Journal of Clinical Anesthesia (2010) 22, 598–602

Original contribution Teaching the surgical airway using fresh cadavers and confirming placement nonsurgically☆,☆☆ Rana Latif MD (Assistant Professor)a,⁎, Nitin Chhabra MD (Resident)a, Craig Ziegler MS (Biostatistician)b, Alparslan Turan MD (Associate Professor)c, Mary B. Carter MD, PhD (Adjunct Assistant Professor)b aDepartment of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA bMedical Education Research Unit, Office of Medical Education, University of Louisville School of Medicine, Louisville, KY cDepartment of Anesthesiology and Perioperative Medicine, Outcomes Research Department, Cleveland Clinic Foundation, Cleveland, OH 44195, USA

Received 17 August 2009; revised 30 March 2010; accepted 11 May 2010

Keywords: Abstract Airway anatomy; Study Objective: To determine if teaching cricothyrotomy with fresh cadavers improves confidence Cadavers; with neck anatomy, patient positioning, procedural steps, and familiarity with a cricothyrotomy kit. Cricothyrotomy Design: Prospective pre- and post-educational. Setting: University medical center. Subjects: 16 anesthesiology residents, one certified registered nurse-anesthetist (CRNA), and 8 medical students. Measurements: Subjects received workshop training with a PowerPoint presentation followed by an instructional video. Subjects then performed cricothyrotomy during supervision on cadavers. The comfort levels of 25 subjects before (pre) and after (post) the workshop were assessed using a 7-point Likert scale. Correct placement of the cricothyrotome was confirmed with visualization of the carina fiberoptically. Main Results: There was a significant increase (P b 0.001) between pre- and post-training comfort levels in identification of neck anatomy, surgical landmarks, and patient positioning (pre, 2.60 ± 1.56; post, 5.64 ± 1.22; mean ± SD); use of cricothyrotomy kit (pre, 1.72 ± 1.22; post, 5.52 ± 1.26), and surgical steps (pre, 1.76 ± 1.17; post, 5.52 ± 1.26). In 24 of 25 attempts (96% success rate), correct placement of the cricothyrotome was confirmed by visualization of the carina fiberoptically. Conclusions: A didactic workshop followed by performance of cricothyrotomy on fresh human cadavers may improve both physician and non-physician anesthesiology care providers’ confidence in performing cricothyrotomy. Published by Elsevier Inc.

☆ Received from the Paris Simulation Center, Office of Medical Education, and the Department of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine, Louisville, KY, United States. ☆☆ Financial support: Institutional and departmental sources at the University of Louisville School of Medicine, Louisville, KY, USA. ⁎ Corresponding author. E-mail address: [email protected] (R. Latif).

0952-8180/$ – see front matter. Published by Elsevier Inc. doi:10.1016/j.jclinane.2010.05.003 Teaching on cadavers 599

