Characterizing and Simulating Needle Insertion Forces for Percutaneous Renal Access.

BACKGROUND: Percutaneous needle access is a critical step of performing percutaneous nephrolithotomy. Development of a synthetic model that accurately represents the forces encountered while gaining percutaneous renal access, allows for high ease of use and prevention of negative skill transfer. The objectives of this study were to define the needle insertion forces used during percutaneous renal access and to develop a multilayer synthetic physical simulator model based on human tissue data that is compatible with the SimPORTAL fluoro-less C-arm trainer (CAT) camera system. MATERIALS AND METHODS: Needle insertion data were collected using in situ fresh human cadaveric tissue within 72 hours of death. Ultrasound guidance was used to place percutaneous reference needles into the kidney, and axial force vs displacement data was collected using a custom-built force measurement device. A novel multilayer model that includes several types of synthetic materials for simulation of distinct tissue layers was developed based on the human tissue reference data. The multilayer prototype model and an existing single material model were subsequently tested using the same needle insertion protocol and the results were compared with human tissue data. RESULTS: Average maximum forces for needle puncture into skin ranged from 2.75 to 2.80 N for human tissue and from 4.53 to 4.19 N for simulated human tissue. The overall slope for all force vs displacement data was 0.35 to 0.59 N/cm for human tissue. The overall slope was comparatively lower for the multilayer model (0.17 N/cm) and was highest in the existing single material model (5.08-9.79 N/cm). CONCLUSIONS: We have defined the forces for percutaneous renal access using fresh human cadaveric tissue and designed a multilayer synthetic simulator model that can be utilized for training percutaneous needle access to the renal collecting system using the CAT camera system.

Feasibility of a perfused and ventilated cadaveric model for assessment of lifesaving traumatic hemorrhage and airway management skills.

BACKGROUND: Training health care providers to manage common life-threatening traumatic injuries is an important endeavor. A fresh perfused cadaveric model with high anatomic and tissue fidelity was developed to assess performance of hemorrhage and airway management skills during a simulated polytrauma scenario. METHODS: Fresh human cadavers were obtained within 96 hours of death. Hemorrhage from a right traumatic amputation and left inguinal wound was simulated using cannulation of the right popliteal and left femoral artery, respectively. The thoracic aorta (thoracotomy method) or external iliac arteries (Pfannenstiel method) were used for catheter access points. Lung ventilation to simulate chest rise and fall was achieved using bilateral chest tubes connected to a bag valve mask. Participants underwent a simulated nighttime field care scenario in which they attempted tourniquet placement, direct wound pressure and packing, and endotracheal intubation. RESULTS: Twenty-four donors were obtained (58-95 years old; mean, 77). There were 305 total scenarios completed using 23 cadavers (mean, approximately 13 scenarios per cadaver). The cost for acquisition and preparation of donors can be estimated at $3,611 to $9,399. CONCLUSION: This model successfully allowed for the demonstration of hemorrhage and airway management skills with high anatomic and tissue fidelity. For the assessment of critical lifesaving skills that are nondestructive in nature, the use of a fresh perfused cadaveric model is feasible and suitable for evaluation of these procedures.

Preliminary evaluation of the SimPORTAL major vessel injury (MVI) repair model.

BACKGROUND: Major vessel injury (MVI) is a dangerous complication associated with laparoscopic surgery that leads, if not properly handled, to blood loss, conversion to open surgery, and eventually death. In this paper, we describe the preliminary evaluation of the SimPORTAL MVI model, created with the goal of simulating an intra-corporeal injury to a large vessel. METHODS: For this study, we created MVI models for 17 residents (PGY 1-4). Each resident was asked to perform an intracorporeal knot on a penrose drain within a maximum time limit of 6 min (in accordance with European basic laparoscopic urological skills rules) and then to subsequently repair a vessel injury on the MVI model, which was perfused with synthetic blood, within a maximum blood loss of 3 L. During the vessel repair, low lights and pulse sounds were used to simulate the operating room environment. All participants filled out a survey pre- and post-task to score various aspects of the model. RESULTS: We successfully created a model that simulates a critical surgical event. None of the participants reported having previous experience repairing a MVI. Six participants were able to perform the intracorporeal knot, and 12 residents (70.5%) were able to repair the MVI model under the given time and blood loss limits. Eleven participants agreed that the MVI model behaves like a real vessel, and six felt to be capable of performing the task prior to attempting it. Sixteen participants thought that the MVI model should be part of laparoscopic curriculums during residency. CONCLUSIONS: The SimPORTAL MVI model is a feasible low-cost model that would be well appreciated as a part of laparoscopic curriculum for residents. Minor improvements, including pressure measurement in the vessel for task assessment, will be made in the future, and further studies are necessary to definitively validate this model.

Multi-Institutional Validation of an OSATS for the Assessment of Cystoscopic and Ureteroscopic Skills.

