Perfused fresh cadavers: method for application to surgical simulation

Teaching courses in the management of visceral trauma

Several changes introduced in the management of trauma during the last two decades have considerably decreased the practical exposure to bleeding trauma patients by residents and young surgeons. Hemorrhage still represents the second cause of death from trauma worldwide, and the surgical maneuvers required for its control must be learned and practised in specific courses. These courses address the "second hour" of trauma, beyond ATLS^©, and also emphasize the decision-making process, communication among team members, and discussion of clinical scenarios. The significant progress made in simulation technologies and virtual reality systems have yet to replace living tissue models to train surgeons in the rapid control of active bleeding, although that replacement is probably not far away.

Vascularized dermal autograft for the treatment of irreparable rotator cuff tears

BACKGROUND

Irreparable rotator cuff tears (IRCTs) are a challenging problem with diverse treatment modalities. We propose a technique for the treatment of IRCTs in which a vascularized dermal autograft is transferred to the posterosuperior region of the rotator cuff using the supraclavicular artery (SCA) island flap.

MATERIALS AND METHODS

Dissection of 11 fresh cadavers (19 shoulders) was performed, and the SCA island flap was harvested in all specimens. A full-thickness posterosuperior rotator cuff defect was created, and the flap was tunneled under the acromion and secured into position over the defect using multiple suture anchors. Simulated flap perfusion was then assessed, and flap measurements were recorded.

RESULTS

There were 4 male and 7 female cadavers (19 shoulders). Flap perfusion was assessed in 10 shoulders. On average, the flap thickness was 4.7 mm (range, 3.5-7.1 mm); width, 32.6 mm (range, 25.5-38.0 mm); and length, 169.2 mm (range, 132.0-235.0 mm). The average distance from the flap tip to the Neviaser portal was 76.2 mm (range, 48.0-99.6 mm), and that from the flap tip to the anterolateral acromial edge was 54.1 mm (range, 29.5-75.1 mm). The pedicle-to-footprint distance was 113.7 mm (range, 88.5-147.0 mm). The average flap length exceeded the pedicle-to-footprint distance by 55.5 mm (range, 43.5-88.0 mm), indicating adequate excursion of the flap. All flaps demonstrated adequate simulated perfusion after fixation.

CONCLUSION

The SCA island flap may be an option for a vascularized dermal autograft for IRCTs, as shown in this cadaveric study. This illustrates a possible technique with vascular viability.

A Novel Expeditionary Perfused Cadaver Model for Trauma Training in the Out-of-Hospital Setting

BACKGROUND

Cadaver training for prehospital surgical procedures is a valid training model. The limitation to date has been that perfused cadavers have only been used in wet laboratories in hospitals or university centers. We endeavor to describe a transportable central-perfused cadaver model suitable for training in the battlefield environment. Goals of design were to create a simple, easily reproducible, and realistic model to simulate procedures in field and austere conditions.

METHODS

We conducted a review of the published literature on cadaver models, conducted virtual-reality simulator training, performed interviews with subject matter experts, and visited the laboratories at the Centre for Emergency Health Sciences in Spring Branch, TX, the Basic Endovascular Skills in Trauma laboratory in Baltimore, MD, and the Fresh Tissue Dissection Laboratory at Los Angeles County and University of Southern California, Keck School of Medicine, Los Angeles, CA.

PROCEDURE

This article will describe a five-step procedure that utilizes extremity tourniquets, right common carotid intra-arterial and distal femur intraosseous (IO) access for perfusion, and oropharynx preparation for airway procedures. The model will then be ready for all tactical combat casualty care procedures, including nasopharyngeal airway, endotracheal intubation, cricothyroidotomy, central-line access, needle decompression, finger and tube thoracostomy, resuscitative endovascular balloon occlusion of the aorta, junctional tourniquets, IO lines, and field amputations.

CONCLUSIONS

This model has been used in the laboratory, field, ground ambulance, and military air ambulance (UH-60) settings with good results. The model described can be used in the field setting with minimal resources and accurately simulates the critical skills for all combat trauma procedures.

Clinical Cadavers as a Simulation Resource for Procedural Learning

"See one, do one, teach one" remains an unofficial, unsanctioned framework for procedural skill learning in medicine. Appropriately, medical educators have sought alternative simulation venues for students to safely learn their craft. With the end goal of ensuring competence, educational programming will require the use of valid simulation with appropriate fidelity. While cadavers have been used for teaching anatomy for hundreds of years, more recently they are being repurposed as a "high-fidelity" procedural skill learning simulation resource. Newly deceased, previously frozen, and soft-preserved cadavers, such as those used in Baltimore and Halifax, produce clinical cadavers with high physical and functional fidelity that can serve as simulators for performing many high-acuity procedures for which there is otherwise limited clinical or simulation opportunities to practice. While access and cost may limit the use of cadavers for simulation, there are opportunities for sharing resources to provide an innovative procedural learning experience using the oldest of medical simulation assets, the human body.

