A1 BAYESIAN RESPONDER META-ANALYSIS of REGIONAL ANESTHESIA to PREVENT CHRONIC PAIN AFTER ILIAC CREST BONE GRAFT HARVESTING Micha
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A1 BAYESIAN RESPONDER META-ANALYSIS OF REGIONAL ANESTHESIA TO PREVENT CHRONIC PAIN AFTER ILIAC CREST BONE GRAFT HARVESTING Michael H. Andreae , M.D.1, Matthew Johnson2, Henry Sacks3 1Anesthesiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, 2Teachers College, Columbia University, 3Preventive Medicine, Mount Sinai School of Medicine, New York, NY, USA Introduction: Iliac crest bone graft (ICBG) remains the gold standard for autologous bone grafting. IBCG harvesting can lead to persistent postsurgical pain (PPSP), devastating and difficult to treat (Brull 1992). Local anesthetics administration may reduce this risk (Singh 2007). PPSP trials typically report heterogeneous outcomes, making classical frequentist meta-analysis in our Cochrane review in print (Andreae 2012) challenging. To overcome this limitation, we developed a Bayesian model on regional anesthesia for the prevention of persistent pain after IBCG harvesting. We pooled dichotomous and continuous pain outcomes at varying follow up intervals. Methods: Methods were detailed in our systematic review for the Cochrane Collaboration in print (Andreae 2012). Search: Briefly, we searched the Cochrane Central, PubMed, EMBASE and CINAHL (1966 to April 2012) without any language restriction using a combination of free text and controlled vocabulary. We searched conference abstracts by hand. Selection: We included randomized and non-randomized controlled clinical trials with pain outcomes at least 12 weeks postoperatively. Included studies compared local or regional anesthesia versus conventional analgesia for chronic pain after ICBG harvest. Data extraction: We assessed trial quality and extracted pain outcome, including information on adverse events. Bayesian model: We developed a longitudinal Bayesian model in OpenBUGS with three time points to estimate the posterior distribution of the odds ratio of chronic pain six months after surgery. Figure 1 illustrates the Bayesian process. We assume a linear time dependence of the odds ratios from one follow up to the next. Results: We identified 4 controlled clinical trials, three of them RCTs, studying local anesthetics or regional anesthesia for the prevention of persistent pain after ICBG harvesting (Table 1). Data from a total of 123 patients with continuous or dichotomous pain outcomes at 12 weeks, three, six and 12 months after harvesting were included (Figure 2) (Table 2). Our evidence synthesis suggests that local anesthetics prevent persistent pain at the donor site six months after ICBG harvesting in about every second patient treated (NNT is 1.96; 95% credible interval (1.26, 12.3). The Bayes Factor for a one-sided hypothesis test is 75, suggesting very high confidence in the results. The methodological quality of the included studies was intermediate. Adverse effects were not studied systematically and reported sparsely. [Firgure 1: Forrest Plot] [Figure 2: Bayesian Process] Study ID Follow up Interval Study Design Outcome reported Gündeş 2000 12 weeks RCT responder data observational trial Brull 1992 6 months responder data with historic controls Singh 2007 4.7 years RCT responder data responder data Blumenthal 2005 3 months RCT estimated from VAS [Table 1: Characteristics of included studies] 95% Credible Study Experimental Control OR (Median) Interval Gündeş 2/30 5/15 0.1670 (.0199, 1.035) Blumenthal 1.7/18* 16.8/18* 0.0216 (.0005,.1305) Brull 2/11 6/11 0.1748 (.0265, 1.190) Singh 0/9 7/11 0.1259 (.0180, .840) Combined 5.7/68* 34.8/55* 0.0917 (.0096, .655) [Table 2: Calculated and pooled odds ratios] Discussion: Local anesthetics may prevent persistent pain at the donor site after ICBG harvesting in about every second patient treated, (NNT is 2). Our innovation is the development of a novel Bayesian model for responder meta-analysis of dichotomous and continuous pain outcome data with variable follow up intervals ranging from three to twelve months. Funding: CTSA Grant UL1 RR025750. References: Andreae. Cochrane Database of Systematic Reviews in print. Blumenthal. Anesthesiology. 2005 Feb;102(2):392-7. Singh. Spine. 2007 Dec 1;32(25):2790-6. Gündeş. Acta Orthop Belg. 2000 Oct;66(4):341-4. Brull. Anesth Analg. 