efficacy of blockade and the exact duration of post-operative analgesia.

Additional File #1:

A B Figure 2 C

Figure 1. Ultrasound image demonstrating normal anatomy of the abdominal musculature. Images were made midway between the iliac crest and the caudal aspect of the rib cage and approximately 3 cm lateral to midline on the left side of the abdomen. Large dot in upper left indicates probe orientation. Small dots on right are 1 cm marks. A. External oblique; B. Internal oblique; C. Transversus abdominus; D. Peritoneal cavity.

A B

C D

Figure 2. Ultrasound image of lynx abdominal wall following deposition of 5 ml of 0.125% bupivacaine solution between the internal abdominal oblique and transversus abdominus (TAP block). Large dot in upper left indicates probe orientation. Small dots on right are 1 cm marks. A. External oblique; B. Internal oblique; LA. Local anesthetic solution; C. Transversus abdominus; D. Peritoneal cavity.

Abstract 94

Ultrasound-Guided Transverse Abdominis Plane (TAP) Block in Infants and Children: An Observational Analysis

Presenting Author: Santhanam Suresh, M.D. FAAP Presenting Author’s City, State: - Chicago, IL Co-Authors: Melanie Kho, M.S. - Children's Memorial Hospital - Chicago, IL Jeffrey Steinfeldt, M.D. - Children's Memorial Hospital - Chicago, IL Gabriel Sivaja, B.S. - Children's Memorial Hospital - Chicago, IL Deli Wang, Ph.D. - Children's Memorial Hospital - Chicago, IL

Abstract Body: The aim of this study was to review the authorsâ€™ clinical experience with the use of ultrasound-guided transversus abdominis plane (TAP) blocks in pediatric patients.

Methods: After IRB approval, all data on TAP blocks performed at a free-standing childrenâ€™s hospital between June 2009 and January 2010 were entered in an Excel database. Descriptive statistics were used on continuous variables and proportions and frequencies were applied to categorical variables. Log- rank test was used to compare the first rescue-free survival among different groups based on the patientâ€™s age and their American Society of Anesthesiologists (ASA) status. Chi-square test or Fisher exact test was conducted to evaluate association between categorical variables. The Cox proportional hazard model was used to identify risk factors for the first rescue-free survival on the day of the procedure. Statistical analysis was performed using the software SAS 9.1 (SAS Institute Inc.; Cary, NC).

Results: A total of 85 patients (30 female, 55 male) were included in this retrospective study. The mean age was 85.5 months (range 9 days to 11 years); 20 patients were infants (age â‰¤ 1 yr). The mean duration (SD) of the procedure was 153.67 (119.5) minutes and there were no significant differences in the procedure duration among age groups (p = 0.9017) or between genders (p = 0.6243). The median time of the first rescue on the operation day was 78.49 minutes. The proportion of patients who had the first rescue on the operation day was significantly lower for infants (35%) than for older children (63.08%) (p = 0.0387). The first rescue-free survival on the operation day was significantly different between ASA status I+II and III+IV (p = 0.0348) and between infants and older patients (p = 0.0035), but not between genders (p = 0.3330). Older children had shorter first rescue-free survival times than infants. Patients with an ASA status of III or IV were less likely to have first-time rescue on the operation day compared to those with an ASA status of either I or II but this was not statistically significant at the 5% level (p = 0.0559, HR=0.56, 95% CI: 0.309-1.015). The total number of rescues was significantly different between infants and older children (p = 0.0313). Patients with ASA I or II tended to require a higher number of rescues than those with an ASA greater than II, but this was not statistically significant at the 5% level (p = 0.0533). The total doses used for rescue were significantly higher in older patients compared to infants (p = 0.034), but not significantly different among ASA statuses (p = 0.2281).

Discussion: The TAP block is a relatively newer analgesic technique that can provide pain relief in infants and children1 and may offer effective postoperative analgesia in this young patient group. With a TAP block, the need for rescue pain medications may be significantly reduced in neonates and infants less than older children. The TAP block may also reduce the amount of rescue medications required by sicker (ASA III or IV) pediatric patients. Future pharmacodynamic and pharmacokinetic studies are warranted to determine the exact dosage guidelines for infants and children receiving TAP blocks for abdominal surgery.

1. Suresh S, Chan VW: Ultrasound guided transversus abdominis plane block in infants, children and adolescents: a simple procedural guidance for their performance. Paediatr Anaesth 2009; 19: 296-9

Abstract 95

Brugada Syndrome: Is Regional Anesthesia Safe?

Presenting Author: Brown R. Anthony, M.B., Ch.B. Presenting Author’s City, State: - New York, NY Co-Authors: Daewha Hong, M.D. - Columbia-Presbyterian Medical Center - New York, NY

Introduction: Shoulder surgery is best performed under an interscalene block supplemented by sedation or general anesthesia. A patient with Brugada syndrome was scheduled for arthroscopic acromioplasty and mini-open rotator cuff repair. We present a case of successful administration of regional anesthesia for shoulder surgery in this unusual and challenging condition. Case Report: A 67 year-old man with Brugada syndrome presented for arthroscopic acromioplasty and mini-open rotator cuff repair. The patient was diagnosed in 2005 with Brugada type 1 ECG changes with no cardiac structural abnormalities on echocardiography, and electrically inducible ventricular tachycardia on electrophysiologic testing. The patient had an ICD placed in 2007 which proved life saving - one episode of symptomatic ventricular tachycardia was terminated by shock, another by pacing with several additional episodes of ventricular tachycardia that terminated spontaneously. The patientâ€™s ICD was turned off on the morning of surgery and external pacer pads were placed. Following 1mg of midazolam, an ultrasound-guided ISB was performed with 40cc of 1.5% mepivacaine. A 12-lead ECG performed before and after placement of the block showed no changes in the Brugada pattern. The surgery was performed in the beach chair position and sedation was achieved with an additional 1mg midazolam and a propofol infusion (titrated up to 75mcg/kg/min) with the patient spontaneously breathing oxygen via nasal cannula. The patient remained hemodynamically stable throughout the procedure. The surgery took 2 hours and the ISB provided analgesia for approximately 3.5 hours. Thereafter the patient was given IV hydromorphone in the PACU resulting in adequate pain control (NPS = 2).

Discussion: Brugada Syndrome is a condition with characteristic ECG changes (ST elevation in the anterior chest leads V1-V3, with apparent right bundle-branch block, although the latter can be absent) in structurally normal hearts, which may present with tachyarrhythmias, syncope, or sudden death. The pathophysiology of the syndrome is complex and anesthetic management can be challenging. Autonomic changes and multiple pharmacologic interactions commonly seen during anesthesia may exacerbate the underlying disease process and trigger Brugada ECG changes and malignant arrhythmias. Beta-blockers, alpha-agonists, and vagotonic agents have been shown to exacerbate the ECG changes typical of Brugada as have pressure on the carotid body, intra- and post-operative hypothermia, â€œlightâ€ anesthesia and postoperative pain. As Brugada syndrome is a cardiac sodium channel defect, the administration of local anesthetics may exacerbate Brugada ECG changes. Two case reports in which bupivacaine was used reported Brugada-type ECG patterns that were attributed to the long-acting local anesthetic. Class 1A and 1C sodium channel blockers are also known to exacerbate Brugada syndrome, however lidocaine (class 1B Na channel blocker) has been administered safely experimentally and clinically. The literature is limited regarding the use of regional anesthesia in this group of patients. We report the successful use of mepivacaine-based regional anesthesia in a patient with Brugada syndrome.

Abstract 96

Placement of Peripheral Nerve Catheters for Lower Extremity Amputation in a Patient with a History of Surgical Revascularization: An Indication for Ultrasound

Presenting Author: Sylvia H. Wilson, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Alon Ben-Ari, M.D. - University of Pittsburgh Medical Center - Pittsburgh, PA

Abstract Body: Continuous peripheral nerve blocks may have increased utility in patient populations where neuraxial techniques are contraindicated. Surgical revascularization procedures alter vascular anatomy and preclude relying solely on anatomical landmarks for regional anesthesia. In this regard, we describe the usefulness of ultrasound for the placement of a continuous peripheral nerve block in a patient with severe peripheral arterial disease, sepsis and dementia requiring above knee amputation several years after femoral arterial bypass. We discuss the benefits of ultrasound for patients with altered anatomical landmarks or altered coagulation status.

Case: A 72 year old Caucasian male with a necrotic left stump following below knee amputation (BKA) and multiple debridements of the stump (most recently 8 day ago) presented for an above the knee amputation (AKA). Past medical history included dementia, hypertension, coronary disease, peripheral neuropathy and chronic obstructive pulmonary disease. Surgical history was significant for coronary artery bypass grafting, bilateral carotid endarterectomy, bilateral femoral bypass surgery followed by graft stenting, bilateral iliac artery stenting, hemicolectoly for colon cancer and left BKA three months ago. The surgical team consulted the acute pain service preoperatively for postoperative pain management. Preoperative medications included vancomycin and metronidazole to treat the infected stump, although there was not growth on any cultures, and clopidogrel (75 mg daily). INR was 1.3. Examination included stable vital signs on room air, orientation only to place, well healed scars from numerous surgeries, temporal wasting, a necrotic left stump and coarse breaths sounds with a wet and productive cough. On palpation of the left groin, a lateral bounding pulse was noted and a more medial faint pulse. After consent was obtained from his power of attorney, standard monitors and oxygen were placed and the patient was positioned supine. The left groin was prepped and draped and an ultrasound probe was draped and applied due to the unclear groin anatomy. Groin sonography combined with 2D doppler revealed a large patent arterial graft with a femoral vein located inferomedial to the graft and the native artery located superiomedial to the femoral vein (Figure 1). 2D doppler demonstrated only minute flow in the native artery and possibly an arteio-venous fistula between the native vessels. The femoral nerve was identified lateral to these three vessels (Figure 2) and stimulated (1.5 milliamperes, 2 hertz, 0.1 milliseconds) under ultrasound visualization. The quadriceps muscles were stimulated and a femoral catheter was placed at this location. A subgluteal sciatic catheter was uneventfully placed under ultrasound guidance shortly after. The patient was followed by the acute pain service for the next three days until his catheters were removed. He did not complain of any pain during this time and he was comfortable during dressing changes. His pain was treated after catheter removal with ketorolac, acetaminophen and small doses of dilaudid as needed.

Additional File #1:

Additional File #2:

Abstract 97

Meta-analysis of the Efficacy of Epidural Naloxone in Decreasing Postoperative Pruritus and PONV

Presenting Author: Harold Gelfand, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: E. David Bravos, M.D. - Johns Hopkins University - Baltimore, M.D. Vineesh Mathur, M.D. - Johns Hopkins University - Baltimore, M.D. Kanupriya Kumar, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: Pruritus and postoperative nausea and vomiting (PONV) may interfere with a parturientâ€™s recovery after Cesarean section. Epidural naloxone has been used postoperatively in an attempt to decrease the incidence of pruritus and PONV; however, the overall efficacy of this intervention is uncertain. We have undertaken a systematic review to examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. Systematic literature searches of the National Library of Medicineâ€™s PubMed and EMBASE databases were conducted using terms related to epidural naloxone. Only randomized controlled trials comparing epidural naloxone infusion to control (either saline infusion or no infusion) were included for analysis. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles. There was no restriction on language for inclusion. Meta-analysis was performed using the Review Manager 4.2.10 (The Cochrane Collaboration, 2004). A random effects model was used.

Results: The literature searches yielded 5 articles which met all inclusion criteria. There were a total of 172 subjects in the naloxone group and 126 subjects in the control group. The dosage of epidural naloxone ranged from 0.08 to 2 microgram/kg/hr. Use of epidural naloxone was associated with a significantly lower risk of PONV [relative risk (RR): 0.47 (95% CI: 0.28, 0.80)] and pruritus [RR: 0.46 (95% CI: 0.30, 0.73)]. There was no difference in visual analog (VAS) pain scores at 4-6 [Weighted mean difference (WM.D.): -0.29 (95% CI: -0.76, 0.18)] and 8-12 hours [WM.D.: -0.52 (95% CI: -1.27, 0.22)] postoperatively.

Conclusions: Our pooled analysis examining the efficacy of epidural naloxone revealed that this intervention is efficacious in reducing postoperative pruritus and PONV without any change in analgesia. However, the results should be interpreted with caution as the overall number of subjects is relatively small and particularly considering the fact that the safety and neurotoxic profile of naloxone via the epidural route has not been fully examined.

Abstract 98

Ambulatory Surgery Under Regional Anesthesia: What Happens at Home?

Presenting Author: Shalini Dhir, M.D. Presenting Author’s City, State: - London, ON Co-Authors: Kevin Armstrong, M.D., F.R.C.P.C. - University of Western Ontario - London, ON Helen Taylor, R.N. - St. Joseph's Healthcare - London, ON Jean Aitken, R.N. - St. Joseph's Healthcare - London, ON Judy Hutchinson, R.N. - St. Joseph's Healthcare - London, ON

Abstract Body: Peripheral nerve blocks provides superior pain relief and a lower incidence of side effects leading to faster and higher quality recovery when compared to general anesthesia (1, 2). However, postoperative pain management may be deficient in these patients. Patient follow up by telephone survey may identify opportunities to improve patient care.

Methods: Over a period of 9 months, 397 outpatients at St. Josephâ€™s ambulatory surgical centre were contacted by phone. Patients having orthopedic or hand procedures represented 120 of those contacted. Data from these patients is presented. IRB approval was not required as the protocol was part of ambulatory surgery quality assurance program. Prior to discharge, patients received written as well as verbal instructions by a nurse. With patient consent, calls were made on the evening of surgery and on postoperative day 3. Data collected included type of anesthesia, pain scores (visual analog scale: 0-10), medications prescribed, presence of side effects, quality of sleep and recall of verbal instructions provided prior to discharge.

Results: Regional anesthesia was used in 76% of patients. Pain score of more than 4 was observed in 100% of patients on the evening of surgery, 83% after 24 hrs and 35% on day 3. Surgical team had prescribed postoperative analgesics for all patients on a prn basis. Details are mentioned in the table. Side effects included nausea/vomiting (61%) constipation (61%) and disrupted sleep (30%).

Most patients were unaware of when to start pain medications and feared using adjunct drugs. Only 50% of patients recalled receiving any instructions prior to discharge.

Discussion and Future Directions: It was apparent that the postoperative analgesics as well as instructions regarding pain management and treatment of side effects after receiving regional anesthesia were highly inadequate. As a result of this followup, existing post-operative discharge medications and instructions are being reviewed and revised. Multidisciplinary pain management strategies need to be developed and implemented.

References: 1. Hadzic A, Williams BA, Karaca PE et al. For outpatient rotator cuff surgery, nerve block anesthesia provides superior same-day recovery over general anesthesia. Anesthesiology 2005;102:1001-7.

2. Rawal N. Postoperative pain relief using regional anaesthesia. Current Anaesthesia & Critical Care 2007; 18 (3), Pages 140-148.

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100% 0% 21% 0% 0%

Postoperative drug prescription on discharge Abstract 99

Ropivacaine Paravertebral Block and Intravenous Dexmedetomidine for Axillobifemoral Bypass Surgery in the Patient with Severe COPD

Presenting Author: Jonathan G. Tlachac, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Beverly A. Pearce-Smith, M.D. - University of Pittsburgh - Pittsburgh, PA

Introduction: At our institution, paravertebral blocks (PVB)s are frequently utilized for the management of post-operative pain. We present a patient in whom single(S) and continuous multi-level PVBs were used for anesthesia in an elderly, ASA IV patient undergoing axillobifemoral bypass surgery (ABFBS).

Case Report: A 76-year-old white female with peripheral vascular disease and severe COPD (FEV1/FVC 49%) presented for right ABFBS. She had smoking related severe COPD requiring home oxygen. To satisfy the surgical requirement performed at the right axilla and bilateral groin, and also to avoid postoperative mechanical ventilation in this patient with a past history of prolonged postsurgical ventilation, we opted to use, for anesthesia, multiple PVBs combined with dexmedetomidine for sedation. PVBs were performed, prior to surgery, with minimum sedation (0.5 mg midazolam and 25 mcg fentanyl). SPVBs were performed at right T1- T3, as well as T11-L1 bilaterally using 3 mL of 0.5% ropivacaine per level. In addition, a PV catheter (C) was placed at T2 (right) and T12 (bilateral). In the operating room, dexmedetomidine was started at 0.2 mcg/kg/hr. Two hrs after the initiation of surgery, each PVBC was infused with 0.25% lidocaine at 3 mL/hour. During the 8-hour procedure only intermittent fentanyl (25 Âµg) and ketamine (5 mg) boluses were given, for total of 150 Âµg and 15 mg, respectively. In the intensive care unit the patientâ€™s numeric pain score was 0/10. She denied recall during the surgery. She remained hemodynamically stable with oxygen saturation of 100% on nasal cannula oxygen at 2 L/min. No symptoms of local anesthetic toxicity were recorded during surgery and recovery. During the first 14 hrs postoperatively, the patient received 0.7 mg of dilaudid. She was transferred from the ICU to the floor on postoperative day #1. She continued to progress well and was discharged to home on postoperative day #5.

Discussion: Patients undergoing vascular surgery often present with significant pulmonary and cardiovascular disease, which increases their anesthetic risk. This case illustrates the usefulness of multi- level PVBs and dexmedetomidine for anesthesia in such patients. However, we recognize that the described approach is exceptional, especially because of the total dose of local anesthetic required to meet the surgical requirements. The choice of ropivacaine and lidocaine, a staged administration of local anesthetics, and the constant monitoring for clinical symptoms of local anesthetic toxicity all contributed to the avoidance of local anesthetic overdose. Since the proposed surgery involved both the axilla and groin, a low thoracic epidural was not considered as an alternative.

Abstract 100

Survey of Outcome Measures Used in Postoperative Pain Research

Presenting Author: Benzon T. Honorio, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Dean Kathyrn, B.A. - Northwestern University - Chicago, Illinois Benzon A. Hubert, M.D. - Northwestern University - Chicago, Illinois

Introduction: Outcome measures for studies on chronic pain have been recommended (1-5). Outcome measures for pediatric postoperative pain research has been recommended but not for adults (6). We surveyed the anesthesiology literature and looked into the outcome measures used in studies on postoperative pain research.

Methods: We surveyed the original articles published in Anesthesiology, Anesthesia and Analgesia, and Regional Anesthesia and Pain Medicine, from 2000 to 2008 and listed the outcome measures and measurement tools that were utilized in the studies on postoperative pain. We noted the outcome domains that were included in the studies, duration of follow-up, and measurement tools used in the different outcome domains.

Results: A total of 549 articles were reviewed: 103 articles for Anesthesiology, 363 articles for Anesthesia and Analgesia, and 83 articles for Regional Anesthesia and Pain Medicine. There were an increased number of outcome measures and measurement tools used in the research studies from 2000 to 2008. Most studies noted pain and adverse events. Studies on pediatric pain employed a number of measurement tools including a tool to evaluate pain in non-communicating children. In addition to the usual side effects, some tools assessed the side effects in more detail. The Opioid-Related Symptoms Distress Scale assesses symptoms related to opioid intake including difficulty passing urine, headache, feeling of lightheadedness, fatigue or weakness. The Mini-Mental Status examination has been used as a measure of sedation as well as the cognitive ability of the patient. The measurement tools on physical conditioning included the SF-36 and its variations SF-12 and SF-8, measurement of ADL, six-minute walking test, mobilization scores, and evaluation of the functions of the arm, shoulder, and hand. Emotional functioning was the least studied outcome domain. The studies that looked at this outcome measure included simple VAS and Likert scales as well as sophisticated scales for anxiety, depression, and mood states. The Profile of Mood States assesses the six aspects of mood including depression, fatigue, anxiety, hostility, vigor, and confusion. Patient satisfaction by the patient or the parents, in terms of overall global efficacy and patient global assessment, were measured by simple VAS or Likert scales. The Patient Global Assessment of Response to Therapy is a categorical scale that combines pain relief and side effects. The more sophisticated tools included the McGill Pain Questionnaire, SF-36, SF-12, SF- 8, Brief Pain Inventory, Quality of Recovery scoring system, American Pain Society Quality Improvement Patient Outcome Questionnaire, and the Health Outcomes Recovery Survey. None of the sophisticated measurement tools measure all the five domains and emotional functioning and physical conditioning were superficially studied in some of the questionnaires.

Discussion: The studies on postoperative pain looked only at pain relief and side effects. None of the more sophisticated measurement tools assess the 5 recommended domains. The durations of follow-up are inadequate to note the incidence of chronic pain after surgery.

References: 1. Turk DC, et al. Pain 2003;106:337-45 2. Dworkin RH, et al. Pain 2005;113:9-19 3. Turk DC, et al. Pain 2006;125:208-15 4. Dworkin RH, et al. J Pain 2008;9:105-21 5. Turk DC, et al. Pain 2008;137:276-85 6. McGrath PJ, et al. J Pain 2008;9:771-83 Abstract 101

The Perioperative Inflammatory Response in Total Knee Arthroplasty Patients: The Impact of Limb Preconditioning

Presenting Author: Anna C. Westrick, M.D. Presenting Author’s City, State: - New York, NY Co-Authors: Alejandro Gonzalez Della Valle, M.D. - Hospital for Special Surgery, Weill Medical Colleg - New York, NY Jennifer Stanton, B.A. - Hospital for Special Surgery - New York, NY Yan Ma, Ph.D. - Hospital for Special Surgery, Weill Medical Colleg - New York, NY Stavros Memtsoudis, M.D., Ph.D. - Hospital for Special Surgery, Weill Medical Colleg – New York, NY

Background and Objectives: Ischemic preconditioning of tissue that is to undergo procedure induced underperfusion has been used in a number of surgical settings to reduce the subsequent inflammatory response and its sequelae. The objective of this prospective, randomized study was to evaluate the effect of ischemic preconditioning on the systemic inflammatory response and degree of lung catabolism associated with total knee arthroplasty (TKA).

Materials: Thirty-four patients undergoing unilateral TKA under tourniquet ischemia were enrolled with half (N=17) being randomized to an episode of limb preconditioning before induction of ischemia for surgery. Markers of inflammation (IL-6, CRP, TNF-alpha, leukocyte count) and elastin catabolism (desmosine) were measured at baseline and various points postoperatively.

Results: No differences were seen between the study and the control group in terms of demographics, blood loss, tourniquet times and fluid administration (see Table 1). A significant increase in the levels of IL-6, CRP, TNF-alpha, and white cell count was observed post operatively in both groups. However, no significant difference between groups was observed for all markers at any given time point, including the primary outcome IL-6 (see Figure 1). Urine desmosine/creatinine ratios did not differ between groups and no significant changes from baseline were seen postoperatively.

Conclusion: When following levels of markers of inflammation and elastin catabolism, preconditioning of the lower extremity in the setting of TKA may have limited value in reducing the systemic inflammatory response and level of lung injury. However with no obvious downside, preconditioning may be associated with beneficial effects not measured in this study and further investigations are warranted.

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IL6

350

300

250

200 Preconditioning

pg/ml 150 Control

100

0 baseline 6h 12h 24h Time Point

Figure 1. Shown are absolute levels of IL-6 over time for both preconditioning and control groups. A significant increase compared to baseline was seen at all collection timepoints postoperatively (P<0.0001). No differences between groups were found (P=0.1148).

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Table 1. Detailed are demographics and intraoperative data for both preconditioning and control group. No differences were found between groups. Control Group Preconditioning Group P-Value Patient Demographics Male/Female (N) 4/13 4/13 1 Age (years) 67.1 ± 9.6 66.5 ± 10.8 0.87 BMI (kg/m2) 35.5 ± 6.9 33.8 ± 4.7 0.41 ASA Classification II/III (N) 6/17 7/17 0.5 Surgical Times (minutes) Surgical Time (minutes) 78.3 ± 11.1 85.6 ± 16.3 0.14 Tourniquet Time (minutes) 51.9 ± 11.2 58.2 ± 10.7 0.1 Intraoperative Fluids (ml) Estimated Blood Loss 247 ± 69 225 ± 38 0.31 Crystalloid 1547 ± 376 1730 ± 394 0.19

Abstract 102

An Interesting Diagnosis of Cubital Tunnel Syndrome in a Nursing Mother

Presenting Author: Daun I. Johnson Milligan, M.D. Presenting Author’s City, State: - Fort Sam Houston, Texas Co-Authors: Jeffrey W. Barr, M.D. - SAUSHEC - Fort Sam Houston, Texas Thomas A. Edell, M.D. - SAUSHEC - Fort Sam Houston, Texas

Abstract Body: The patient is a 24-four-year-old female referred to Wilford Hall Pain Clinic for evaluation of left breast pain referred to her left forearm and fifth digit. She has no medical or surgical history and takes only a vitamin. She had recently given birth to a male infant via spontaneous vaginal delivery after an uneventful pregnancy. She reported she had been breastfeeding the infant every four hours since his birth three months prior.

One month ago, the patient noticed a hard lump in her left armpit, situated high in the tail of her breast tissue, and was able to resolve it with extra breastfeeding. When the lump reappeared, more tender and larger in size, she visited her obstetrician and was diagnosed with mastitis. Her doctor prescribed more frequent breastfeeding on the left breast. She thus began nursing on the left breast as often as hourly. Several days later, she noticed a new and excruciating pain in the left forearm at the lateral border of the elbow extending to the fifth digit. She reported that the pain seemed to radiate from the lump in her armpit to her pinky finger. By the time she arrived to us, she had been seen by multiple doctors, to include general surgery for possible excision of the clogged milk duct for pain relief. She had been taking acetaminophen without relief of the pain. Upon evaluation, she was suffering dysesthesias, numbness, and mild motor weakness exclusively in the ulnar nerve distribution of the left arm. Coincidentally, her mastitis had resolved with the frequent breastfeeding, which she was still practicing.

It seemed highly unlikely that breast tail mastitis could cause isolated ulnar neuropathy without affecting other components of the brachial plexus; as well, the pain was increasing in intensity as the mastitis was resolving. During a thorough history, the patient described the timing of the arm pain in relation to her frequent breastfeeding: her pain exacerbations started at the end of nursing sessions of the left breast and lasted up to one hour after completion. When asked to demonstrate how she nursed the infant, she requested a rocking chair. It was at that point we realized she was supporting her elbow on a hard wooden rocking chair armrest for the duration of the nursing sessions, with the weight of the infant pressing her cubital tunnel against the unpadded wood. An EMG study performed later that afternoon revealed a focal relative conduction velocity slowing across the cubital tunnel segment of the left elbow (a drop from 72m/s-right to 55m/s-left) and no evidence of left radial or median neuropathy. Additionally, there was no evidence of left brachial plexopathy from impingement by the clogged axillary duct as previously thought.

For further confirmation and therapeutic relief, we performed an ulnar nerve block at the elbow. A one- inch neurostimulating needle was advanced proximal to the olecranon with 2Hz motor stimulation down to 0.45mA; a total of 40mg methylprednisolone and 2.5ml 2% lidocaine was injected. The patientâ€™s pain decreased from 7/10 to 0/10. She was sent home with lidocaine patches to place on her elbow until the neuropathy resolved and instructed to not nurse in a position that left her cubital tunnels vulnerable to pressure damage. The patient has since made a full recovery.

Abstract 103

Idiopathic Intractable Chronic Hiccups(Ich) Successfully Treated with a Series of Ultrasound Guided Phrenic and Vagus Nerve Blocks

Presenting Author: Arsenio J. Avila Insambergth M.D.,F.R.C.P.C., F.C.C.P.,D.A.P.M. Presenting Author’s City, State: - Toronto, Ontario Co-Authors: Carlos E. Restrepo, M.D. - Sunnybrook HSC - toronto, ontario Ali Arvantaj, M.D. - Baylor Medical School - Dallas , Texas Maximillian Avila, B.Sc. - All Saints Medical School - Toronto, Ontario Joseph Tropiano, Highschool Degree - Oshawa High School - Oshawa, Ontario

Introductio: Hiccups are universal physiological complex experiences that remains poorly understood carecterized by involuntary diaphragmatic contractions associated with early sudden closure of the glottis terminating inspiration and resulting in a distinctive sound gasp or sight. Episodes are usually brief and benign and self limited,when persistent lasting>48 hours could produce metabolic unbalanced,leading to(singultus) Intractable chronic hiccups lasting > 1 month with significant physiological derangements,disabling sleep,respiratory muscle fatigue failure and rarely even death.Pharmacotherapy remains the first simple treatment approach since transient hiccuping is common associated often with gastric distention ,sudden temperature changes or emotions,these events either resolves spontaneously or responds to simple nonpharmacologic measures which target the hiccup reflex arc by simple maneuvers ,affecting the Vagus/Phrenic nerve in its afferent/efferent pathway.However the hiccup could persist and become intractable chronic .More than 100 medical conditions have been associated with hiccup but often its cause is not discovered leading to Idiopathic Chronic Intractable Hiccup (ICH), which require challenging medical and pharmacological therapies in addition to creative neuromodulation and Nerve blocks targeting the Hiccup reflex arc while keeping a fine balance in its risk benefit ratio.We report a case of ICH ,a 13 years old who after 8 months of hiccups responded to a series of Vagus, Phrenic Nerve blocks ultrasound guidance .

Methods: Case reports and review of published data of diagnoses and treatment trials in patients with ICH.

Case Report: A 13 years old girl was diagnosed with Idiopathic ICH after 8 months of intractable hiccups with a frequency than >10 per minute, assessed by pediatricians, neurologists, respirologists and Thoraxic surgeons,underwent neurophysiological, metabolic and rheumatological studies without evidencing any etiological explanation for the ICH, in addition to Psychological evaluation.Multyple pharmacological and non medical therapies failed to produced benefit but side effects,therefore was refered to our service where a series of Vagus and Phrenic Nerves block ultrasound guidance ,to a total of 3 series produced a total hiccup relief > 6 months

Discussion The pathophysiology of Hiccups remains unclear,ICH is a complex entity with a challenging diagnoses and unsettled treatment, but understanding the hiccup reflex arc : afferent ( vagus phrenic and sympathetic T6-T12)efferent(phrenic,brachial ,intercostal nerves)and central connection C3-C5 and Brainstem: is fundamental to establish an algorithm in the treatment trials of ICH , including medications such as dopaminergic antagonists,Gaba agonists,calcium and sodium channel blockers ,gabapentinoids , Interventional blocks and neuromodulation trials.