Systematic review of surgical training on reperfused human cadavers

BACKGROUND

The role of reperfused human cadavers in surgical training has not been established.

METHODS

Reports describing reperfused human cadaver models in terms of simulated surgeries, the use of tools to assess technical competency and skills transfer to patients, cadaver status and reperfusion techniques were included.

RESULTS

Thirty-five reports were included. Most participants practised vascular (n = 27), flap (n = 6) and trauma (n = 4) procedures. Training progression was evaluated objectively in only two studies. In two publications, flap techniques were practised on cadavers and repeated successfully in patients. Eighteen studies employed whole bodies. Fresh and embalmed cadavers were both used in 17 publications. Most embalmed cadavers were formalin-fixed (n = 10), resulting in stiffness. Few trainings were offered on soft Thiel-embalmed cadavers (n = 5). Only arteries were reperfused in 20 studies, while in 13 publications, the arteries and veins were filled. Arteries and/or veins were mostly pressurized (n = 21) and arterial flow was generated in 14 studies.

CONCLUSIONS

Various reperfused human cadaver models exist, enabling practise of mainly vascular procedures. Preservation method determines the level of simulation fidelity. Thorough evaluation of these models as surgical training tools and transfer effectiveness is still lacking.

The Development of a Novel Perfused Cadaver Model With Dynamic Vital Sign Regulation and Real-World Scenarios to Teach Surgical Skills and Error Management

The landscape of graduate medical education has changed dramatically over the past decade and the traditional apprenticeship model has undergone scrutiny and modifications. The mandate of the 80-hour work-week, the introduction of integrated residency programs, increased global awareness about patient safety along with financial constraints have spurred changes in graduate educational practices. In addition, new technologies, more complex procedures, and a host of external constraints have changed where and how we teach technical and procedural skills. Simulation-based training has been embraced by the surgical community and has quickly become an essential component of most residency programs as a method to add efficacy to the traditional learning model. The purpose of this paper is twofold: (1) to describe the development of a perfused cadaver model with dynamic vital sign regulation, and (2) to assess the impact of a curriculum using this model and real world scenarios to teach surgical skills and error management. By providing a realistic training environment our aim is to enhance the acquisition of surgical skills and provide a more thorough assessment of resident performance. Twenty-six learners participated in the scenarios. Qualitative data showed that participants felt that the simulation model was realistic, and that participating in the scenarios helped them gain new knowledge, learn new surgical techniques and increase their confidence performing the skill in a clinical setting. Identifying the importance of both technical and nontechnical skills in surgical education has hastened the need for more realistic simulators and environments in which they are placed. Team members should be able to interact in ways that allow for a global display of their skills thus helping to provide a more comprehensive assessment by faculty and learners.

An enhanced fresh cadaveric model for reconstructive microsurgery training

BACKGROUND

Performing microsurgery requires a breadth and depth of experience that has arguably been reduced as result of diminishing operating exposure. Fresh frozen cadavers provide similar tissue handling to real-time operating; however, the bloodless condition restricts the realism of the simulation. We describe a model to enhance flap surgery simulation, in conjunction with qualitative assessment.

METHODS

The fresh frozen cadaveric limbs used in this study were acquired by the University. A perfused fresh cadaveric model was created using a gelatin and dye mixture in a specific injection protocol in order to increase the visibility and realism of perforating vessels, as well as major vessels. A questionnaire was distributed amongst 50 trainees in order to assess benefit of the model. Specifically, confidence, operative skills, and transferable procedural-based learning were assessed.

RESULTS

Training with this cadaveric model resulted in a statistically significant improvement in self-reported confidence (p < 0.005) and prepared trainees for unsupervised bench work (p < 0.005). Respondents felt that the injected model allowed easier identification of vessels and ultimately increased the similarity to real-time operating. Our analysis showed it cost £10.78 and took 30 min.

CONCLUSIONS

Perfusion of cadaveric limbs is both cost- and time-effective, with significant improvement in training potential. The model is easily reproducible and could be a valuable resource in surgical training for several disciplines.Level of Evidence: Not ratable.

Techniques of cadaver perfusion for surgical training: a systematic review

PURPOSE

The objective of this study was to identify the most appropriate cadaver perfusion techniques for surgical training through a systematic review with a description of the protocols used.

METHODS

The search strategy included PubMed and reference tracking. Studies were identified by searching the electronic Medline databases. The search concepts included perfusion, cadavers and simulation training, and the protocol used is reported. This resulted in a qualitative review of 12 articles out of 250 articles consulted. We collected all the important data from these 12 articles.

