Michael Minneti

Simulation of plastic surgery and microvascular procedures using perfused fresh human cadavers

INTRODUCTION Surgical simulation models are often limited by their lack of fidelity, which hinders their essential purpose, making a better surgeon. Fresh cadaveric tissue is a superior model of simulation owing to its approximation of live tissue. One major unresolved difference between dead and live tissue is perfusion. Here, we propose a means of enhancing the fidelity of cadaveric simulation through the development of a perfused cadaveric model whereby simulation is further able to approach life-like surgery and teach one of the more technically demanding skills of plastic surgery: microsurgery. METHOD Fresh tissue human cadavers were procured according to university protocol. Perfusion was performed via cannulation of large vessels, and arterial and venous pressure was maintained by centrifugal circulation. Skin perfusion was evaluated with incisions in the perfused regions and was evaluated using indocyanine green angiography. Surgical simulations were selected to broadly evaluate applicability to plastic surgical education. RESULT Surgical simulation of 38 procedures ranging in complexity from skin excisions to microsurgical cases was performed with high priority given to the accurate simulation of clinical procedures. Flap dissections included perforator flaps, muscle flaps, and fasciocutaneous flaps. Effective perfusion was noted with ICG angiography and notable bleeding vessels. Microsurgical flap transfer was successfully performed. CONCLUSION We report the establishment of a high fidelity surgical simulation using a perfused fresh tissue model in a realistic environment akin to the operating room. We anticipate utilization of this model prior to entering the operating room will enhance surgical ability and offer a valuable resource in plastic surgical education.

Central Venous Catheterization Using a Perfused Human Cadaveric Model: Application to Surgical Education

OBJECTIVE The purpose of this article is to present a unique training model using a perfused human cadaver for central line placement training with the ultimate goal of reducing central venous catheter mechanical complications. DESIGN The applicability of the fresh tissue cadaver model for central line placement was assessed using a 10-item questionnaire with a 5-point Likert-type scale. Respondents were asked to rate their opinions as strongly agree, agree, neutral, disagree, or strongly disagree. SETTING All participants received a didactic lecture followed by supervised practice on a commercially available simulator. The students were then relocated to the Fresh Tissue Dissection Laboratory where they practiced central vein catheterization on a fresh perfused human cadaver. PARTICIPANTS Course participants included 87 physicians from various medical specialties at different stages of training. RESULTS Results of the survey demonstrated that 91% of the participating physicians found the perfused cadaveric model to be a true simulation of conditions that exist in live patients, and 98% reported that the use of this model promoted acquisition of technical skills. CONCLUSION The integration of central line placement training on perfused cadavers into residency and fellowship training provides an unparalleled realistic simulation to participants. Further study is needed to assess whether realistic simulation translates into objective end points such as decreased mechanical complications.

Simulation of a high-flow extracranial-intracranial bypass using a radial artery graft in a novel fresh tissue model.

BACKGROUND: Microsurgical vascular anastomosis techniques are technically challenging and used in only a narrow spectrum of neurosurgical procedures. Opportunities for instruction and application have become increasingly rare during standard neurosurgery residencies. OBJECTIVE: To create a neurovascular simulation model that more closely approximates the clinical environment. This article describes a novel surgical model using vascular pressurization in a fresh cadaver to simulate an extracranial-to-intracranial bypass. METHODS: Fresh cadavers were obtained according to the standard operating procedures of the University of Southern California Fresh Tissue Dissection Laboratory. The femoral vessels were cannulated and the entire cadaver pressurized. A high-flow bypass from the common carotid artery to the middle cerebral artery was performed using a radial artery graft. RESULTS: This system has several advantages for neurosurgical simulation. The fresh tissue reproduces intraoperative haptics and anatomy. Extracranial-to-intracranial bypass is a physically demanding procedure and can become fatiguing and frustrating for beginners. This model more closely simulates clinical operative time and conditions. The surgeon is able to rehearse the steps and progression of the operation as opposed to simply focusing on the anastomosis. Surgeon positioning and microscope placement are often difficult for novices. By simulating the operating room conditions, these steps can be practiced, providing experience that can be directly translated to the clinical arena. CONCLUSION: Despite the decrease in frequency, indications for bypass procedures still exist in neurosurgery. The fresh tissue pressurization model offers significant benefits when training neurosurgeons to perform these technically demanding procedures. ABBREVIATIONS: EC-IC, extracranial-intracranial FTDL, Fresh Tissue Dissection Laboratory PVC, polyvinyl chloride

