ELITE -Theex vivotraining unit for NOTES: Development and Validation

Esophageal bougination: a novel ex vivo endoscopic training model correlated with clinical data

BACKGROUND

Esophageal bougination is a worldwide standard endoscopic procedure. Clinical methods and recommendations are based on clinical experiences only. Mechanical properties have never been described. Aim of the study was to establish a realistic ex vivo training model. Therefore, detailed assessment of relevant mechanical features of esophageal bougination should be evaluated ex vivo and in patient setting and correlated against.

PATIENTS AND METHODS

A three-step concept was used to evaluate mechanical properties at stenosis level. First, insertion forces were evaluated in an ex vivo linear single stenosis model during steady mechanical insertion. Second, adding friction and properties of the pharynx and upper esophagus, the model was integrated in an artificial endoscopic training model (ELITE training model). Third, in vivo measurements were taken to correlate ex vivo data with parameters of a realistic patient setting.

RESULTS

With the presented setup, we were able to assess insertion force and pressure levels in an artificial stricture using different sizes of commercially available standard bougies. In all models, there was a relevant increase in insertion force with higher stricture pressure levels. Insertion force levels in the ELITE model show higher levels compared to the linear stenosis model. Having regard to the maximum forces in patients, there is also a constant increase in mean insertion force according to higher bougie sizes, but lower forces were measured as in the ELITE model.

DISCUSSION

The applied models are suitable to appraise mechanical properties of esophageal bougination in an ex vivo model and patient setting. Forces could be constituted reliable, significant increase was documented according to stenosis level and results were comparable to patient data. This was comparable to patient data. Further clinical evaluation in different kinds of stenosis is necessary.

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.

Face and content validation of a Virtual Translumenal Endoscopic Surgery Trainer (VTEST™)

BACKGROUND

Natural orifice translumenal endoscopic surgery (NOTES) is an emerging surgical paradigm, where peritoneal access is achieved through one of the natural orifices of the body. It is being reported as a safe and feasible surgical technique with significantly reduced external scarring. Virtual Translumenal Endoscopic Surgical Trainer (VTEST™) is the first virtual reality simulator for the NOTES. The VTEST™ simulator was developed to train surgeons in the hybrid transvaginal NOTES cholecystectomy procedure. The initial version of the VTEST™ simulator underwent face validation at the 2013 Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR) summit. Several areas of improvement were identified as a result, and the corresponding modifications were implemented in the simulator. This manuscript outlines the results of the subsequent evaluation study, performed in order to assess the face and content validity of the latest VTEST™ simulator.

METHODS

Twelve subjects participated in an institutional review board-approved study that took place at the 2014 NOSCAR summit. Six of the 12 subjects, who are experts with NOTES experience, were used for face and content validation. The subjects performed the hybrid transvaginal NOTES cholecystectomy procedure on VTEST™ that included identifying the Calot's triangle, clipping and cutting the cystic duct/artery, and detaching the gallbladder. The subjects then answered five-point Likert scale feedback questionnaires for face and content validity.

RESULTS

Overall, subjects rated 12/15 questions as 3.0 or greater (60 %), for face validity questions regarding the realism of the anatomical features, interface, and the tasks. Subjects also highly rated the usefulness of the simulator in learning the fundamental NOTES technical skills (3.50 ± 0.84). Content validity results indicate a high level of usefulness of the VTEST™ for training prior to operating room experience (4.17 ± 0.75).

Pre-clinical Training for New Notes Procedures: From Ex-vivo Models to Virtual Reality Simulators

Natural orifice transluminal endoscopic surgery (NOTES) is a newer field of endoscopic surgery that allows for scarless treatment of pathologic entities, using novel transluminal approaches. There has been a shift of focus from a clinical and research standpoint from the development and dissemination of "first-generation" NOTES procedures to "new NOTES" procedures that traverse the mucosa of luminal structures, yet do not stray far into the peritoneal cavity. It has been a challenge to find appropriate and effective ways to train gastroenterologists and surgeons in these novel approaches. We review the importance of simulation in training and discuss available simulation options.

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

INTRODUCTION AND STUDY AIM

A virtual translumenal endoscopic surgical trainer (VTEST) is being developed to accelerate the development of natural orifice translumenal endoscopic surgery (NOTES) procedures and devices in a safe and risk-free environment. For a rapidly developing field such as NOTES, a needs analysis must be conducted regularly to discover emerging research trends and areas of potential high impact for a virtual simulator. This paper presents a survey-based study which follows a similar study conducted by this group in 2011 (Sankaranarayanan et al. in Surg Endosc 27:1607-1616, 2013).

METHODS

A 32-point questionnaire was distributed at the 2012 Natural Orifice Surgery Consortium for Assessment and Research annual meeting. These data were subsequently augmented by an identical online survey, targeted at the members of the American Society for Gastrointestinal Endoscopy and the Society of American Gastrointestinal and Endoscopic Surgeons, and analyzed.