1. Introduction 2. Materials and methods

Endotracheal intubation is a very common procedure The University of Louisville Human Studies Committee that is performed both in and out of the hospital setting. approved this study, and subjects gave their written, However, in some patients, even the most skilled clinicians informed consent to participate in the study. All subjects experience difficulty in performing endotracheal intuba- completed a pre-workshop questionnaire rating their tion. The reported incidence of “unable to intubate, unable comfort level of their knowledge of neck anatomy, surgical to ventilate” cases requiring emergency surgical airway landmarks, surgical steps, patient positioning, and the varies between 2.5 per 10,000 cases to 0.5 per 10,000 cases cricothyrotomy kit. Subjects rated their comfort level using [1]. The surgical airway remains the final option on all a 7-point Likert scale, in which 1 = very uncomfortable and failed airway algorithms [2], but two surveys from the 7 = very comfortable. Participants were also requested to United Kingdom and United States indicate that anesthe- document the number of surgical airways performed siologists lack formal training in performing the surgical previously, either with dilation percutaneous tracheostomy airway [3,4]. Although there are different forms of surgical or cricothyrotomy. airway [5], cricothyrotomy is perhaps the most safe and Participant instruction included a 15-minute PowerPoint effective [6,7], with a reasonably low complication rate and presentation (Microsoft, Redmon, WA, USA) about the high success rate compared with other surgical techniques indication, anatomy, patient positioning, and steps involved [8,9]. Cricothyrotomy is difficult to teach on actual patients in wire-guided cricothyrotomy and how to confirm the due to the limited number of patients requiring cricothyro- correct position of the cricothyrotome in the . This tomies in most clinical settings, and the obvious ethical was followed by a 5-minute instructional video about problems of performing a percutaneous cricothyrotomy in performing cricothyrotomy (Cook Critical Care). the elective setting. Subjects then performed cricothyrotomy on cadavers with Although the use of fresh cadavers to teach invasive a Melker Emergency Cricothyrotomy Catheter Set with cuff airway skills has been documented previously, investiga- using the Seldinger [14] technique with the direct supervi- tors in the past have resorted to surgical dissection of the sion of an experienced anesthesia faculty member. Subjects neck in cadavers in order to confirm correct placement of extended the neck of the cadaver by placing a role under the the surgical airway [8,10]. We maintain that confirmation shoulders. After identification of neck structures, subjects of correct placement of the surgical airway while teaching made a 2-centimeter vertical incision with a scalpel in the cricothyrotomy procedures on cadavers is extremely skin overlying the cricothyroid membrane. For subsequent important. We propose that proper placement of the uses, 2-inch plastic tape (3M Scotch Brand 471; 3M, Inc., St. cricothyrotome may be confirmed endoscopically by Paul, MN, USA) was applied to the cadaver's neck to visualization of the carina usinga2.8mmfiberoptic simulate the skin. An 18-gauge needle attached to a syringe bronchoscope passed through a three mm commercially was inserted through the incision, through the underlying available cricothyrotome. cricothyroid membrane, and into the trachea at a 45° angle in There are several methods to teach surgical cricothyr- a caudal direction. Air was aspirated into the syringe to otomy to clinicians, but the three most common techniques confirm placement in the trachea. Once confirmed, the are the standard surgical technique, the catheter-over-needle syringe was removed and a guide wire was inserted through (eg, Rusch QuickTrach; Teleflex Medical, Research Triangle the needle. The needle was removed over the wire, and the Park, NC, USA) technique, and the wire-guided cricothyr- dilator-airway assembly was advanced over the guide wire otomy technique [11]. Although ventilation can be estab- into the trachea. Finally, the dilator and guide wire were lished within the same time frame with any of the above removed, leaving the Melker cricothyrotome in place. techniques [12], wire-guided cricothyrotomy is the preferred Correct placement of the surgical airway was confirmed technique by emergency [11] and anesthesia physicians [13]. with a 2.8mm STORZ fiberoptic bronchoscope (Karl Storz This is mainly because the wire-guided technique is similar GrnbH & Co. KG, Tuttlingen, Germany) passed through the to placement of vascular access lines by the Seldinger Melker cricothyrotome to allow visualization of the carina. If technique [14]. For this reason, we elected to use the Melker the carina was not visualized, the fiberoptic bronchoscope Emergency Cricothyrotomy Catheter Set with cuff (Cook was introduced orally through the vocal cords, guided by a Critical Care, Bloomington, IN, USA), a wire-guided Williams Airway Intubator (SunMed, Inc., Largo, FL, USA). cricothyrotomy catheter set, to teach cricothyrotomy. The position of the cricothyrotome was visualized and noted. We tested the hypothesis that participating in a cricothyr- Four cadavers were used to teach 25 learners. After each otomy workshop improves confidence among participants, attempt – before the next subject made his or her attempt – which will translate to a successful demonstration of the plastic tape was re-applied to the cadaver's neck to give a wire-guided cricothyrotomy technique on the first attempt consistency comparable to skin overlying the cricothyroid while performing a surgical airway on fresh cadavers. We membrane [15]. also planned to confirm correct placement of the cricothyr- Immediately after the workshop was complete, subjects otome in the trachea using a fiberoptic bronchoscope. completed a post-workshop questionnaire identical to the 600 R. Latif et al. pre-workshop questionnaire, rating their comfort level with Correct positioning of the cricothyrotome was confirmed knowledge of neck anatomy, surgical landmarks, surgical fiberoptically in 24 of 25 attempts (96% success rate). In one steps, patient positioning, and the cricothyrotomy kit. case, we were unable to identify the carina when the SPSS software version 17.0 (SPSS, Chicago, IL, USA) fiberoptic scope was introduced into the trachea through the was used to analyze quantitative data. Descriptive cricothyrotome. In this case, the fiberoptic scope was statistics included frequency, mean, and standard deviation introduced orally guided by a Williams airway intubator (SD). Changes in subjects’ perceptions of comfort, as and the position of the cricothyrotome was visualized above captured in the pre- and post-workshop Likert-scaled data, the cords. On a subsequent attempt, the subject was able to were analyzed using the Wilcoxon signed-rank tests. All place the cricothyrotome correctly into the trachea. P-values were two-tailed. Owing to the multiple testing of the Likert scale items, statistical significance was set at 4. Discussion P ≤ 0.01.