Incorporation of Fresh Tissue Surgical Simulation into Plastic Surgery Education: Maximizing Extraclinical Surgical Experience

BACKGROUND As interest in surgical simulation grows, plastic surgical educators are pressed to provide realistic surgical experience outside of the operating suite. Simulation models of plastic surgery procedures have been developed, but they are incomparable to the dissection of fresh tissue. We evolved a fresh tissue dissection (FTD) and simulation program with emphasis on surgical technique and simulation of clinical surgery. We hypothesized that resident confidence could be improved by adding FTD to our resident curriculum. METHODS Over a 5-year period, FTD was incorporated into the curriculum. Participants included clinical medical students, postgraduate year 1 to 7 residents, and attending surgeons. Participants performed dissections and procedures with structured emphasis on anatomical detail, surgical technique, and rehearsal of operative sequence. Resident confidence was evaluated using retrospective pretest and posttest analysis with a 5-point scale, ranging from 1 (least confident) to 5 (most confident). Confidence was evaluated according to postgraduate year level, anatomical region, and procedure. RESULTS A total of 103 dissection days occurred, and a total of 192 dissections were reported, representing 73 different procedures. Overall, resident predissection confidence was 1.90±1.02 and postdissection confidence was 4.20±0.94 (p<0.001). The average increase in confidence correlated with training year, such that senior residents had greater gains. When compared by anatomical region, confidence was lowest for the head and neck region. When compared by procedure, confidence was lowest for rhinoplasty and face-lift, and highest for radial forearm and latissimus flaps. CONCLUSIONS A high-volume FTD experience was successfully incorporated into the residency program over 5 years. Training with FTD improves resident confidence, and this effect increases with seniority of training. Although initial data demonstrate that resident confidence is improved with FTD, additional evaluation is needed to establish objective evidence that patient outcomes and surgical quality can be improved with FTD.

The impact of heat stress on operative performance and cognitive function during simulated laparoscopic operative tasks.

BACKGROUND Increasing ambient temperature to prevent intraoperative patient hypothermia remains widely advocated despite unconvincing evidence of efficacy. Heat stress is associated with decreased cognitive and psychomotor performance across multiple tasks but remains unexamined in an operative context. We assessed the impact of increased ambient temperature on laparoscopic operative performance and surgeon cognitive stress. STUDY DESIGN Forty-two performance measures were obtained from 21 surgery trainees participating in the counter-balanced, within-subjects study protocol. Operative performance was evaluated with adaptations of the validated, peg-transfer, and intracorporeal knot-tying tasks from the Fundamentals of Laparoscopic Surgery program. Participants trained to proficiency before enrollment. Task performance was measured at two ambient temperatures, 19 and 26°C (66 and 79°F). Participants were randomly counterbalanced to initial hot or cold exposure before crossing over to the alternate environment. Cognitive stress was measured using the validated Surgical Task Load Index (SURG-TLX). RESULTS No differences in performance of the peg-transfer and intracorporeal knot-tying tasks were seen across ambient conditions. Assessed via use of the six bipolar scales of the SURG-TLX, we found differences in task workload between the hot and cold conditions in the areas of physical demands (hot 10 [3-12], cold 5 [2.5-9], P = .013) and distractions (hot 8 [3.5-15.5], cold 3 [1.5-5.5], P = .001). Participant perception of distraction remained greater in the hot condition on full scoring of the SURG-TLX. CONCLUSION Increasing ambient temperature to levels advocated for prevention of intraoperative hypothermia does not greatly decrease technical performance in short operative tasks. Surgeons, however, do report increased perceptions of distraction and physical demand. The impact of these findings on performance and outcomes during longer operative procedures remains unclear.