Abstract 104

Patient Perspective during Transition from IV PCA or Epidural to Oral Pain Medications

Presenting Author: Joseph Hung, M.D. Presenting Author’s City, State: - Baltimore, MD Co-Authors: Michelle Petrovic, M.D - Johns Hopkins University - Baltimore, MD Kanupriya Kumar, M.D - Johns Hopkins University - Baltimore, MD Elaina Lin, M.D - Johns Hopkins University - Baltimore, MD Marie Hanna, M.D. - Johns Hopkins University - Baltimore, MD

Introduction: Patients who undergo major surgical procedures routinely receive advanced (high technology) analgesic techniques such as epidural analgesia (EA) or intravenous patient-controlled analgesia (IV PCA). These effective techniques are used as bridges for acute postoperative pain control until patients can tolerate oral analgesics (low technology). This transition period from high to low technology analgesic techniques has not yet been thoroughly investigated. The purpose of this study is to prospectively study patient experiences during this time period.

Methods: Patients undergoing elective abdominal, thoracic, or spine procedures completed preoperative surveys regarding their expectations of perioperative nausea, vomiting, pain, fatigue, and expected time to recovery. Patients received either perioperative EA or IV PCA for acute postoperative analgesia after surgery. Postoperatively, they completed daily Visual Analog Scale (VAS) assessments of their current pain, nausea, pruritus, fatigue, and their current estimate of percentage to full recovery. A Quality of Recovery (QoR) survey was conducted after the transition from high to low technology. At the end of the study, 100 patients successfully completed the survey. We had 88 patients in the IV PCA group and 12 patients in the EA group.

Results: Correlation coefficients were calculated and analyzed with regards to previous surgical experiences, perioperative expectations, and actual postoperative assessments. There was a strong correlation (coefficient 0.77) between prior nausea and prior vomiting. There were no significant correlations between prior surgical experiences (nausea, vomiting, significant pain), expected surgical predictions, and actual postoperative VAS assessments.

Patient VAS assessments on the transition day were coded as numeric variables. Two tailed t-tests for independent samples were performed for statistical comparison. Patients were more satisfied with nursing care in the epidural group (p=0.03). Overall pain control (better with EA, p=0.08) and nausea (worse with EA, p=0.06) approached but did not reach statistical significance.

Graphic trends depicting minimum, average, median, and maximum scores for pain, nausea, vomiting, fatigue, and percent to full recovery showed improvement across postoperative days for both groups. Visually, there was more apparent improvement in fatigue across postoperative days in the IV PCA group.

Conclusion: These data suggest that there is no statistical correlation between previous surgical experiences and actual postoperative assessments. Graphic analysis shows daily improvement in nausea, vomiting, pain and fatigue for both groups regardless of the analgesic modality used. There was more improvement of fatigue in the IV PCA group. These results suggest the need for a larger randomized study to investigate the transition from IV PCA or Epidural to oral analgesics in the postoperative period.

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Abstract 105

Needle depth guards may enhance the safety and decrease the difficulty of ultrasound-guided supraclavicular brachial blocks performed by junior anesthesia residents

Presenting Author: Ahmad Elsharydah, M.D. Presenting Author’s City, State: - Dallas, Texas

Introduction: Pneumothorax is still one the feared complication of ultrasound guided supraclavicular brachial plexus blocks. One of the key factors to minimize this risk is the ability to follow the needle movement during ultrasound visualization and control its depth. Junior anesthesia residents who have minimal or no experience performing these blocks usually have a great difficulty manipulating the block needle, especially with the short needle. To help my trainees in this matter, I started using a simple technique of needle depth guard made from small IV extension.

Materials and Methods: Supraclavicular brachial plexus nerve blocks were done for upper arm dialysis access. Residents assigned to these cases are usually CA-1 or CA-2 with no or little experience doing these blocks. These blocks done with combined nerve stimulator and ultrasound (in plane technique)) or nerve stimulator only. EchoStim block needle with length of 5 cm or 10 cm are usually used. After visualization the subclavian artery, I keep the artery in the middle of the view and I measure the distance from the skin (lateral end of the ultrasound probe) to the angle between the subclavian artery and first rib (SS) utilizing the ultrasound machine or rough visual estimate. I cut a small tubing extension (TE) using the formula (for the 10 cm needle): TE (cm) =10- SS (cm). Then, the IV extension piece is slided over the 10 cm needle. Practically, this technique will allow the resident to have a longer needle (easier to manipulate) with a shorter safe â€œallowableâ€ depth (figure 1 and 2).

Discussion: Needle depth guards have been described in different needle procedures such as percutaneous biopsy (1) and aspiration needles (2). This device helps to control the depth of needle and stabilize the needle when it reaches its target. I believe this simple technique may prevent or minimize the risk of accidental deep placement of the needle into the pleura while the new trainee is trying to visualize the needle in the ultrasound field and to give him/her more â€œroomâ€ to manipulate that needle. Significant clinical pneumothorax after these blocks is very uncommon complication, therefore knowing the effectiveness of this technique is not possible without a study on a large sample of patients.

References (1) Samuel MC. Simple method of limiting needle depth during percutaneous biopsy. Radiology 143: 269, April 1982. (2) Gauderer MW. A simple technique to enhance the safety of abscess aspirations. J Pediatr Surg. 2010 Feb;45(2):457-458.

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Abstract 106

Acute Pain Management in a Pediatric Patient Following Reptile Limb Amputation

Presenting Author: Dominic S. Carollo, M.D. Presenting Author’s City, State: - New Orleans, LA Co-Authors: Leslie C. Thomas, M.D. - Ochsner Clinic Foundation - New Orleans, LA Bobby D. Nossaman, M.D. - Ochsner Clinic Foundation - New Orleans, LA

Abstract Body: Pediatric acute pain management can be difficult, especially after a traumatic event. Opioid analgesics are the mainstay of prescribed medications for acute pain by many surgical services. Here we present an interesting acute pain management scenario involving a traumatic amputation of a patient's entire arm.

A12 year old was swimming in the bayou in Southeast Louisiana. A large alligator well known to inhabit this bayou attacked the child. The reptile disarticulated the left upper extremity. The patient was immediately rescued transferred to our facility. The alligator was captured, sacrificed, and the severed arm was retrieved. No reattachment attempt was made due to the length of ischemic time of the limb. Post-operatively, the patient's pain was not controlled. Dressing changes required general anesthesia. On post-operative day #3, the acute pain service was consulted and following as assessment, an interscalene catheter was recommended.

Following general anesthesia and dressing change, ultrasound identified the left interscalene bundle and traced cephalad to the root level (figure 1). Utilizing sterile technique, a 20 gauge polyurethane catheter was inserted into the interscalene nerve sheath. Following a negative aspiration and test dose, ten mLs of 0.2% ropivacaine was injected into the sheath with adequate neuronal spread confirmed on ultrasound. A perineural catheter regimen of 0.2% ropivicaine at a rate of six mLs per hour and a three mL bolus dose with a twelve minute lockout was programmed.

One post-catheter insertion (POC) day #1, the patient reported his pain as 1/10. On POC day #2, the patient tolerated an awake dressing change. Pregabalin, 50 mg po bid, to help with the onset of neuropathic pain. The previously started intravenous narcotics were discontinued and the patient was slowly transitioned to oral pain medications. The catheter was discontinued on POC day #5. On POC day #6, the patient was discharged to home on pregabalin and acetaminophen with outpatient rehabilitation.

The use of interscalene catheters placed under ultrasound is not new for post-operative pain in the pediatric population.(1,2) Case reports describe the use of interscalene catheters in children for cancer pain (3) and following post-surgical amputation (4) have been published. Also, the use of perinueral catheters have recently been described after traumatic injuries in adults serving in the Iraq war (5,6). However, this is the first known reported case of the use of an interscalene catheter after traumatic amputation on a pediatric patient.

Abstract 107

Two Unilateral Continuous Thoracic Paravertebral Blocks for the Pain Management of Very Extensive Rib Fractures (>6)

Presenting Author: Vladislav I. Shick, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Fenny Anthikad, M.D. - UPMC - Pittsburgh, Pa Alon Ben-Ari, M.D. - UPMC - Pittsburgh, PA Jacques Chelly, M.D. - UPMC - Pittsburgh, PA

Introduction: Multiple rib fractures are a common injury in trauma patients which carries high morbidity and mortality. Mortality is correlated with the number of affected fractured bones. Early mobilization and respiratory physiotherapy correlate with improved morbidity outcome. Effective pain control is critical infacilitating respiratory therapy. We report our experience using 2 paravertebral catheters for the management of pain following very extensive rib fractures (>6).

Main Results: We present two patients with extensive rib fractures. In both patients two continuous paravertebral catheters were inserted on the affected side. In patient 1, dramatic improvement of respiratory parameters was observed with concomitant pain relief. In patient 2, an important decrease in the consumption of opioids and visual analogue pain scores were observed following the performance of the nerve blocks.

Conclusion: The use of 2 continuous paravertebral catheters as an option appears to be an interesting alternative for effective pain management following very extensive rib fractures.

Discussion: Our case report suggests that the use of two continuous thoracic paravertebral blocks may represent an interesting approach for the management of pain associated with very extensive rib fractures. The use of epidural anesthesia is limited in the trauma patient due to the need for anticoagulation. Karmakar et al demonstrated that the use of a continuous paravertebral block was also effective in managing pain while improving oxygenation and other respiratory parameters (1,2). Since the spread associated with a paravertebral injection is limited (3,4)the use of one continuous thoracic paravertebral catheter is unlikely to provide a spread extensive enough to allow the diffusion of local anesthetics beyond 3-5 segments. Therefore, in patients with very extensive rib fractures the placement of 2 paravertebral catheters is required and this report further provides the evidence for the double paravertebral catheter placement in the extensive unilateral rib fractures.

Reference: 1. Karmakar MK, Chui PT, Joynt GM, Ho AM. Thoracic paravertebral block for management of pain associated with multiple fractured ribs in patients with concomitant lumbar spinal trauma. Reg Anesth Pain Med 2001;26:169-73. 2. Karmakar MK, Critchley LA, Ho AMH, et al. Continuous thoracic paravertebral infusion of bupivacaine for pain management in patients with multiple fractured ribs. Chest 2003;123:424-31. 3. Cheema S, Richardson J, McGurgan P. Factors affecting the spread of bupivacaine in the adult thoracic paravertebral space. Anaesthesia 2003; 58:684-7. 4. Naja MZ, Ziade MF, El Rajab M, et al. Varying anatomical injection points within the thoracic paravertebral space: effect on spread of solution and nerve blockade. Anaesthesia 2004;59:459-63.

Abstract 108

Systematic Review of Direct Costs comparing Regional to Local or General Anesthesia

Presenting Author: Artemis Flagg, M.D. Presenting Author’s City, State: - Baltimore, M.D. Co-Authors: Christopher Deng, B.S. - Johns Hopkins University - Baltimore, M.D. Kanupriya Kumar, M.D. - Johns Hopkins University - Baltimore, M.D. Calvin Eng, M.D. - Johns Hopkins University - Baltimore, M.D. Christopher Wu, M.D. - Johns Hopkins University - Baltimore, M.D.

Objective: With the increasing concern over rising health care costs, there may be increased scrutiny on the relative costs of different anesthetic/analgesic agents. Although the comparisons of regional versus general anesthesia may mostly focused on morbidity and mortality, relatively little work has been undertaken to compare the costs between these options. We have undertaken a systematic review to examine this issue.

Method: This study qualified for exemption from the Johns Hopkins IRB. Systematic literature searches of the National Library of Medicineâ€™s PubMed and EMBASE databases were conducted using terms related to postoperative use of cost and regional anesthesia. Only trials comparing neuraxial or peripheral regional anesthesia to local anesthesia or general anesthesia were considered. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles.

Results: The literature searches yielded 19 articles which met all inclusion criteria. Of the 19 studies, 7 compared peripheral regional anesthesia to general anesthesia, 12 compared neuraxial to general anesthesia, and 4 compared local to regional anesthesia. The direct costs most commonly included for analysis in these studies were drugs and equipment used, personnel time, and operating room/recovery times. Of the peripheral regional anesthesia studies, 4 of 7 showed no difference in measured costs between peripheral nerve and general anesthesia. Of the neuraxial anesthesia studies, 6 of 12 showed no difference in costs when compared to general anesthesia while 6 suggested that use of neuraxial anesthesia was associated with lower costs. All 4 local anesthetic infiltration studies indicated that use of local anesthesia infiltration was associated with lower costs compared to either regional or general anesthesia.

Conclusions: Our systematic review revealed relatively few studies examining direct costs between local, regional and general anesthesia. With the exception of local anesthetic infiltration associated with lower costs compared to either regional or general anesthesia, the vast majority of the data was equivocal in comparing regional to general anesthesia with regard to costs. There was significant variability in the inputs into cost determination.

Abstract 109

In Plane-Ultrasound Guided Continuous Thoracic Paravertebral Block for Post Operative Analgesia in Patient with History of Left Lung Transplant

Presenting Author: Richa Wardhan, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Mario Montoya, M.D. - UPMC - Pittsburgh, PA Sylvia Wilson, M.D. - UPMC - Pittsburgh, PA Jacques E. Chelly, M.D., Ph.D., M.B.A. - UPMC - Pittsburgh, PA

Background: In UPMC,Shadyside hospital, postoperative analgesia for abdominal, thoracic and hepatic surgeries is achieved by performing dermatomal congruent thoracic paravertebral blocks. We frequently perform this block by using landmark technique but have recently embraced the use of ultrasound in performing these blocks.

Methods: A 65 year old Caucasian woman (BMI 35.2) was scheduled for left open partial nephrectomy, for a mass in the lower pole of the kidney. She had a left lung transplant seven years ago for eosinophillic granuloma. The right lung was not replaced secondary to excessive scarring. She used oxygen at night and during the day when O2 saturation was less than 85%.She denied shortness of breath. Her other comorbidities were HTN, DM, depression, anxiety, GERD.

We saw her two hours before the proposed surgery and offered her postoperative pain management. We performed an ultrasound guided continuous T8 Paravertebral block with no noted complications.

Discussion: The anterolateral limit of the paravertebral space consists of the pleura which should preferably not be perforated. Also during the block by landmark technique, superior costotransverse ligament can be missed and the needle tip can end up in the inter pleural space (tested by saline bubble being sucked on inspiration)which leads to inferior analgesia as compared to paravertebral block.

In any patient where there is doubt about integrity of interpleural space like previous pleurodesis,lung cancer, an ultrasound technique with needle visualization is preferable. In this patient we were concerned about the integrity of the interpleural space with the possibility of being obliterated by adhesions. In presence of a non functioning right lung this patient was at risk for respiratory compromise if her only functioning transplanted lung was injured. The patient was positioned in sitting position with her feet resting comfortably on a chair. Her heart rate,BP and oxygen saturation were monitored throughout the procedure and oxygen was given by nasal cannula at 3l/min.The block was performed under all aseptic precautions. The transverse process of the thoracic vertebra and left rib were identified at the T8 thoracic level using a low frequency ultrasound probe placed in parasaggital plane. An in-plane needle insertion approach from cranio to caudal was used, and a total of 15 mL ropivacaine 0.5% was injected through the needle and a catheter was threaded, while the spread of local anesthetic was observed. The process was repeated on the right side. The patient reported no signs of deteriorating respiratory status and the procedure went uneventful. Her operative course was uneventful except for an episode of post operative delirum which was evaluated by neurology service.She reportedly had a similar episode after her lung transplant.

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Abstract 110

Nerve Injury after Femoral Nerve Block for ACL Repair

Presenting Author: Minda L. Patt, M.D. Presenting Author’s City, State: - Miami, FL Co-Authors: Shawn Banks, M.D. - University of Miami/Jackson Memorial Hospital - Miami, FL Andres Missair, M.D. - University of Miami/Jackson Memorial Hospital - Miami, FL Ralf E. Gebhard, M.D. - University of Miami/Jackson Memorial Hospital - Miami, FL

Intro: Nerve injury after peripheral nerve blockade (PNB) is an infrequent event. Serious neurologic injury reported in a large prospective study occurred in 2.4 per 10,000 PNBs. Potential mechanisms of injury include blunt trauma, local anesthetic and adjuvant toxicity, compressive, stretch, and ischemic injury. Surgery itself can cause nerve injury by direct surgical trauma or stretch, compressive dressings/casts, hematoma or abscess formation, perioperative inflammation, and improper pt positioning. Tourniquet application may also contribute to peripheral nerve injury by causing mechanical deformation and ischemia. Risk factors for tourniquet injury are postop bleeding, total tourniquet time > 120 min, and preexisting peripheral neuropathy. We present a case of transient nerve injury after ACL reconstruction and lateral meniscus repair.

MCC: A 19 yo M athlete with no significant PMH underwent ACL reconstruction and lateral meniscus repair under GA without apparent complications. A single cuff tourniquet was used; total tourniquet time was 77 minutes at 300 mmHg. A femoral nerve block was performed postoperatively with sterile technique using a 50 mm insulated needle at a depth of 3 cm with stimulation current as low as 0.48 mA. Thirty mL of 0.2% ropivicaine was injected after negative aspiration for blood in 5 mL increments. On postop day 1, the surgical team noted that the pt complained of mild numbness of the lateral thigh, with intact sensation of the rest of the LE. They also noted quadriceps weakness and requested examination by the regional anesthesia team. A complete neurological status was obtained, demonstrating a normal sensory exam to warmth, cold, and pin-prick in the left thigh as well as complete loss of motor function in the femoral n. territory. A search of the literature revealed these symptoms to be consistent with tourniquet injury caused by mechanical compression or pneumatic compression ischemia. Weekly f/u visits were initiated. The pt regained full motor function within the next 3 weeks.

Discussion: Tourniquets may cause nerve damage by both ischemia and mechanical deformation. In prolonged tourniquet application, large-diameter myelinated fibers are particularly affected. Therefore, characteristic findings of tourniquet-induced neuropathy are motor loss and diminished touch, vibration, and position sense, with preserved senses of heat, cold, and pain. According to the literature, tourniquetâ€“induced nerve injury is not rare, especially in knee meniscectomy sx. Kornbluth et al. reported femoral n. palsy as a result of prolonged tourniquet use. Dobner et al. reported femoral n. palsy as a result of tourniquet use in arthroscopic knee sx in 10 of 24 pts. Generally, pts with pre-existing neuropathy are at greatest risk (â€œdouble-crushâ€ phenomenon). Femoral n. injuries generally have a good prognosis and are likely to recover over days to a few months.

Conc: There are many causes for post-sx nerve injury including pre-existing injury, surgical manipulation, tourniquet application and neurological injuries assocâ€™d with RA. When a pt presents postoperatively with impaired sensory and/or motor function, a thorough neurological exam considering all potential causes should be initiated.

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Figure from: Sorenson EJ. Neurological injuries associated with regional anesthesia. Reg Anesth Pain Med. 2008 Sep-Oct;33(5):442-8.

Abstract 111

Is an INR of 1.3 the Safe Upper Limit for Performing â€œ deepâ€ Continuous Blocks?

Presenting Author: Diamond N. Harris, Medical Student Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Jacques Chelly, M.D., Ph.D., M.B.A. - University of Pittsburgh - Pittsburgh, PA

Introduction: The increased appeal of regional anesthetic techniques along with the evolution of thromboprophylaxis has created a conundrum demanding an intricate balance between optimum pain management and patient safety. The most recent ASRA consensus lists an INR <1.4 as the upper limit to perform neuroaxial and â€œdeepâ€ nerve blocks. (1) The purpose of this report is to evaluate hemorrhagic complications following the placement of lumbar plexus and paravertebral continuous nerve blocks in patients with pre operative INR â‰¥ 1.4.

Methods: Our IRB approved database was reviewed for the pre-procedure INR of patients in whom continuous lumbar plexus and paravertebral nerve blocks were performed prior to surgery. The database was also queried for all related major hemorrhagic and neurologic complications. Since the INR distribution was found to not be normal, data are presented as median and range.

Results: The preoperative INR of 3,093 patients in whom continuous lumbar plexus or paravertebral nerve blocks were performed prior to surgery at UPMC Shadyside Hospital between May 27, 2008 and December 31, 2009 were reviewed. In this subset of patients, an INR â‰¥ 1.4 was found in 81 patients (2.62%). The median INR was 1.4 with a range from 1.4-2.30. The distribution of patients according to the type of blocks performed was 59 patients (72.8%) for continuous paravertebral blocks and 22 patients (27.2%) for lumbar plexus blocks. A total of 31 (38.37%) patients were noted to receive warfarin in the days prior to surgery. In this subset of patients, no major bleeding and/or hematomas was observed following the performance of blocks with an INR â‰¥1.4.

Discussion: We previously demonstrated the safety of removing lumbar plexus catheter from patients with INR > 1.4. (2) This limited report also suggests that an INR upper limit of â‰¤ 1.3 to perform deep continuous nerve blocks may be too conservative as are the theoretical considerations on which the ASRA consensus based this recommendations.(3) Additional clinical evidence is required to determine the optimum upper INR limits allowing to balance the benefit that performing continuous lumbar plexus and paravertebral nerve blocks provide (4) without compromising patient safety.

References: 1.Horlocker T, Wedel D, Rowlingson J, et al. Reg Anesth Pain Med 2010;35 102-105

2.Chelly JE, Szczodry D, Neumann K. Br J Anaesth 2008; 101:250-254

3.Horlocker TT, Wedel DJ. Rowlingson JC, et al. Reg Anesth Pain Med. 2010; 35:64-101.

4.Marino J, Russo J, Herenstein R, et al. Continuous psoas compartment block vs. continuous femoral block or PCA for total hip arthroplasty. J Bone Joint Surg Am. 2009 ;91:29-37

Abstract 112

Determining Placement Accuracy of Continuous Bilateral Paravertebral Catheters: A Comparison Between Ultrasound Guidance and Blind Technique

Presenting Author: Daniela Ghisi, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Alon Ben-Ari, M.D. - University of Pittsburgh Medical Center - PIttsburgh, PA

Background: Ultrasound guided catheterization of the paravertebral space through the intercostal space has been already described (1,2). We compared the accuracy of catheter placement in the paravertebral space performed either under ultrasound guidance or blind technique.

Methods: From our IRB approved database, we retrospectively reviewed 13 patients who underwent abdominal surgery and bilateral continuous paravertebral nerve blocks (cPVBs) for postoperative analgesia. All 26 cPVBs were placed preoperatively using either ultrasound guidance (group US, n = 12 blocks) or a blind approach (group B, n = 14 blocks). The catheters were postoperatively infused with 0.25% lidocaine at 7 ml/h. On first postoperative visit, each patient's catheters were injected with 10 ml of 1% lidocaine and evaluated 20 min later with a pin-prick test (T7 - T12 bilaterally), assessing sensory dermatomal spread. The block was considered successful if the injection of 1% lidocaine produced sensory block at the level of two or more contigue dermatomes. Secondary end points included hydromorphone consumption at 24 hrs, and Numerical Rating Scores for pain at rest (NRSr) and during deep breathing (NRSi, maximal incentive spirometry) at 24 hrs.

Results: Groups were comparable in age, gender and BMI (Table 1). The "success" rate of the block was higher with the use of US compared to the blind approach: 58 (CI 27-84)% in group US versus 7 (CI 0- 30)% in group B, p = 0.016. The distribution of number of dermatomes blocked for each technique is shown in Figure 1. However, NRSr, NRSi and opioid consumption did not differ significantly between the two groups (p = 0.557, p = 0.414 and p = 0.96, respectively).

Discussion: Ultrasound guided placement of cPVBs was more accurate than the blind approach. The lack of clinical impact between the two techniques deserves further clinical investigation.

References 1. Burns DA, Ben-David B, Chelly JE, Greensmith JE. Anesth Analg 2008;107:339-4 2. Ben-Ari A, Moreno M, Chelly JE, Bigeleisen PE. Anesth Analg. 2009;109:1691-4.

Additional File #1: Table 1. Demographic characteristics of the population. BMI Gender (f: m) Age (mean ± SD) 25.9 ± 5.1 6 : 7 59.5 ± 10.8

Additional File #2: Figure 1. Frequency of affected levels for each technique as measured with pin-prick test.

5 Group US Group B 0 1

Number of blocks performedNumber 2 3 4 5

number of blocked dermatomes

Abstract 113

Sonographic Evaluation of Lumbar Interspinous Space Opening Using a Variety of Positioning Techniques for Neuraxial Anesthesia

Presenting Author: Alexander Nelken, M.D. Presenting Author’s City, State: - Brooklyn, NY Co-Authors: Dennis Dimaculabgan, M.D. - SUNY Downstate - Brooklyn, NY Vasudha Goel, MBBS - SUNY Downstate - Brooklyn, NY David Seligsohn, M.D. - Suny Downstate - Brooklyn, NY Lei Li, M.D. - SUNY Downstate - Brooklyn, NY

Introduction: Neuroaxial anesthesia is a relatively blind procedure commonly performed in the fetal position (sitting or lateral decubitus) in an attempt to widen the lumbar inter-spinous spaces. A variety of other patient positioning techniques have been introduced to increase comfort of both, patient and anesthesiologist, during performance of neuraxial anesthesia.1,2 However, none of these techniques have been objectively evaluated for the differences in inter-spinous space opening. Ultrasound (US) has shown to effectively evaluate the anatomy of the neuraxis.3,4 We undertook a study to determine which position provides the best interspinous space (ISS) opening using ultrasonography.

Methods: Descriptive study. Inclusion criteria: Volunteers over age 18, not undergoing surgery. Exclusions: Volunteers who cannot sit without assistance, cannot comfortably assume all study positions, are not able to follow simple instructions, are pregnant, have had previous back surgery, low back pain syndrome or any disease of the spine. ISS opening at L3-L4 was measured using US via paramedian approach in baseline upright and four study positions on all subjects.

Position 1 (baseline upright): subject sitting with lower legs hanging freely over edge of operating room (OR) table, arms on the side with back erect (90Â°).

Position 2 (standard semi-fetal): subject sitting with lower legs hanging freely over edge of OR table, arms on laps with the back curved in partial fetal position.

Position 3 (table tilt): subject sitting with lower legs hanging freely over edge of OR table tilted at 15 degrees angle, arms on laps with the back curved to volunteer's subjective sense of comfort and balance.

Position 4 (mid-calf): Subject sitting with lower legs resting mid-calf over edge of OR table, arms on laps with the back curved in partial fetal position.

Position 5 (exercise ball): Subject sitting with lower legs hanging freely over edge of OR table, while hugging a large sub-maximally inflated exercise ball.

Primary outcome measure: Change in ISS opening from baseline upright sitting position to the different positioning techniques. Data were analyzed using the paired t test. Subjects were surveyed as to what position was most comfortable to assume.

Results & Discussion: ISS measurements were made on 9 volunteers in all five positions using US imaging via the paramedian approach. Mean ISS opening in baseline upright position was 3.2 Â± 0.12 cm (Mean Â± SEM). Compared to baseline upright position, all other study positions except table tilt (position 3) showed significantly larger ISS opening. No significant difference in ISS opening was found among the four study positions. Most volunteers (78%) preferred the sitting position with a large sub-maximally inflated exercise ball. There were no significant correlations between ISS opening and weight, height or body mass index (BMI). The study is ongoing to determine the impact of these findings on neuraxial block placement.

References: 1. Schultz JR, Br J Anaesth 2006. 2. Stone PA, Anaesthesia 1990. 3. Grau T, Br J Anaesth 2001. 4. Chan V, A Practical Guide to Ultrasound Imaging for Regional Anesthesia 2009.

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Abstract 114

Combined Ultrasound and Neurostimulation High-Fidelity Phantom for Pain Management Interventions

Presenting Author: Imanuel R. Lerman, M.D., M.S. Presenting Author’s City, State: - New Haven , CT Co-Authors: Maria Leonova, M.D. - Yale New Haven Hospital - New Haven , CT Dmitri Souzdalnitski, M.D., Ph.D. - Yale New Haven Hospital - New Haven , CT Thomas Halazynski, M.D. - Yale New Haven Hospital - New Haven , CT

Abstract Body: Ultrasound (US) guided interventions are relatively new and continue to be a rapidly developing field of pain medicine. US interventions allow targeted delivery of drugs, sparing of systemic opioids in pain management and minimizing exposure of both patient and operator to radiation associated with fluoroscopy.

US guidance is a challenging skill in which new trainees need to appreciate the concept and integration of two and three dimensional anatomy, needle advancement techniques, mastering basic calibration, and appropriate utilization of an US device (1,2). US guidance combined with neurostimulation has been shown to increase success rate of pain management interventions (3).

High fidelity simulation can be a vital component in US training. Currently there are no known high fidelity systems described that can simulate US guided interventions with neurostimulation.

A model of a high fidelity combined US and neurostimulation simulator has been developed that includes an anatomically correct US phantom. Trainees will experience feedback comprised of both visual (LED light) and audio (piezoelectric buzzer) signals that will orient the operator with regard to proximity of the advancing needle toward a targeted structure. Such high-fidelity simulators will also mimic patient extremity movements during US guidance of needle placement (with and without neurostimulation).

Implementation of this high fidelity simulation system into a pain medicine curriculum may improve trainee education, advancement and proficiency in US guided pain management techniques.

1. Sites BD et al. Reg Anesth Pain Med. 2007;32 (2): 107-15 2. Sites BD et al. Reg Anesth Pain Med. 2004;29 (6): 544-548 3. Dufour E et al. Anesth Analg. 2008;106 (5): 1553â€“1558

Abstract 115

High Fidelity Combined Ultrasound and Flouroscopic Phantom for Cervical Transforaminal Injections

Presenting Author: Imanuel R. Lerman, M.D., M.S. Presenting Author’s City, State: - New Haven , CT Co-Authors: Dmitri Souzdalnitski, M.D., Ph.D. - Yale New Haven Hospital - New Haven , CT Thomas Halazynski, M.D. - Yale New Haven Hospital - New Haven , CT

Abstract Body: Ultrasound (US) guided interventions are relatively new and continue to be a rapidly developing field in regional anesthesia and pain medicine. US technology is exponentially growing which translates into improved real time and high resolution ultrasound images. The use of combined US and fluoroscopic interventional pain procedures minimizes the risks associated with radiation exposure to both the patient and practitioner (1).