The present study shows that a systematic teaching 3. Results approach in a workshop setting, using didactic instruction followed by proper supervision of hands-on implementation, Thirteen anesthesiology residents, one certified regis- improves the confidence of health care providers in tered nurse-anesthetist (CRNA), three interns, and 8 medical performing a cricothyrotomy. Unfortunately, it is difficult students consented to participate in this study. Of our 25 to teach surgical airway procedures in the normal elective participants, 23 reported that they had never been in a clinical setting. The emergency surgical airway is still a fairly situation requiring cricothyrotomy for definitive airway on rare occurrence, and the focus on re-establishing the airway a patient, and 24 reported no previous procedural supersedes that of instruction. In the clinical setting, most experience using the Seldinger technique for cricothyrot- patients requiring surgical airway are in cardiac arrest prior to omy. Analysis of the entire sample showed a significant the procedure and hence have poor outcomes [16-18]. Scrase increase between pre- and post-workshop comfort level as and Woollard [5] indicated that if we exclude this subset of measured on a Likert scale (Table 1). Average scores of patients from the analysis, the survival rate after surgical comfort level for the identification of neck anatomy, airway in a failure-to-intubate situation is 34% to 75%, with surgical landmarks, and patient positioning increased 9% to 34% having good neurological outcome [16]. Hence, twofold. In addition, scores of participants’ comfort in use evidence supports the teaching of cricothyrotomy to doctors, of the cricothyrotomy kit and knowledge of the surgical nurses, and . steps increased more than threefold. Although the incidence of “cannot intubate, cannot Because cricothyrotomy is an advanced airway manage- ventilate” is low, a surgical airway remains the final option ment skill, it was possible that including medical students’ in these patients. The use of the Esophageal-Tracheal- and first-year residents’ perceptions might have skewed our Combitube (Covidien, Mansfield, MA, USA) and Laryngeal results. Therefore, we re-analyzed our data after omitting the Mask Airways (LMA North America, Inc., San Diego, CA, data obtained from medical students and interns. The USA) in the difficult airway are recognized [19,20]; analysis again showed similar statistically significant however, successful placement of these devices is not increases in participants’ confidence of their knowledge of always guaranteed [21]. This situation makes teaching and neck anatomy, surgical landmarks, patient position, and mastering the surgical airway a matter of paramount surgical steps; and use of a cricothyrotomy kit. importance for anesthesia care providers.

