Preliminary evaluation of the pattern cutting and the ligating loop virtual laparoscopic trainers.

INTRODUCTION: The Fundamentals of Laparoscopic Surgery (FLS) trainer is currently the standard for training and evaluating basic laparoscopic skills. However, its manual scoring system is time-consuming and subjective. The Virtual Basic Laparoscopic Skill Trainer (VBLaST©) is the virtual version of the FLS trainer which allows automatic and real time assessment of skill performance, as well as force feedback. In this study, the VBLaST© pattern cutting (VBLaST-PC©) and ligating loop (VBLaST-LL©) tasks were evaluated as part of a validation study. We hypothesized that performance would be similar on the FLS and VBLaST© trainers, and that subjects with more experience would perform better than those with less experience on both trainers. METHODS: Fifty-five subjects with varying surgical experience were recruited at the Learning Center during the 2013 SAGES annual meeting and were divided into two groups: experts (PGY 5, surgical fellows and surgical attendings) and novices (PGY 1-4). They were asked to perform the PC or the ligating loop task on the FLS and the VBLaST© trainers. Their performance scores for each trainer were calculated and compared. RESULTS: There were no significant differences between the FLS and VBLaST© scores for either the PC or the ligating loop task. Experts' scores were significantly higher than the scores for novices on both trainers. CONCLUSION: This study showed that the subjects' performance on the VBLaST© trainer was similar to the FLS performance for both tasks. Both the VBLaST-PC© and the VBLaST-LL© tasks permitted discrimination between the novice and expert groups. Although concurrent and discriminant validity has been established, further studies to establish convergent and predictive validity are needed. Once validated as a training system for laparoscopic skills, the system is expected to overcome the current limitations of the FLS trainer.

Validation of the VBLaST peg transfer task: a first step toward an alternate training standard.

BACKGROUND: The FLS trainer lacks objective and automated assessments of laparoscopic performance and requires a large supply of relatively expensive consumables. Virtual reality simulation has a great potential as a training and assessment tool of laparoscopic skills and can overcome some limitations of the FLS trainer. This study was carried out to assess the value of our Virtual Basic Laparoscopic Surgical Trainer (VBLaST(©)) in the peg transfer task compared to the FLS trainer and its ability to differentiate performance between novice, intermediate, and expert groups. METHODS: Thirty subjects were divided into three groups: novices (PGY1-2, n = 10), intermediates (PGY3-4, n = 10), and experts (PGY5, surgical fellows and attendings, n = 10). All subjects performed ten trials of the peg transfer task on each simulator. Assessment of laparoscopic performance was based on FLS scoring while a questionnaire was used for subjective evaluation. RESULTS: The performance scores in the two simulators were correlated, though subjects performed significantly better in the FLS trainer. Experts performed better than novices only on the FLS trainer while no significant differences were observed between the other groups. Moreover, a significant learning effect was found on both trainers, with a greater improvement of performance on the VBLaST(©). Finally, 82.6% of the subjects preferred the FLS over the VBLaST(©) for surgical training which could be attributed to the novelty of the VR technology and existing deficiencies of the user interface for the VBLaST(©). CONCLUSION: This study demonstrated that the VBLaST(©) reproduced faithfully some aspects of the FLS peg transfer task (such as color, size, and shape of the peg board, etc.) while other aspects require additional development. Future improvement of the user interface and haptic feedback will enhance the value of the system as an alternative to the FLS as the standard training tool for laparoscopic surgery skills.

The added value of virtual reality technology and force feedback for surgical training simulators.

Laparoscopic surgery requires more specialized training of the surgeons than traditional open surgery. The Virtual Basic Laparoscopic Surgical Trainer (VBLaST) is being developed as a virtual version of the Fundamentals of Laparoscopic Skills (FLS) trainer. This study assessed the current haptic and virtual reality (VR) technology of a virtual peg transfer task of the VBLaST, based on the subjective preference of surgeons and their objective task performance measures. Twenty-one surgical residents, fellows and attendings performed a peg-transfer task in the FLS and the VBLaST. Each subject performed 10 trials on each simulator. Results showed that subjects performed significantly better on the FLS than on the VBLaST. Subjects showed a significant learning effect on both simulators, but with an accelerated improvement on the VBLaST. Even so, 81% of the subjects preferred the FLS over the VBLaST for surgical training which could be attributed to the novelty of the VR technology and existing deficiencies of the haptic interface. Despite the subjective preference for the physical simulator, the performance results indicate an added value of VR and haptics in surgical training, which is expected to be demonstrated in more surgically relevant tasks such as suturing and knot-tying.

Effect of haptic feedback in laparoscopic surgery skill acquisition.