RESULTS

Regarding the characteristics of the studies and the declotting or perfusion techniques, the results were heterogeneous. Indeed, in several studies, a good deal of information was unclear or insufficiently precise, making it unfeasible to summarize the data. The methods used were not sufficiently explicit and detailed. However, a majority of the fresh cadavers used tap water for declotting. Perfusion, type of fluid, number of pumps, pressure, pulsatility, and arterial or venous approaches differed greatly. Only two studies fulfilled five of our six realism criteria for surgical simulation.

CONCLUSIONS

This systematic review provided an overview of all the different cadaver perfusion techniques. It could be used to establish a reference method of a simulation model.

Objective Validation of Perfusion-Based Human Cadaveric Simulation Training Model for Management of Internal Carotid Artery Injury in Endoscopic Endonasal Sinus and Skull Base Surgery

BACKGROUND

The emergence of minimally invasive endoscopic endonasal skull base surgery has necessitated reproducible and realistic simulators of rare vascular injuries.

OBJECTIVE

To assess the face and content validity of an innovative perfusion-based cadaveric model developed to simulate internal carotid artery (ICA) injury during endoscopic surgery.

METHODS

Otolaryngology and neurosurgery trainees attempted 3 consecutive trials of endoscopic control of a parasellar ICA injury, with standardized technical feedback. Time to hemostasis (TTH) and blood loss were trended. All participants completed validated questionnaires using a 5-point Likert scale to assess the domains of confidence gain, face validity, content validity, and curriculum applicability.

RESULTS

Among all participants (n = 35), TTH and mean blood loss significantly decreased between first vs second attempt (P = .005), and first vs third attempt (P = .03). Following the first attempt, trainees experienced an average 63% reduction in blood loss and 59% reduction in TTH. In the quartile of most improved participants, average blood loss reduction was 1115 mL (84% reduction) and TTH of 259 s (84% reduction). There were no significant differences between trainees of varying postgraduate year or specialty. Average pre and postprocedural confidence scores were 1.38 and 3.16, respectively (P &lt; .0001). All trainees reported model realism, which achieved mean face validity 4.82 ± 0.41 and content validity 4.88 ± 0.33.

CONCLUSION

The perfusion-based human cadaveric ICA injury model achieves high ratings of face and content validity across all levels of surgical trainees, and enables safe, realistic simulation for standardized skull base simulation and future curriculum development. Objective improvements in performance metrics may translate to improved patient outcomes.

Preoperative surgical rehearsal using cadaveric fresh tissue surgical simulation increases resident operative confidence

BACKGROUND

Rehearsal is an essential part of mastering any technical skill. The efficacy of surgical rehearsal is currently limited by low fidelity simulation models. Fresh cadaver models, however, offer maximal surgical simulation. We hypothesize that preoperative surgical rehearsal using fresh tissue surgical simulation will improve resident confidence and serve as an important adjunct to current training methods.

METHODS

Preoperative rehearsal of surgical procedures was performed by plastic surgery residents using fresh cadavers in a simulated operative environment. Rehearsal was designed to mimic the clinical operation, complete with a surgical technician to assist. A retrospective, web-based survey was used to assess resident perception of pre- and post-procedure confidence, preparation, technique, speed, safety, and anatomical knowledge on a 5-point scale (1= not confident, 5= very confident).

RESULTS

Twenty-six rehearsals were performed by 9 residents (PGY 1-7) an average of 4.7±2.1 days prior to performance of the scheduled operation. Surveys demonstrated a median pre-simulation confidence score of 2 and a post-rehearsal score of 4 (P<0.01). The perceived improvement in confidence and performance was greatest when simulation was performed within 3 days of the scheduled case. All residents felt that cadaveric simulation was better than standard preparation methods of self-directed reading or discussion with other surgeons. All residents believed that their technique, speed, safety, and anatomical knowledge improved as a result of simulation.

CONCLUSIONS

Fresh tissue-based preoperative surgical rehearsal was effectively implemented in the residency program. Resident confidence and perception of technique improved. Survey results suggest that cadaveric simulation is beneficial for all levels of residents. We believe that implementation of preoperative surgical rehearsal is an effective adjunct to surgical training at all skill levels in the current environment of decreased work hours.

The Evolution of Surgical Simulation: The Current State and Future Avenues for Plastic Surgery Education

Alongside the ongoing evolution of surgical training toward a competency-based paradigm has come the need to reevaluate the role of surgical simulation in residency. Simulators offer the ability for trainees to acquire specific skills and for educators to objectively assess the progressive development of these skills. In this article, the authors discuss the historical evolution of surgical simulation, with a particular focus on its past and present role in plastic surgery education. The authors also discuss the future steps required to further advance plastic surgery simulation in an effort to continue to train highly competent plastic surgery graduates.