Table 1 Pre-training (Pre) and post-training (Post) comfort levels with the cricothyrotomy procedure (all participants, n = 25) Question Assessment Likert Scale (% of participants Mean (SD) P time marking within range) a 1-3 4 5-7 How comfortable are you identifying Pre 64% 24% 12% 2.6 (1.6) ≤0.001 the anatomy, surgical landmarks, and Post 8% 8% 84% 5.6 (1.2) patient positioning for cricothyrotomy? How comfortable are you with the use Pre 84% 12% 4% 1.7 (1.2) ≤0.001 of a cricothyrotomy kit? Post 8% 12% 80% 5.5 (1.3) How comfortable are you with the Pre 88% 8% 4% 1.8 (1.2) ≤0.001 surgical steps of cricothyrotomy? Post 8% 12% 80% 5.5 (1.3) a Likert Scale: 1 = most uncomfortable, 7 = most comfortable. Data for the Likert scale are given as the percentage of participants who scored their comfort level at 1-3 (uncomfortable), 4 (neutral), or 5-7 (comfortable). Teaching airway management on cadavers 601

The 96% success rate for correct placement of the We conclude that patient care providers who deal with cricothyrotome on the first attempt in our study is similar to airway management, such as anesthesiologists, CRNAs, that previously reported by Chan et al. [22] but higher than intensive care physicians, emergency rooms physicians, what has been reported elsewhere [11,12]. We believe that and emergency medical technicians, should attain skill the detailed didactic instruction of surgical airway steps and in surgical cricothyrotomy and maintain this skill. A neck anatomy, familiarity with the surgical airway instru- workshop for teaching wire-guided cricothyrotomy to ments, and supervision by an expert faculty member may clinicians greatly increased participant confidence with have been responsible for the 96% success rate of our this procedure. Participants showed a success rate of 96% participants. We hope that such knowledge and hands-on on the first attempt. experience reduces complication rates during future proce- dures when it comes to performance on patients [23,24]. We acknowledge that practice on fresh human cadavers References does not necessarily reflect the experience in live patients. Fresh cadavers do not bleed, nor do they form hematomas [1] Berkow LC, Greenberg RS, Kan KH, et al. Need for emergency that might distort neck anatomy and thus make surgical surgical airway reduced by a comprehensive difficult airway program. cricothyrotomy very challenging for the care provider. Anesth Analg 2009;109:1860-9. However, cadavers are the closest simulation model that [2] Caplan RA, Benumof JL, Berry FA, et al. Practice guidelines for accurately reproduces the anatomy and spatial relationship management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the of the cricothyroid membrane to the rest of the airway. The Difficult Airway. Anesthesiology 2003;98:1269-77. use of only 4 cadavers for 25 learners may not have been [3] Ezri T, Szmuk P, Warters RD, Katz J, Hagberg CA. Difficult airway satisfactory to assure that all learners recognized the management practice patterns among anesthesiologists practicing in anatomical structures. The plastic tape to replace the skin the United States: have we made any progress? J Clin Anesth 2003;15: may not provide the same feeling to learners as real skin. 418-22. [4] Ratnayake B, Langford RM. A survey of emergency airway If this study is repeated, a greater cadaver-to-learner ratio management in the United Kingdom. Anaesthesia 1996;51:908-11. is desirable. [5] Scrase I, Woollard M. Needle vs surgical cricothyroidotomy: a short One limitation of the current study is that we did not cut to effective ventilation. Anaesthesia 2006;61:962-74. measure the body mass index (BMI) of the 4 cadavers. A [6] Greisz H, Qvarnstörm O, Willén R. Elective cricothyroidotomy: a decreased patient BMI might have rendered the surgical clinical and histopathological study. Crit Care Med 1982;10:387-9. [7] Bennett JD, Guha SC, Sankar AB. Cricothyrotomy: the anatomical airway procedure easier for our participants and thus basis. J R Coll Surg Edinb 1996;41:57-60. improved our success rate. Increased BMI impedes oro- [8] Eisenburger P, Laczika K, List M, et al. Comparison of conventional , especially when associated with larger surgical versus Seldinger technique emergency cricothyrotomy per- neck circumference [25]. formed by inexperienced clinicians. Anesthesiology 2000;92:687-90. Another limitation of the current study is that we did not [9] Hawkins ML, Shapiro MB, Cué JI, Wiggins SS. Emergency cricothyrotomy: a reassessment. Am Surg 1995;61:52-5. measure how long participants took to perform surgical [10] Davis DP, Bramwell KJ, Hamilton RS, Chan TC, Vilke GM. Safety cricothyrotomy on their first attempt. In the setting of and efficacy of the Rapid Four-Step Technique for cricothyrotomy working with cadavers, participants were not under pressure using a Bair Claw. J Emerg Med 2000;19:125-9. and there was no time limit to insert a surgical airway. [11] Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, However, real airway emergencies requiring cricothyrotomy Marres HA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. have significant time pressure. This sense of time pressure Anaesthesia 2004;59:1008-11. and urgency may increase complication rates and lower [12] Dimitriadis JC, Paoloni R. Emergency cricothyroidotomy: a success rates on patients [15,23]. Reducing elapsed time to randomised crossover study of four methods. Anaesthesia 2008;63: insert a surgical airway is important in the clinical setting so 1204-8. as to prevent hypoxic brain injury. Future studies or [13] Hagberg CA. Percutaneous dilational cricothyrotomy and tracheosto- my. In: Hagberg CA, editor. Benumof's Airway Management. New workshops should measure time to perform surgical airway York: Mosby Elsevier; 2007. p. 678-96. on the first or any attempt. [14] Seldinger SI. Catheter replacement of the needle in percutaneous We showed that a fiberoptic bronchoscope may be used arteriography: a new technique. Acta Radiol 1953;39:368-76. to confirm correct placement of the cricothyrotome in a [15] Vadodaria BS, Gandhi SD, McIndoe AK. Comparison of four different cadaver by visualization of the carina nonsurgically. This emergency airway access equipment sets on a human patient simulator. Anaesthesia 2004;59:73-9. method is quick and reliable compared with surgical [16] Fortune JB, Judkins DG, Scanzaroli D, McLeod KB, Johnson SB. dissection, but it does not identify any associated injuries Efficacy of prehospital surgical cricothyrotomy in trauma patients. to the surrounding structures as surgical dissection can. J Trauma 1997;42:832-6. Nonetheless, the aim of performing cricothyrotomy in the [17] Marcolini EG, Burton JH, Bradshaw JR, Baumann MR. A standing- emergency situation is to place the cricothyrotome into the order protocol for cricothyrotomy in prehospital emergency patients. Prehosp Emerg Care 2004;8:23-8. trachea and provide oxygen to the patient's . Using the [18] Spaite DW, Joseph M. Prehospital cricothyrotomy: an investigation of fiberoptic bronchoscope in our study was sufficient to indications, technique, complications, and patient outcome. Ann Emerg confirm that a proper airway was established. Med 1990;19:279-85. 602 R. Latif et al.