RESULTS

Twenty-eight NOTES experts participated in the 2012 study. Cholecystectomy (CE) procedure remained the most commonly performed NOTES technique, with 18 positive responses (64%). In contrast to 2011, the popularity of the NOTES appendectomy (AE) was significantly lower, with only 2 (7%) instances (CE vs. AE, p < 0.001), while the number of peroral endoscopic myotomy (POEM, PE) cases had increased significantly, with 11 (39%) positive responses, respectively (PE vs. AE, p = 0.013). Strong preference toward hybrid rather than pure NOTES techniques (82 vs. 11%, p < 0.001) was also expressed. Other responses were similar to those in the 2011 study, with the VTEST™ utility in developing and testing new techniques and instruments ranked particularly high.

CONCLUSION

Based on the results of this study, a decision was made to focus exclusively on the transvaginal hybrid NOTES cholecystectomy procedure, including both rigid and flexible scope techniques. The importance of developing a virtual NOTES simulator was reaffirmed, with POEM identified as a promising candidate for future simulator development.

OpenHELP (Heidelberg laparoscopy phantom): development of an open-source surgical evaluation and training tool

Background

Apart from animal testing and clinical trials, surgical research and laparoscopic training mainly rely on phantoms. The aim of this project was to design a phantom with realistic anatomy and haptic characteristics, modular design and easy reproducibility. The phantom was named open-source Heidelberg laparoscopic phantom (OpenHELP) and serves as an open-source platform.

Methods

The phantom was based on an anonymized CT scan of a male patient. The anatomical structures were segmented to obtain digital three-dimensional models of the torso and the organs. The digital models were materialized via rapid prototyping. One flexible, using an elastic abdominal wall, and one rigid method, using a plastic shell, to simulate pneumoperitoneum were developed. Artificial organ production was carried out sequentially starting from raw gypsum models to silicone molds to final silicone casts. The reproduction accuracy was exemplarily evaluated for ten silicone rectum models by comparing the digital 3D surface of the original rectum with CT scan by calculating the root mean square error of surface variations. Haptic realism was also evaluated to find the most realistic silicone compositions on a visual analog scale (VAS, 0–10).

Results

The rigid and durable plastic torso and soft silicone organs of the abdominal cavity were successfully produced. A simulation of pneumoperitoneum could be created successfully by both methods. The reproduction accuracy of ten silicone rectum models showed an average root mean square error of 2.26 (0–11.48) mm. Haptic realism revealed an average value on a VAS of 7.25 (5.2–9.6) for the most realistic rectum.

Conclusion

The OpenHELP phantom proved to be feasible and accurate. The phantom was consecutively applied frequently in the field of computer-assisted surgery at our institutions and is accessible as an open-source project at www.open-cas.org for the academic community.

Endoscopic horizon stabilization in natural orifice translumenal endoscopic surgery: a randomized controlled trial

BACKGROUND

Spatial orientation in natural orifice translumenal endoscopic surgery (NOTES) has been identified as a potential barrier to clinical application. We aim to evaluate a triaxial inertial sensor and software that automatically corrects any movements on the roll axis of the flexible endoscope, allowing for stabilization of the image horizon during NOTES operations in a randomized controlled trial.

METHODS

A total of 18 participants (11 surgeons/7 gastroenterologists) performed a transgastric task in the ELITE simulator, which included navigation to the appendix and gallbladder, diathermy of the appendix base and gallbladder fossa, and clipping of the cystic duct using a single-channel gastroscope. Each participant performed the task twice with randomization to horizon stabilization occurring at the second attempt. The primary end point was change in overall performance (time taken and errors made) between the first and second attempt, and secondary end points were absolute performances in the second attempt and subjective evaluation.

RESULTS

Without horizon stabilization, there was a median improvement of 42.4% in time taken and 38% in number of errors made from the first to the second attempt; however, with the software turned on, there was a statistically significant deterioration of 4.9% (P = .038) in time taken and an increase in errors made of 183% (P = ns).

CONCLUSIONS

Although the software corrects the view to that preferred during surgery, the endoscopic control mechanism as well as the exit point of the instrument are altered in this process, leading to a deterioration of overall performance. Potential solutions include deploying intermittent horizon stabilization or using a robotic interface to achieve fully aligned perceptual-motor control.

A randomized controlled trial evaluating endoscopic and laparoscopic training in skills transfer for novices performing a simulated NOTES task

BACKGROUND

The NOSCAR white paper lists training as an important step to the safe clinical application of natural orifice translumenal endoscopic surgery (NOTES). The aim of this randomized controlled trial was to evaluate whether training novices in either a laparoscopic or endoscopic simulator curriculum would affect performance in a NOTES simulator task.