PURPOSE: We evaluated the internal and construct validity of an assessment tool for cystoscopic and ureteroscopic cognitive and psychomotor skills at a multi-institutional level. MATERIALS AND METHODS: Subjects included a total of 30 urology residents at Ohio State University, Columbus, Ohio; Penn Presbyterian Medical Center, Philadelphia, Pennsylvania; and Mayo Clinic, Rochester, Minnesota. A single external blinded reviewer evaluated cognitive and psychomotor skills associated with cystoscopic and ureteroscopic surgery using high fidelity bench models. Exercises included navigation, basketing and relocation; holmium laser lithotripsy; and cystoscope assembly. Each resident received a total cognitive score, checklist score and global psychomotor skills score. Construct validity was assessed by calculating correlations between training year and performance scores (both cognitive and psychomotor). Internal validity was confirmed by calculating correlations between test components. RESULTS: The median total cognitive score was 91 (IQR 86.25, 97). For psychomotor performance residents had a median total checklist score of 7 (IQR 5, 8) and a median global psychomotor skills score of 21 (IQR 18, 24.5). Construct validity was supported by the positive and statistically significant correlations between training year and total cognitive score (r = 0.66, 95% CI 0.39-0.82, p = 0.01), checklist scores (r = 0.66, 95% CI 0.35-0.84, p = 0.32) and global psychomotor skills score (r = 0.76, 95% CI 0.55-0.88, p = 0.002). The internal validity of OSATS was supported since total cognitive and checklist scores correlated with the global psychomotor skills score. CONCLUSIONS: In this multi-institutional study we successfully demonstrated the construct and internal validity of an objective assessment of cystoscopic and ureteroscopic cognitive and technical skills, including laser lithotripsy.

Validity and acceptability of a high-fidelity physical simulation model for training of laparoscopic pyeloplasty.

PURPOSE: The objective was to determine the acceptability and preliminary construct validity for a high-fidelity synthetic renal pelvis/ureter tissue analogue model for use as a simulation model for training of laparoscopic pyeloplasty. MATERIALS AND METHODS: The pyeloplasty model was designed with incorporated assessment lines for use in post-task Black Light Assessment of Surgical Technique (BLAST)™. Practicing urologists participating in the 2011 and 2012 American Urological Association Mentored Renal Laparoscopy courses performed a simulated laparoscopic pyeloplasty procedure and completed a post-task evaluation of the model. RESULTS: Practicing urologists found the model acceptable and rated the model favorably in terms of content and face validity. Urologists who had performed a laparoscopic pyeloplasty procedure in the last 5 years outperformed those who had not by demonstrating increased patency (P<0.05), decreased twisting (P<0.05), and decreased leakage (P<0.10) at the anastomosis. CONCLUSIONS: The BLAST™ pyeloplasty model demonstrated evidence of acceptability and content, face, and construct validity for training practicing urologists to perform laparoscopic pyeloplasty.

Validation study of a computer-based open surgical trainer: SimPraxis(®) simulation platform.

BACKGROUND: Technological advances have dramatically changed medical education, particularly in the era of work-hour restrictions, which increasingly highlights a need for novel methods to teach surgical skills. The purpose of this study was to evaluate the validity of a novel, computer-based, interactive, cognitive simulator for training surgeons to perform pelvic lymph node dissection (PLND). METHODS: Eight prostate cancer experts evaluated the content of the simulator. Contextual aspects of the simulator were rated on a five-point Likert scale. The experts and nine first-year residents completed a simulated PLND. Time and deviations were logged, and the results were compared between experts and novices using the Mann-Whitney test. RESULTS: Before training, 88% of the experts felt that a validated simulator would be useful for PLND training. After testing, 100% of the experts felt that it would be more useful than standard video training. Eighty-eight percent stated that they would like to see the simulator in the curriculum of residency programs and 56% thought it would be useful for accreditation purposes. The experts felt that the simulator aided in overall understanding, training indications, concepts and steps of the procedure, training how to use an assistant, and enhanced the knowledge of anatomy. Median performance times taken by experts and interns to complete a PLND procedure on the simulator were 12.62 and 23.97 minutes, respectively. Median deviation from the incorporated procedure pathway for experts was 24.5 and was 89 for novices. CONCLUSION: We describe an interactive, computer-based simulator designed to assist in mastery of the cognitive steps of an open surgical procedure. This platform is intuitive and flexible, and could be applied to any stepwise medical procedure. Overall, experts outperformed novices in their performance on the trainer. Experts agreed that the content was acceptable, accurate, and representative.

Introduction and validation of the American Urological Association Basic Laparoscopic Urologic Surgery skills curriculum.

BACKGROUND AND PURPOSE: The Fundamentals of Laparoscopic Surgery (FLS(™)) skills curriculum has validity evidence supporting use for assessing laparoscopic skills for general surgeons. As charged by the American Urological Association (AUA) Laparoscopy, Robotic, and New Surgical Technology Committee, we sought to develop and validate a urology-specific FLS, referred to as the Basic Laparoscopic Urologic Surgery (BLUS(©)) skills curriculum. The psychomotor component consists of three existing FLS tasks and one new clip-applying task. MATERIALS AND METHODS: An animate renal artery model was designed for a clip-applying skills task. We assessed the acceptability and construct validity of using BLUS for basic laparoscopic skills assessment for urologists. A cohort of practicing urologists, fellows, residents, and medical students completed the tasks at the AUA Annual Meetings in 2010 and 2011. RESULTS: All exercises were acceptable and demonstrated excellent face and content validity (>4.5/5 on a five-point Likert scale). Practicing clinical urologists (N=81) outperformed residents and medical students (N=35) in time to completion of circle cut (P<0.01) and in keeping scissor tips toward the center of the circle (P<0.01). Practicing urologists who reported >3 laparoscopic procedures per week were faster at the peg-transfer exercise (P<0.05) and the cutting exercise (P<0.01) than those reporting one to two procedures. More errors were committed for clip-applying among practicing urologists who perform one to two laparoscopic procedures (1.24) vs. those who perform >3 procedures (0.57) per week (P<0.01). CONCLUSIONS: All exercises including the novel clip-applying model demonstrated good acceptability and evidence of construct validity (face, content, concurrent and convergent validity) for assessment of basic laparoscopic skill for urologic surgeons.