US guided techniques have been combined with fluoroscopic guidance and applied to procedures of cervical nerve root injections (2). Cervical transforaminal injections carried out under US guidance combined with fluoroscopic guidance provide the advantage of real time visualization of bony landmarks, nerves and vasculature that may minimize the risk for intravascular complications and improve on these interventional procedures (2).

US guidance is a challenging skill in which new trainees need to appreciate the concept and integration of two and three dimensional anatomy, needle advancement techniques, mastering basic calibration and appropriate utilization of an US device (3, 4). Trainees make repeated errors and exhibit potentially compromising technical behaviors during US guided interventions that can be potentially remediated when trained with high fidelity US phantoms (3, 4).

A high fidelity combined US and fluoroscopic phantom (CUF-P) for simulation of US and fluoroscopic guided cervical transforaminal nerve block procedures has been developed. The CUF-P was developed using a commercially available cervical spine anatomical model submersed in a polyvinyl medium. The CUF-P sonographically simulates human tissue as well as imitating the tactile texture of human skin. The CUF-P contains anatomically correct fluid filled vertebral arteries that exhibit pulsed flow under Doppler US examination. Under fluoroscopic examination the CUF-P simulated vertebral arteries will also exhibit uptake of contrast dye if mistakenly injected.

Implementation of this high fidelity simulation system into a curriculum may improve trainee education, advancement and proficiency in combined US guided and fluoroscopic guided pain management techniques.

1. Narouze S et al. Reg Anesth Pain Med 2009;34 (5): 458-474 2. Narouze S et al. Reg Anesth Pain Med 2009;34 (4): 343-348 3. Sites BD et al. Reg Anesth Pain Med. 2007;32 (2): 107-115 4. Sites BD et al. Reg Anesth Pain Med. 2004;29 (6): 544-548

Abstract 116

Real-Time Ultrasound Guided Spinal/Epidural Anaesthesia – A Description of Tranverse In-Plane Approach on a Phantom Spine Model

Presenting Author: Packianathaswamy Balaji, M.B.B.S., M.D., D.N.B., F.R.C.A. Presenting Author’s City, State: - Kingston-upon Hull, North Humberside Co-Authors: Baskar Manickam, M.B.B.S., M.D., F.R.C.A. - Darlington Memorial Hospital - Darlington, Durham

Background and Aims: Pre- procedure ultrasound (US) imaging of the spine allows visualization of anatomical landmarks, identification of puncture level and estimation of the depth of the spinal/epidural space. Knowledge of such information, although useful, may not necessarily improve block success with blind techniques. Real time observation of epidural fluid injectate has been described previously. However, direct needle guidance under US is often considered to be difficult and cumbersome, due to the limited bony window in the spine. A recent report of real-time US guided epidural access recommends a longituidinal paramedian in-plane approach with good success. We investigated the feasibility of a transverse in- plane needle approach for block performance under real -time US guidance using a phantom spine model.

Methods: A lumbosacral spine water-based phantom model was used for the evaluation of tranverse in- plane needle approach to the bony laminar window. The dimensions of the laminar window and ease of needle visualisation was assessed at L2 -L3, L3-L4, L4-L5 and L5 -S1 interspace using a 25G/ 22G spinal needle and 18G tuohy needle.

Results: Our preliminary evaluations indicate that the transverse axis US imaging of the interspinous space provides wider access to the laminar window and offers suitable route for an inplane needle approach. We believe that the tranverse axis US imaging provides better medial to lateral orientation of the spine and may be helpful in accurate guidance of the needle to the midline and avoid misinterpretation of the paravertebral space for the laminar window.

Conclusions: We have described a new technique for spinal/epidural needle insertion under real - time US guidance using a transverse in-plane approach that allows successful needle placement on a phantom model. Furthur studies are planned to evaluate its clinical application on patients and compare the ease of needle insertion and block success with paramedian longituidinal axis in-plane approach

Abstract 117

Ultrasound Guided Suprascapular Nerve Block in the Supraclavicular Fossa

Presenting Author: Bigeleisen E. Paul, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: David Ruttum, M.D. - University of Pittsburgh - Pittsburgh, PA Alon Ben-Ari, M.D. - University of Pittsburgh - Pittsburgh, PA

Background: The suprascapular nerve supplies sensation to the posterior portion of the gleno-humeral and acromioclaviuclar joints as well as motor innervation to the supraspinatus and infraspinatus muscles.

Block of the suprascapular nerve can provide analgesia for scapular surgery, traumatic fracture of the scapula, and arthroscopic shoulder surgery in combination with axillary nerve block. It can also be used as a diagnostic tool for chronic shoulder pain to rule out suparascapular nerve entrapment. Traditionally, block of the suprascapular nerve has been performed by blind infiltration in the suprascapular notch, identification of the notch with fluoroscopy, and more recently by ultrasound guided suprascpaular nerve block in the suprascapular notch. We postulated that we could identify and anaesthetise the suprascapular nerve in the supraclaicular fossa where it frequently takes origin from the superior trunk of the brachial plexus (figure 1).

Materials and Methods: We attempted to identify the nerve in 10 successive patients presenting for arthroscopic surgery of the shoulder in whom we planned to perform a proximal supraclavicular block or an interscalene block at the C6 level. We began scanning in the supraclaviuclar fossa with a standard parasagittal approach. (SonoSite, S Nerve Platform, 13 MHz linear scanner). After scanning proximally and distally along the superior trunk, by rotating the probe to a purely sagittal orientation, we were able to identify a nerve which travelled distally and posterior in 8 of 10 patients (figure 2).The use of a nerve stimulator (B Braun, 0.8mA, 2Hz) allowed us to further identify this nerve by observing the contraction produced by neural stimulation.

Results: In 7 patients, stimulation produced contraction of the supraspinatus muscle and external rotation of the arm. In one patient, stimulation produced contraction of the deltoid muscle.

Discussion: We were able to identify the suprascapular nerve in the supraclavicular fossa using ultrasound guidance and electrostimuation in 7 of 10 patients. After anesthesia of the suprascapular nerve and nerve trunks, all 7 patients underwent successful anesthesia of the shoulder with excellent postoperative analgesia. The other patients received interscalene blocks with good postoperative analgesia.

References: 1. Checcucci G, Allegra A, Bigazzi P, Gianesello L, Ceruso M, Gritti G. A new technique for regional anesthesia for arthroscopic shoulder surgery based on a suprascapular nerve block and an axillary nerve block: An evaluation of the first results. Arthroscopy 2008; 24:689-696.

2. Harmon D, Hearty C. Ultrasound-guided suprascapular nerve block technique.Pain Physician. 2007 Nov;10(6):743-6.

3. Price DJ. The shoulder block: A new alternative to interscalene brachial plexus blockade for the control of postoperative shoulder pain. Anaesthesia Intensive Care 2007;35:575-581.

Abstract 118

Modification of Catheter Placement Utilizing CO2 Injection to Improve Success Rate of Continuous Supraclavicular Peripheral Nerve Blockade

Presenting Author: Jason Capra, M.D. Presenting Author’s City, State: - San Antonio, TX Co-Authors: Jonathan Rogers, M.D. - SAUSHEC - Lackland AFB, TX Lisa Rogers, M.D. - SAUSHEC - Lackland AFB, TX

Intro: A great deal of advancement has been made in regional anesthesia over the past several years due to ultrasound guidance. However; continuous peripheral nerve blocks still remain challenging due to difficulty in visualizing catheter placement. Stimulating catheters are now widely available to help facilitate placement, but recent data suggests that use of ultrasound compared to electrical stimulation may take less time, produce less procedure related pain, and prevent inadvertent vascular puncture. Techniques using agitated local anesthetic have been described to verify catheter placement, but with limited sample size . We describe the use of carbon dioxide to verify supraclavicular catheter position in a cohort of 62 patients.

Materials and Methods: Using sterile technique, a MicroMaxx (Sonosite, Inc, Bothell, WA) ultrasound with the HFL38X 13-6 MHZ probe was used to locate the brachial plexus at the supraclavicular, level. An 18g 1Â1⁄2 inch Contiplex Tuohy needle (B. Braun) was used for catheter placement. The needle was inserted in plane under direct visualization until the tip of the needle was within the sheath of the brachial plexus. Thirty mL of 0.5% ropivacaine with 1:400K epinephrine was injected. After injection, a catheter was advanced through the tuohy needle until it was estimated to be 2-4 cm beyond the tip. Prior to securing the catheter its approximate location was determined with ultrasound and 1mL of CO2 was injected with a 3mL syringe. Based on the location of the echogenicity produced by injection the catheter was either left in place, pulled back until the 3 catheter orifices were within the sheath, or removed and replaced using the above described technique. After confirmation of position, the catheter was secured. This technique was applied to 62 patients requiring upper extremity blocks for various surgical procedures.

Results: Of 62 supraclavicular blocks, 41 (66.1%) were confirmed to have correct catheter placement after injection of CO2 and were not adjusted, 14 (22.6%)were thread past the brachial plexus sheath and required pull-back, and 7 (11.3%) required removal of the catheter and needle and replacement .

Discussion: Continuous peripheral nerve blocks have been shown to result in lower resting and break through pain scores than conventional treatment with oral or parenteral analgesics when treating postoperative pain. However, even with ultrasound guidance, visualizing correct catheter placement remains a challenge. If catheters are placed outside the neurovascular sheath, there is a low chance they will be successful in providing adequate analgesia. In the current report we describe a series of 62 supraclavicular blocks and demonstrate that confirmation of catheter placement with CO2 helped to convert 33.9% of catheters placed outside of the supraclavicular neural sheath into correctly placed catheters. A good deal of these conversions (22.6%) required only slight pull back of the catheter, which can be easily accomplished with incremental injections of CO2 to locate the catheter tip. This technique does not cause the patient additional pain, is easy to accomplish, and can be performed by a single operator while maintaining the sterility required for perineural catheter placement.

Abstract 119

Importance of Volume and Concentration for Ropivacaine Interscalene Block in Preventing Recovery Room Pain and Minimizing Motor Block after Shoulder Surgery

Presenting Author: Michael J. Fredrickson, M.D Presenting Author’s City, State: - Epsom, Auckland

Background: Little is known regarding the relative importance of volume and concentration for peripheral nerve blockade, or of their optimum combination for interscalene block. This 3-staged study estimated the volume and concentration of interscalene ropivacaine that would prevent recovery room pain following shoulder surgery under general anesthesia.

Methods: An ultrasound guided interscalene catheter was placed preoperatively in all patients. Stages 1/2: Catheter ropivacaine administration was by a 10% incremental up-down sequential manner depending on the presence of recovery room pain in the previous patient. Stage 1: Ropivacaine 0.5% volume was varied from 30 ml. Stage 2: Ropivacaine 20 ml (the ED(volume)95 estimate from stage 1) concentration was varied from 0.45%. Effective 95th percentiles were derived using the mu3 estimator following application of the pooled adjacent violators algorithm (isotonic regression). Stage 3: Subjects were randomly assigned to receive ropivacaine 0.5% 30 ml (conventional dose) or 0.375% 20 ml (the estimated ED(volume+concentration)95 from stages 1/2). A postoperative ropivacaine 0.2% 2ml/h elastomeric infusion was administered. Grip strength was measured in the recovery room and time to first pain at 24 hours.

Results: Stage 1 (n=34) (Fig 1): Ropivacaine 0.5% ED(volume)50/ED(volume)95 (95% confidence interval) estimates were 2.7/20.5 ml (2.4-9.5/17.3-25.8). Stage 2 (n=29) (Fig 2): Ropivacaine 20 ml ED(concentration)50/ED(concentration)95 (95% confidence interval) estimates were 0.15/0.34% (0.13- 0.30/0.29-0.43). The ED(dose)50 was similar for stages 1/2 (13.5 vs. 30 mg) but the ED(dose)95 was higher for stage 1 (102.5 vs. 68 mg). Stage 3 (n=40): Satisfaction (0-10) was modestly higher for the new/lower dose [median (interquartile range) = 10 (10-10) vs. 9 (8-10), p=0.007]. Pooled data regression analysis showed that increasing ropivacaine concentration increased grip weakness (Fig 3) but not block duration. No association (grip strength or block duration) was found for ropivacaine volume.

Conclusions: Ropivacaine interscalene block requires a threshold volume and concentration, with concentration primarily determining motor block. When combined with continuous blockade, supra- threshold ropivacaine doses do not significantly prolong primary block duration but may compromise patient satisfaction.

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Abstract 120

Process for Development of a Site Identification Universal Protocol to Prevent Wrong-Sided Peripheral Nerve Blocks

Presenting Author: Ali Ekbatani, D.O., M.B.A. Presenting Author’s City, State: - Philadelphia, PA Co-Authors: Kishor Gandhi, M.D., M.P.H. - Thomas Jefferson University - Philadelphia, PA Eugene Viscusi, M.D. - Thomas Jefferson University - Philadelphia, PA

Introduction: Wrong site surgery and wrong patient procedures have a devastating effect on both patients and providers. Despite efforts by the Joint Commission, wrong site and wrong patient procedures remain the most frequently reported sentinel event in the Joint Commission database. A recent wrong- sided block at our institution provided the impetus to develop a system solution to avoid any future wrong- sided blocks. After a review of the literature and multidepartmental deliberations, a regional anesthesia Universal Protocol for site identification was developed with certain modifications to make its implementation more effective for our practice. The purpose of this abstract is to present the process for analysis and development of such a policy and protocol and to provide the resulting system based solution.

Methods: The wrong-sided block was reported as a sentinel event to the Joint Commission and resulted in a root cause analysis meeting. This was a multidepartmental meeting with the goal of identifying the error causing the sentinel event and establishing parameters to prevent its recurrence. While prudent practice dictates patient and site identification, a quality review of anesthesiology documentation demonstrated no consistent Method of site identification.

Results: The wrong-sided block was classified as a system-based practice problem because there was not a protocol in place aimed at preventing wrong-sided peripheral nerve blocks. A pubmed search of the surgical literature provided evidence that a Universal Protocol decreases wrong site, wrong-sided surgery (Seiden, 2006; Makary, 2007; Cohen, 2009). Based on this evidence and the staff familiarity with our existing surgical Universal Protocol, we implemented a Universal Protocol specifically for preoperative peripheral nerve blocks. To make the process more streamlined and effective, we used the existing surgical Universal Protocol form already present in the patient chart. Core components of the Universal Protocol were maintained with special emphasis on peripheral nerve block (PNB) site marking independent from the surgical site marking. After multidepartmental approval, and a brief pilot period, the Universal Protocol for peripheral nerve blocks was implemented.

Discussion: Following a sentinel event involving a wrong-sided peripheral nerve block, a root cause analysis was performed resulting in a system based solution. Using the existing surgical model and protocol, a multidepartmental team developed an adaptation that was both efficient and practical for a large, busy academic tertiary care practice environment with numerous healthcare providers.

Conclusion: Wrong-sided PNBs are an uncommon but serious problem that involves all members of the operating room team. Hence, a system based solution is warranted. A multidisciplinary approach to a system problem engenders a team approach with â€œbuy-inâ€ from all parties facilitating cooperation and compliance.

Abstract 121

The Discovery of Faster Onset of the Ultrasound Guided Nerve Block with Lower Probe Frequency May Herald New Treatment Paradigm and Novel Technology

Presenting Author: Dmitri Souzdalnitski, M.D., Ph.D. Presenting Author’s City, State: - Branford, CT

Abstract Body: The use of ultrasound guidance (UG) has resulted in a striking increase in success rates and shortened block placement times (Abrahams et al.2009; Baldi et al.2007; Fjuwara et al.2008; Koscielniak-Nielsen 2008; Liu et al.2009, Tran et al.2007; Walker 2009). The last century paradigm â€œthe blocks do not work and they take too longâ€ has changed to â€œsurely they work, but take some timeâ€ (Sites et al, 2008). The time of the block onset continue casting a shadow on the triumph of regional anesthesia.

Objectives: To investigate the phenomena of faster onset of nerve blocks when ultrasound used for guidance and explore the perspectives of development of novel technological tools based on the findings.

Methods: The literature review performed based on our observations that lower frequency ultrasound is associated with hastening the onset of an UG nerve block. All available (17) randomized controlled trails (RCT) focused on the comparison of block onset time between UG and neurostimulation which encompassed 1552 patients in relevant groups were included in meta-regression (Fig. 1).

The systematic reviews (8), RCT demonstrating lover effective volumes of local anesthetic (LA) with UG (4) RCT demonstrating difference in onset times between UG nerve blocks and landmark technique (2) were appraised.

Results: In addition to significantly faster onset of the nerve block, revealed with meta-analysis (Fig 2), there was the evident link between the ultrasound wave frequency emitted by the probe and the speed of block onset discovered (Fig 3). The data showed that utilization of lower frequency ultrasound probes reliably (p<0.001) associated with faster onset of nerve block.

Discussion: A dozen years ago the higher success rate, faster onset and lower volume of LA required for UG nerve blocks was discovered. These phenomena were explained mainly by better visualization of targeted structures the needle tip, and theretofore, more precise injection. The explanation was altered recently with discovery of facilitated absorption of LA associated with UG (Weintraud et al.2009). Even with that the current rate of complications of nerve blocks reported to be very low. The nature of discovered ultrasound properties and its correspondence to the known effects and applications of ultrasound in medicine will be discussed in the presentation. The potential useful properties of low intensity low frequency ultrasound (LILFU) have been underutilized. The skin represents a major obstacle for LA, limiting the propagation of the medications applied to the skin surface (Phonophoresis) to the subcutaneous tissues. The LILFU was found to be weak therapeutic factor ether if applied alone.

The transportation of the drug through the skin to underlying tissues with block needle with simultaneous application of the same LILFU speeds up the onset of nerve blocks, and may be accelerated even further.

Currently a new type of ultrasound transducer designed specifically for regional anesthesia and pain medicine interventions has been developed (patenting in progress).

With observed dramatic increase in popularity of nerve blocks the increase of the reliability and faster time of the block onset with proposed technology may provide significant economic benefits.

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Abstract 122

True Tetracaine Allergy Following Spinal Anesthesia, Manifesting as Asymmetric Urticaria

Presenting Author: Elizabeth Freck, M.D. Presenting Author’s City, State: - Winston-Salem, NC Co-Authors: Robert Weller, M.D. - Wake Forest University School of Medicine - Winston-Salem, NC Candace Anz, M.D. - Wake Forest University School of Medicine - Winston-Salem, NC John Shields, M.D. - Wake Forest University School of Medicine - Winston-Salem, NC Jason Caldwell, D.O. - Wake Forest University School of Medicine - Winston-Salem, NC

Introduction: True IgE-mediated hypersensitivity reactions to preservative-free local anesthetics (LA) are extremely rare, and reactions to ester LA are routinely attributed to the metabolite para-aminobenzoic acid (PABA) (1). We report a case of extensive, asymmetric urticaria appearing 20 minutes after tetracaine spinal anesthesia; true allergy to tetracaine was demonstrated by skin testing on 2 occasions postoperatively.

Case: A 50-yr-old man presented for revision and reinsertion of left hip arthroplasty. The original hip arthroplasty was complicated by MRSA infection requiring multiple drainage procedures, explantation of the left hip prosthesis 3 months earlier, and IV vancomycin for 6 weeks. The hip explantation was complicated by post-op massive pulmonary embolism. He was resuscitated and ventilated for 4 days; no procainamide was given during his resuscitation. He noted allergies to Percocetâ„¢, BetadineÂ®, and adhesive tape. On admission, preoperative oral celecoxib and pregabalin, and IV vancomycin, fentanyl and midazolam were initiated at 10:45. A left posterior lumbar plexus block was performed with 25 ml of preservative-free 0.25% bupivacaine with 1:200,000 epinephrine and 50 mcg clonidine injected at 10:58. A spinal anesthetic with 10 mg preservative-free 1% tetracaine (dilution of lyophilized crystals with saline), 200 mcg epinephrine, and 20 mcg fentanyl was injected at 11:09. Urticaria (0.5-1 cm diameter) was noted on the left thigh at 11:30 (Fig 1). Most lesions occurred near the previous incision site, but wheals were also present on the chest and right leg. The patient had no hypotension, wheezing, dyspnea or pruritus, but surgery was canceled and consultation obtained from the Allergy Division of Medicine. Skin testing was performed immediately and at 8 weeks using serial dilutions of lidocaine, bupivacaine and tetracaine; positive intradermal response occurred only to histamine and tetracaine (Tables 1 and 2).

Discussion and Implications: The CSF has little cholinesterase, and tetracaine is absorbed without metabolism into the circulation (2). Although metabolized in blood, tetracaine is detectable in the plasma of mammals after spinal anesthesia (3) and true allergy to this ester LA, and not only to the PABA metabolite, is possible. Repeat provocative exposure in this patient to confirm the allergy was considered too risky, since an alternate amide LA showed no reaction and could be used for future anesthetics. IgE- mediated allergic reaction may present as urticaria distributed asymmetrically; delay and monitoring for more extensive systemic signs and symptoms is warranted. We postulate the concentration of inflammatory cells at the prior incision may have contributed to the preponderance of urticaria in that location.

References (1) Atlee JL. Complications in Anesthesia, 2nd ed. Philadelphia: Saunders Elsevier, 2007:233 (2) Kambam JR. Anesth Analg 1989;68:486-488 (3) Hino Y. Forensic Sci Int 2001;124:130â€“1

Abstract 123

Continuous Supraclavicular and Paravertebral Catheters in a Patient Undergoing Hand Transplantation

Presenting Author: Jason D. Merrell, M.D. Presenting Author’s City, State: - San Antonio, Texas Co-Authors: Elvin Cruz-Zeno, M.D. - SAUSHEC - San Antonio, Texas Jonathan Rogers, M.D. - SAUSHEC - San Antonio, Texas Jared Fuller, D.O. - SAUSHEC - San Antonio, Texas

Introduction: Hand transplantation is a rare and well-planned event involving multispecialty teams that cooperate to make transplantation successful. Anesthesia plays a significant intraoperative as well as postoperative role in this procedure. Continuous peripheral nerve blockade (CPNB) allows control of postoperative pain and also results in sympathectomy, thereby increasing perfusion and improving probability of successful transplantation. The following case is an example of CPNB catheters that were placed for hand transplantation.

Case report: The patient is a 58 year old female who was injured by a mail bomb in 2001. She sustained multiple injuries including to the left eye (resulting in blindness), to the abdomen and to the upper extremities resulting in traumatic loss of multiple fingers of the right hand, the entire left hand and distal forearm. The patient had been waiting several years for a donor hand to become available. The surgery called for CPNB of the arm to include potential surgery to the axilla. The plan was for both T2 paravertebral and supraclavicular CPNB on the left side. The patient was also to have general anesthesia for the duration of the procedure. Paravertebral nerve blockade was completed first with T1-T3 blocked with 5ml each of 1% Ropivacaine; ultrasound was used to initially identify landmarks. A catheter was placed at T2 with 3cm remaining within the paravertebral space. Next, a supraclavicular catheter was placed using ultrasound guidance with the placement of 30ml of 1% Ropivacaine before advancement of the catheter. Catheter location within the brachial plexus was confirmed using CO2 bubble test and the position was ideal. Within 10 minutes the patient had total loss of motor and sensory function to the left arm. The patient did well during the 10 hour case and was started on postoperative infusions of 0.2% Ropivacaine with 12ml/hr for the supraclavicular catheter and 10ml/hr for the T2 paravertebral catheter. Catheters remained in place three weeks, thereby providing pain control and increased perfusion to the transplanted hand. The patient is presently doing well and recovering from transplantation.

Discussion: The ability of CPNB to control postoperative pain as well as to allow increased perfusion is an important factor in the course of recovery from hand transplantation. The use of CPNB to aid in perfusion of extremities has been well established. It should be noted that CPNB may also decrease new onset neuropathic pain associated with newly constructed innervation pathways. The combination of both brachial plexus blockade and paravertebral blockade allows total anesthesia to the extremity and axilla. Maximal pain pathway coverage and sympathectomy is thereby accomplished, leading to increased perfusion and likelihood of transplant success.

Abstract 124

The Effect of Music Therapy, in the Form of Ocean Sounds, on Open Heart Surgery Patient’s Comfort Level

Presenting Author: Melanie New, R.N. B.S.N., Graduate APN Student Presenting Author’s City, State: - Trumann, AR

Background: It is very common for patientâ€™s to have decreased comfort levels prior to surgery; this research study explores the possibilities of increasing their comfort levels prior to surgery with the intervention of ocean sounds as music therapy. The process of acquiring subjects for this pilot study entitled, â€œThe Effect of Music Therapy, in the form of Ocean Sounds, on Open Heart Surgery Patientâ€™s Comfort Levelâ€ is as follows: The patients have been selected by viewing the surgery schedule and locating those patients scheduled for Coronary Artery Bypass Graft and /or Valve Replacement. These patients were approached by the clinical investigator, Melanie New RN, BSN, in association with Arkansas State Universityâ€™s Graduate Nursing Program. There were five patients who listened to ocean sounds and five patients who did not listen to ocean sounds. These patients continued to be in the hospital at St. Bernardâ€™s Medical Center while awaiting their surgery. The proposed pilot study was discussed in full with the patients and after answering all questions to the patientâ€™s satisfaction, an informed consent was obtained. The actual Introduction to ocean sounds occurred one hour prior to the patient being transported from their room to the surgical suite. The ocean sounds were played in the form of a bedside portable music-playing device. After the twenty minutes of time that the patients listened to the ocean sounds, those patients were provided a comfort level questionnaire to complete. Those patients not receiving music therapy also completed the comfort level questionnaire prior to leaving their room for surgery. Those patients receiving music therapy left their room for their scheduled surgery with an increased comfort level as evidenced by this pilot study.

Methods: The method used in this research is in the form of a cross sectional pilot study done prospectively.

Results: See Attached.

Conclusion: As this research study has confirmed, there is an increase in the patientâ€™s comfort levels by using the intervention of music therapy in the form of ocean sounds. This is very encouraging in the quest to control pre-operative patientâ€™s stress and anxiety by increasing their level of comfort. The knowledge of this study allows the patient to use music therapy via ocean sounds as a vital coping mechanism, not only can this be used as an intervention in their pre-operative status but in other areas in their life as well.According to Lazarus, coping is most difficult at the point in time the person identifies they are facing a stressful event and the person feels helpless (without resources) to cope with the new stressor. . This pilot study has introduced a potential method of coping (self-regulation enabling self to feel comfort) during the stressful event of awaiting cardiac surgery. A difference in comfort levels has been identified through the patientâ€™s use of ocean sounds in the form of music therapy. The patients in this study have identified a difference in their comfort level when using music therapy, a new method of empowering patients to help themselves cope in what was previously perceived as a helpless situation (cardiac operation) has been developed.

Therefore, there is a difference in the level of comfort identified by a group of cardiac surgery patients using music therapy vs. a group of cardiac surgery patients not using music therapy is now positively evident.

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Abstract 125

Duration of Efficacy of Local Anesthetic Blocks and Pulsed Radiofrequency Lesioning for Occipital Neuralgia: A Retrospective Study

Presenting Author: Deepti Agarwal, M.D. Presenting Author’s City, State: - Chicago, IL Co-Authors: Megan E. Rodes, M.D. - Northwestern University Feinberg School of Medicin - Chicago, IL Honorio T. Benzon, M.D. - Northwestern University Feinberg School of Medicin - Chicago, IL Khalid Malik, M.D. - Northwestern University Feinberg School of Medicin - Chicago, IL

Introduction: Local anesthetic peripheral nerve blocks are commonly used to break the cycle of pain as well as to decrease analgesic intake. Pulsed radiofrequency (PRF) ablation may result in long-term benefit (1) and is not associated with numbness, dysesthesia, and allodynia (2). We performed a retrospective study where we looked at the efficacy and duration of pain relief from local anesthetic blocks and PRF.

Methods: Following IRB approval records from patients who had occipital nerve blocks (22 patients) or PRF (8 patients) since 2006 were reviewed. Greater and lesser occipital nerve blocks (ONBs) were performed lateral to the greater occipital protuberance with 8-10 ml of 0.25% bupivacaine. PRF ablation was performed in the area of the occipital nerve based on the location of the paresthesia with the tip of the needle heated to 42 C for 120 sec; two lesions were performed each time. The following data were noted: patient demographics, diagnosis, degree and duration of pain relief, and side effects. Efficacy of the block was based on >50% pain relief (1-3). Duration of effective pain relief was based on the duration of >50% pain relief.

Results: Twenty-two patients (5M/17F) had ONBs for occipital neuralgia or cervicogenic HA. The duration of pain relief lasted 28.6 +/- 24 days. Fifteen out of 20 patients reported >50% relief. Eight patients (4M/4F) who previously responded to LA blocks had PRF. The duration of relief lasted 23 +/- 16.7 days, 6 patients reported >50% relief. None of the patients who had the LA blocks or the PRF decreased their pain medications, which were mostly non-opioids. No side effects noted for either procedure.

Discussion: The 28-day average duration of pain relief from LA blocks in our study is similar to the findings of Naja et al (4). There is a case report of PRF of the occipital nerve twice and the patient had 70% relief for 4 and 5 months (5). Our study showed that the duration of >50% relief from LA nerve blocks and pulsed RF are similar. There appears to be no advantage of pulsed RF over LA nerve blocks for duration of pain relief. Our study has limitations because it was retrospective. Future studies should be prospective, randomized, and blinded with appropriate outcome measures.

References: 1. Malik K, Benzon HT. Anaesth Intensive Care 2007;35:863-73. 2. Malik K, Benzon HT. Anesthesiology 2008;109:527-42. 3. VanBoxem K. Pain Pract 2008;8:385-93 4. Naja ZM. Pain Practice 2006;6:89-95 5. Navani A. Pain Med 2006;7:453-56

Abstract 126

The Effect of Type of Graft Utilized in Anterior Cruciate Ligament Reconstruction on the Efficacy of Postoperative Femoral Nerve Blockade: A Retrospective Review

Presenting Author: Kristopher M. Schroeder, M.D. Presenting Author’s City, State: - Madison, WI Co-Authors: Rohan K. Jain, B.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Christopher S. Schmidt, M.D. - University of Wisconsin School of Medicine and Pub – Madison, WI Seungbong Han, M.S. - University of Wisconsin School of Medicine and Pub - Madison, WI Melanie J. Donnelly, M.D. - University of Wisconsin School of Medicine and Pub - Madison, WI

Introduction: Anterior Cruciate Ligament (ACL) reconstruction involves at least three different graft types. This has important implications with regard to which peripheral nerve block might provide the most effective postoperative analgesia. Traditionally, a femoral nerve block is offered for postoperative analgesia following ACL reconstruction surgery. We proposed that those patients undergoing ACL reconstruction with a hamstring graft, as compared to a patellar or allograft, would have less pain relief resulting from a femoral nerve block secondary to pain originating from the posterior knee autograft harvest site.

