A Role for Live-Animal Models in Undergraduate Surgical Education During the Cadaver Shortage.

Abstract

Cadaveric dissection is a time-honored tradition in undergraduate medical education and serves as the primary source by which young medical students learn anatomy.1 In graduate medical education, particularly surgical training, cadavers are used for advanced anatomy and simulation. With improvements in technology, some institutions and medical schools have begun transitioning away from this traditional method and to virtual anatomy models. Unfortunately, the COVID-19 pandemic has been accompanied by a cadaver shortage which has hastened this transition and threatened the ability to engage in such educational programs.2–4 Our institution runs a capstone course for graduating fourth-year medical students preparing to enter surgical residency programs. The goals of this course are to prepare students who have matched into surgical residencies for their intern year by covering didactics in floor work, consult experience, and operative techniques. Since inception in 2017, the hallmark of this course has been a 2-day, hands-on experience operating on fresh frozen cadavers. Traditionally, the objectives of this component included developing awareness and comfort with basic surgical techniques, instruments, and anatomy of common general surgery procedures. This past year, in the face of the cadaver shortage, we were unable to obtain sufficient cadaver volume (3–4) to support this component of the course. After consideration of various options, we chose to transition to a live-animal porcine model for use in student surgical simulation. Our institution maintains an active IACUC protocol (A229-21-11) for surgical education using live-animal labs as a component of several of our surgical residency programs. Given our experience with this model in graduate medical education, we decided to extend this program to our fourth-year medical student course. Course directors worked with attendings from the department of surgery and lab personnel to plan 3 sessions: (1) open procedures, (2) laparoscopic procedures, and (3) trauma injuries and procedures (Table 1). Prior goals and objectives were maintained, with a focus on operating and tissue handling, while recognizing the anatomic limitations of such a model. Objectives were also expanded to include laparoscopy and energy devices. Industry collaborators contributed suture, energy devices (electrocautery and ligasure), and staplers. Veterinary staff and technologists were immediately available for anesthesia, analgesia, and animal welfare concerns. Animals were intubated and sedated per our longstanding IACUC protocol. TABLE 1. - Operative Procedures Performed in Each Live Animal Lab Session Open Procedures Laparoscopic Procedures Trauma Procedures Midline laparotomyRunning the bowelSmall bowel resectionStapled small bowel anastomosisHand-sewn small bowel anastomosisEnd ileostomyDiverting loop ileostomyCholecystectomySplenectomyNephrectomyClosing fascia Hasson and Veress needle entryDiagnostic laparoscopyRunning the bowelSmall bowel resectionSalpingo-oopheractomy (simulated appendectomy)CholecystectomyEndo-close for fascia Exploratory laparotomyPenetrating Injuries to Repair: Enterotomy Cystotomy IVC injury Liver lacNephrectomySplenectomyNeck explorationChest tubesThoracotomyCardiotomy and repairIVC Repair Altogether, there were 15 graduating fourth-year medical students in attendance. Students were given the option to opt-out of this portion of the course if they had ethical concerns with the use of animals for simulation. Although participation in the live-animal lab was not mandatory as part of the course, all students wished to attend and participate. Students were divided into groups of 3–4 and paired with a general surgery resident (PGY-3 or 4) for all procedures. Each session had 1–2 attending surgeons circulating among tables for further guidance and instruction. The feedback from students was overwhelmingly positive with several citing this as, “The most educational,” and, “best experience,” in medical school. One student remarked that they, “Really felt like I was operating for the first time.” Particular skills they noted as helpful included how to handle tissue, suture ligation, pass ties, performing a laparotomy, and closure of fascia. Resident and faculty instructors noted that relative to cadaveric specimens, the porcine model had higher-quality tissues for teaching procedures and tissue handling. Further, laparoscopy was feasible and students learned the basics of visual (Hasson) versus blind (Veress) entry, driving a 0- and 30-degree laparoscope, and using different types of graspers. As a group, they concurred that this model was high fidelity, and met the goals of the capstone course even better than the cadaveric models. At conclusion of the course, students, residents, and faculty agreed the live-animal model was a success and should be offered in future years in lieu of cadaveric dissection. Given the ongoing pandemic, it is unlikely the cadaver shortage will resolve quickly. Considering additional options for teaching advanced surgical anatomy and procedures will be important in undergraduate and graduate medical education. We found utilizing live-animal porcine models to be an excellent educational experience for graduating fourth-year medical students. Although anatomy is not a perfect correlate to cadaveric models, the live-animal model provides better exposure to tissue handling and a greater opportunity to teach the fundamentals of hemostasis. Further, it provides an opportunity to use energy devices and there is a greater utility for intra-abdominal procedures, particularly bowel resection and anastomosis. The utilization of animal models in surgical education is not a novel approach for simulation. There are reports of utilizing both mouse and porcine models for preclinical and clinical medical students to enhance their experience on the surgical clerkship.5,6 Several training programs use a porcine model for early laparoscopic training and resident evaluation.7–9 Further, utilization of porcine models is well established in military trauma simulation and associated courses such as Advanced Trauma Operative Management (ATOM).10–13 We feel that evidence of this model’s efficacy in tandem with our recent experience supports translating this model to early stages of surgical education. To our surprise, the transition from fresh frozen cadavers to live porcine models also decreased the cost of this portion of our course by 92%. Although we found this transition to be relatively seamless and cost-effective, implementing a live-animal model into such capstone courses does require resources and infrastructure that may not be available at all institutions. For instance, our institution has an onsite animal facility and trained veterinary personnel. We work closely with educational staff in our simulation lab for administrative support in planning and executing such sessions. Further, we have a long-standing IACUC protocol on which faculty must undergo training to lead such labs. Medical schools lacking these resources and infrastructure may benefit from partnering with others in their area or sites that are accredited in other live animal educational programs, such as ATOM. Beyond the physical barriers, surgical educators should reinforce differences in the live porcine model and human anatomy and physiology to students. For instance, the anatomic configuration of the colon (spiral in pigs), number of lobes of the liver, lack of appendix, and the position of the urogenital opening. Perhaps this can be optimized by supplementing the live porcine model with an intraoperative video review of surgical anatomy. Moving forward we anticipate continuing to use the live-animal model in this capstone course, as well as exploring additional implementation into undergraduate medical education. We will continue to evaluate the educational objectives and utility of such models, with more formalized curricular development and surveys aimed at senior medical students. While each institutional structure is different, we encourage other institutions to consider the adoption of porcine models for high-fidelity simulation as a cost-effective strategy that can supplant cadaveric education and simulation. ACKNOWLEDGMENTS The authors would like to acknowledge the Duke Surgical Education and Activities Lab (SEAL) staff for their assistance in the execution of our medical student and resident educational programs, many of which heavily utilize the use of porcine models for technical training.