Cerebrospinal fluid reconstitution via a perfusion-based cadaveric model: feasibility study demonstrating surgical simulation of neuroendoscopic procedures.

Cadaveric surgical simulation carries the advantage of realistic anatomy and haptic feedback but has been historically difficult to model for intraventricular approaches given the need for active flow of CSF. This feasibility study was designed to simulate intraventricular neuroendoscopic approaches and techniques by reconstituting natural CSF flow in a cadaveric model. In 10 fresh human cadavers, a simple cervical laminectomy and dural opening were made, and a 12-gauge arterial catheter was introduced. Saline was continuously perfused at physiological CSF pressures to reconstitute the subarachnoid space and ventricles. A neuroendoscope was subsequently inserted via a standard right frontal bur hole. In 8 of the 10 cadavers, adequate reconstitution and endoscopic access of the lateral and third ventricles were achieved. In 2 cadavers, ventricular access was not feasible, perhaps because of a small ventricle size and/or deteriorated tissue quality. In all 8 cadavers with successful CSF flow reconstitution and endoscopic access, identifying the foramen of Monro was possible, as was performing septum pellucidotomy and endoscopic third ventriculostomy. Furthermore, navigation of the cerebral aqueduct, fourth ventricle, prepontine cistern, and suprasellar cistern via the lamina terminalis was possible, providing a complementary educational paradigm for resident education that cannot typically be performed in live surgery. Surgical simulation plays a critical and increasingly prominent role in surgical education, particularly for techniques with steep learning curves including intraventricular neuroendoscopic procedures. This novel model provides feasible and realistic surgical simulation of neuroendoscopic intraventricular procedures and approaches.

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.

Perfusion-based human cadaveric specimen as a simulation training model in repairing cerebrospinal fluid leaks during endoscopic endonasal skull base surgery

OBJECTIVE Competency in endoscopic endonasal approaches (EEAs) to repair high-flow cerebrospinal fluid (CSF) leaks is an essential component of the neurosurgical training process. The objective of this study was to demonstrate the feasibility of a simulation model for EEA repair of anterior skull base CSF leaks. METHODS Human cadaveric specimens were utilized with a perfusion system to simulate a high-flow CSF leak. Neurological surgery residents (postgraduate year 3 or greater) performed a standard EEA to repair a CSF leak using a combination of fat, fascia lata, and pedicled nasoseptal flaps. A standardized 5-point Likert questionnaire was used to assess the knowledge gained, techniques learned, degree of safety, benefit of CSF perfusion during repair, and pre- and posttraining confidence scores. RESULTS Intrathecal perfusion of fluorescein-infused saline into the ventricular/subarachnoid space was successful in 9 of 9 cases. The addition of CSF reconstitution offered the residents visual feedback for confirmation of intraoperative CSF leak repair. Residents gained new knowledge and a realistic simulation experience by rehearsing the psychomotor skills and techniques required to repair a CSF leak with fat and fascial grafts, as well as to prepare and rotate vascularized nasoseptal flaps. All trainees reported feeling safer with the procedure in a clinical setting and higher average posttraining confidence scores (pretraining 2.22 ± 0.83, posttraining 4.22 ± 0.44, p < 0.001). CONCLUSIONS Perfusion-based human cadaveric models can be utilized as a simulation training model for repairing CSF leaks during EEA.

Pressurized Cadaver Model in Cardiothoracic Surgical Simulation

Simulation is increasingly recognized as an integral aspect of thoracic surgery education. A number of simulators have been introduced to teach component cardiothoracic skills; however, no good model exists for numerous essential skills including redo sternotomy and internal mammary artery takedown. These procedures are often relegated to thoracic surgery residents but have significant negative implications if performed incorrectly. Fresh tissue dissection is recognized as the gold standard for surgical simulation, but the lack of circulating blood volume limits surgical realism. Our aim is to describe the technique of the pressurized cadaver for use in cardiothoracic surgical procedures, focusing on internal mammary artery takedown.

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.