Methods: Following IRB approval, the charts of 211 patients who underwent ACL reconstruction surgery with postoperative ultrasound guided femoral nerve block placement from 1/15/08 - 10/9/09 were reviewed. Graft types utilized were hamstring autografts, patellar autografts, and various types of allografts (Table 1). A multiple regression and logistic regression analysis was used to determine how the graft type, when adjusted for age, sex, ASA score, and BMI, influenced a variety of perioperative clinical variables.

Results: The graft type used during the ACL repair did not significantly impact PACU Phase I variables. Use of the hamstring graft resulted in increased phase II opioid consumption. Pain scores were similar among the groups in both Phase I and II. Finally, the type of graft utilized did not have a significant impact on the amount of nausea experienced by patients postoperatively (Table 2).

Discussion: As we attempt to provide increasingly effective and targeted regional analgesia, it is important to carefully tailor our analgesic plan to the specific surgical procedure and anticipated distribution of pain. We proposed that a postoperative femoral nerve block would provide inferior analgesia among hamstring autograft patients compared to the analgesia experienced among patients with other graft types. Contrary to our proposal, pain scores were similar among the different graft types, though more opioid was required by the hamstring group in phase II of the recovery room. However, all other variables appeared similar between the three groups. A future study to evaluate the analgesic efficacy of femoral versus sciatic nerve blocks for ACL surgery with a hamstring autograft may provide more insight with regard to the ideal analgesic therapy in this population.

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TABLE 1: BASELINE PATIENT CHARACTERISTICS Table 1 shows the baseline patient characteristics about sample mean and standard deviation for age, height, weight, BMI, and ASA. For the discrete variable of sex, it shows the number of patients for each category. POSTOPERATIVE BLOCK Hamstring Patellar Allograft COMBINED Age 31.3 ± 8.7 25.3 ± 7.2 37.2 ± 12.1 31.0 ± 10.1

Height 68.5 ± 4.0 69.3 ± 3.4 68.4 ± 3.6 68.7 ± 3.8

Weight 80.9 ± 17.9 76.9 ± 15.0 85.4 ± 21.0 80.9 ± 18.1

BMI 26.6 ± 4.7 24.7 ± 4.0 28.3 ± 6.8 26.5 ± 5.2

ASA 1.4 ± 0.5 1.2 ± 0.4 1.6 ± 0.5 1.4 ± 0.5

Female 44 19 23 86 Male 62 38 25 125 TOTAL 106 57 48 211

TABLE 2: OUTCOME VARIABLES The model was adjusted for age, sex, ASA, and BMI. * p-value based on likelihood ratio test.

POSTOPERATIVE PARAMETERS (Mean±SD) Hamstring Patellar Allograft P*

PHASE I POSTOPERATIVE PARAMETERS Time Required for Block Placement (min) 9.7 ± 4.6 9.8 ± 3.0 10.1 ± 3.8 0.723 Phase I Time (min) 61.1 ± 23.3 62.2 ± 24.6 61.1 ± 20.5 0.803 Phase I Time After Block (min) 28.2 ± 20.4 33.5 ± 28.1 26.5 ± 17.7 0.081 Immediate Phase I Postoperative Pain (0-10) 4.9 ± 2.8 4.5 ± 2.5 4.7 ± 2.8 0.837 Peak Phase I Postoperative Pain (0-10) 5.8 ± 2.2 5.7 ± 2.0 5.4 ± 2.5 0.278 Total Phase I IV Morhpine Equivalent (mg) 6.9 ± 6.6 6.3 ± 5.8 5.5 ± 6.2 0.205 Post Block Phase One IV Morphine Equivalent (mg) 2.7 ± 4.1 1.9 ± 3.2 1.7 ± 3.8 0.262 Phase I Nausea 12 (11.3%) 5 (8.8%) 1 (2.1%) 0.177

PHASE II POSTOPERATIVE PARAMETERS Phase II Peak Pain (0-10) 4.0 ± 1.8 3.5 ± 1.8 3.3 ± 2.1 0.162 Phase II Mean Pain (0-10) 3.0 ± 1.4 2.6 ± 1.7 2.5 ± 1.6 0.144 Phase II IV Morphine Equivalent (mg) 2.1 ± 1.8 1.9 ± 1.9 1.3 ± 1.7 0.040 Phase II Nausea 13 (12.3%) 9 (16.1%) 3 (7.1%) 0.645

Abstract 127

Bilateral Transversus Abdominis Plane Catheters, a Viable Adjunct for Postoperative Pain Control Following Open Abdominal Surgeries

Presenting Author: David W. Munitz, M.D. Presenting Author’s City, State: - Lackland Air Force Base, TX Co-Authors: Jonathan Rogers, M.D. - Wilford Hall Medical Center - Lackland Air Force Base, TX

Introduction: The use of bilateral transverses abdominis plane blocks can reduce both VAS scores and narcotic need in patients undergoing abdominal surgery1. In this case a 53 year old female undergoing bowel resection with a history of scoliosis, lumbar stenosis, and with chronic low back pain, underwent a preoperative TAP block with placement of bilateral TAP catheters for intraoperative and postoperative pain control.

Materials and Methods: Using sterile technique, a MicroMaxx (Sonosite, Inc, Bothell, WA) ultrasound with the HFL38X 13-6 MHZ probe was used to locate the transverses abdominis plane using a subcostal technique. A 20G X 4â€ toughy needle (BBraun,) was inserted under direct visualization using an ultrasound guided in-plane approach with injection of 20 ml of 0.5% ropivacaine. A (BBraun) catheter was then inserted and positioning confirmed by ultrasound visualization. The procedure was then repeated on the opposite side. Two Curlin Medical 4000 Plus infusion pumps were attached in the PACU postoperatively and an infusion of 0.2 % ropivicaine was set at 10 ml/hr into each catheter post-operatively.

Results: Based on daily VAS scores, the patient reported a 0-1/10 score for incisional pain with analgesia from approximately T7-T11 dermatomes. The patient required iv opiod only for treatment of her preexisting chronic back pain. The patient was able to ambulate with catheters in place.

Discussion: The use of bilateral TAP catheters following abdominal surgery is a viable alternative to other regional techniques and can provide effective pain control. In this patient, who had a number of factors that made epidural anesthesia less favorable, TAP catheters offered extended analgesia while reducing the need for PRN or PCA opiods. By introducing catheters, the analgesia can be extended to include multiple postoperative days. In addition, this technique does not cause any lower extremity motor block, allowing for ambulation.

Bibliography 1. Transversus abdominis plane block: The Holy Grail of anaesthesia for (lower) abdominal surgery, Jankovic, Z. Periodicum Biologorium UDC 57:61 VOL. 111, No 2, 203â€“208, 2009

Abstract 128

Comparison of Duration of Analgesia from Peripheral Nerve Blockade With and Without the Addition of Dexamethasone: A Retrospective Analysis

Presenting Author: Stephanie B. Rasmussen, M.D. Presenting Author’s City, State: - Nashville, TN Co-Authors: Nahel N. Saied, M.B., B.Ch - Vanderbilt University Medical Center - Nashville, TN Clifford Bowens, M.D. - Vanderbilt University Medical Center - Nashville, TN Randall Malchow, M.D. - Vanderbilt University Medical Center - Nashville, TN

Introduction: Peripheral nerve blocks (PNBs) are used at an increasing rate to provide selective and excellent analgesia with, among the benefits, a reduced need for opioids and potential early hospital discharge . Dexamethasone (Dex) has been shown to be effective in prolonging analgesia in peripheral nerve blocks.

Materials and Methods: Retrospective review of a regional anesthesia database and patientâ€™s medical records of 1810 patients who underwent various orthopedic surgical procedures and received single shot PNBs from November 2008 through August 2009. Chi-Square test was used to compare means whenever appropriate.

Results: A total of 1806 patients were available for analysis; 1,026 upper extremity (UE) and 780 lower extremity (LE) PNBs (Table 1). Dex (as the only adjunct) was used in only 6 patients and was not used for this comparison (Table 1). Epinephrine (Epi) alone (1:400,000) didn't significantly increase the duration of action of local anesthetics (p=0.84). Dex (8 mg) and Epi did significantly increase the duration of LE-PNBs compared to EpiEpi alone (p=0.05). and increased UE-PNBs by 7 h. (Fig. 1)

Discussion: It is unclear why adding Epi to various local anesthetics didnâ€™t increase the mean duration of PNBs. One possible cause is that the use of a lower concentration (1:400,000) which may exert less vasoconstrictive effect due to the beta receptor dilatory effect. Additionally, adding Epi (1:400,000) to Dex didn't increase duration. Our results confirm that Dex almost double the duration of action of local anesthetics. However, further studies are needed to examine the effect of Epi on PNBs at such low concentration.

Referernces: Hebl, Dilger et al. 2008 Epstein-Barash, Shichor et al. 2009

Abstract 129

Management of Post Dural Puncture Headache in a Patient with Posterior Reversible Encephalopathy Syndrome

Presenting Author: Monique Espinosa, M.D. Presenting Author’s City, State: - Miami, FL Co-Authors: Nicholas Nedeff, M.D. - University of Miami/Jackson Memorial Hospital - Miami, FL

Abstract Body: A 37-year-old female presented to our Labor and Delivery unit at 39 weeks gestation in active labor. Anesthesiology was consulted for labor analgesia. The patient had no significant past medical history. Surgical history included laparoscopic cholecystectomy. Social history was unremarkable. The prenatal course was uncomplicated. She had a history of two prior normal spontaneous vaginal deliveries. She was taking no medications other than prenatal vitamins. Physical exam was unremarkable. Combined spinal epidural was planned for labor analgesia.

A 17-Ga Tuohy needle was inserted at the L4-L5 interspace. Dural puncture was noted at 5.5cm. At this point, the decision was made to place an intrathecal catheter for labor analgesia. A solution was prepared with 0.1% bupivicaine and 2.5mcg/mL fentanyl and infused at 2.5mL/hr. The intrathecal catheter was later used to provide anesthesia for a bilateral tubal ligation. The catheter was in place for 6 hours and 20 minutes. It was removed with the tip intact. There were no immediate post-partum or post-op complications. The patient was discharged home on post-partum day 2.

During this admission, the anesthesiology team evaluated the patient daily. She complained of a mild headache. It was not postural in nature, and it was relieved with acetaminophen. Our team routinely follows patients with dural punctures with phone calls at home until post-partum day 5, or until symptoms resolve. On post-partum day 5 this patient reported that her headache had become severe. At this point she was advised to come to the OB triage unit. The patient was evaluated by the anesthesiology team. The patient complained of headache in the occipital region, radiating to the neck. The pain was exacerbated by laying supine and relieved by ambulation. She denied photophobia. She denied bowel or bladder incontinence. She was afebrile. Physical exam was unremarkable, with no focal neurological deficits. At this time, it was decided that this headache was unlikely to be a post dural puncture headache. This was discussed in detail with the patient and the obstetrician.

Shortly after this evaluation, the patient was witnessed to have a generalized tonic-clonic seizure with tongue biting. Neurology was immediately consulted. The patient was admitted to their service for further evaluation.CT scan of the brain was unremarkable. MRI of the brain was consistent with Posterior Reversible Encephalopathy Syndrome. The patient was discharged 3 days post-seizure with a follow-up appointment at the Neurology Clinic.

The patient returned to the hospital with worsening headache and numbness of the left arm. MRV of the brain ruled out sinus thrombosis and stroke. At this point, the headache had become postural. Anesthesiology was consulted. An epidural blood patch was performed. The patient reported immediate alleviation of her symptoms. On the following day, the patient developed visual changes. A new MRI revealed acute infarct in the left occipital lobe, parietal lobe, and cerebellum.

Our case presentation will include a review of the literature and other case reports of neuraxial anesthesia in patients with PRES. Our goal is to analyze the risks and benefits of treatment with epidural blood patch in this setting.

Abstract 130

Patterns of Regional Anesthesia Practices in the United States

Presenting Author: Kishor Gandhi, M.D., M.P.H. Presenting Author’s City, State: - Philadelphia, PA Co-Authors: Eugene Viscusi, M.D. - Thomas Jefferson University Hospital - Philadelphia, P.A. Ali Ekbatani, D.O., M.B.A. - Thomas Jefferson University Hospital - Philadelphia, P.A. Kent Steinride, B.A. - Outpatient Surgery - Malvern, P.A.

Introduction: Regional anesthesia has gained popularity in recent years, particularly with the Introduction of ultrasound guidance. The recent popularity and success of regional anesthesia has allowed historically inpatient procedures to be performed in an outpatient setting. Practice behaviors in both ambulatory surgical centers (ASC) and hospitals are receiving greater attention. We surveyed surgical facilities in the United States to assess the current trends and behaviors in regional anesthesia techniques1.

Methods: 3251 practitioners were sent an objective survey to measure practice behaviors. Respondents were asked a series of questions based on clinical Background, practice setting, utilization of regional anesthesia procedures (single injection versus continuous catheters), and the use of ambulatory catheters. Descriptive statistics was conducted on the response rates and chi-square analysis with p=0.05 was used to compare responses between ASC and hospital settings.

Results: 170 practioners responded to the questionnaire. The breakdowns of respondents were 99 anesthesiologists, 16 CRNAs, and 48 RNâ€™s. There were 109 respondents from ambulatory surgery centers and 59 from hospital settings (Table 1). Comparison of practice behaviors show minimal difference in frequency of nerve blocks utilized between ASC and hospital settings. Practitioners at ASCs have a higher usage of nerve stimulation and are less likely to use continuous catheters for postoperative analgesia. Paresthesia technique is still employed by some practitioners in both settings.

Discussion: While US guidance is gaining popularity, nerve stimulation remains more popular in the ambulatory setting. Surprisingly, 17% of ASC practitioners continue to use paresthesias for localization. The majority of respondents rarely use continuous peripheral nerve blocks for postop analgesia. There remains an opportunity to expand newer RA techniques of US guidance and CPNB techniques.

References: 1. Viscusi E, Gandhi K, Steinriede K. Peripheral nerve blocks have come a long way. Outpatient Surgery. Page 46-52. October 2009.

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Table 1: Practice Behaviors among Respondents

ASC (n=109) Hospital P value (n=59) Compared to 5 years ago, frequency of PNB’s? Less 10 (9.1) 4 (6.7) p=0.489 More 90 (82) 55 (93) Use of paresthesia for nerve localization? No 81 (74) 49 (83) p=0.503 Yes 18 (17) 8 (14) Use of nerve stimulator (NS) vs. ultrasound (USG) NS 53 (49) 15 (25) p=0.05 for nerve localization? USG 7 (6.4) 6 (10) Both 37 (34) 34 (58) Frequency of block failure? <5% 56 (51) 31 (52) p=0.220 5-10% 14 (12) 15 (25) 10-25% 10 (9.1) 4 (6.8) Frequency of continuous catheters with PNB’s? Often 6 (5.5) 8 (14) p=0.02 Sometimes 21 (19) 24 (41) Rarely 72 (66) 26 (44) Type of infusion given through catheter? Continuous 14 (12.8) 11 (18.6) p=0.976 only 1 (0.1) 1 (1.6) PCA only 15 (13.7) 13 (22) Continuous + PCA Most common reason for catheter failure? Migration 22 (20) 32 (54) P=0.508 Non- 6 (5.5) 5 (8.4) compliance 2 (1.8) 1 (1.7) Pump failure Frequency in use of ambulatory catheters and 0% 71 (65) 33 (55.9) P=0.227 pumps? 1-10% 15 (14) 13 (22) 10-25% 6 (5.5) 6 (10) 25-50% 1 (0.9) 3 (5) >50% 7 (6.4) 4 (6.7) P<0.05 based on Pearson’s Chi-square analysis (%)

Abstract 131

Bilateral Gluteal Compartment Syndrome Following a Right Total Knee Revision: A Case Report. Presenting Author: Kristie Osteen, M.D. Presenting Author’s City, State: - New Orleans, LA Co-Authors: Shireen Haque, M.D., M.P.H. - Ochsner Medical Center - New Orleans, LA

Abstract: Gluteal compartment syndrome is a rare occurrence that has traditionally been found in the setting of extended immobilization from either altered mental status, drug induced intoxication, or improper intraoperative positioning. Thrombolytics and medications with myositis as a potential side effect have also been implicated in a few isolated cases of spontaneous compartment syndrome. Early signs are pain on passive stretching and pain out of proportion to physical exam findings. Erythema, edema, and tensing of the affected area are also typically present. Elevated CPK further supports a diagnosis of compartment syndrome. Failure to recognize and definitively treat compartment syndrome within the first 24-36 hours can lead to permanent limb loss and morbidity from a host of systemic complications such as hyperkalemia, renal failure, and sepsis.

We present a case of bilateral gluteal compartment syndrome in a 52 year old patient following a right total knee revision. Despite effective epidural analgesia to the point of causing transient numbness in the hours immediately following the procedure, the patient began to complain of severe pain on postoperative day 1 accompanied by an area of redness on the left buttock. Following removal of the epidural catheter on day 2, the patient became agitated and appeared in severe distress from bilateral buttock pain. On physical exam, the right and left gluteal region was tense, hard, and erythematous. Light touch precipitated 10/10 pain and patient would not allow further palpation. Creatinine phosphokinase (CPK ) and liver function tests (LFT) ordered at the time were significantly elevated. Following emergency fasciotomy, a thorough review was conducted of the operative course, medication history, and imaging studies. Simvastatin, a medication associated with case reports of spontaneous compartment syndrome, was withdrawn from our patient's daily medications and LFT's were followed over the course of his hospital stay. By day of discharge, both CPK and LFT's were decreasing and the patient had significant resolution of his gluteal pain.

The etiology of bilateral gluteal compartment syndrome in our patient could have been a combination of intraoperative length and positioning with simvastatin induced myositis. Obesity presented an additional risk factor. This case highlights the importance of identifying patients at increased risk of compartment syndrome in the preoperative assessment and following them with more intensive intraoperative and postoperative monitoring. Special attention should be directed at operative position, the appropriate use of traction, and the need for cushioning areas at risk of compression. Increasing awareness of the signs of compartment syndrome with patient care technicians, nursing staff, and physical therapists could also facilitate early diagnosis and treatment.

Additional File #1:

Taken from Liu HL, Wong DS Asian J Surg. 2009 Apr;32(2):123-6

Additional File #2:

MRI showing bilateral edema of the gluteal muscles Abstract 132

An Ambulatory Brachial Plexus Catheter Program: A Pain Service's Experience

Presenting Author: Mona Sawhney, R.N., N.P., M.N., Ph.D.(c) Presenting Author’s City, State: - Toronto, Ontario Co-Authors: Alayne Kealey M.D., FRCPC - Sunnybrook Health Sciences Centre - Torontp, Ontario

Background: In Canada, the number of patients having ambulatory surgical procedures has increased dramatically over the past two decades. The Canadian Institute of Health Information (CIHI) reports that the number of patients having outpatient procedures has increased by 31% since 1996 (CIHI 2007). However, 60% to 71% of patients who undergo ambulatory surgery experience unrelieved moderate to severe pain immediately post-operatively (McGrath et al., 2004) and 34% to 55% patients continue to have pain seven days after their surgery (Mattila et al., 2005; Watt-Watson et al., 2004). Upper extremity surgery, including shoulder surgery has been identified as one of the most painful ambulatory surgeries with patients reporting moderate to severe pain even 7 days after surgery (McGrath et al., 2004; Watt- Watson et al., 2004). Most patients are using only oral analgesics to manage their pain at home postoperatively. Continuous ambulatory interscalene nerve blocks have been shown to be effective in reducing pain and opioid-related side-effects in patients undergoing orthopedic surgery of the shoulder (Ilfeld et al, 2003). Therefore, starting in March 2009 patients undergoing ambulatory or short stay upper extremity surgery at Sunnybrook Health Sciences Centre, Holland Orthopaedic and Arthritic Centre were offered a continuous brachial plexus block (CBPB) as part of their pain management regime in addition to oral analgesics.

Aim: This quality improvement initiative describes our Acute Pain Service's experience with patients who were discharged to home with a continuous brachial plexus block following upper extremity surgery.

Method: Patients were first given information by the anesthesiologist about our ambulatory CBPB program during their pre-operative assessment, several days to weeks prior to their surgery. Patients who resided within a 1 hour driving radius from the hospital and had a family member or care giver willing to help manage and remove the CBPB were discharged home with a disposable infusion pump of 0.15% ropivacine at 5cc/h, along with verbal and written instructions for the management of the CBPB. Patients were also provided with an emergency contact all-hour telephone number. During the time that the CBPB was in place, the patients were telephoned daily and were assessed for symptoms of local anesthetic toxicity, evidence of sensory or motor block, and pain scores.

Results: Fifty-one patients who underwent upper extremity surgery were discharged home with a CBPB between March 2009 and January 2010, almost all (96%) with an interscalene catheter. Seventy-five percent of these patients were discharged home on the day of their surgery. The mean reported pain score on post-operative days one and two was 3 (out of 10). Patients were actively encouraged to use oral analgesics in addition to the CBPB to manage their pain during their telephone assessment. The majority (76%) of patients removed their catheter without incident on post-operative day 2. Eight patients returned to hospital for the following reasons: difficulty in removing the catheter at home (n=5), unmanageable pain requiring CBPB bolus (n=2), severe hand pain and sensory block that resolved with catheter removal (n=1). All patients who required a bolus of the CBPB did not use oral analgesics optimally.

Discussion: Daily telephone contact allowed for patient assessment the opportunity to provide advice regarding oral analgesic use. The majority of patients had good analgesia with the CBPB and oral analgesics and no major complications were noted. It is unclear if the patients who returned to hospital due to difficulties with their CBPB could have been identified pre-operatively.

Abstract 133

Unreliability of Ultrasound for Identification of the L5-S1 Interspace

Presenting Author: Kelly Baird, M.D. Presenting Author’s City, State: - Winston-Salem, NC Co-Authors: Robert Weller, M.D. - Wake Forest University School of Medicine - Winston-Salem, NC

Introduction: Lumbar vertebral interspace identification using surface landmarks was found to higher than actual vertebral level in 32% of patients, using ultrasound of the sacrum as the primary measure of level (1). Other investigators have used the ultrasound view of the sacrum to identify the L5-S1 interspace (2), and the sacrum has been used to number the lumbar transverse processes (TP) for posterior lumbar plexus block (LPB) (3). We noted potential for error using L5-S1 identification by ultrasound while investigating surface landmark accuracy for LPB.

Methods: This study used ultrasound to test the accuracy of surface landmarks for LPB. Recruitment target was 30 patients undergoing surgery with LPB for postoperative analgesia. After informed consent, standard surface landmarks were used to determine the needle entry point assumed to be over the L4 TP (TP4). Ultrasound was then used (2-5MHz transducer, Sonosite, Bothell,WA) to identify the lumbar spinous processes, laminae and articular processes in transverse axis. The probe was rotated 90 degrees over the articular processes, and moved caudad until the sacrum was identified by continuous hyperechoic cortical line. The first interruption in the cortical line was considered the L5-S1 interspace (Fig 1), and the probe was moved cephalad to center the L4-5 interspace in the field. The probe was then moved laterally in the parasagittal plane and the TP just cephalad to the L4-5 interspace labeled TP4 and centered on the ultrasound screen. A template was used to mark the exact transducer center on the skin, and TP3 and TP5 were similarly marked. The accuracy of the surface landmark was graded using a 4- point scale.

Results: In 4 of 7 patients initially recruited, ultrasound identified the surface landmark needle entry was over TP3 or between TP3 and TP4. Many of these patients also had pelvic x-rays or CT scans, and review of these x-rays questioned the correctness of our ultrasound identification of L5-S1, since â€œTP4â€ was imaged caudad to the iliac crest by ultrasound. One of the patients had abnormal lumbosacral junction anatomy with an S1-S2 opening. In 3 patients, x-rays suggested the cortical opening noted inferior to the L5-S1 articular process may have been the S1 foramen or transverse opening rather than the L5-S1 interlaminar space. Measurement of TP4 on x-ray at 7-8 cm above the PSIS, and clearly cephalad to the iliac crest corroborated our incorrect labeling of TP4 by ultrasound.

Discussion: Abnormal lumbosacral junction anatomy with lumbarization of S1 or sacralization of L5 is relatively common, noted in 12-18% of the population (4,5) (Fig 2). Transverse opening in the sacrum may be present below S1 even without this diagnosis. Although we and others have considered ultrasound identification of the sacrum to be simple and reliable for determining the L5-S1 interspace, our preliminary results suggest some potential for error with this approach.

References 1) Whitty R Anesth Analg. 2008;106:538-540 2) Borges CR Reg Anesth Pain Med 2009;34:581-585 3) Kirchmair L Anesth Analg 2001;93:477-481 4) Bron JL Acta Orthop Belg. 2007;73:687-95 5) Kim NH Bull Hosp Jt Dis. 1997;56:161-6

Abstract 134

Lumbar Sympathetic Blockade for a Multiple Sclerosis Patient with Neuropathic Leg Pain

Presenting Author: Samir I. Abdo, M.D. Presenting Author’s City, State: - Ann Arbor, MI Co-Authors: Chad Brummett, M.D. - University of Michigan - Ann Arbor, MI Tiffany Braley, M.D. - University of Michigan - Ann Arbor, MI

Abstract Body: We present a 44 year-old African-American female with a history of relapsing and remitting multiple sclerosis (MS). She initially presented to the pain clinic with neuropathic symptoms of a burning, lancinating pain with associated numbness and tingling extending from her left buttock area down her anterior thigh and left lateral leg to the dorsum of her foot. The patient was initially started on duloxetine but had to stop for side effects. Trials of amitriptyline and nortriptyline made the patient feel crazy. She reported some relief with gabapentin. At one point, the patient tried oxycodone and hydrocodone, which did not help her symptoms.

A MRI of the patient's brain and spinal cord showed a single enhancing lesion in the left dorsolateral aspect of cord at C2 level and a new single lesion of left corpus callosum along with some chronic lesions consistent with her history of MS. Her lumbar spine MRI did not show any degenerative disk disease or any component of nerve compression.

The patient subsequently underwent a left lumbar sympathetic block at the L3 level, where 15 mL of 0.25% bupivacaine with 100 mcg of clonidine were instilled without complications. Sympathectomy was confirmed with an appropriate temperature rise. She experienced complete relief in her left lower extremity for 24 hours. At her subsequent clinic visit three weeks later she had an overall 50% reduction in her symptoms in her left lower extremity. Approximately six weeks after her initial sympathetic block, the patient underwent a second sympathetic block on the left at L3. After this second block she reported an approximate 90% resolution of symptoms in her left lower extremity at her follow-up visit 5 weeks after the second block.

Discussion: Pain is an important symptom in multiple sclerosis patients with a prevalence around 29%.1 The pain associated with MS is termed central pain, which is defined by the International Association of Pain (IASP) as â€œpain initiated or caused by a primary lesion of the CNS. Central pain is often refractory to treatments and complete pain relief is rare. It is associated with various components of pain, including steady dysesthetic, intermittent neuralgic, and evoked pain which must all be addressed. As such, traditionally, multidisciplinary approaches are recommended for treating the central pain associated with multiple sclerosis. Pharmacotherapy often begins with tricyclic antidepressants, with membrane stabilizers as a second step. Opioids in small doses may also be of limited benefit, but are not considered first line agents. Finally, more invasive therapies, including dorsal column stimulation or intrathecal therapy, can be considered. To our knowledge, this is the first case describing the use of sympathetic blockade for the treatment of neuropathic extremity pain in a patient with MS. Sympathectomy has been used to treat other types of neuropathic pain. Although further experience is necessary, it appears that sympathetic blocks provide another option for a difficult clinical situation.

Ref: Clifford DB, Trotter JL: Arch Neurol 1984;41 Merskey H, Bogduk N: Classifications of chronic pain: descriptions of chronic pain syndromes and definitions of pain terms. Seattle, IASP Press, 1994

Abstract 135

Evolving Compartment Syndrome not Masked by a Peripheral Nerve Catheter

Presenting Author: Benjamin J Walker M.D. Presenting Author’s City, State: - Seattle, WA Co-Authors: Adrian T Bosenberg MBChB - Seattle Children's Hospital - Seattle, WA

Introduction: Compartment syndrome is defined by reduced tissue perfusion secondary to elevated pressure within a confined fascial plane. Whether regional anesthesia techniques delay the diagnosis of compartment syndrome has been a subject of great controversy. Numerous case reports, primarily involving epidurals but also a few single-injection peripheral nerve blocks, have both supported and rejected this assertion. To our knowledge, there have not been any published case reports implicating peripheral nerve catheters (PNC). We present a case of evolving compartment syndrome in which breakthrough pain led to prompt treatment in the presence of a PNC.

Case: A 19-year-old, 79-kg woman presented for left calcaneal osteotomy. She had difficulty with nausea and vomiting secondary to opioids in the past. The anesthetic plan was a general anesthetic combined with a popliteal catheter (0.5% bupivacaine 15-ml bolus, 0.2% ropivacaine 8 ml/hr infusion) and a single- injection saphenous nerve block (0.5% bupivacaine 5 ml). In the morning of postoperative day (POD) 1, she had a dense sensory block of the left foot, thought to be from her initial bolus, and her infusion rate was turned down to 6 ml/hr by the acute pain service (APS). She was discharged later that morning. In the evening, she called the APS because of increasing pain in her left foot, so her catheter rate was increased back to 8 ml/hr. Her pain continued to worsen overnight, and she presented to the emergency department (ED) in the early hours of POD2 complaining of â€œpain and tightnessâ€ in her lower leg and ankle. She had decreased sensation in her toes, but no motor block, and normal capillary refill. Her pain was immediately relieved after splitting of her cast and application of spacers. Her catheter remained in place until POD4, at which time it was removed uneventfully at home. Upon removal of her cast four weeks later, the patient had evidence of prior skin breakdown on the anterior aspect of her ankle, which had healed spontaneously in the interim.