METHODS

A total of 30 third-year medical undergraduates were recruited. They were randomized to 3 groups: no training (control; n = 10), endoscopy training on a validated colonoscopy simulator protocol (n = 10), and training on a validated laparoscopy simulator curriculum (n = 10). All participants subsequently completed a simulated NOTES task, consisting of 7 steps, on the ELITE (endoscopic-laparoscopic interdisciplinary training entity) model. Performance was assessed as time taken to complete individual steps, overall task time, and number of errors.

RESULTS

The endoscopy group was significantly faster than the control group at accessing the peritoneal cavity through the gastric incision (median 27 vs 78 s; P = .015), applying diathermy to the base of the appendix (median 103.5 vs 173 s; P = .014), and navigating to the gallbladder (median 76 vs 169.5 s; P = .049). Endoscopy participants completed the full NOTES procedure in a shorter time than the laparoscopy group (median 863 vs 2074 s; P < .001).

CONCLUSION

This study highlights the importance of endoscopic training for a simulated NOTES task that involves both navigation and resection with operative maneuvers. Although laparoscopic training confers some benefit for operative steps such as applying diathermy to the gallbladder fossa, this was not as beneficial as training in endoscopy.

Education and training in NOTES: a systematic review

INTRODUCTION

Since the first published work on natural orifice translumenal endoscopic surgery (NOTES) a decade ago, progress has been made in the domain of education and training, although questions posed by the original White Paper remain. This article aims to review the current status of education and training in NOTES.

METHODS

A review of the literature was conducted to evaluate the following: (1) What are the current training methods/modalities used for NOTES; what is the level of evidence to support their use? (2) How has NOTES clinical training been quantified; what is the evidence relating to performance of different NOTES operators? (3) What clinical NOTES training programs have been established and what are the wider training needs?

RESULTS

A total of 25 studies were included: 11 nonanimal studies, 8 animal studies, and 6 descriptions of education programs. Several animal and simulator models demonstrated construct validity, but no study showed human predictive validity. Logarithmic learning curves in animal models demonstrate 10 to 15 cases achieving a proficiency level. Current trends are that gastroenterologists prefer it for diagnostic and basic procedures, whereas surgeons prefer it for complex therapeutic cases.

CONCLUSION

The development of a new specialty is intriguing but currently unviable. Training programs have been initiated, but information is limited; the common theme is surgeons receiving endoscopic training. Despite the research done, our knowledge of training and educating in NOTES procedures is limited, preventing a meta-analysis or formal review from being performed. Further research is needed to integrate NOTES into routine clinical procedure.

Needs analysis for developing a virtual-reality NOTES simulator

INTRODUCTION AND STUDY AIM: Natural orifice translumenal endoscopic surgery (NOTES) is an emerging surgical technique that requires a cautious adoption approach to ensure patient safety. High-fidelity virtual-reality-based simulators allow development of new surgical procedures and tools and train medical personnel without risk to human patients. As part of a project funded by the National Institutes of Health, we are developing the virtual transluminal endoscopic surgery trainer (VTEST) for this purpose. The objective of this study is to conduct a structured needs analysis to identify the design parameters for such a virtual-reality-based simulator for NOTES.

METHODS

A 30-point questionnaire was distributed at the 2011 National Orifice Surgery Consortium for Assessment and Research meeting to obtain responses from experts. Ordinal logistic regression and the Wilcoxon rank-sum test were used for analysis.

RESULTS

A total of 22 NOTES experts participated in the study. Cholecystectomy (CE, 68 %) followed by appendectomy (AE, 63 %) (CE vs AE, p = 0.0521) was selected as the first choice for simulation. Flexible (FL, 47 %) and hybrid (HY, 47 %) approaches were equally favorable compared with rigid (RI, 6 %) with p < 0.001 for both FL versus RI and HY versus RI. The transvaginal approach was preferred 3 to 1 to the transgastric. Most participants preferred two-channel (2C) scopes (65 %) compared with single (1C) or three (3C) or more channels with p < 0.001 for both 2C versus 1C and 2C versus 3C. The importance of force feedback and the utility of a virtual NOTES simulator in training and testing new tools for NOTES were rated very high by the participants.

CONCLUSION

Our study reinforces the importance of developing a virtual NOTES simulator and clearly presents expert preferences. The results of this analysis will direct our initial development of the VTEST platform.

Simulation in surgical education

The pedagogical approach to surgical training has changed significantly over the past few decades. No longer are surgical skills solely acquired through a traditional apprenticeship model of training. The acquisition of many technical and nontechnical skills is moving from the operating room to the surgical skills laboratory through the use of simulation. Many platforms exist for the learning and assessment of surgical skills. In this article, the authors provide a broad overview of some of the currently available surgical simulation modalities including bench-top models, laparoscopic simulators, simulation for new surgical technologies, and simulation for nontechnical surgical skills.