Natural orifice translumenal endoscopic surgery (NOTES): emerging trends and specifications for a virtual simulator

Transvaginal laparoscopic appendectomy using innovative submucosal tunnels: a conducive modification for improving hybrid NOTES access and its critical appraisal

Currently, transvaginal natural orifice transluminal endoscopic surgery (NOTES), the most minimally invasive option for laparoscopic surgery, suffers various technological restraints limiting its implementation. We discuss a simple modification for vaginal access to improve the existing hybrid NOTES technique. We retrospectively studied 18 women at our rural hospital in central India, who, under defined criteria, underwent transvaginal appendicectomy using innovative strategically designed submucosal tunnels. The procedure was successfully completed in all but the first three cases. None required additional abdominal trocar or analgesia beyond the first 6 h. The mean operative and hospitalisation times were 27.5 min and 18.5 h, respectively. We had no intraoperative complications and only one patient experienced postoperative self-limiting vaginal spotting. All patients were very pleased with the cosmetic results and sexual life as assessed by locally devised scales. On regular follow-up, all were progressing well. We recommend the method presented, as it is not only feasible and safe but has the potential to improve overall results. Clearly, a larger volume randomised trial would be optimal to confirm our conclusion.

Validation of NOViSE

The goal of this study was to establish face, content, and construct validity of NOViSE—the first force-feedback enabled virtual reality (VR) simulator for natural orifice transluminal endoscopic surgery (NOTES). Fourteen surgeons and surgical trainees performed 3 simulated hybrid transgastric cholecystectomies using a flexible endoscope on NOViSE. Four of them were classified as “NOTES experts” who had independently performed 10 or more simulated or human NOTES procedures. Seven participants were classified as “Novices” and 3 as “Gastroenterologists” with no or minimal NOTES experience. A standardized 5-point Likert-type scale questionnaire was administered to assess the face and content validity. NOViSE showed good overall face and content validity. In 14 out of 15 statements pertaining to face validity (graphical appearance, endoscope and tissue behavior, overall realism), ≥50% of responses were “agree” or “strongly agree.” In terms of content validity, 85.7% of participants agreed or strongly agreed that NOViSE is a useful training tool for NOTES and 71.4% that they would recommend it to others. Construct validity was established by comparing a number of performance metrics such as task completion times, path lengths, applied forces, and so on. NOViSE demonstrated early signs of construct validity. Experts were faster and used a shorter endoscopic path length than novices in all but one task. The results indicate that NOViSE authentically recreates a transgastric hybrid cholecystectomy and sets promising foundations for the further development of a VR training curriculum for NOTES without compromising patient safety or requiring expensive animal facilities.

Graphic and haptic simulation for transvaginal cholecystectomy training in NOTES

BACKGROUND

Natural Orifice Transluminal Endoscopic Surgery (NOTES) provides an emerging surgical technique which usually needs a long learning curve for surgeons. Virtual reality (VR) medical simulators with vision and haptic feedback can usually offer an efficient and cost-effective alternative without risk to the traditional training approaches. Under this motivation, we developed the first virtual reality simulator for transvaginal cholecystectomy in NOTES (VTEST™).

METHODS

This VR-based surgical simulator aims to simulate the hybrid NOTES of cholecystectomy. We use a 6DOF haptic device and a tracking sensor to construct the core hardware component of simulator. For software, an innovative approach based on the inner-spheres is presented to deform the organs in real time. To handle the frequent collision between soft tissue and surgical instruments, an adaptive collision detection method based on GPU is designed and implemented. To give a realistic visual performance of gallbladder fat tissue removal by cautery hook, a multi-layer hexahedral model is presented to simulate the electric dissection of fat tissue.

RESULTS

From the experimental results, trainees can operate in real time with high degree of stability and fidelity. A preliminary study was also performed to evaluate the realism and the usefulness of this hybrid NOTES simulator.

CONCLUSIONS

This prototyped simulation system has been verified by surgeons through a pilot study. Some items of its visual performance and the utility were rated fairly high by the participants during testing. It exhibits the potential to improve the surgical skills of trainee and effectively shorten their learning curve.