Discussion: We believe that this case is notable for our patient experiencing breakthrough pain at an early stage of presumably elevated compartment pressure. Skin surface pressures underneath a cast correlate well with compartment pressures. Had her cast not been split, it is likely that the swelling would have progressed to cause further damage. After reviewing the relevant literature, we can conclude that classic signs of compartment syndrome are somewhat subjective and generally late findings. They have proven unreliable, especially in children and obtunded patients. The most important diagnostic tools are a high index of suspicion, monitoring for escalations in postoperative analgesic needs, and effective communication with surgeons and patients regarding pain expectations. An acute pain service, with experience in regional techniques and a singular focus on analgesia, is ideal for managing these patients. Compartment syndrome is a rare complication that should not prevent the overwhelming majority of patients from receiving optimal postoperative analgesia.

Abstract 136

Continuous Analgesia for Forequarter Amputation Using a Combined Cervical Paravertebral and High Thoracic Epidural Catheter Approach

Presenting Author: Everett Petersen, M.D. Presenting Author’s City, State: - Gainesville, FL Co-Authors: Linda Le-Wendling, M.D. - University of Florida College of Medicine – Gainesville, FL Mark Scarboroughm, M.D. - University of Florida College of Medicine - Gainesville, FL

Abstract Body: Management of perioperative analgesia for forequarter amputation has been described previously using techniques such as placement of intraoperative nerve sheath catheters or by the use of dual cervical and thoracic paravertebral catheters. Effectiveness of post-operative control of phantom limb pain and phantom limb sensation following amputation using neural blockade is conflicting. We document the use of both a cervical paravertebral and T2-T3 epidural catheters for perioperative pain control for forequarter amputation.

Case: A 67-year old female presented for right forequarter amputation due to recurrent right axilla leiomyosarcoma with intractable pain secondary to brachial plexopathy and preoperative radiation therapy. Preoperative MRI showed a large mass in the right axilla extending to the scapula and encasing the right axillary artery and brachial plexus. The patientâ€™s home medication regimen included transdermal fentanyl 175 mcg/hour, effexor 150 mg daily, and gabapentin 600 mg TID. Due to the extensive nature of the surgery and the complicated innervations of the upper extremity and lateral chest wall, we chose to place a C6 cervical paravertebral catheter (CPVC) and T2-T3 epidural for intra- and post-operative analgesia. Both catheters were bolused preoperatively with ropivacaine 0.5% (20 milliliters through the CPVC and 5 milliliters through the T2- 3 epidural). Catheter infusions were then maintained with ropivacaine 0.2% at 10 and 6 ml/hr respectively after bolusing. At the end of the case the patient was extubated and placed on her baseline home pain regimen throughout the perioperative period. The patient received a morphine PCA (patient-controlled analgesia) in the first 36 hours postoperatively. The perineural catheters were discontinued on catheter day number 7. Pain scores were assessed multiple times daily using numeric pain scales and the patient was questioned regarding phantom limb pain and sensation.

Discussion: The patient reported overall â€œgoodâ€ pain control and satisfaction during the 7 days duration of catheter placement. She reported an average VAS (visual analog scale) score of 4.2 in the first 24 hours after surgery. Average daily VAS scores ranged from 1.3 to 2.8 over the next 6 days of catheter duration. Pt. reported some phantom limb sensation but not pain during her hospital stay. On POD #17 the patient first reported intermittent phantom limb pain in her right hand.

Conclusion: Adequate perioperative pain control was achieved using a continuous cervical paravertebral and T2-T3 epidural technique for forequarter amputation. This however, did not prevent subsequent phantom limb pain 17 days after surgery in this cancer patient with preexisting pain secondary to brachial plexopathy and radiation therapy.

Abstract 137

Total Shoulder Arthroplasty as an Outpatient Procedure

Presenting Author: Allison S. Haller, M.D. Presenting Author’s City, State: - Gainesville, FL Co-Authors: Andre Boezaart, M.D., Ph.D. - University of Florida - Gainesville, FL Thomas Wright, M.D. - University of Florida - Gainesville, FL Douglas Theriaque, M.S. - University of Florida - Gainesville, FL Linda Le-Wendling, M.D. - University of Florida - Gainesville, FL

Background: Most patients undergoing a total shoulder arthroplasty (TSA) traditionally remain hospitalized until postoperative day (POD) 1 or 2. A pilot study showed that, with the use of an ambulatory brachial plexus block, all of six patients enrolled in the ambulatory phase of the study met discharge criteria in the postanesthesia care unit (PACU). This study seeks to further identify factors that can be used to stratify patients for early discharge.

Methods: After IRB approval, we preoperatively enrolled patients undergoing unilateral, primary TSA after they consented to have general anesthesia and to have a cervical paravertebral catheter placed for postoperative pain control. Exclusion criteria included BMI > 35, opioid dependence, clinically significant hepatic or renal insufficiency, cardiac or lung dysfunction, or a peripheral neuropathy. A cervical paravertebral nerve block was performed and a catheter (SimuCath; Arrow International, Reading, PA) was inserted using a biceps twitch with less then 1.0 mA. Following a negative test dose, twenty mL of ropivicaine, 0.5%, was injected via the catheter with aspiration every five mL. An ambulatory pump (PainPump 2, Stryker, Kalamazoo, MI) was connected to the catheter for local anesthetic infusion with ropivicaine, 0.2%, set at a rate of 5 ml per hour and a patient bolus setting of 10 ml and a lockout time of 120 minutes. Patients received a general anesthetic for the surgery. Instructions were given to the PACU nurse to administer acetaminophen for mild pain, oxycodone and a catheter ropivicaine bolus for moderate pain, and a bolus plus IV morphine or dilaudid for severe pain. Patients were followed daily until their catheters were removed and asked about pain control, nausea and opioid use through POD 7. Patients who met criteria and consented to be followed in the study but who did not want to go home on the day of surgery were enrolled as controls.

Results: This study is ongoing. Twenty-three patients have been enrolled. Ages ranged from 63 to 81. Twelve patients initially agreed to discharge from the PACU. To date only one patient has been successfully discharged home on POD 0. Ten met discharge criteria in the PACU but were sent home on POD 1 secondary to PACU and hospital confusion, late or delayed surgery, or patient choice. Nausea kept the remaining patient from discharge until POD 1. Of the eleven patients enrolled as controls in the study, four of them met discharge criteria in the PACU.

Conclusions: Despite a carefully selected cohort, most TSA patients do not consider same day discharge a viable option. Although many of those patients anticipating early discharge did meet criteria in the PACU, all but one stayed until POD 1. With only one patient thus far successfully leaving from the PACU, no preoperative factors can be isolated which contribute to remaining in house despite meeting discharge criteria. While it is clear that a successful cervical paravertebral block and excellent pain control contribute to less opioid use, less nausea and vomiting and increased patient satisfaction, it has not thus far proven useful for changing TSA to an outpatient surgery in this institution.

Additional File #1:

Pain Orders (PACU and Floor)

Date: ______Time: ______Weight: ______lb/kg (circle one)

Allergies: ______

When patient reaches recovery area, push the patient-controlled bolus button on cervical paravertebral catheter pump.

If patient has VAS pain score 3 to 4, treat with oral acetaminophen 650mg po to 1000mg Q 6 hours prn pain.

If VAS score 5 to 7 (moderate pain), treat with oxycodone PO 5 to 10 mg Q3 hours prn pain and notify anesthesiology provider at (pager below) and administer patient-controlled bolus via peripheral nerve catheter of 10ml ropivacaine 0.2% via disposable Stryker pump.

If VAS score 8 and above (severe pain), may give morphine 2mg IV every 5 minutes until pain score decreases below 5. For patients allergic to morphine, may give dilaudid 0.2mg IV every 5 minutes until pain score decreases below 5. Please hold IV doses of morphine or dilaudid if SpO2 below 92% or respiratory rate below 8. Please notify anesthesiology provider (pager below) and administer patient controlled bolus of 10ml ropivacaine 0.2% via disposable Stryker pump.

Anesthesiology provider pager #: ______

Additional File #2:

Eligibility Checklist

PI: Linda Le-Wendling, MD___ Study Title: Total Shoulder Arthroplasty as an Outpatient Procedure___ IRB #: ______GCRC # ______Subject #: ______

To qualify for this study, each subject must meet the following criteria: 1. ASA class I, II or III 2. Male or female between the ages of 18 and 85 3. If female, cannot be pregnant. 4. Undergoing unilateral total shoulder arthroplasty 5. Has caretaker who will remain with the patient entire duration of local anesthetic infusion 6. Live within 30 minutes of an emergency department

Subjects meeting any of the following criteria will be excluded from the study: 1. Contraindication to cervical paravertebral catheter 2. History of opioid dependence (h/o of central sensitization or CRPS, using more than the equivalent of 20 mg/day oxycodone consistently for over 4 weeks) 3. Pregnancy or breast feeding 4. Has a known hypersensitivity or allergy to local anesthetics or oral and intravenous analgesics 5. known clinically significant hepatic or renal insufficiency 6. Has BMI > 40 7. Has peripheral neuropathy 8. History of OSA 9. Severe heart or lung disease (SpO2 below 95%) that affects their functional status

Subjects must qualify for discharge criteria within the first postoperative day to be discharged:  Analgesia: pain score less than 5 (mild pain)  Opioids: less than 5mg intravenous morphine required for analgesia (<4mg in PACU)  Mobility: ambulation without assistance or light-headedness  Orals: tolerating oral liquids without vomiting  Oxygenation: SpO2 above 92% on room air with a respiratory rate less than 20  Vital Signs: Temperature < 38.5 degrees Celsius, Heart Rate below preoperative baseline + 10 bpm, Systolic blood pressure below preoperative baseline + 20 mmHg  Nausea: minimal nausea not requiring treatment  Estimated blood loss: less than weight (kg) x 10ml  Medical Issues: no medical issues requiring admission

Abstract 138

A Comparison of Lumbar Plexus Catheters to Lumbar Epidural Catheters for Postoperative Pain Control Following Hip Surgery in Children

Presenting Author: Benjamin J. Walker, M.D. Presenting Author’s City, State: - Seattle, WA Co-Authors: David E. Liston, M.D., M.P.H. - Seattle Children's Hospital - Seattle, WA Grant McFadyen, M.B.Ch.B. - Seattle Children's Hospital - Seattle, WA Adrian T. Bosenberg, M.B.Ch.B. - Seattle Children's Hospital - Seattle, WA Flack H. Sean, M.B.Ch.B. - Seattle Children's Hospital - Seattle, WA

Introduction: Lumbar epidurals (LEP) can provide effective continuous postoperative analgesia following hip surgery in children. The increasing use of continuous peripheral nerve catheters offers lumbar plexus catheters (LPC) as a potential alternative. The most effective method of pain control following major hip surgery in children has not been established. Previous data from our institution comparing LPC to LEP produced equivocal results, possibly because pain in the sciatic distribution was a confounder when LPC and LEP for surgery on the posterior thigh or femur were compared. We therefore sought to compare the efficacy of LPC and LEP for management of postoperative pain following major hip surgery.

Methods: After Institutional Board Approval, a retrospective case control study of patients undergoing major hip surgery (primarily pelvic osteotomy) was performed. The sample group of patients received a LPC for postoperative pain management, while the control group received a LEP. The two groups were matched for age and type of surgery. During the first 48 hours postoperatively, the following outcome variables were compared; average and maximum pain scores using a numerical pain scale (0-10), amount of opioid used and opioid side effects. Catheter duration and hospital length of stay were also recorded. Opioids were converted to morphine equivalents. Antiemetics and antipruritics were given in standardized doses based on weight, thus the number of doses was recorded.

Results: A total of 30 children were enrolled (n=15 in each group). Results for major outcome variables are provided in Table 1. Average pain scores were similar between groups, but maximum reported scores were slightly higher for the LPC group. Postoperative opioid use varied considerably within our sample. Notably, there was a trend toward a shorter hospital stay and longer catheter duration in the LPC group. No serious complications were reported in either group.

Discussion: LPC provides similar pain control to LEP after major hip surgery in children. Advantages of the LPC over LEP include avoidance of urinary catheterization, elimination of the risk of spinal cord injury with catheter placement, and potential for discharge with the catheter in situ. Although children in the LPC group used more opioid, we did not account for epidural opioids in the LEP group (typically hydromorphone 5 mcg/ml), as we only recorded prn opioids given if patients were transitioned to oral analgesics. Therefore, postoperative opioid use is not an accurate reflection of the total amount of opioid received by patients in the LEP group. Overall, LPC group patients had a shorter hospital stay despite keeping their catheters for a longer duration. The economic benefit of at least one less day in hospital is significant. Although our study is limited by its retrospective nature and lack of randomization, the results are encouraging. A randomized, prospective study with a larger sample is planned to further examine the relative benefits of these two techniques.

Additional File #1: Variable LPC LEP p-value Age (years) 10.7 + 6 9.1 + 1.3 0.43 Weight (kg) 37.8 + 5.8 36.6 + 4.9 0.87 Hospital Stay (days) 3 (1-4) 4 (3-4) 0.067 Catheter duration (days) 3 (1-4) 2 (1-3) 0.077 Avg pain PACU (0-10) 4.3 (3-6) 1.43 (0-4.3) 0.09 Max pain PACU (0-10) 6 (6-9) 5.5 (0-8) 0.15 Avg pain floor (0-10) 2.3(1.5-3.6) 1.75 (1.1-3.1) 0.2 Max pain floor (0-10) 7 (5-8) 6 (5-8) 0.72 Morphine use – floor (mcg/kg) 41.9 (13.1-66.7) 20 (8.5-53.8) 0.29 Antiemetic (no. of doses) 0 (0-2) 2 (0-5) 0.054 Antipruritic (no. of doses) 0 (0-0) 0 (0-1) 0.33

Table 1. Patient demographics and outcome variables for children receiving lumbar plexus catheter (LPC) and lumbar epidural catheter (LEP) for postoperative pain control following hip surgery. Data are reported as mean + SD or median (IQR). P-values were calculated with the appropriate statistical test (student’s t-test or Mann-Whitney test).

Abstract 139

Comparison of Epidural Analgesia with Peripheral Nerve Blockade for Bilateral Knee Arthroplasty - A Retrospective Analysis

Presenting Author: Sivasenthil Arumugam, M.D. Presenting Author’s City, State: - Hartford, CT Co-Authors: Jonathan Abrams, M.D. - St.Francis Hospital & Medical Center - Hartford, CT Michael Archambault, M.D. - University of Connecticut - Farmington, CT Courtland Lewis, M.D. - Connecticut Joint Replacement Institute - Hartford, CT Sanjay Sinha, M.D. - St.Francis Hospital & Medical Center - Hartford, CT

Introduction: Even though combined femoral-sciatic blocks as part of multimodal therapy are routinely used for post-operative pain control after unilateral TKR, epidural analgesia is commonly used in patients undergoing bilateral TKR. Previous studies have shown that peripheral nerve blocks with multimodal analgesic regimen are superior to epidural analgesia for unilateral TKR,(1,2) but there is paucity of data regarding the use of peripheral nerve blocks(PNB) in patients undergoing bilateral TKR. We performed a retrospective analysis comparing epidural analgesia with combined femoral-sciatic nerve block as part of multimodal therapy in patients having bilateral knee arthroplasty.

Methods: We identified patients who underwent sequential bilateral TKA under one anesthetic from November 2006 to October 2008 from our database after IRB approval. Patients who received either epidural or continuous femoral nerve block combined with single injection sciatic nerve blocks for postoperative analgesia were identified. All patients in the PNB group were given a standard premedication consisting of Celebrex, Pregablin and Acetaminophen which was continued for the rest of their hospital stay. Oxycontin was added to the post operative pain therapy and Oxycodone or iv hydromorphone was available for breakthrough pain. In the epidural group, boluses of local anesthetic solution via epidural catheter and increasing the basal infusion rate were used for controlling increasing pain. All patients received general anesthesia for surgery.

Results: 187 of the 221 patients who had bilateral TKR during the two year period met the criteria for analysis: 127 had epidural and 60 had PNB. The remaining 34 patients were not included in the study as they had PCA or other modalities for postoperative management. There were no differences in patient characteristics. The number of physician interventions required to manage post op pain prior to PACU discharge were similar between the groups. However episodes of hypotension and desaturation were observed more often in the epidural group in the PACU. Blood transfusion rates, incidence of urinary retention and pruritis were also higher in the epidural group. Even though PE was diagnosed in 5 patients (all in the epidural group) the difference was not statistically significant. The risk of cardiac complications was similar between the groups. (See table-1) None of the patients demonstrated any evidence of local anesthetic toxicity.

Discussion: Data from our retrospective study demonstrates that bilateral peripheral nerve blockade is safe, as well as associated with fewer side effects and complications than epidural in patients undergoing bilateral knee arthroplasty. Despite the limitations of being a retrospective study, our data suggests that the beneficial effects of PNB as part of multimodal analgesia, that have been demonstrated for unilateral TKA can be extended to patients undergoing bilateral TKA. A prospective trial to substantiate our findings is warranted.

References: 1.Zaric D : Anesth Analg - 01 Apr 2006; 102(4) : 1240-6 2.Fowler S : BJA 2008; 100(2): 154-64

Additional File #1: Epidural PNB Significance

Number of patients 127 60 x

Hypotension 52 10 0.0008

Blood transfusion 115 43 0.0019

Cardiac 12 3 0.393 complications Desaturation 20 3 0.054

Intervention for Pain 40 18 0.867

Urinary retention 25 1 0.0004

Pruritis 21 2 0.0086

Nausea, Vomiting 32 11 0.354

Abstract 140

Spinal Anesthesia for a Patient on High Dose Aspirin with Churg-Strauss Syndrome

Presenting Author: Linda R. Kawam, Doctor of Osteopathy, D.O. Presenting Author’s City, State: - Livingston, New Jersey Co-Authors: Robert Dorian, M.D. - Saint Barnabas Medical Center - Livingston, New Jersey

Abstract Body: Churg-Strauss Syndrome or allergic granulomatosis is a rare and most likely under- reported disorder characterized by extravascular granulomas, hypereosinophilia, and pulmonary and systemic small-vessel vasculitis. The annual incidence of the disorder is estimated at 2.4-4 cases per million in the general population, while among asthma patients an average of 34.6 cases per million has been reported. Adult-onset asthma and allergic rhinitis are usually results of the allergic granulomatosis and angiitis. Churg-Strauss syndrome is divided into 3 phases: 1. Allergic phase - characterized by rhinitis, sinus pain, headaches, cough, wheezing, and asthma. 2. Eosinophilic phase - characterized by hypereosinophilia and eosinophilic tissue infiltrations that may produce pneumonia, gastroenteritis, and general manifestations such as weight loss, fever, and sweating. 3. Vasculitic phase - characterized by all of the manifestations of multi-systemic vasculitis including pulmonary small vessel vasculitis causing worsening asthma, coughing, and hemoptysis, cardiomyopathy, cardiac gallops, pericardial friction rubs, JVD, and peripheral edema.

Our patient, in early vasculitic phase, was scheduled for an exploratory laparotomy and oophorectomy for a 15 x 10 cm ovarian tumor. Because of our patientâ€™s severe reactive airway disease and her desire to avoid general anesthesia, we administered a spinal anesthetic. Another complicating factor was our patientâ€™s prior diagnosis of Sampterâ€™s Triad â€“ asthma, nasal polyposis, and aspirin allergy. As she did not tolerate corticosteroids, the usual treatment of Churg-Strauss Syndrome, she underwent deliberate desensitization to aspirin in the Intensive Care Unit. Small doses of aspirin were increased incrementally until she was able to tolerate 325 mg PO TID. This successfully controlled her asthma and other vasculitic symptoms. Our patientâ€™s aspirin dose was reduced to 325 mg PO BID one week prior to surgery and she took her morning dose only 2 hours before surgery. Spinal anesthesia was performed with no complications. The American Society of Regional Anesthesiology and Pain Medicine (ASRA) suggest in their guidelines that NSAIDs represent no significant risk for the development of spinal hematoma in patients having neuraxial anesthesia and that there is no correlation between the timing of the performance of neuraxial anesthesia and the dosing of NSAIDs. We are reporting this case to increase awareness of Churg-Strauss Syndrome, a multi-system disease which has many direct anesthetic implications. Since recent publications have shown the risks of exacerbation of asthma and pulmonary vasculitis by general anesthesia and endotracheal intubation in Churg-Strauss patients, we decided that the benefits of regional anesthesia outweighed the risks of general anesthesia, even in light of our patientâ€™s high dose aspirin therapy. It was our experience that patient comfort, safety, and anesthetic goals were successfully achieved while following ASRA guidelines for neuraxial anesthesia. This case demonstrates that neuraxial anesthesia, even in a patient on high dose aspirin, is a viable alternative to general anesthesia in patients with Churg-Strauss Syndrome.

Abstract 141

The Role of Functional Discography in Evaluating Chronic Low Back Pain

Presenting Author: Binit J. Shah, M.D. Presenting Author’s City, State: - Cleveland, OH Co-Authors: Al-Amin Khalil, M.D. - University Hospitals/Case Western Reserve – Cleveland, OH

Introduction: Chronic low back pain (CLBP) is the most common cause of disability with an annual cost of >$50 billion in the US alone(1). The most common cause is internal disk disruption(IDD), affecting as many as 40% of sufferers(2). Currently, disc provocation via lumbar discography remains the only means of diagnosis. However, given the high false positive rates of up to 52-83%(3,4), its diagnostic utility is questionable. Our experience shows that functional discography gives greater diagnostic clarity by not only eliciting pain, but also testing of pain relief by injection of licodaine directly into discs.

Case Report: TA is a 35 yo WF referred by her surgeon for pre-operative discography. She has a 4-year history of constant coccyx and left-sided back pain with poor response to conservative therapy. Lumbar discography was undertaken in concordance with International Spine Intervention Society (ISIS) guidelines at the L3-4, L4-5 and L5-S1 levels. She had concordant, 10/10 pain at each level, therefore the L2-3 disc was also tested. Disc morphology and manometry readings are noted in Table 1. Given no pain at the L2-3 disc, the introducer & needle were removed. At the remaining levels, catheters were introduced into the nucleus pulposus before removing the needles. Functional testing began in the recovery room. At each level and beginning at the L3-4 disc, 1 cc of 4% lidocaine was injected through the catheter. TA was then assessed for change in pain level as well as improvement in range of motion. She had mild improvement in pain and no improvement in motion at the L3-4 disc, no improvement in pain or motion at the L4-5 disc, and significant (>75%) improvement in pain and motion at the L5-S1 disc (Table 1).

CZ is a 40 yo WF with long-standing CLBP after multiple car accidents who also was referred to us for pre-operative discography. She had lumbar discography at the L3-4, L4-5, and L5-S1 levels per ISIS guidelines. She had concordant 10/10 pain at the L3-4 disc and nonconcordant 9/10 pain at the L4-5 disc and no pain at the L5-S1 disc. Disc morphology and manometry readings are noted in Table 1. Catheters were left in the L3-4 and L4-5 levels (Figure 1) and she had functional testing as described above. She had 50% improvement in her pain and range of motion at the L3-4 disc, but no improvement at the L4-5 disc (Table 1).

Conclusion: Functional discography is a technique that is easily performed, adds no significant morbidity, and provides greater diagnostic utility than conventional discography in evaluating discogenic pain.

References: 1. Frymoyer JW, Cats-Baril WL. An overview of the incidence and costs of low back pain. Orthop Clin N Am 1991;22:263-71. 2. Endres S, Bogduk N. Practice guidelines and protocols: lumbar disc stimulation. Presented at the International Spine Intervention Society 9th Annual Scientific Meeting, Boston, MA, Sept 14-16, 2001, pp56-7. 3. Derby R, Lee SH, Kim BJ, et al. Pressure-controlled lumbar discography in volunteers without low back symptoms. Pain Med 2005;6:213-21. 4. Carragee EJ, Tanner CM, Khurana S, et al. The rates of false-positive lumbar discography in select patients without low back symptoms. Spine 2000;25:1373-80.

Additional File #1:

Disc Opening Max Pain Concordant? Morphology Pressure Pressure (0-10/10) (PSI) (PSI) Patient 1 L2-3 18 75 0 N/A Bi-lobular (TA) L3-4 9 56 10 Yes Fissured L4-5 4 50 10 Yes Fissured L5-S1 5 45 10 Yes Fissured Patient 2 L3-4 2 50 10 Yes Fissured (CZ) L4-5 23 80 9 No Bi-lobular L5-S1 6 100 0 N/A Cotton-ball

Abstract 142

Management of a Patient with Extreme Obesity with Regional Anesthesia: A Case Report

Presenting Author: Sarah J. Laduzenski, M.D. Presenting Author’s City, State: - Gainesville, Florida

Abstract Body: The anesthetic management of severely obese patients can be challenging. We present the management of such a patient who presented for excision of a large left medial thigh mass with regional anesthesia only.

The patient was a 51 year-old 6 feet tall male who weighed 284 kg (626lb; BMI 85). His past medical history included type 2 diabetes, hypertension, asthma, and obstructive sleep apnea, which require CPAP and oxygen at night. He also suffered from pulmonary edema, degenerative joint disease, chronic pain and depression. Orthopnea prevented him totally from lying flat, and he had to remain in an upright position at all times. In addition, his airway was judged as Mallampati 4, he had a small oral cavity with a 3-fingerbreadth mouth opening, and a full beard.

Considering the above, and because the starting time and duration of surgery was impossible to predict a continuous spinal was selected for the anesthetic management, while a left continuous lumbar paravertebral block was selected for post-operative pain control in order to minimize possible perioperative opioid use and to minimize the risk of further respiratory compromize.

The continuous spinal was placed with the patient in the sitting position. A 17G x 15cm Tuohy needle was used through a midline approach at the L3-4 level, which was identified ultrasonographically. Loss of resistance to normal saline was encountered at 12cm, and a dural puncture was made at a depth of 13cm from the skin. A 20G polyamide close tip multi-orifice catheter was then advanced intrathecally through the needle for 6 cm, and secured at the skin at 19cm with Mastisol, Tegaderm and Medipore tape. The lumbar paravertebral block was performed, with the patient remaining in the sitting position, using a 17G x 15cm Touhy needle with nerve stimulation set to deliver a 1.00 mA current, at 300 microseconds and 2 Hz. After identifying the psoas compartment with loss of resistance to air and, after advancing the needle a further 2 cm and eliciting a quadriceps motor response, a 20G x 90 cm stimulating catheter (Stimucath â„¢, Arrow Int, Reading PA) was advanced 5 cm beyond the needle tip, while continuous quadriceps twitches were maintained. The catheter was secured at the skin at 20cm after a negative test dose was performed.

In the operating room, the patient was placed on a specific bariatric operative bed in steep 45-degree reverse Trendelenberg position. He was comfortable in this position and his respiration was normal and supplemented with oxygen by nasal canula only. After intravenous preloading with 1L of Lactated Ringers, a bolus of 2 mL hyperbaric bupivacaine 0.75% was injected through the intrathecal catheter in 0.5 mL increments, while the lumbar paravertebral infusion was initiated with 0.2% ropivacaine at 15ml/hr.

The intraoperative surgical course was uneventful and well-tolerated by the patient. The spinal catheter was removed after surgery, which lasted 3 hours, and the post-operative pain was well-controlled; requiring only a total of 25mg oxycodone and 0.5mg of intravenous hydromorphone. The lumbar paravertebral infusion was discontinued on the fourth postoperative day and the patient was discharged from the hospital the next day weighing 27 Kg (60 lb) lighter.

Abstract 143

Catheter Tip Location and its Influence on Analgesic Requirement After Low Thoracic Epidural Placement

Presenting Author: Meghan Rodes, M.D. Presenting Author’s City, State: - Chicago, Illinois Co-Authors: Mark C. Kendall, M.D. - Northwestern University, Feinberg School of Medici - Chicago, Il Antoun Nader, M.D. - Northwestern University, Feinberg School of Medici - Chicago, Il Robert J. McCarthy, Phar.M.D. - Northwestern University, Feinberg School of Medici - Chicago, Il

Introduction: Catheter tip location may influence the total amount of local anesthetic given to achieve satisfactory analgesia.1 The aim of this prospective double blind study is to determine the catheter tip direction and assess its effect on analgesic consumption and pain scores at 1 and 24 hours following low thoracic epidural placement.

Methods: Following IRB approval, written informed consent was obtained from 20 ASA I-III female patients (>18 y/o) undergoing uterine artery embolization, all receiving thoracic epidural analgesia for postoperative pain relief. Thoracic epidural catheters were placed using loss of resistance to air technique at the intended T10-11 vertebral interspace. All patients received a test dose of lidocaine 1.5% with epinephrine 1:200K 5mL. Epidural catheter tip location was confirmed using fluoroscopy prior to the embolization procedure. Postoperatively all patients had a PCEA consisting of bupivacaine 0.1% with fentanyl 5mcg/mL delivered at a maximum rate of 24mL/hr. Data collected include position of catheter tip relative to insertion site, and postoperative local anesthetic consumption and VAS at 1 and 24 hours.

Results: Epidural catheter tips pointed cephalad and caudad in 8 and 12 subjects respectively. Catheter tip location did not influence analgesic consumption or VAS initially or at 24 hours (table).

Discussion: Based on our study, thoracic epidural catheters are less likely to point in a cephalad direction, unlike lumbar epidural catheters.2 Our preliminary data suggest there is no relationship between catheter tip location and analgesic consumption or pain score in the first 24 hours postoperatively from uterine artery embolization.

References: 1. Reg Anesth 1993 18(5):308-311. 2. Masui 2009 58(6):692-699.