[19] Mort TC. Laryngeal mask airway and bougie intubation failures: the [22] Chan TC, Vilke GM, Bramwell KJ, Davis DP, Hamilton RS, Rosen P. Combitube as a secondary rescue device for in-hospital emergency Comparison of wire-guided cricothyrotomy versus standard surgical airway management. Anesth Analg 2006;103:1264-6. cricothyrotomy technique. J Emerg Med 1999;17:957-62. [20] Grier G, Bredmose P, Davies G, Lockey D. Introduction and use of the [23] Boon JM, Abrahams PH, Meiring JH, Welch T. Cricothyroidotomy: a ProSeal laryngeal mask airway as a rescue device in a pre-hospital clinical anatomy review. Clin Anat 2004;17:478-86. trauma anaesthesia algorithm. Resuscitation 2009;80:138-41. [24] Helm M, Gries A, Mutzbauer T. Surgical approach in difficult airway [21] Mercer MH, Gabbott DA. Insertion of the Combitube airway with the management. Best Pract Res Clin Anaesthesiol 2005;19:623-40. cervical spine immobilised in a rigid cervical collar. Anaesthesia [25] Brodsky JB, Lemmens HJ, Brock-Utne JG, Vierra M, Saidman LJ. 1998;53:971-4. Morbid obesity and tracheal intubation. Anesth Analg 2002;94:732-6.