Evaluation of Three-Dimensional Versus Conventional Laparoscopy for Kidney Transplant Procedures in a Human Cadaveric Model

OBJECTIVES

There are increased reports that kidney transplant can be performed by laparoscopic surgery. The further development of this technique could revolutionize human kidney transplant surgery. However, laparoscopic kidney transplant demands a high level of skill for vascular anastomoses. The emerging technology of the three-dimensional, high-definition laparoscopic system may facilitate the application of this technique. Therefore, in this study, we evaluated this system in performing kidney transplant surgery versus the two-dimensional laparoscopic system.

MATERIALS AND METHODS

Four fresh-frozen human cadavers were used in this study, with 2 for the 3-dimensional and 2 for the 2-dimensional system. Kidneys were retrieved by using the retroperitoneoscopic technique for living donor nephrectomy from the same cadaver. The kidney graft was transplanted at the right iliac fossa using a laparoscopic technique by extraperitoneal approach. The procedure was recorded, and the vessel anastomotic time was analyzed.

RESULTS

Kidney transplant procedures were conducted successfully in the 3-dimensional, high-definition and the 2-dimensional groups. We recorded no significant differences in terms of vessel anastomotic time between the 2 groups. The total surgery time was shorter in the 3-dimensional, high-definition group than in the 2-dimensional group (P = .02).

CONCLUSIONS

This pilot study reinforces that kidney transplant with either the 3-dimensional, high-definition or 2-dimensional laparoscopy is feasible in a human cadaveric model. The operation was the same as open kidney transplant, but the procedure was performed by a laparoscopic approach with a smaller incision.

[Simulation in surgical training]

BACKGROUND

Patient safety during operations hinges on the surgeon's skills and abilities. However, surgical training has come under a variety of restrictions. To acquire dexterity with decreasingly "simple" cases, within the legislative time constraints and increasing expectations for surgical results is the future challenge.

OBJECTIVES

Are there alternatives to traditional master-apprentice learning?

MATERIALS AND METHODS

A literature review and analysis of the development, implementation, and evaluation of surgical simulation are presented.

RESULTS

Simulation, using a variety of methods, most important physical and virtual (computer-generated) models, provides a safe environment to practice basic and advanced skills without endangering patients. These environments have specific strengths and weaknesses.

CONCLUSIONS

Simulations can only serve to decrease the slope of learning curves, but cannot be a substitute for the real situation. Thus, they have to be an integral part of a comprehensive training curriculum. Our surgical societies have to take up that challenge to ensure the training of future generations.

Evaluation of Percutaneous First Annular Pulley Release: Efficacy and Complications in a Perfused Cadaveric Study

PURPOSE

Trigger finger is the most common entrapment tendinopathy, with a lifetime risk of 2% to 3%. Open surgical release of the flexor tendon sheath is a commonly performed procedure associated with a high rate of success. Despite reported success rates of over 94%, percutaneous trigger finger release (PFTR) remains a controversial procedure because of the risk of iatrogenic digital neurovascular injury. This study aimed to evaluate the safety and efficacy of traditional percutaneous and ultrasound (US)-guided first annular (A1) pulley releases performed on a perfused cadaveric model.

METHODS

First annular pulley releases were performed percutaneously using an 18-gauge needle in 155 digits (124 fingers and 31 thumbs) of un-embalmed cadavers with restored perfusion. A total of 45 digits were completed with US guidance and 110 digits were completed without it. Each digit was dissected and assessed regarding the amount of release as well as neurovascular, flexor tendon, and A2 pulley injury.

RESULTS

Overall, 114 A1 pulleys were completely released (74%). There were 38 partial releases (24%) and 3 complete misses (2%). No significant flexor tendon injury was seen. Longitudinal scoring of the flexor tendon was found in 35 fingers (23%). There were no lacerations to digital nerves and one ulnar digital artery was partially lacerated (1%) in a middle finger with a partial flexion contracture that prevented appropriate hyperextension. The ultrasound-assisted and blind PTFR techniques had similar complete pulley release and injury rates.

CONCLUSIONS

Both traditional and US-assisted percutaneous release of the A1 pulley can be performed for all fingers. Perfusion of cadaver digits enhances surgical simulation and evaluation of PTFR beyond those of previous cadaveric studies. The addition of vascular flow to the digits during percutaneous release allows for Doppler flow assessment of the neurovascular bundle and evaluation of vascular injury.

CLINICAL RELEVANCE

Our cadaveric data align with those of published clinical investigations for percutaneous A1 pulley release.