Abstract 144

Comparing Combined Spinal Epidural Anaesthesia vs. Spinal Anaesthesia Using Sufentanil as an Adjunct in High Risk Geriatric Patients for Major Orthopaedic Surgery

Presenting Author: Ravinder D. Bhanot, M.B.B.S.,D.N.B. Presenting Author’s City, State: - Pondicherry , Pondicherry Co-Authors: T.R. Ramachandran, M.D. - Pondicherry Institute of Medical Sciences – Pondicherry , Pondicherry Koshy S. George, D.A., M.D. - Pondicherry Institute of Medical Sciences – Pondicherry , Pondicherry David V. George, M.D. - Pondicherry Institute of Medical Sciences - Pondicherry , Pondicherry Ranjan R.V., D.A., D.N.B. - Pondicherry Institute of Medical Sciences - Pondicherry , Pondicherry

Introduction: Combined spinal epidural anaesthesia (CSEA) is one of the greatest advances in the field of central neuraxial block. It is particularly suitable for high risk geriatric patients as it offers rapid onset, efficacy and safety with minimal chances of toxic effects combined with potential for improving an inadequate block and prolonging duration of analgesia intraoperatively and post operatively. As geriatric patients have reduced cardio respiratory reserve and often have concomitant diseases, it is of paramount importance to maintain the hemodynamic stability. Hence, in this study a lipophilic opiod (sufentanil) was added to hyperbaric bupivacaine and the clinical effects of combined spinal epidural anaesthesia versus spinal anaesthesia were compared in high risk geriatric patients undergoing major orthopaedic procedure.

Methods: Eighty patients aged 65 and above, ASA III were randomly allocated into two equal groups. Group A (n=40) received sequential combined spinal epidural anaesthesia with 1 ml (5 mg) of 0.5% hyperbaric bupivacaine with 5Âµg sufentanil through spinal route, and the expected incompleteness of spinal block was managed with small incremental dose of 0.5% isobaric bupivacaine through epidural catheter, 1.5 to 2 ml for every unblocked segment, to achieve T10 sensory level.

Group B (n=30) received spinal anaesthesia with 2 ml (10 mg) of 0.5% hyperbaric bupivacaine and 5Âµg sufentanil.

Results: Both the groups showed rapid onset, excellent analgesia and good quality motor block. Group A showed a significantly less incidence of hypotension (p< 0.01) along with the provision of prolonging analgesia as compared to group B. The side effects profile was comparable in both the groups, the result of which was, however, not significant.

Discussion: Sequential combined spinal epidural anaesthesia is a safe, effective, reliable technique which offers greater flexibility to provide adequate anesthesia as well as gradual onset of sympathetic block to reduce the haemodynamic side effects, which otherwise prove detrimental in high risk geriatric patients. It also provides the means to prolong analgesia compared to spinal anaesthesia assuring better patient satisfaction and comfort.

References: 1. Wakamatsu M, Katoh H, Kondo U et al. Masui 1991; 40: 1766-69. 2. HaM.D.ani GA, Chohan U, Zubair NA. J Anaesth Clin Pharmacol 2002; 18(2): 163-66.

Abstract 145

Donâ€™t Forget Nerve Blocks for Pain Management in the Intensive Care Unit!

Presenting Author: Jenna A Hansen M.D., M.S. Presenting Author’s City, State: - Stanford, California Co-Authors: Ludwig H Lin M.D. - Stanford University School of Medicine - Stanford, California

Abstract Body: We present here the case of a critically ill patient who developed a necrotizing soft tissue infection following infiltration of a peripheral IV. This patientâ€™s ICU course was further complicated by analgesic requirements that hindered attempts at extubation. This case highlights a unique management option that anesthesia-trained intensivists can offer critically ill patients: regional nerve blocks.

The ICU team was consulted on a 58 year old male with confusion, fever, tachycardia, and hypotension refractory to fluid resuscitation. His ongoing medical problems were extensive, including metastatic cancer, cirrhosis, and renal insufficiency. His left forearm was found to be eccymotic, edematous, and exquisitely tender. Significant erythema was concentrated around an 18G peripheral IV. Progress notes indicated that this was the patientâ€™s only IV, and although â€œfunctioning poorly,â€ was the route for the resuscitative effort. The patientâ€™s floor nurse suspected that the peripheral IV had infiltrated.

In the ICU, initial treatment for hypovolemic and septic shock included fluids, blood products, antibiotics and pressors. Central access, lab and culture data were obtained. Intubation and mechanical ventilation were initiated for impending respiratory failure. Surgeons consulted for the extremity findings suspected necrotizing soft tissue infection, and the patient emergently underwent extensive surgical debridement (see photo). The OR pathology report was consistent with necrotizing fasciitis, with E.Coli positive blood and tissue cultures.

On Post-op days 1-3, though hemodynamically stable and weaned off pressors, the patient had significant opioid requirements for pain from the surgical debridement. He remained intubated as weaning trials failed from low respiratory rates with high tidal volumes, and frequent apneic episodes, all suggesting opioid induced respiratory depression. On Post-op day 4, the ICU team - including two anesthesiologists - placed a left supraclavicular nerve catheter under ultrasound guidance in an effort to wean the patient from opioids while effectively managing his pain. Within minutes of the local anesthetic bolus through the catheter, the patient communicated that his pain was relieved. Opioids were tapered, and the patient was successfully extubated later that same day. On Post-op 5, the patient was transferred out of the ICU, with pain managed via catheter infusion of local anesthetic.

This particular patient presented multiple challenges, from multi-system dysfunction with concomitant necrotizing soft-tissue infection, to extubation and pain management. This case demonstrates several principles of peri-operative and intensive care medicine: First, even routine procedures like peripheral intravenous cannulation have the potential for serious complications. Second, continual careful assessment of the reliability of catheters, tubes, and devices placed by ourselves and others is crucial in both the ICU and the operating room. And finally, don't forget peripheral nerve blocks as a viable and definitive method for pain management in the appropriate critically ill patient! In our case the block allowed us to discontinue opioids and liberate our patient from the ventilator, diverting him from a prolonged ICU course.

Abstract 146

Spinal Cord Stimulator for Chronic Pelvic Pain Secondary to Bladder Pain Syndrome or Interstitial Cystitis

Presenting Author: Methat F. Mikhael, M.D Presenting Author’s City, State: - Long Beach, California Co-Authors: William Barreto, M.D. - Hoag Memeorial Hospital , Pain Medicine Asssociate - Long Beach , CA Hany Nasr, M.D. - Hoag Memeorial Hospital , Pain Medicine Asssociate - Long Beach, CA

Introduction: An international consensus panel sponsored by the Society for Urodynamics and Female Urology was able to generally agree on a definition of bladder pain syndrome/IC: an unpleasant sensation (pain, pressure, discomfort) perceived to be related to the urinary bladder, associated with lower urinary tract symptoms of more than 6 weeks duration, in the absence of infection or other identifiable causes.

Interstitial cystitis (IC) is a clinical syndrome characterized by daytime and nighttime urinary frequency, urgency, and pelvic pain of unknown etiology. Interstitial cystitis has no clear etiology or pathophysiology and undefined diagnostic criteria. Despite considerable research, universally effective treatments do not exist for interstitial cystitis, and therapy usually consists of various supportive, behavioral, and pharmacological measures. Surgical intervention is very rarely indicated. ***

The International Continence Society has coined the term painful bladder syndrome (suprapubic pain with bladder filling associated with increased daytime and nighttime frequency in the absence of proven urinary infection or other obvious pathology) and reserves the diagnosis of interstitial cystitis for patients with characteristic cystoscopic and histologic features of the condition. To clarify the criteria for diagnosis, some clinicians prefer the term painful bladder syndrome or interstitial cystitis, defined as a syndrome of chronic pain, pressure, or discomfort associated with the bladder, usually accompanied by urinary frequency in the absence of any identifiable cause.

Case Report: A seventeen year old female with history of extensive pelvic pain secondary to interstitial cystitis since been diagnosed at eight years old, presents with pelvic pain sharp, stabbing, spastic in nature, constant to the pelvic area and suprapubic area, patient graded her pain as 9-10/10 when severe with a baseline of 5/10 throughout most of the day. At night time patient have frequent painful urgency to urinate with small volume of urine. Failed numerous treatment modalities including chronic pain management, transdermal Fentanyl patch 125mcq every seventy two hours with oral hydromorphone four mg every four hours for breakthrough pain ( total dose around 20 mg in twenty four hours), multiple hypogastric plexus blocks, botulinum toxin type A injections and Interstim therapy by urology. Spinal cord stimulator trail was performed with one Octad lead to the opposite side of the interstim (figure 1) and the permanent implantation was performed with two double percutaneous Octad leads targeting the bilateral lower sacral roots, a retrograde approach were used with complete coverage of the patients symptomatic pelvic area (figure 2).

Discussion: Chronic pelvic pain secondary to Bladder pain syndrome or interstitial cystitis can be controlled with spinal cord stimulator using two double percutaneous Octad leads targeting the bilateral lower sacral roots

***Interstitial Cystitis Author: Eric S Rovner, M.D., Professor, Department of Urology, Medical University of South Carolina Coauthor(s): Colin Murrah Goudelocke, M.D., Fellow in Pelvic Surgery, Department of Urology, Medical University of South Carolina College of Medicine

Abstract 147

Predictors of Phrenic Nerve Paralysis Following Supraclavicular Block

Presenting Author: Thomas Maliakal, M.D. Presenting Author’s City, State: - New York, New York Co-Authors: Daquan Xu, M.B., M.P.H. - St. Luke's-Roosevelt Hospital Center – New York, New York Ali Shariat, M.D. - St. Luke's-Roosevelt Hospital Center - New York, New York Vijay Patel, M.D. - St. Luke's-Roosevelt Hospital Center - New York, New York Jeff Gadsden, M.D., F.R.C.P.C., F.A.N.Z.C.A. - St. Luke's-Roosevelt Hospital Center – New York, New York

Introduction: Phrenic nerve paralysis is a common occurrence after brachial plexus blockade with incidence of nearly 100% with interscalene block. However the predictors of its incidence after supraclavicular block (0 to 67%)1-4 have not being adequately studied. In this ongoing prospective study, we attempted to identify the predictors of phrenic nerve paresis related to technique of supraclavicular block.

Methods: After IRB approval, patients undergoing upper extremity surgery during the period of Nov2009- Jan2010 were recruited. Patients with respiratory impairment (diaphragmatic paresis or COPD) were excluded. Supraclavicular blocks were performed using ultrasound (US) and nerve stimulator guidance. Ultrasound images of ipsilateral diaphragmatic movement before and after block, as well as bedside spirometry were assessed before the block, 10 minutes post-block and 30 minutes after surgery in the PACU. The magnitude of diaphragmatic excursion was measured using the B-mode ultrasound imaging (Fig: A&B). Diaphragmatic movement reduction more than 75% was defined as complete paresis,4 the reduction between 75%-50% was defined as partial paresis, and reduction less 50% was considered no paresis. Information about the needle placement, injection pressure (BSmartâ„¢, Concert Medical, Needham MA), and local anesthetic volume was collected by blinded observers.

Results: Of the 13 patients currently enrolled in the study, 7 patients had complete diaphragmatic paresis, 6 patients had no paresis; no patient showed partial paresis. Age, baseline peak expiratory flow (PEF) and local anesthetic volume were the significant predictors of phrenic nerve paresis (p<0.01, p=0.07, and p=0.07 respectively) (Table: 1). Gender, BMI, injection pressure, needle placement and FEV1/FVC did not show any association with the occurrence of diaphragmatic paralysis.

Discussion: Advanced age, low baseline PEF and large local anesthetic volume are significant predictors of phrenic nerve paresis after supraclavicular block. Due to the small sample size of this pilot study, the effect of each potential predictor on the incidence of diaphragmatic paresis is still uncertain. Match study design will be warranted to evaluate the effect of each potential factor on phrenic nerve paresis in the future.

Fig. A&B Measurements of the excursion of diaphragm during forced expiration (A) and inspiration (B) respectively. Table. 1 Comparisons of demographics, pulmonary function and nerve block data from patients with and without phrenic nerve paresis

References 1. Anaesth Intensive Care 1979; 7: 346-9 2. Anesth Analg 1998; 86: 1239-44 3. Anaesthesia 2001; 56: 352-6 4. Reg Anesth Pain Med 2009; 34: 595-9

Additional File #3: Table: 1. Comparisons of demographics, pulmonary function and nerve block data from patients with and without phrenic nerve paresis

Paresis No paresis P-value (n=7) (n=6) Decreased diaphragmatic movement (%) 90.6 ± 6.6 10.1 ± 21.1 (78.6–100) (0–39.6) Diaphragmatic movement before nerve block (cm) 4.9 ± 1.2 5.0 ± 1.1 0.87 (2.8–6.6) (3.6–6.6) Demographic data

Age (yrs) 62.4 ± 9.3 46.5 ± 7.8 <0.01 (52–78) (31–52) Gender (Female/Male) 6/1 3/3 0.27

2 BMI (kg/m ) 29.1 ± 4.8 31.0 ± 5.4 0.55 (21.6–33.3) (26.6–40.4) Surgical information

Duration of surgery (hrs) 1.3 ± 0.6 1.3 ± 0.2 0.96 (0.5–2.2) (1.1–1.5) Surgical side (left/right) 2/5 2/4 1.00

Nerve block information

Local anesthetic(s) volume (mL) 30.0 ± 9.6 21.7 ± 4.1 0.07 (20.0–40.0) (20.0–30.0) Injection pressure 6/1 5/1 1.00 (>20psi/<15psi) Injection type 3/4 2/4 1.00 (Multiple/Single) Needle Placement 3/4 2/4 1.00 (Outside/inside nerve bundle) Pulmonary Function

PEF before Nerve Block (L/min) 206 ± 82 320 ± 113 0.07 (128–363) (189–495) FEV1/FVC before Nerve Block (%) 87 ± 17 86 ± 16 0.96 (55–99) (65–99) PEF in PACU (L/min) 143 ± 60 232 ± 80 0.10 (92–213) (139–343) FEV1/FVC in PACU (%) 73 ± 35 81 ± 11 0.69 (41–96) (70–94)

Abstract 148

Economic Perspective of Three Common Analgesic Modalities for Total Knee Arthroplasty Presenting Author: Brad M. Taicher, D.O., M.B.A. Presenting Author’s City, State: - Philadelphia, PA Co-Authors: Keith Scarfo, D.O., M.S. - Thomas Jefferson University Hospital - Philadelphia, PA Kishor Gandhi, M.D., M.P.H. - Jefferson Medical College - Philadelphia, PA Eugene R. Viscusi, M.D. - Jefferson Medical College - Philadelphia, PA

Introduction: Following total knee arthroplasty (TKA), patients at our institution undergo a regimented postoperative protocol such that time to planned hospital discharge is similar regardless of analgesic modality. Even in this setting there may be a significant economic impact resulting from shifting between various cost centers. The purpose of this retrospective review was to analyze the economic perspective of three commonly used analgesic modalities; continuous epidural analgesia (CEA), femoral nerve block (FNB), or extended-release epidural morphine (EREM).

Methods: This was an IRB approved retrospective chart review of patients having primary TKA within a two month period. All patients received spinal anesthesia for surgical anesthesia. Patients were divided into three post-operative analgesic study groups (CEA, FNB, or EREM). Epidural dosing and FNB were performed in the PACU after regression of spinal anesthesia. Charts were reviewed for time spent doing spinal/combined spinal epidural (CSE), intra-operative time, time spent in the PACU, common postoperative side effects (nausea, vomiting, pruritus) and length of stay. Statistical analysis of spinal/CSE time, intra-operative time, and time spent in the PACU was performed.

Results: There were no significant demographic differences or common post-operative side effects among the 3 groups. Patients in groups CEA, FNB, or EREM had average spinal/CSE times of 11.8, 9.1 and 13.2 minutes (P=0.05) respectively. (Table 1) Average PACU duration in groups CEA, FNB, or EREM was 272.1, 238.8 and 166.8 minutes respectively. There was significant difference in PACU duration between groups EREM and CEA (P<0.05), but not between EREM and FNB (P=0.195).

Discussion: The cost of OR time is greater than that of PACU, and PACU greater than that of general medical floor (GMF). Since overall time to discharge was unaffected by analgesic modality, the greatest economic impact would come from a shift of the burden between cost centers, either from OR to PACU, or from PACU to GMF. The clinical relevance between the groupsâ€™ spinal/CSE times is minimal (range 9.1 â€“ 13.2 minutes). The slowest time of 13.2 minutes (for EREM) is well below our OR turnover times of 20-30 minutes, likely negating the impact of any time variability between the modalities for all but the first case of the day, where OR readiness is implied. However, the reduction in PACU time of 105.3 minutes for EREM compared to CEA and of 72 minutes for EREM compared to FNB is clinically significant, though of undetermined economic significance. EREM also reduces the need for indwelling catheters and pumps. With wider utilization of EREM, further accrued reduction in PACU times may result in economic benefit. Shorter PACU stays and reduced burden of technology improves the ratio per patient of nursing care and time. Selection of anesthetic and analgesic modality must be tailored to each patientâ€™s needs. When utilized, EREM may reduce the burden on the PACU. A prospective randomized study is warranted.

Additional File #1: Continuous Epidural Femoral Nerve Extended-Release Infusion Block Epidural Morphine Spinal/CSE Time 11.8 min 9.1 min 13.2 min Intra-operative Time 70.25 min 77.1 min 80.95 min PACU Time 272.1 min 238.8 min 166.8 min

Abstract 149

Prevention of Postdural Puncture Headache in Obstetric Patients Having Epidural Catheters for Labor Analgesia: A Systematic Review of Randomized Clinical Trials

Presenting Author: Carol L. Bradbury, M.B.B.S., F.R.C.A. Presenting Author’s City, State: - London, Ontario Co-Authors: Sudha Singh, M.D., F.R.C.P.C. - St. Joseph's Hospital - London, Ontario Philip Jones, M.D., F.R.C.P.C. - St. Joseph's Hospital - London, Ontario Sarah Badder, B.Sc. - St. Joseph's Hospital - London, Ontario Laura I. Wakely, M.D. - St. Joseph's Hospital - London, Ontario

Background: Postdural puncture headache (PDPH) is a reasonably common and frequently debilitating complication of labor epidurals. It effects women at a time when it is particularly important that they are mobile in order to care from their newborn baby. This systematic review will assess: a) the evidence supporting the different Methods which have been suggested to decrease the incidence of accidental dural puncture (ADP), and b) the evidence supporting interventions used to reduce the incidence of PDPH, once ADP has occurred, in pregnant women having epidural catheters for labor analgesia.

Methods: Databases were searched for prospective randomized studies that evaluated methods to avoid ADP and PDPH in pregnant women having epidural catheters for labor analgesia. The terms "postdural puncture headache", "epidural headache", "obstetric", "parturient" and "labor" were searched. Limits imposed were English language, clinical trials, female gender and all adults. Published trials were evaluated using the Jadad score.

Results: Eleven clinical trials were found to investigate the prevention of PDPH. Of these, seven concerned methods of reducing the risk of ADP and the remainder looked at the incidence of headache with a dural puncture.

Techniques which reduced the risk of ADP were: use of lidocaine or a combination of lidocaine and air for loss of resistance as opposed to use of air alone. Methods which didn't significantly influence the incidence of ADP were: use of a combined spinal epidural (CSE) as opposed to epidural analgesia; use of an 18G Special Sprotte epidural needle as opposed to a 17G Tuohy needle; epidural needle bevel orientation; gauge of epidural needle.

Interventions, which in at least one study, resulted in a lower incidence of PDPH once ADP was identified were: administration of epidural morphine; prophylactic epidural blood patch; epidural needle bevel orientation; use of an 18G Special Sprotte epidural needle as opposed to a 17G Tuohy needle. The use of a prophylactic blood patch and orientation of the epidural needle bevel were controversial, yielding conflicting results in different studies. Methods which failed to show a significant difference in the incidence were: use of CSE; medium used for loss of resistance technique.

Conclusions: The risk of ADP during epidural catheter placement in obstetric patients may be reduced by the use of lidocaine, or a combination of lidocaine and air, as the loss of resistance medium. The risk of PDPH after placement of an epidural catheter in pregnant patients may be reduced with epidural morphine injections or the use of a Special Sprotte epidural needle. In general, low manuscript quality weakens the strength of these Conclusions. Further well-conducted, large studies are needed to provide answers to this important clinical problem.

Abstract 150

Dorsal Column Steerability with Dual Parallel Lead Using Dedicated Power Sources: A Computational Model

Presenting Author: Dongchul Lee, Ph.D. Presenting Author’s City, State: - Valencia, CA Co-Authors: Ewan Gillespie, M.B.A. - Boston Scientific Neuromodulation - Valencia, CA

Introduction: In Spinal Cord Stimulation (SCS), two leads are frequently placed in parallel in order to provide flexibility to steer stimulation mediolaterally on the dorsal column and achieve better pain- paresthesia overlap. We studied (1) the ability of dual parallel leads to steer stimulation between adjacent contacts on dual parallel leads using a single source system, and (2) the ability of an SCS device with a dedicated power source for each contact to steer stimulation in an identical lead configuration.

Method: A volume conductor model of a low-thoracic spinal cord with epidurally-positioned cylindrical narrowly-spaced (4mm ctr-ctr) percutaneous leads was created, and the electric field was calculated using ANSYS, a finite element modeling tool. The activating function for 10 um fibers was computed as the second difference of the extracellular potential along the nodes of Ranvier on the nerve fibers in the dorsal column. The volume of activation (VOA) and the central point of the VOA were computed using a predetermined threshold of the activating function. The model compared the field steering results with single source versus dedicated power source systems on dual 8-contact stimulation leads. The model explored (1) the ability of single-source devices to target nerve fibers when shifting stimulation mediolaterally between adjacent contacts, and (2) the ability of a device with dedicated power sources for each contact to target nerve fibers when steering stimulation mediolaterally under identical conditions.

Results: The computational model makes the following predictions: (1) Single source devices that provide a single, shared power source for all contacts (Figure 1A) can target three central points of stimulation when shifting stimulation mediolaterally. Assuming a 2.0 mm separation between leads, that implies a step size of 1.0 mm (2.0 mm with 3 steps) on average. (2) A device with a dedicated power source for each contact (Figure 1B) can target 100 central points laterally in the dorsal column when fractionalizing current in 1% increments, or 10 central points when fractionalizing in 10% increments. Assuming a 2.0 mm separation between leads, that enables a step size of 0.02 mm for 1% steps and 0.2 mm for 10% steps on average.

Conclusions: When steering stimulation mediolaterally between dual leads to achieve better pain- paresthesia overlap, a computational model predicts that a device with a dedicated power source for each contact can target more central points of stimulation on the dorsal column than a single source system (100 vs 3). Therefore, the mean steering step for dedicated power sources is 1 mm for single source systems vs. 0.02 mm for systems using dedicated power source for each contact, implying an approximately 50 times finer targeting resolution for mediolateral steering when using dedicated power sources.

Additional File #1:

Abstract 151

Opioid Use and Abuse in a 21 y.o Male with a Pilocytic Astrocytoma

Presenting Author: Baker A. Mitchell, M.D. Presenting Author’s City, State: - Rochester, New York Co-Authors: Joel Kent, M.D. - University of Rochester - Rochester, New York David Korones, M.D. - University of Rochester - Rochester, New York

Abstract Body: AW is a 21 year old male with a lifelong history of back discomfort, as well as having been diagnosed with attention deficit disorder as a young child and bipolar personality disorder as a teenager. In May of 2008, the patient injured his back at work. He was initially diagnosed with lumbar sprain when the emergency departmentâ€™s x-rays revealed no fractures or dislocations. This was treated conservatively and the patient was started on Percocet at that time.

Over the next 8 months AW had 5 Emergency Department visits for worsening back pain. By December he had lost 60 pounds, developed a significantly kyphotic posture, had severe pain with Valsalva maneuvers, and had developed weakness in his right leg resulting in difficulty ambulating.

An MRI was done on 12/12/2008 which showed an extensive syrinx, swelling of the entire cord and a focal intramedullary tumor at the level of C7 to T3 with suspected subependymal seeding and hemorrhagic components with suspicion of tumor infiltration through the neural foramina into the paraspinal soft tissue. The patient was started on steroids and a T1 laminectomy with biopsy showed pilocytic astrocytoma. A surgical resection was not an option due to the extensive tumor growth. He was treated with chemotherapy and radiation therapy.

The patientâ€™s care was then managed by the pediatric oncology and palliative care services. He was initially on Percocet 5/325, 8 pills per day. Ten months later, he was taking oxycodone SR 80mg TID and oxycodone IR 15mg with use exceeding 12 doses per day. The oncology and palliative care team had a number of concerns which resulted in their referring AW to the multidisciplinary pain clinic: â€¢ His pain complaints persistently escalated despite objective findings that his tumor had responded well to treatments. Other patients with similar pathology were well managed with a fraction of this patientâ€™s opioid requirement AW repeatedly used his opioids above the prescribed guidelines despite counseling. There was concern that opioids were being used inappropriately by AW to manage his dysthymia. AW had a chaotic home life and his parents had an antagonistic relationship with healthcare providers, leaving the patient without any responsible supervision. AW shows a strong reluctance to try any non-opioid strategies to deal with his pain and promote improved functional status. The patientâ€™s disregard for dosing parameters could result in an inadvertent overdose. After careful consideration, his referring team determined that the patient's behavior was most consistent with opioid misuse as opposed to pseudo-addiction. This is a difficult clinical judgment to make. However, the fact that his aberrant behavior showed no signs of improving despite multiple dosage escalations suggested it was not a case of pseudo-addiction. Given the concern for opioid misuse, it was felt that a multidisciplinary pain practice may be the most appropriate setting for him.

We attempted a number of strategies to provide adequate pain control in a safe manner for the patient. Ultimately, despite progression of his disease, the opioid dosage has remained less than his peak consumption.

Abstract 152

Ultrasound Contact Surface Temperatures Vary With Spatial Orientation

Presenting Author: Howard D. Palte, M.B., Ch.B., F.C.A.(SA) Presenting Author’s City, State: - Miami, FL Co-Authors: Steven I. Gayer, M.D., M.B.A. - University of Miami - Miami, FL Izuru Nose, B.S.E.E. - University of Miami - Miami, FL Jean-Marie Parel, Ph.D. - University of Miami - Miami, FL

Background: A commonly held belief is that bedside real-time ultrasound for regional anesthesia is safe, non-invasive and thrifty. However, at maximal output, ultrasonographic equipment has potential to deliver significant quantities of harmful energy to underlying tissues. Deleterious effects may result from either thermal or non-thermal (mechanical) injury. Thermal-mediated dermal and superficial tissue injuries have been highlighted in case reports pertaining to the utilization of ultrasound for lipoplasty. The eye is a sensitive organ and may be particularly susceptible to thermal insult. This bench study investigates the effect of spatial orientation on ultrasonic transducer surface temperatures.

Method: Thermocouples were attached to the Micromaxx P-10 (8-4 MHz) transducer tip (Sonosite, Bothell, WA), its mid-shaft and an observer's palm. After allowing for equilibration between the equipment and ambient room temperature, the transducer was activated in a downward-facing orientation. Continuous temperature recordings were made over a ten minute interval. Following a pause (â‰ˆ20 minutes) for environmental re-equilibration, the experiment was repeated with the transducer in an upward-facing orientation.

Results: The rate of appreciation and final temperature of the transducer surface are greater with the probe in an upward-facing position. Although initial temperature rises were similar for both orientations, a time-dependent difference became evident after two minutes. At ten minutes, the upward-orientated transducer was 2C (40.5C-38.5C) warmer.

Conclusions: The surface temperature of the Micromaxx P-10 transducer rose significantly. This has clinical relevance because ultrasound equipment is infrequently turned off between examinations. There is a temporal-related rise in the transducer surface temperature particularly when it is oriented in an upward-facing direction. Sensitive organs, such as the eye, may be at risk for thermal injury. Ideally, ultrasonic transducers should be turned off between uses. Alternatively, they should be housed facing downwards.

Abstract 153

Total Knee Replacement in a Patient with Myelodysplasia and Bronchectasis

Presenting Author: Kiran Chekka, M.D. Presenting Author’s City, State: - Chicago, Illinois

Introduction: Regional anesthesia may be preferred in a subject with bronchectasis. However, patients with myelodysplastic syndrome and bronchectasis may represent a unique challenge for neuraxial anesthesia due to low platelet counts and concerns for bleeding. We report a case of a subject with myelodysplastic syndrome with low platelet counts and bronchectasis who received peripheral nerve blocks for total knee replacement surgery (TRK).

Case report: An 86 y/o man with a history of myelodysplastic syndrome, chronic bronchectasis, HTN, OSA, type II DM, hyplerlipidemia, Parkinson's disease, and CAD s/p stent presented for a revision of a right total knee arthroplasty. His platelet count at admission was 47 x103/mL and he received 2 U of platelets the day prior to surgery. Pre-operatively the platelet count was 73 x103/mL. The decision was made to proceed with surgery under regional anesthesia. A right sciatic nerve block and femoral nerve block were performed under ultrasound guidance and nerve stimulation. Additionally, an obturator nerve block and lateral femoral cutaneous nerve block were performed under ultrasound guidance. A total of 45ml of 0.5% ropivacaine with epinephrine 1:300K was injected: 15ml for the right sciatic nerve block, 15ml for the femoral nerve block, 10ml for the obturator nerve block, and 5ml for the lateral femoral cutaneous nerve block. Complete sensory analgesia and motor block were achieved. The patient underwent successful revision of total knee replacement with excellent post-operative pain control during his hospital stay.

Discussion: The minimal platelet count at which one can safely administer regional anesthesia remains controversial. Minimal suggested platelet counts based on limited data and expert opinion for neuraxial procedures vary from 80-100 x103/mL. The British Committee for Standards in Haematology have guidelines for platelet transfusions and recommend that the platelet count should be raised to at least 50 x103/mL for lumbar puncture and epidural anesthesia.1 Conservatively, these suggestions have also been adopted for peripheral nerve blocks. In this case we believe that the risk of bleeding from reduced platelets was less than the potential complication of general anesthesia in this patient. In addition, our case demonstrates that peripheral nerve blocks can provide adequate surgical anesthesia in TKA.