1992 Jan;74(1):145-7. A2 COMPARISON OF ANALGESIC EFFECTIVENESS OF COMBINED INTRAPERITONEAL INSTILLATION AND PERIPORTAL INFILTRATION OF BUPIVACAINE WITH INTRAPERITONEAL INSTILLATION OR PERIPORTAL INFILTRATION ALONE AFTER LAPAROSCOPIC CHOLECYSTECTOMY Prajjwal Raj Bhattarai1, Balkrishna Bhattarai , M.D.1, Birendra Prasad Sah1, Shailesh Adhikary2, Ashish Ghimire1 1Anesthesiology and Critical Care, 2Surgery, BP Koirala Institute of Health Sciences (BPKIHS), Dharan, Nepal Introduction: Acute pain after laparoscopic cholecystectomy is complex in nature1. Though postsurgical periportal infiltration and intraperitoneal instillation of local anesthetics have been reported to provide effective analgesia following laparoscopic cholecystectomy2, they are yet not standardized. Further, such reports are typically lacking from community based resource constrained settings. Therefore, the present study compared the effectiveness of combination of intraperitoneal instillation and periportal infiltration of bupivacaine with either of the techniques alone in such a setting. Materials and method: With institutional ethical approval, 90 adult patients undergoing elective laparoscopic cholecystectomy under general anesthesia were randomized prospectively into 3 groups. Patients in group PI (n=30) received periportal infiltration with 10 ml of 0.25% bupivacaine, patients in group II (n=30) received intraperitoneal instillation of 20 ml of 0.5% bupivacaine, and patients in group C (n=30) received combination of periportal infiltration with 10 ml of 0.25% bupivacaine and intra peritoneal instillation of 20 ml of 0.5% bupivacaine just prior to closing of the surgical ports. Surgery was accomplished using the 4-port standard technique in all the patients. Time to first postoperative analgesic requirement in min, 24 hour postoperative analgesic (injection tramadol in mg) requirement and pain Visual Analogue Score (VAS) taken at ½ h, 1 h, 4 h, 8 h, 12 h and 24 h after the surgery were the main outcome variables. Results: The mean duration of analgesia of 356±96.87 min with a median duration of 450 min (Inter Quartile Range: 195-510) in group C was significantly longer (p< 0.001) than 180.67±112.76 min with a median duration of 195 min (Inter Quartile Range: 60-270) in group II and 64.5±54.76 min with a median duration of 30 min (Inter Quartile Range: 30- 76.25) in group PI. Overall, the VAS recorded was the least (less than 3 at all time points except 24 h) in group C followed by II and PI respectively. The mean 24 h postoperative analgesic (injection tramadol) requirement in group C was almost one third less than that in group PI (116.67±27.33mg versus 173.33±25.37mg, p< 0.001) and almost one fifth less than in group II (116.67±27.33mg versus 148.33±20.69mg, p< 0.001). Discussion: In a community based resource-constrained setting with limited analgesic options (both due to unavailability and legal restrictions), the present study has shown clinically superior analgesia during the first few crucial postoperative hours with the combination of simple intra-peritoneal instillation and periportal infiltration of easily available bupivacaine compared to either of the techniques alone. The lower pain VAS and less analgesic requirement during first 24 h (which may translate to earlier discharge3) further imply regular use of the combined technique in such settings. References: 1. Wills VL, Hunt DR. Pain after laparoscopic cholecystectomy. Br J Surg 2000; 87: 273-84 2. Boddy AP, Mehta S, Rhodes M. The effect of intra-peritoneal local anesthesia in laparoscopic cholecystectomy: A systemic review and meta-analysis. Anesth Analg 2006; 103:682-688. 3. Paulson J, MellingerJ, Baguley W. The use of intraperitoneal bupivacaine to decrease the length of stay in laparoscopic cholecystectomy. Am Surg 2003; 69: 275-8. Conflict of interest: None declared. Funding: Departmental. A3 THE EFFECT OF OUTPATIENT KETAMINE INFUSIONS ON PATIENT HEMODYNAMICS, LEVEL OF SEDATION AND PAIN Genaro J. Gutierrez , M.D.1, May L. Chin2, Richard Amdur3, Elvis Rema1 1Department of Anesthesiology and Critical Care Medicine, The George Washington University School of Medicine and Health Sciences, 2Deptartment of Anesthesiology and Critical Care Medicine, The George Washington University Pain Center, 3Department of Anesthesiology and Critical Care Medicine, and Department of Surgery, The George Washington University, Washington, DC, USA Objectives and background: Ketamine, an NMDA receptor antagonist, helps reduce severe debilitating neuropathic pain in patients unresponsive to conventional treatment. Potential ketamine side effects include sedation, hallucinations, hypertension and tachycardia. There have been no published studies to date examining these side effects in outpatient ketamine infusions. Our goals are to determine 1) the safety of outpatient ketamine infusions and 2) the effect of ketamine infusions on pain. Methods: With IRB approval, we reviewed the vital signs, sedation assessment and pain scores of 46 patients diagnosed with severe chronic neuropathic pain. Each patient underwent 3 consecutive days of 4 hour ketamine infusions. Ketamine doses ranged from 0.2 mg/kg/hr to 1.2 mg/kg/hr for a total of 4 hours. Vital signs and Sedation-Agitation Scale (SAS) scores were recorded at baseline, every 15 minutes during the infusion. Pre-infusion