References: 1. Br J Haematol 2003:122:10-23

Abstract 154

Influence of Perioperative Pain Treatment in Postoperative Morbility in Femur Fractured Patients Over Sixty-Five Years Old: A Randomized Study

Presenting Author: Raquel Ortiz de la Tabla Gonzalez Srta. Presenting Author’s City, State: - Seville, Spain Co-Authors: Ãngel Martinez Navas D. - Valme Hospital - Seville, Spain Mercedes Echevarra Moreno Sra. - Valme Hospital - Seville, Spain

Objetive: to evaluate the influence of perioperative analgesic treatment in postoperative morbimortality in 6 months after femur fractured patients over 65 years old.

Material and Methods: a prospective, randomized study in patients older than 65 years-old with neck fracture scheudeled for surgical treatment. When patient arrived to hospital the preoperative treatment was started. In group 1, analgesic treatment was intravenous metamizol 2 gr/6h. In group 2 a continuous femoral nerve blockade guided by ultrasonography and nerve stimulation was performed with 0,2% ropivacaina 15 ml followed by an infusion of 0,2% ropivacaine 5 ml/h with bolus of 10 ml/30 minutos. Rescue analgesia was intravenous tramadol 100 mgr with ondasetron 4 mgr. Pain was valorated by a verbal analogic scale (VAS) 0-10.

Results: 49 patients were included: 38 in group 1 (77,6%) and 11 in group 2 (22,4%). Groups were homogeneus in age, sex, weigh, heigh and ASA. The main age was 81,86 +7,51. At the arrival to hospital main VAS was 4,43+2,82 at rest and 8,52+1,59 during movement. In preoperative period VAS was 3,18 + 2,91 at rest and 6,96 + 2,81 during movement. Postoperative VAS was 2,38 + 2,52 at rest and 6 + 2,67 during movement in first 24 hours and 1,88 + 2,33 at rest and 4,23 + 3,17 during movement in 48 hours. Four deaths were registered all in group one, two in 48 postoperative hours and two in the first postoperative month.

Conclusions: VAS was similar in both groups and all deaths registered were in group one, but it should be necesary to continue this study to demostrate the diferences if they exit. 1. N. B. Foss, H. Kehlet. Mortality analysis in hip fracture patients: implications for design of future outcome trials. Br J Anaesth 2005;94(1): 249. 2. JW Roche, RT Wenn, O Sahota, G Morgan. Effect of comorbidities and postoperative complications on mortality after hip fracture in elderly people: prospective observational cohort study. BMJ 2005;331:1374- 9.

Abstract 155

Minimizing SCS Lead Migrations: The â€œAnchor-Loop-Anchorâ€• Approach to Percutaneous Lead Implantation Presenting Author: Mahendra R Sanapati M.D. Presenting Author’s City, State: - Evansville, IN Co-Authors: Francis J. McDonnell M.D. - Deaconess Hospital - Evansville, IN

Introduction: It is well-established that one of the most common technical complications from spinal cord stimulator (SCS) implants is one of percutaneous lead migration, a complication that often results in reduction or loss of parasthesia/pain overlap. Researchers have found that nearly three-fourths of patients undergoing SCS surgery will have some lead migration, and that the most significant migration takes place within the first two weeks of the procedure.1 We report here a novel lead implant technique that has resulted in zero incidents of lead migration, of 24 leads implanted, as measured two weeks post- implant.

Materials & Methods: Twelve patients were implanted with dual-lead percutaneous SCS systems from March to July of 2009. These patients had previously passed an SCS trial for chronic, intractable low- back &/or lower-extremity pain, and were therefore qualified for permanent implant of SCS system. All twenty-four leads were introduced at levels L1/L2 or L2/L3. Final positions of distal tips of leads were between superior portion of T7 vertebral body and superior portion of T12 vertebral body, depending on patient pain patterns and parasthesia coverage needs.

Following are the steps taken to anchor leads, following lumbar cut-down, Tuohy needle insertion, placement of lead in epidural space, and needle removal (i.e. starting with cut down performed and leads in place):

*** See attachment to this submission for outline of technique***

Results: A/P fluoroscopy images of lead positions were taken at implant, and again at two-week follow- up appointments. Images from implant were compared with those taken at two-week follow-up visit. None of the twenty-four leads implanted using this anchoring technique showed any signs of lateral or cephalocaudal migration at two-week post-implant.

Discussion: We believe that this implant technique prevented lead migration primarily due to three factors: 1. The use of medical adhesive to assist in binding lead body to anchor. Without the use of adhesive, body fluid lubricates the area between the anchor and the lead, allowing the lead to move easily. The application of medical adhesive displaces body fluid and increases adhesion between anchor and lead. 2. The use of two anchors per lead, as opposed to the conventional use of one anchor only. We postulate that the use of two anchors â€“ one on either side of strain-relief loop â€“ provides an extra level of protection against potential longitudinal forces on SCS system. 3. The absorption of rostral and/or caudal forces on lead by strain-relief loop.

The benefits to patient, physician, and healthcare system in reducing potential for SCS lead migration are numerous, and include protection of initial investment with therapeutic gains, and also avoidance of revision surgery with associated risk and expense. As this report looks only at two-week post-op migration occurrence rate, it is perhaps premature to suggest that this implant technique can lead to reduction in long-term migration rates. However, we believe these initial results to be quite promising, and warrant further investigation to evaluate long-term efficacy.

Additional File #1:

Surgical Technique Report

Minimizing SCS Lead Migrations: The “Anchor-Loop- Anchor” Approach to Percutaneous Lead Implantation

Mahendra R. Sanapati MD, Advanced Pain Care Clinic PSC, Evansville, Indiana

INTRODUCTION

It is well-established that one of the most common technical complications from spinal cord stimulator (SCS) implants is one of percutaneous lead migration, a complication that often results in reduction or loss of parasthesia/pain overlap. Researchers have found that nearly three-fourths of patients undergoing SCS surgery will have some lead migration, and that the most significant migration takes place within the first two weeks of the procedure.1 We report here a novel lead implant technique that has resulted in zero incidents of lead migration, of 24 leads implanted, as measured two weeks post-implant.

MATERIALS & METHODS

Twelve patients were implanted with dual-lead percutaneous SCS systems from March to July of 2009. These patients had previously passed an SCS trial for chronic, intractable low-back &/or lower-extremity pain, and were therefore qualified for permanent implant of SCS system. All twenty-four leads were introduced at levels L1/L2 or L2/L3. Final positions of distal tips of leads were between superior portion of T7 vertebral body and superior portion of T12 vertebral body, depending on patient pain patterns and parasthesia coverage needs.

1) A small quantity (~0.3 cm3 – a dollop roughly the size of Figure 1 a grain of rice) of silicone elastomer medical adhesive (Type A Sterile) was placed on the lead body at the point at which lead enters supraspinous ligament/dorsal fascia.

2) A 2.3cm silicone suture sleeve (anchor) was inserted over the proximal tip of the lead, and the anchor was then slid down to the insertion point of the lead – sliding up to and over the adhesive applied in Step 1.

3) The anchor was then sutured to surrounding tissue through two anchor holes using 2-0 non-absorbable suture.

4) The anchor was then further ligated to the lead by tying a 2-0 non-absorbable suture around the center groove of the anchor circumferentially.

5) A ~4 cm diameter strain relief loop was then created proximal to the 2.3 cm anchor.

6) A second dollop of adhesive was applied to lead body ~1cm proximal to base of strain relief loop.

7) A 1 cm silicone anchor was inserted over the proximal tip of the lead and slid up to and over location of second adhesive application.

8) Anchor was sutured to supraspinous ligament/dorsal fascia as outlined in Steps 3 & 4.

9) Process was repeated for 2nd lead. (Note: Figure 1 shows this process halfway through the securing of second lead). Strain relief loops were then tucked into incision – sometimes requiring a minimal amount of blunt dissection lateral to incision.

IPG pocket was then created and leads were tunneled from midline incision to pocket. Leads were connected to IPG, IPG was tucked into pocket, and both incisions were then closed.

Figure 2 diagrams the mechanical layout of anchoring technique. Diagram not to scale.

RESULTS

A/P fluoroscopy images of lead positions were taken at implant, and again at two-week follow-up appointments. Images from implant were compared with those taken at two-week follow-up visit. None of the twenty-four leads implanted using this anchoring technique showed any signs of lateral or cephalocaudal migration at two-week post-implant.

DISCUSSION

We believe that this implant technique prevented lead migration primarily due to three factors: 1) The use of medical adhesive to assist in binding lead body to anchor. Without the use of adhesive, body fluid lubricates the area between the anchor and the lead, allowing the lead to move easily.2 The application of medical adhesive displaces body fluid and increases adhesion between anchor and lead. 2) The use of two anchors per lead, as opposed to the conventional use of one anchor only. We postulate that the use of two anchors – one on either side of strain-relief loop – provides an extra level of protection against potential longitudinal forces on SCS system. 3) The absorption of rostral and/or caudal forces on lead by strain-relief loop. In the event that one or the other anchor used in this implant technique becomes dislodged or otherwise ineffective, the use of a strain-relief loop provides an additional buffer to system against potential effects of longitudinal forces, further minimizing lead migration potential.

1 Heller, A., (2009). Lead Migration After SCS – A „Universal Problem‟ Pain Medicine News, Volume 7/Number 4, Pages 1 & 11. 2 Renard, V.M., North, R.B., (2006). Prevention of percutaneous electrode migration in spinal cord stimulation by a modification of the standard implantation technique. J Neurosurg Spine. 2006 Apr;4(4):300- 3.

Abstract 156

Dynamic Hip Screw Fixation of a Femoral Neck Fracture in an Elderly Patient With Severe Aortic Stenosis Under Femoral Nerve Block and Remifentanil Infusion

Presenting Author: Marc T. Stalder, M.D. Presenting Author’s City, State: - London, Ontario Co-Authors: Paidrig M. Armstrong, M.D. - U.W.O. - London, Ontario

Introduction: The incidence of proximal femur fractures, as well as associated hospital length of stay and mortality, increases exponentially with advancing age (1). Many elderly patients whom sustain femoral neck fractures are often dehydrated, malnourished and have significant co-morbidities upon presentation (2). While there are numerous options for the anesthetic management of these patients, it appears that spinal anesthesia is the technique preferred by many anesthesiologists (3). However, in patients with aortic stenosis (AS) such a technique must be considered cautiously (4).

Literature documenting the use of femoral nerve block (FNB) for dynamic hip screw (DHS) is limited primarily to its role in peri-operative pain management (5). We would therefore like to report our management of an elderly patient presenting for emergency DHS surgery.

Case: An 89 year old male presented for DHS fixation after sustaining a fracture of his right femoral neck. He had been admitted with congestive heart failure and had fallen while in hospital four days previously. He had documented poor left ventricle (LV) function (EF 20-25%) and severe AS with an aortic valve area (AVA) of 0.41cm2 and peak gradient of 55-65mm Hg. He was dialysis dependent and had been dialyzed earlier that day.

A left radial arterial line was inserted under local anesthesia for monitoring. A FNB was performed under combined ultrasound and peripheral nerve stimulator (PNS) guidance. A total of 20 ml of 1.5% plain lidocaine and 12 mL of 0.5% ropivicaine were used. Supplemental local infiltration of 1% lidocaine and a low dose intravenous remifentanil infusion (0.03mcg.kg/min) were administered during surgery. Hemodynamics were stable throughout and the patientâ€™s major complaint was discomfort in his non- operative hip.

Discussion: We describe an 89 year old male patient with severe AS and significant LV dysfunction who successfully underwent DHS fixation of a fractured right hip under FNB. FNB alone is perhaps not the anesthetic technique of choice as it does not provide complete coverage of the hip joint. However, considering the potential disturbances of both spinal and general anesthesia in this patient due to his AS and poor LV function we chose to proceed with a FNB as the primary anesthetic. Other options include epidural anesthesia, or other regional techniques such lumbar plexus block and sciatic nerve block.

Conclusion: A single shot femoral nerve block is a viable alternative to general or neuraxial anesthesia for hip surgery in patients with severe aortic stenosis. When anesthesiologists are presented with similar high risk, elderly patients this technique is an option that provides good surgical anesthesia and stable hemodynamics.

References: 1). CMAJ 1997; 157 (10):1357-1363 2) J Bone Joint Surg BR 2002; 84B: Supp_1 3) Anesthesia 2008 Sep;63 (9): 250-258 4) CJA 2002;49(9): 946-949 5) Am J Emerg Med. 2010 Jan;28(1):76-81

Abstract 157

Bilateral Continous Infraclavicular Block for Analgesia After Bilateral Hand Degloving Injury Presenting Author: Aysin, M.D., Agritmis Specialist Presenting Author’s City, State: - Kocaeli, Turkey Co-Authors: Semih, M.D., Takka Specialist - Anadolu Health Center - Kocaeli, Turkey Fatma M.D., Yurdakul Specialist - Anadolu Health Center - Kocaeli, Turkey

Abstract Body: A 27-yr-old man (64 kg, 174 cm, ASA I) with bilateral hand degloving injury was admitted to our hospital after an industrial accident.The patient who had total degloving of both hands, caused by a roller injury, left hand up to the distal forearm level and right hand up to the proximal forearm level. He had minimal pneumothorax and liver laceration after blunt thoraco-abdominal trauma.The man has never been to a hospital before, is normally fit and well, and is on no regular medications. The initial laboratory analysis, including a CBC count and a basic metabolic panel, was within normal limits.On physical examination, the patient had vital signs, including a heart rate of 120 bpm (sinus rhythm), a respiratory rate of 28 breaths/min, a blood pressure of 110/60 mmHg, and a pulse oximetry reading showing an oxygen saturation of 95 % while breathing room air. He was agitated and uncomfortable. The patient was noted to have a moderately increased work of breathing, so he was intubated,CVP, arterial cannula and bladder catheter were inserted in ICU. The patient was fluid-resuscitated with i.v crystalloids, colloids and blood products. The patient was admitted to OR after the maintenance of adequate circulating blood volume. Monitoring included a continuous three-lead EKG,invasive blood pressure measurement,CVP ,urinay output and sPO2. The arms were abducted to 90Â°. The entire upper chest was prepared with Betadine and draped in a single field. The deltopectoral areas on both sides were scanned for the optimal image with 5-10-MHz Linear probe (Sonoline G50), and the outline of the probe was marked at each site. A 20- gauge catheter (Pajung PlexlongSono) was placed between the axillary artery and the posterior cord.The procedure was repeated on the opposite side using the same technique. Catheters were subcutaneously tunneled over 5 cm through an 18-gauge intravenous cannula and fixed to the skin with adhesive tape (Tegaderm). Continuous perfusion of 0.2% bupivacaine was started rate of 5 ml/h on each side 10 ml/h via the infraclavicular catheters by two perfusion pumps durig the operation. Surgery was uneventful and lasted 9 hours. He was transferred to ICU.After surgery, 0.2% bupivacaine infusion was initiated using a portable, programmable, disposable, electronic infusion pump (Hospira Gemstar PCA machine). The pumps were programmed by investigators and the infusion basal rate (5 ml/h) and patient controlled bolus dose volume (5 ml) with a 20 min lock-out. In replantation surgery, the sympatholytic effects of CPNB improve the perfusion of the reattached limb, reduce perioperative blood loss, and support frequent returns to the operating room and postoperative rehabilitation.Several minor operations, including interdigitation, defatting, and the formation of palmar and digital creases, were required to obtain the final appearance and function of the hand. Because of the likelihood of multiple operations and the adverse effects of opioids, we tried continuous peripheral nerve block for primary pain management on day 20.In conclusion, continuous infraclavicular brachial block is a potentially effective treatment modality for acute pain control for hand , forearm major surgery.

Abstract 158

The utility of regional anesthesia in developing countries Presenting Author: Melany K. Grogan, M.D. Presenting Author’s City, State: - Seattle, Wa Co-Authors: Ryan Jense, M.D. - University of Washington - Seattle, Wa

Introduction: In March 2009, we traveled as part of an orthopedic medical aid trip with Healing the Children to Juticalpa, Honduras. We anesthetized twelve pediatric and young adult patients, otherwise healthy, with isolated orthopedic problems. Our major peri-operative concerns for these patients were PONV and post-operative pain control. Additionally, post-operative monitoring was a major concern. Despite the hospital being the main care center for the state of Olancho, its resources were very limited. Of relevance to our patients, once on the inpatient wards, there was no nursing care, monitoring by trained medical personnel, or ability to dose medications intravenously. Patients family members provided their inpatient care, monitoring, and oral medication dosing.

In order to address these issues, all twelve patients underwent regional anesthesia procedures to decrease their post-operative pain, thus limiting opioid usage and its accompanying adverse effects, of particular concern in this situation, PONV and respiratory depression.

Methods: All patients received a regional block prior to the surgery (but after induction of anesthesia for the pediatric patients). All blocks were performed with 0.5% bupivicaine with 1:200k of epinephrine under ultrasound guidance with doses below 2mg/kg bupivicaine to avoid possible local anesthetic toxicity. We had no adverse events associated with the blocks.

All patients received a prophylactic dose of ondansetron (0.1mg/kg up to 4mg) prior to emergence.

Patients parents were given oral opioids and instructions on when and how much to dose their children. Patients received hydrocodone, oxycodone or codeine. The amounts of oral opioids were converted into equivalent doses of oxycodone for comparison.

Results: During the first 24 hours post-operatively, half of the patients did not receive any opioids. The other six patients received, on average 0.185 mg/kg (range 0.1-0.24mg/kg) of an oxycodone equivalent.

No patients experienced PONV.

Conclusions: Regional anesthesia provides a safe, effective anesthetic option for patients undergoing surgery in developing countries where access to postoperative care is lacking. Half of patients required no post-op opioids, with the other half averaging 0.18 mg/kg of oxycodone within the first 24 hours. In our case series, the incidence of both PONV and respiratory depression was zero.

This experience can be translated to the outpatient setting in developed countries as well, where the similar postoperative concerns exist.

Abstract 159

Neck Mass Diagnosed During Intescalene

Presenting Author: Nelson Nicolas Algarra, M.D. Presenting Author’s City, State: - Lansing, Kansas

Introduction: Neck masses usually present with complains of dyspaghia, dysphonia and other mass effect in the small area of the neck. A midline mass with homogeneous appearance is usually a thyroid adenoma with possible cancerous origin.

Case Report: This is a 58 year old male who presented to our institution for shoulder surgery due to pain and rotator cuff damage. He was consented for post operative intescalene block for pain control. In the PACU, the patient was seen and after neurovascular assessment of the left arm, the ultrasound probe was placed on his neck to prepare for the block. During examination of the neck with ultrasound a large mass was noted on right side. The mass appeared to have a necrotic center and a well defined capsule, it extended below the clavicle inferiorly, The mass was closely associated with the carotid and it displaced the carotid and Internal Jugular lateral and posterior. Examination of the contra lateral neck appears normal to palpation and to ultrasound exam. The thyroid function was evaluated with TSH and T4 with normal results. The patient was sent for ultrasound and head and neck MRI and revealed a large mass with necrotic center. After resection the mass was found to be thyroid cancer

Pictures to follow

Abstract 160

Greater Occipital Nerve Block: Extra-Foraminal Sonoanatomy

Presenting Author: Thomas B. Clark, DC, RVT Presenting Author’s City, State: - Vista, CA

The Greater Occipital Nerve (GON) can be sonographically localized by consistent identifiable musculature and boney landmarks. Under ultrasound guidance the GON can be identified as is exits the C2 neural foramen and followed both transversely as well as longitudinally as it turns posteriorly and superiorly over the rectus capitus inferior oblique. With the GON well localized, the radicular and suboccipital arteries adjacent the GON are then identified using low flow Doppler.

The significants of this study is demonstrating the GON extra-foraminally not only in transverse but in longitudinal. Longitudinally the GON Block can then be inspected to confirm proper bolus flow from the extra-foraminal peri-neural location toward the occiput. This advanced sonoanatomy can not only improve the chances of a "complete" block but reduce the chance of retrograde peri-neural anesthetic flow and/or inadvertent vascular inject.

Abstract 161

Ultrasound-Guided Retrobulbar Block is Feasible and Safe in Patients Undergoing Vitrectomy Surgery

Presenting Author: Sean DaSilva, M.D. Presenting Author’s City, State: - London, Ontario Co-Authors: Sugantha Ganapathy, FRCPC - University Western Ontario - London, Ontario Maxim Rachinsky, M.D. - University Western Ontario - London, Ontario

Introduction: The retrobulbar block, described by Atkinson in 1963, is a unique method of providing complete surgical anesthesia and akinesia of the eye and orbit. Though it is a widely accepted anesthetic block for opthalmic surgery, its routine use has declined, perhaps due to such rare and devastating complications as intra-optic nerve injection and blindness, subarachnoid injection and loss of consciousness, brainstem anesthesia, and possible death. In 2008, Luyet et al. were able to demonstrate dye spread into the retrobulbar space of cadavers with both ultrasound and CT scans, however, the study was criticized, in part, for not adhering to industry approved standards of its ultrasound equipment for human eye scans. The purpose of this study is to demonstrate the potential benefits of an industry approved ultrasound device in patients undergoing eye surgery under retrobulbar blockade.

Methods: Patients will be consented to participate in an ultrasound guided retrobulbar block, prior to vitrectomy surgery at our institution. Patients will be excluded for opthalmic contraindications (e.g., high myopia), increased intraocular pressure, patient refusal, and eye infection. The anesthesiologist will place the opthalmic ultrasound probe (L25X/13-6 transducer and M-TURBO Sonosite ultrasound machine; approved by Health Canada for ophthalmic use, MI â‰¤ 0.23; TI â‰¤ 1.0 ) with ophthalmic gel to visualize orbital structures prior to, and during performance of the block. The block will be performed by the consultant opthalmologist by as per routine technique of prior blockade of the ipsilateral 7th cranial nerve by the modified O'Brien's approach, followed by landmark Atkinson's approach to the retrobulbar block. A total of 3 ml of 1:1 mixture of 0.75% bupivicaine and 2% lidocaine will be injected intraconally.

Results: Data is yet to be announced (TBA) and includes a prescan description of eye globe and orbit anatomy, final distance from needle tip to opthalmic nerve, the ability to visualize local anesthetic spread, and overall patient satisfaction of the ultrasound guided technique.

Discussion: Ultrasound has the potential to improve the safety of the retrobulbar block by early identification of abnormal eye anatomy, as well as direct visualization of both the needle tip and spread of local anesthetic.

This study is yet to be underway and sample data shown is TBA (to be announced); included is a sample image of a volunteer's eye to demonstrate some of the structures of interest under ultrasound.

This pilot study will be limited to twenty patients. It is our hope that this data will be used for further studies to compare the classic landmark and ultrasound guided techniques, in terms of reducing the incidence of rare and serious complications associated with the retrobulbar block.

Additional File #1: Figure A: Ultrasound image of eye globe

Abstract 162

Total Intravenous Anesthesia for Classical Cesarean Section in a patient with Osteogenesis Imperfecta

Presenting Author: Abhinava S Madamangalam MBBS, M.D. Presenting Author’s City, State: - Oklahoma City, OK Co-Authors: Jamie C Koch M.D. - University of Oklahoma Health Sciences Center - Oklahoma City, OK

Abstract Body: Osteogenesis Imperfecta (OI) is a systemic inherited disorder with severe and milder forms, all sharing the key characteristic of high degrees of bone fragility and frequent fractures from minimal or even no trauma. Other common findings are blue sclera, hyper mobile joints, abnormally brittle teeth, progressive hearing loss and short stature. Some forms of OI allow for survival to adulthood and pregnancies are reported in such patients, as fertility is unaffected in OI. Estimated to occur once in about 25,000 pregnancies, many may require preterm cesarean section due maternal respiratory compromise or bony morbidity in mother or in the fetus. We present our approach to a 20 year old wheelchair bound OI primigravida with a 32 week pregnancy and an antenatal diagnosis of fetal OI.

Our patient carried a diagnosis of OI Type I and as did her mother. She had had multiple UE and LE bone fracture repairs, rib fractures and spine surgery for progressive kyphoscoliosis and suffered from some conductive hearing loss. Advancing pregnancy had caused a rib fracture and implanted rods in her back to work loose. She had been medically stable during the pregnancy with respect to respiratory and cardiovascular parameters.

Her singleton fetus at 32 weeks gestation was in cephalic presentation and estimated at 1980 grams by ultrasound. Level II sonographic fetal survey indicated a shortened left femur, left ulna, and a misshapen skull. Fetal heart showed endocardial cushion defects, all indicative of fetal OI. Maternal history of having cardiac arrhythmias during spine surgery requiring defibrillation to revive her raised the suspicion of MH. She received parenteral steroids to help with fetal lung maturity prior to cesarean section and was on routine prenatal vitamins. She was deemed to have a class I airway, with a previous history of easy intubations.

We chose to monitor her blood pressure with a cuff and to use invasive monitoring only in case of any observed instability. Owing to her refusal of a regional anesthetic we performed a general endotracheal anesthetic with appropriate aspiration prophylaxis, cricoid pressure and rapid sequence induction with propofol and intubated her using a styletted 6.0 ETT with manual inline stabilization. We used rocuronium for muscle relaxation for intubation.

Total intravenous anesthesia with propofol was used for maintenance anesthesia following her history of significant intra-operative arrhythmia. Her temperature was monitored continuously. A female infant of 1970 grams was delivered via a classical C/S to minimize fetal trauma and handed over to neonatology. APGARS were 7/4/8. The C/S concluded uneventfully. Her post operative course was routine with pain control via an IV PCA. She was discharged home on the 4th post operative day. The infant continued to be a NICU resident and was doing well when she visited her for her post-partum follow up.

Such patients are best managed by a multidisciplinary team approach that takes into consideration the pathophysiology of mother and that of the potentially affected neonate. Careful planning and weighing the advantages of regional versus general anesthesia will greatly assist in optimal care being delivered to mother and newborn.

Abstract 163

Failed Spinal Anesthesia Shortly After a Preemptive Blood Patch

Presenting Author: Stefan Hariskov, M.D. Presenting Author’s City, State: - Boston, MA Co-Authors: Dragos Diaconescu, M.D. - Tufts Medical Center - Boston, MA Pei-Shan Zhao, M.D. - Tufts Medical Center - Boston, MA

Abstract Body: The success rate of neuraxial anesthesia performed after an epidural blood patch (EBP) is unclear. Retrospective studies on epidural anesthesia in patients with accidental dural puncture followed by an EBP have shown conflicting results. We report a case of failed spinal soon after a preemptive EBP.

Case: The patient is a healthy 33-year-old G3P2 parturient who presented to the labor and delivery floor at 29 weeks gestational age with pre-term labor. The epidural anesthesia was performed in the sitting position, using a 17 ga Tuohy epidural needle and loss of resistance to saline technique. The first attempt was made at L3-L4 and resulted in intravascular placement. The catheter was removed and a second attempt at L4-L5 resulted in an accidental dural puncture. The needle was withdrawn. The catheter was placed on a third attempt at L2-L3 and was followed by a negative test dose. The patient had an adequate bilateral sensory block on an epidural mix of Bupivacaine 0.1%, Fentanyl 2 mcg/ml infused at 8 ml/h. After delivery, decision was made to perform a preemptive epidural blood patch, given her prior history of postdural puncture headache as well as the recent dural puncture. Twenty ml of blood were drawn in a sterile manner and injected in the epidural space through the catheter without any discomfort reported by the patient. The following morning (18hrs after the EBP), the patient was scheduled for a tubal ligation. Spinal was performed in the sitting position at L3-L4 using a 25 ga Whitacre needle. The intrathecal space was localized at the first attempt and there was clear cerebrospinal fluid (CSF) return. A mixture of 1.6 ml hyperbaric Bupivacaine 0.75%, 200 mcg of Epinephrine and 10 mcg Fentanyl was slowly injected. Positive CSF aspiration during and at the end of the injection confirmed the intrathecal position of the tip of the needle. The patient was then placed in the supine position. Fifteen minutes later, no sensory block was noted on the patient's abdomen. An exam revealed mild patchy sensory deficits on the anterior aspect of the thighs and no motor block in the lower extremities. Decision was then made to induce general endotracheal anesthesia and the patient had an uneventful surgery.

Discussion: The implications of an EBP for subsequent neuraxial anesthesia are controversial. It is conceivable that the presence of coagulated blood could impede the spread of local anesthetic in the epidural space for several hours after EBP. Accidental dural puncture or EBP can cause disruption of the dural/arachnoid interface. Subdural space injection was shown to occur when pressure exerted by mechanical forces (air, fluid injection, etc.) disrupts the cellular junctions between the two meningeal layers.(1) Consequently, injection in subdural space or the epidural space could be the mechanism for our spinal anesthetic failure. Local anesthetic leak through the dural hole, while least likely, could be yet another explanation for our failed spinal anesthetic. Although a single previous report of a successful spinal anesthesia exists after a recent EBP, we feel that the anesthesia provider should be aware and expect possible spinal anesthetic failure after a recent EBP.(2)

1. Reina et al. A&A 2002. 2. Loughrey et al. A&A 2003.

Abstract 164

Intradiscal Contrast Spread During Transforaminal Epidural Steroid Injection

Presenting Author: Tamer Elbaz M.D. Presenting Author’s City, State: - NYC, NY Co-Authors: Stacy Serebintsky M.D. - St. Lukes Roosevelt Hospital Center - NYC, NY Ariel Fenig M.D. - St. Lukes Roosevelt Hospital Center - NYC, NY Ronny Hertz M.D., D.D.S. - St. Lukes Roosevelt Hospital Center - NYC, NY

Abstract Body: 38 year-old male, otherwise healthy, presents with low back pain and left lower extremity radiculopathy. On physical exam, patient did not have any sensory or motor deficits, straight leg raise was negative bilaterally, and Patrickâ€™s test was positive for left hip pain. MRI demonstrated an extruded left L4-5 foraminal disk herniation with mass effect on the left L4 nerve root, as well as smaller disk herniations at L2-3 and L5-S1. The patient was offered a transforminal epidural steroid injection at L4-5 and he agreed to proceed. The procedure was performed under fluoroscopic guidance using a 22 gauge 5 inch spinal needle. The use of real-time and continuous imaging was employed to verify appropriate epidural spread. When the spinal needle was in appropriate position, as confirmed with anterior-posterior and lateral views, the contrast was injected epidurally through the transforaminal approach and demonstrated intradiscal spread. The spinal needle was withdrawn about 1-2 mm and contrast was once again injected to demonstrate an epidurogram.

Intradiscal spread is one potential complication of transforaminal epidural steroid injection. However, very few case reports have been reported. On extensive literature search, we found only two reported cases of intradiscal spread of contrast with transforaminal injections (Vallejo et al 2007). The first reported case in the United States was in a 72 year-old male, published in 2005 (Finn 2005). Discographic spread of contrast on fluoroscopy implies that despite proper placement of the needle in the foramen, the spinal needle penetrated the annulus fibrosis with resultant spread into the nucleus pulposis. This is possible with far lateral disc herniations. It is important to be aware of all possible complications so that they can be appropriately treated or the procedure be abandoned if necessary. Should the rare complication of intradiscal injection occur, the patient can develop discitis and should be treated prophylactically with intravenous antibiotics. (Vallejo et al 2007). In our experience, discitis did not occur after two episodes of intradiscal spread of contrast during transforaminal epidural steroid injections without prophylactic antibiotics. This further emphasizes the need for fluoroscopy and contrast enhancement whenever performing injections from the transforaminal approach.

References Candido KD, Raghavendra MS, Chinthagada M, Badiee S, Trepashko DW: A Prospective Evaluation of Iodinated Contrast Flow Patterns with Fluoroscopically Guided Lumbar Epidural Steroid Injections: The Lateral Parasagittal Interlaminar Epidural Approach Versus the Transformainal Epidural Approach. Anesthesia and Analgesia - 01-FEB-2008; 106(2): 638-44, table of contents

Vallejo R, Benyamin R, Yousuf N, Kramer J: Intradiscal Intravasation of Contrast During a Transforaminal Epidural Injection. Pain Practice - Volume 7, Issue 3 (September 2007)

Benedetti EM, Siriwetchadarak R, Stanec J, Rosenquist RW: Epidural steroid injections: Complications and management. Techniques in Regional Anesthesia & Pain Management - Volume 13, Issue 4 (October 2009)

Finn K.P., Case J.L.: Disk entry: A complication of transforaminal epidural injectionâ€”A case report. Arch Phys Med Rehabil 86. 1489-1491.2005

Manchikanti L, Cash KA, Pampati V, Damron KS, McManus CD. Evaluation of lumbar transforaminal epidural injections with needle placement and contrast flow patterns: a prospective, descriptive report. Pain Physician. 01- Apr 2004;7(2):217â€“223.

Abstract 165

Pneumothorax After an Ultrasound-Guided Supraclavicular Block

Presenting Author: Vanny Le, M.D. Presenting Author’s City, State: - Newark, NJ Co-Authors: Ross Moore, M.D. - UM.D.NJ-New Jersey Medical School - Newark, NJ Da Wang, M.D. - UM.D.NJ-New Jersey Medical School - Newark, NJ

Abstract Body: The supraclavicular nerve block is a common block used for surgical anesthesia of the brachial plexus because of the ease of execution, rapid onset and consistent sensory coverage. However, it fell out of favor after being associated with an unacceptably high rate of pneumothorax of 0.5% to 6.0%.1, 2 With the recent Introduction of ultrasound-guided techniques, the supraclavicular block has become more accepted due its ability to identify the first rib and pleura.2, 3 Although the ultrasound has given operators more comfort in performing the block, increased safety with ultrasound is a misnomer. There are an inadequate number of studies and few low-powered reports that demonstrate fewer complications with an ultrasound-guided technique versus nerve stimulation.4

We report a case of clinically significant pneumothorax after an ultrasound-guided supraclavicular nerve block that has not been previously reported. A 59 year-old female with a past medical history of mild intermittent asthma, long-term smoker of approximately 40 pack years, osteoporosis, and morbid obesity (BMI 36), presented to the same day surgery suite. She had avascular necrosis of her left lunate bone or Kienbockâ€™s disease, requiring an osteotomy of her left wrist. A supraclavicular block was chosen for surgical anesthesia and was performed by a CA-3 resident under supervision. The left brachial plexus was identified under ultrasound guidance and a 21 gauge, 4 inch insulated block needle was advanced in a long axis view in a lateral-to-medial direction. Needle movement was observed in real-time. Satisfactory position was achieved after full visualization of the length of needle was seen with the tip under the nerve cluster. Additional confirmation was obtained using nerve stimulation with a motor response at 0.5 mA. After negative aspiration, approximately 5 mL of local anesthetic was injected when the patient began to cough violently. Control of the needle position was lost by the resident. The case was subsequently cancelled and when the patient complained of pleuritic chest pain, a 40% pneumothorax was seen on chest x-ray.

The important element of this case emphasizes that ultrasound techniques do not eliminate the potential complications of the supraclavicular block. A definitive conclusion regarding the improved safety of ultrasound guided regional anesthesia over nerve stimulation cannot be determined until additional large, well-powered, prospective randomized controlled trials are done.4, 5

1 Brown DL, Cahill DR, Bridenbaugh LD. Supraclavicular nerve block: anatomic analysis of a method to prevent pneumothorax. Anesth Analg. 1993; 76: 530-4. 2 Kapral S, Krafft P, Eibenberger K, Fitzgerald R, Gosch M, Weinstabl C. Ultrasound-guided supraclavicular approach for regional anesthesia of the brachial plexus. Anesth Analg. 1994; 78: 507-13. 3 Chan VW, Perlas A, Rawson R, Odukoya O. Ultrasound-guided supraclavicular brachial plexus block. Anesth Analg. 2003; 97: 1514-7. 4 Klaastad O, Sauter AR, Dodgson MS. Brachial plexus block with or without ultrasound guidance. Curr Opin Anaesthesiol. 2009; 22: 655-60.

Abstract 166

Long Term Safety, Tolerability and Efficacy of Repeat Cryoanalgesia: A Case Report

Presenting Author: Douglas L Constant M.D. Presenting Author’s City, State: - Brookline , MA Co-Authors: Joystana Nagda M.D. - Harvard Medical School, Beth Israel Deaconess Medi – Brookline, MA

Key words: Cryoablation, Neuroma

Abstract: The use of cryoanalgesia in the management of chronic pain syndromes has gained acceptance and popularity across several medical specialties. It is an outpatient procedure with minimal adverse effects which patients find acceptable as an alternative to pharmacologic pain killers.1 We present a patient who has undergone repeated cryotherapy ablation since 1991 for her chronic painful scar neuroma.

Introduction: The use of cryoanalgesia in the management of chronic pain syndromes has gained acceptance and popularity across several medical specialties. Its use for relief of painful neuromas is just one indication; however, there is a paucity of literature that discusses the application of cryoanalgesia therapy for this particular condition.

Case Report: A 48-yr-old female with a long history of painful ulnar nerve damage, stemming from a work related injury in 1986 presented in our pain clinic with chronic elbow pain. Her pain initially occurred at work while pronating and supinating her arm turning a screw driver. Her surgical history was significant for four radial nerve decompressive surgeries before her initial contact with our pain clinic. She underwent a series of injections (trigger point injections and stellate ganglion blocks resulting in sympathectomy), intravenous guanethidine therapy, TENS therapy and cognitive behavioral therapy. She failed injection with steroids and local anesthetic, splinting, physical therapy and anti-inflammatory drugs. She tried Tegretol, Xanax, Feldene, Doxepin, Prozac, Percocet, Darvocet, Clonidine patch, Fentanyl patch, various other non-steroidal anti-inflammatory drugs, and Inderal all without sufficient relief of her discomfort. Despite this aggressive multimodal approach, she still reported her pain as a 10/10 on the Visual Analogue Scale (VAS). She underwent her first cryotherapy ablation of the scar neuroma on May 30th, 1991. Post-procedure day number one she reported her VAS score as 0/10, which lasted for several months. She has undergone a total of 32 cryoablation therapy treatments at our pain clinic. The interval time between these treatments has steadily increased over the past 18 years. She initially had cryoablation therapy treatments every 3 months back in the early 1990s. The interval has now been extended to approximately 9-13 months between treatments. Additionally, the patient reported subsequent increased functionality of the affected limb. She is now able to play golf and has been able to reenter the work force. She continues to be followed in our pain clinic and receives cryotherapy in yearly intervals for her chronic pain associated with her scar neuroma. Her physical exam has remained stable and unchanged for over 15 years now.

Techniques: 1cc of 1% lidocaine was introduced as a skin wheal over the right anterolateral elbow region just inferior to her surgical scar. A 19-gauge needle was then introduced to produce a skin nick. A 12-gauge angiocatheter was then inserted at the site. Next, the cryotherapy probe was inserted through the 12-gauge angiocatheter. Electrical stimulation was performed to ensure that the needle tip was a safe distance from the radial and ulnar nerves. Three lesioning cycles of two minutes were performed. After the cryoprobe was removed, the wound was injected with 2cc 0.25% Marcaine and 40mg of triamcinolone.

Conclusion: Cryoablation therapy is a simple, safe and inexpensive office procedure for the treatment of chronic painful neuromas. It is particularly useful in painful conditions that do not respond to other therapies as evidenced in this case report.

Abstract 167

Should Imaging be Mandatory Prior to Epidural Blood Patch?

Presenting Author: Luminita M. Tureanu, M.D., F.R.C.P.C. Presenting Author’s City, State: - Chicago, IL Co-Authors: Sugantha Ganapathy, M.D., F.R.C.P.C. - The University of Western Ontario - London, Ontario

Introduction: Lumbar puncture (LP) is a commonly performed procedure for diagnostic purposes, or for spinal anesthesia. Postdural puncture headache (PDPH) has an incidence of at least 30%.(1) The diagnosis of PDPH is essentially clinical. The epidural blood patch (EBP) is an effective option when conservative treatment failed.(2) We present a case of intracranial pathology masquerading PDPH after repeat LPs.

Description: We were consulted for an EBP in a 55 yo female with persistent headache (HA) after repeated LPs. PMH was significant for sinus HA, hypothyroidism, and C4-5 spinal fusion. 3 weeks prior she had acute onset of severe vertex/frontal HA, after hearing a â€˜popâ€™ with straining. The HA was accompanied by photophobia, nausea and vomiting, worse with light and movement. The neurologic exam was normal, diagnostic LP and head CT were negative. She was discharged on conservative treatment. The patient returned to ED at another facility with worsening HA, and 2 LPs, CT and brain MRI were done, all negative. The HA was severe, throbbing, frontal, worse with movement and standing, with nausea, no vomiting, visual or neurologic deficits, fever, or chills. Neurologic exam was nonfocal. The HA was poorly controlled with NSAIDs and PO Oxycodone SR 10mg BID. A careful review of history, physical exam and neuroimaging showed an inconsistent PDPH pattern, suggesting a broader differential diagnosis. We requested a repeat brain MRI, looking for signs of low ICP and CSF leak. MRI showed recent infarcts in the left cerebellar hemisphere/occipital lobe,(Fig.1) on angiogram middle to small vessels vasculitis, no CSF leak. The patient underwent craniotomy and brain biopsy; the specimen showed nonspecific reactive changes. Vasculitis screen was negative. She was discharged home on PO Prednisone 50mg daily, Ibuprofen 400mg QID for 2 weeks, Oxycodone SR 20mg BID, acetaminophen/codeine #3 as needed, ASA 81mg daily, and IV Cyclophosphamide 1000mg/month for 6 months. She followed up with Neurology service and the HA almost resolved one month later. No neurologic deficit was ever present.

Discussion: PDPH is common after LP and may result in serious morbidity. While the exact pathophysiology remains unclear, possible mechanisms are persistent CSF leak and low ICP with traction and stretching of cerebral structures.(2) A broad differential diagnosis should always be kept in mind.(3,4) In cases of intracranial hypotension brain MRI may show meningeal enhancement, myelo-CT and MR may reveal extradural spinal collections, and point of CSF leakage.(4,5)Primary CNS vasculitis, a rare vascular inflammatory condition, is a diagnostic and therapeutic challenge.(6) Angiogram and cerebral biopsy are essential for early diagnosis. Most patients respond well to glucocorticoids alone or combined with cyclophosphamide. In our patient, the persistent HA with postural component, in the setting of repeated LPs was suggestive of PDPH. However, low ICP syndrome was not confirmed by repeat MRI. The importance of careful history in a patient with suspected PDPH cannot be overstated. While neuroimaging prior to every EBP can be cost prohibitive, in selective cases such as ours it can prove extremely valuable, by providing the correct diagnosis and avoiding an invasive procedure.

Additional File #1:

Fig 1. MRI brain, axial view: recent infarction within the left cerebellar hemisphere and left occipital lobe.

Additional File #2: References 1. Kuntz K et al. Post-lumbar puncture headaches: experience in 501 consecutive procedures. Neurology1992;42(10):1884-7.

2. Turnbull DK, et al. Post-dural puncture headache: pathogenesis, prevention and treatment. Br J Anaesth. 2003;91(5):718-29.

3. Ahmed SV, et al. Post lumbar puncture headache: diagnosis and management. Postgrad Med J 2006;82(973):713-6.

4. Mokri B. Low cerebrospinal fluid pressure syndromes. Neurol Clin N Am 2004;22:55–74.

5. Chiapparini L, et al. Headache and intracranial hypotension: neuroradiological findings. Neurol Sci. 2004;25 Suppl 3:S138-41.

6. Salvarani C, et al. Primary central nervous system vasculitis: analysis of 101 patients. Ann Neurol. 2007;62(5):442-51.

Abstract 168

Efficacy of In-Plane vs Out-Of-Plane Placement of Continuous Femoral Nerve Catheter

Presenting Author: Kevin M. Tou, M.D. Presenting Author’s City, State: - San Antonio, TX Co-Authors: Jonathan Rogers, M.D. - WHMC - San Antonio, TX Lisa Rogers, M.D. - WHMC - San Antonio, TX

Introduction: Continuous femoral nerve catheters can be successfully placed utilizing both the in-plane and out-of-plane approach. However, in comparison of 96 patients receiving total knee arthroplasty with combined femoral and sciatic nerve catheters for post operative analgesia it appears that the in-plane approach results in lower rate of catheter failure.

Material and Methods: Utilizing sterile technique, a MicroMaxx (Sonosite, Inc, Bothell, WA) ultrasound with HFL38X 13-6 MHZ probe and nerve stimulator were used to locate the femoral nerve. A Braun Contiplex Tuohy Continuous Nerve Block Set (18 Ga. 2in Tuohy with 20 Ga. Polyamide catheter) was utilized to place femoral catheters. The out-of-plane catheter placement was completed (45 patients) with the tip of the needle lying just anterior to the nerve with a .48 mA stimulation of the quadriceps muscle. 30ml of 0.5% Ropivicaine was visualized pushing the nerve against the iliopsoas muscle forming a volume anterior to the nerve prior to catheter placement. The catheter was then advanced 5 cm beyond the tip of needle. All catheters were noted to have threaded easily in this approach. The in-plane approach was completed (51 patients) placing the tip of the needle posterior to the femoral nerve at a point between the femoral nerve and the iliopsoas muscle with a .48 mA stimulation of the quadriceps muscle. 30ml of 0.5% Ropivicaine was visualized raising the femoral nerve off the iliopsoas muscle with subsequent circumferential spread of local anesthetic around the femoral nerve. The tuohy bevel was then rotated proximally and the catheter was threaded 5cm posteriorly along the femoral nerve. Catheter placement in the in-plane approach was noted to me more difficult to thread in some cases. Catheter placement was confirmed using the bubble test.The catheters were kept in for 3 days post-op and pain scores were evaluated 3 times a day. The catheters were determined to be a failure if the patientâ€™s mid/anterior knee pain was greater than 4/10.

Results: 96 patients included in this analysis. 45 femoral catheters placed out-of-plane with 15 expressing a pain score of greater than 4/10 and were classified failed femoral catheters post-operatively. 51 femoral catheters placed in-plane with 7 expressing a pain score of greater than 4/10 and were classified failed catheters post-operatively. Posterior knee pain was also utilized to evaluate sciatic catheter failure rates.

Discussion: Although more technically demanding due to the 90 degree redirection superiorly, the in- plane placement of a continuous femoral nerve catheter resulted in fewer failed catheters for postoperative analgesia following total knee arthroplasty. The posterior location of the catheter relative to the femoral nerve may result in a higher success rate of catheter function. As the local anesthetic is absorbed, and the anatomy returns to its pre-injection state, the catheter becomes compressed between the catheter and femoral nerve.

Abstract 169

Bilateral Continuous Thoracic Paravertebral Infusion as Part of a Multimodal Approach for Analgesia and Ventilator Weaning in a Patient with Blunt Thoracic Trauma and History of Opioid Abuse.

Presenting Author: Michael L. Boisen, M.D. Presenting Author’s City, State: - Pittsburgh, PA Co-Authors: Jonathan G. Tlachac, M.D. - University of Pittsburgh - Pittsburgh, PA Beverly A. Pearce-Smith, M.D. - University of Pittsburgh - Pittsburgh, PA

Background: Thoracic paravertebral block has been well described for post-operative analgesia after thoracic surgery (1), and to relieve pain and improve respiratory parameters in patients with multiple rib fractures (2). We report the use of bilateral continuous paravertebral infusions to provide analgesia and facilitate ventilator weaning in a patient with a history of opioid abuse who had respiratory insufficiency and difficult-to-control pain due to blunt thoracic trauma.

Case Report: The patient, an otherwise healthy 26 year-old male but for a past medical history of opioid abuse, was admitted after having been ejected during a motor vehicle crash. He sustained blunt thoracic injury with bilateral pulmonary contusions and hemopneumothoraces. Endotracheal intubation and bilateral thoracostomy tube placement were performed in the emergency department. His injuries included fractures of the right 4th through 9th and left 1st through 7th ribs, a depressed skull fracture, and grade 4 hepatic laceration with hepatic venous injury. Tracheosotomy was performed on hospital day 2. The regional anesthesia/acute pain service was consulted on hospital day 6 because of severe chest wall pain refractory to opioids causing multiple failed trials at weaning from mechanical ventilation. On the day of consultation, the patientâ€™s visual analog pain (VAS) score was 10/10 on a regimen consisting of fentanyl infusion at 100mcg/hr and intravenous patient-controlled hydromorphone (PCA) with 24-hour total consumption of 47mg. Paravertebral catheters were placed at T4 on the left and T7 on the right. 15 mL 0.5% ropivicaine bolus was injected incrementally through each catheter followed by a 0.25% lidocaine infusion at 7 mL/hr. The fentanyl infusion was stopped. Ketamine 10 mg was administered intravenously followed by continuous ketamine infusion at 10 mg/hr. Ketorolac 15 mg iv q6h for 72 h was also ordered as an adjunct. Following paravertebral blockade, the patient reported VAS scores of 1-2/10 at rest and 4/10 with activity. On hospital day 7 the patient was able to progress from assist-control to pressure-support mode of ventilation; the 24-hr hydromorphone total was 38mg. On hospital day 8, mechanical ventilation was discontinued and the patient was able to tolerate spontaneous breathing with an aerosol tracheostomy mask; the 24-hr hydromorphone total was 43mg. On hospital day 9 the hydromorphone total was 16mg and the PCA was discontinued. On hospital day 10 the TPVB paravertebral catheters were removed.

Discussion: We describe the use of bilateral continuous paravertebral infusion of local anesthetic as part of a multimodal approach to provide analgesia and improve pulmonary function in a mechanically ventilated patient with multiple rib fractures and history of opioid abuse. This technique confers technical and clinical advantages over other modalities and deserves more rigorous investigation.

References 1. Davies et al: A comparison of the analgesic efficacy and side-effects of paravertebral vs epidural blockade for thoracotomy--a systematic review and meta-analysis of randomized trials. British Journal of Anaesthesia 2006; 96:418

2. Karmakar MK: Thoracic paravertebral block. Anesthesiology 2001;95:771

Abstract 170

Peripheral Nerve Blocks for Surgical Anesthesia in Haiti Earthquake Victims

Presenting Author: Ralf E. Gebhard, M.D. Presenting Author’s City, State: - Miami, Florida Co-Authors: Alexandru Visan, M.D. - University of Miami - Miami, Florida Joni Maga, M.D. - University of Miami - Miami, Florida Jeffrey Frohock. M.D. - University of Miami - Miami, Florida Andres Missair, M.D. - University of Miami - Miami, Florida

Introduction: Several anesthetic techniques including general anesthesia, neuraxial anesthesia, monitored anesthesia care, and brachial plexus blocks have been previously utilized to provide surgical anesthesia for natural disaster victims (1,2). However, especially in the early time period after the event, medical equipment and supplies may not always be readily available. In addition, in the presence of sepsis, hypovolemia, and rhabdomyolysis, general anesthesia or neuraxial anesthesia may not be the ideal technique even if equipment is available. Consequently, complications such as hemodynamic instability, oxygen desaturation, and aspiration pneumonia have been described (1). We present our experience utilizing mainly peripheral nerve blocks for surgical anesthesia during the early phase medical disaster relief after the Haiti earthquake.

Methods: After IRB approval, the operating room records of 140 consecutive surgeries performed in the immediate aftermath of the Haiti earthquake at the University of Miami medical facilities in Haiti will be analyzed. Anesthetic techniques, type of surgery, age of patients, and incidence of complications will be reported. Demographic will be reported as mean Â± SD. Type of surgery, type of anesthetic technique and complication will be presented as percentages.

Results: In the absence of oxygen, blood supplies, laboratory equipment, anesthesia ventilators, and adequate monitoring, a specific anesthetic protocol was established: All major orthopedic procedures such as amputations or amputation revisions received either interscalene or axillary blocks for the upper extremity or combined femoral/sciatic blocks for the lower extremity. Sedation with midazolam and ketamine was added as necessary. Minor orthopedic procedures were performed just under midazolam/ketamine sedation. Detailed results will be presented after IRB approval.

Discussion: Peripheral nerve blocks as technique to provide surgical anesthesia appears to be a favorable alternative to other anesthetic techniques in a clinical scenario such as the early medical relief after the Haiti earthquake. Advantages include the lack of hemodynamic side effects and the practicality in a scenario without oxygen or anesthesia ventilators. In addition peripheral nerve blocks are associated with a favorable risk profile when electrolyte or coagulation status are unknown but disturbances are highly likely. Our data may result in a change in anesthesia practice in the immediate medical response after natural catastrophes. In a scenario dictated by extremity injuries and especially open fractures, peripheral regional anesthesia can be fast deployed and can be practiced independently from oxygen supplies, electricity (nerve stimulators are battery operated) and if necessary with only limited monitoring. In addition, a concept which would allow for early availability of orthopedic surgeons and regional anesthesia trained anesthesiologists for future catastrophes may result in timely treatment of open fractures and compartment syndromes and may result in salvation of extremities which otherwise would certainly require amputations.

References: 1) Charuluxananan S et al. Acta Anaesthesiol 2006; 50: 320-3 2) Jiang J et al. Injury 2009; Epub ahead of print

Abstract 171

Successful Ultrasound Guided Regional Anesthesia Despite Significantly Irregular Presentation of the Brachial Plexus

Presenting Author: Batyrjan Bulibek, M.D. Presenting Author’s City, State: - Albany, NY Co-Authors: Andras Laufer, M.D. - Albany medical center - Albany, NY

Background: Failed brachial plexus regional anesthesia could be secondary to anatomic variations of the nerve trunks, which have been demonstrated in past studies. (5) Ultrasound guidance may improve success rate, decrease performance and onset times, prolong duration of anesthesia, and reduce complications (1,2,3,4) by accurately identify the exact location of the irregular target structures which could be missed without visualization.

Methods: Our patient was scheduled for upper extremity vascular surgery with regional anesthesia. Using linear high-frequency ultrasound probe, lateral and medial orientation was confirmed and the brachial plexus was identified. Local anesthetics were deposited around the nerve trunks utilizing the standard in-plane needle placement approach.

Results: Image-1 demonstrates irregular presentation of brachial plexus medial to anterior scalene muscle. Image-2 demonstrates the brachial plexus medial to subclavian artery. Image-3 demonstrates spread of local anesthetic around the brachial plexus. Our patient had successful regional block and surgery with minimal sedation and good postoperative pain control.

Conclusion: Ultrasonography may be essential to identify unusual presentation of brachial plexus which may be otherwise missed with utilizing only surface landmarks and nerve stimulator technique.

Reference: 1. Sites BD, Beach ML, Spence BC et al: Ultrasound guidance improves the success rate of a perivascular axillary plexus block. Acta Anaesthesiol Scand 2006 2. Williams SR, Chouinard P, Arcand G et al: Ultrasound guidance speeds execution and improves the quality of supraclavicular block. Anesth Analg 2003 3. Soeding PE, Sha S, Royse CE et al: A randomized trial of ultrasound-guided brachial plexus anaesthesia in upper limb surgery. Anaesth Intensive Care 2005 4. Liu FC, Liou JT, Tsai YF et al: Efficacy of ultrasound-guided axillary brachial plexus block: a comparative study with nerve stimulator-guided method. Chang Gung. Med J 2005 5. Kessler J, Gray AT: Sonography of scalene muscle anomalies for brachial plexus block. Reg Anesth Pain Med 2007

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Abstract 172

Double Blind Randomized Bilateral Continuous Thoracic Paravertebral Nerve Blocks Comparison Between Lidocaine 0.25% and ropivacaine 0.2% for for Post-bowel Surgery Analgesia

Presenting Author: Andrea Fanelli, M.D. Presenting Author’s City, State: - Pittsburgh, Pennsylvania Co-Authors: Bruce Ben-David, M.D. - UPMC - Pittsburgh, Pennsylvania Jacques Chelly, M.D., Ph.D., M.B.A. - UPMC - Pittsburgh, Pennsylvania

Background: From 2004 until 2008, bilateral continuous thoracic paravertebral nerve blocks have been infused with ropivacaine 0.2% (R) for postoperative analgesia in patients undergoing bowel surgery. However, economical considerations have made us explore some less expensive alternative including lidocaine because of its established safety profile.1 This report presents the preliminary data of the comparison between lidocaine 0.25% (L) and R for bilateral continuous paraverterbal infusions.

Methods: The data are reported based on the enrollment of 10 patients who underwent elective laparoscopic abdominal bowel surgery and who were randomized to receive either R (Group R; n=5) or L (Group L n=5) via continuous bilateral paravertebral infusions for postoperative analgesia (7ml/h; PRN 3ml bolus every 30minutes). All patients were also given free access to hydromorphone PCA for breakthrough pain (bolus: 0.2mg bolus; lockout: 8min; no limit). The primary outcome was the Numerical Rating Score (NRS) for pain during deep breathing after 48 hours. Data are presented as mean Â± SD

Results: There was no difference in NRS during deep breathing at 48 hrs between the (3 Â± 2 in Group R vs 4 Â± 2 in Group L; p = 0.17), in the hydromorphone consumption at 48h (12.3 Â± 8.5 mg Group R vs 25.2 Â± 18.3 mg Group L; p = 0.28) or in the length of stay (5.8 Â± 1.7 days in Group R, vs 6.4 Â± 2.1 days in Group L; p = 0.39). No sign of local anesthetic toxicity were recorded in any of the patients.

Conclusions: The study was designed to enroll a total of 60 patients. The preliminary presented suggest that both ropivacaine 0.2% and lidocaine 0.25% in combination with a free access to an hydromorphine PCA provide effective pain control in patients undergoing elective laparoscopic abdominal bowel surgery. However, these data may also suggest that ropivacaine 0.2% is more effective than lidocaine 0.25%, since the opioid consumption was higher in the Group L.

References: 1. Casati A, Vinciguerra F, Scarioni M et al. Lidocaine versus ropivacaine for continuous interscalene brachial plexus block after open shoulder surgery. Acta Anaesthesiol Scand. 2003 Mar;47(3):355-60.

Abstract 173

Continuous Femoral Nerve Block Using Levobupivacaine 0.18%: Effects on the Rehabilitation Following Total Knee Arthroplasty with Subvastus Approach

Presenting Author: Maria Grazia Militello, Anaesthetist Presenting Author’s City, State: - Pontedera (Pisa), Tuscany Co-Authors: Dino Di Pasquale, Anaesthetist - Felice Lotti General Hospital – Pontedera (Pisa), Tuscany Enrico Bonicoli, Ortthopaedic Surgeon - Felice Lotti General Hospital - Pontedera (Pisa), Tuscany

Abstract Body: Adequate control of postoperative pain has major impact on the rehabilitation of patients undergoing total knee arthroplasty. The aim of our study was to analyze the effects of continuous femoral block with levobupivacaine 0.18% for 48 hours on in-hospital rehabilitation patients undergoing knee replacement surgery with subvastus approach. We studied 44 ASA II-III patients undergoing unilateral knee arthroplasty with subvastus approach. Anesthetist inserted perineural femoral catheter when a current below 0.5 mA and 0.1 msec frequency causes contraction of the quadriceps with sliding of the patella; bolus of 20ml levobupivacaine 0.5%. for spinal anesthesia (interspace L3-L4, 22/27G spinal needle) levobupivacaine 0.5% 10mg + fentatienil 5mcg were administered. All patients were given acetaminophen 1g/iv and tramadol 100mg/iv followed by continuous infusion with elastomer ketorolac 60mg and tramadol 200mg for 24 hours. After surgery, group cases begun continuous infusion of levobupivacaine 0.18% at 7ml/h for 48 hours via the femoral catheter. The rehabilitation program started 8 hours after surgery with passive flexion of the operated knee. Every morning up to 48 hours after surgery the strength of the quadriceps muscle was rated using a six point numerical scale (MRC scale). VAS was also recorded during movement (for VAS > 4 acetaminophen 1g/iv was administered). The value of MRC at 8 hours after surgery was higher in the control group (p< 0.01 Pearsons test). The values of knee flexion in the case group were higher (p<0.001, Wilcoxon rank-sum test) at 8-24-48 postoperative hours. The case group has better pain control at each observation during the two postoperative days (Wilcoxon rank-sum test p<0.001) and walk earlier (Wilcoxon rank-sum test p<0.001). This study shows a positive effect of continuous femoral block on postoperative rehabilitation program adopted in our center in terms of range of passive flexion of the knee and early ambulation combined with better control of postoperative pain. The MRC scale shows no statisically significant differences between the two groups at 48 and 72 hours postoperatively, suggesting that the strength of the quadriceps muscle after knee replacement surgery is influenced not by the continuous femoral block with levobupivacaine 0.18% but by subvastus surgical approach because it spares the quadriceps muscle's tendon. These data seem to be in agreement with those already present in literature.