BACKGROUND: The benefits of haptic feedback in laparoscopic surgery training simulators is a topic of debate in the literature. It is hypothesized that novice surgeons may not benefit from the haptic information, especially during the initial phase of learning a new task. Therefore, provision of haptic feedback to novice trainees in the early stage of training may be distracting and detrimental to learning. A controlled experiment was conducted to examine the effect of haptic feedback on the learning curve of a complex laparoscopic suturing and knot-tying task. METHODS: The ProMIS and the MIST-VR surgical simulators were used to represent conditions with and without haptic feedback, respectively. A total of 20 novice subjects (10 per simulator) were trained to perform suturing and knot-tying and practiced the tasks in 18 sessions of 1 h each. RESULTS: At the end of the 3-week training period, the subjects performed equally fast but more consistently with haptics (ProMIS) than without haptics (MIST-VR). The subjects showed a slightly higher learning rate and reached the first plateau of the learning curve earlier with haptic feedback. CONCLUSION: In general, learning with haptic feedback was significantly better than learning without it for a laparoscopic suturing and knot-tying task, but only during the first 5 h of training. Haptic feedback may not be warranted in laparoscopic surgical trainers. The benefits of a shorter time to the first performance plateau and more consistent initial performance should be balanced with the cost of implementing haptic feedback in surgical simulators.

Haptic Detection of Artificial Tumors by Hand and with a Tool in a MIS Environment.

Minimally invasive surgery uses optical cameras and special surgical tools in order to operate from an environment one step removed from the body cavity of interest to the surgeon. It has been suggested that constraints posed by this arrangement, in particular the lack of direct haptic feedback to the surgeon, may affect the surgeon's ability to identify tissues and accurately maneuver inside the body cavity. In the present study, the ability of laypeople to detect artificial tumors of various hardness values embedded in silicone gels was assessed in a simulated MIS environment. Participants explored the gels under three conditions all with remote viewing; using the unrestricted bare finger, using a stick-like surgical tool also unrestricted, and using the surgical tool restricted by its insertion through an operating port as in MIS. Participants were significantly more accurate and more efficient at tumor detection with the finger as compared to the other methods of exploration, and they were also better at detecting harder tumors as compared to softer ones. The potential implications of these results for the role of haptic perception in minimally invasive surgery are discussed.

Using a dynamic training environment to acquire laparoscopic surgery skill.

BACKGROUND: Current physical laparoscopic surgical simulators provide training only for static tasks, which do not develop the more advanced hand-eye coordination skills needed to navigate the dynamic surgical environment. A novel dynamic minimally invasive training environment (DynaMITE) was developed to address this need. This study aimed to evaluate further the utility of the system as a training and skill assessment tool. Two studies were performed with a second-generation design. The authors hypothesized that the dynamic task environment would be challenging to novices and would differentiate experienced surgeons from the inexperienced by emphasising the dynamic skills gained through surgical experience. METHODS: The participants in the first study were 42 novice and experienced surgeons attending the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) 2007 Learning Center, whereas the second controlled laboratory study had 16 participants (5 novices and 11 experienced surgeons). The participants performed two tasks: an aiming task and an object manipulation task. Both tasks were positioned on a dynamic platform that moved in five different trajectories. RESULTS: The subjective feedback from the surgeons at the SAGES Learning Center was positive. The results from the controlled study showed significant performance deterioration in the fast diagonal task compared with the task of aiming and manipulating in the static environment for both experience groups but no performance differences between the groups. CONCLUSIONS: Dynamic tasks are challenging, and surgeons need to be trained specifically for these tasks. The DynaMITE system can provide training benefits for dynamic skill development, even for expert surgeons who may have had no opportunity to gain these skills through their surgical practice.

Effects of experience on force perception threshold in minimally invasive surgery.

BACKGROUND: Distorted haptic feedback by the surgical instrumentation is a major problem in minimally invasive surgery (MIS). Friction force generated by the rubber seal in the trocars masks the haptic information needed to perceive the properties and structure of the target tissue, resulting in an increased haptic perception threshold in naïve subjects. This can lead to over application of forces in surgery. OBJECTIVE: This paper examines the effect of surgical experience on the psychophysics of force perception and force application efficiency in MIS. METHOD: A controlled experiment was conducted using a mixed design, with friction and vision as independent within-subjects factors, experience as a between-subjects factor, and applied force and detection time as dependent measures. Fourteen subjects (eight novices and six experienced surgeons) performed a simulated tissue probing task. Performance data were recorded by a custom-built force-sensing system. RESULTS: When friction was present, higher thresholds and longer detection times were observed for both experienced and inexperienced subjects. In all cases, experienced surgeons applied a greater force than novices, but were quicker to detect contact with tissue, resulting in higher force application efficiency. CONCLUSION: Surgeons seem to have adapted to the higher threshold in haptic perception by reacting faster, even while applying more force to the tissue, keeping within the limits of safety.

How much feedback is necessary for learning to suture?

BACKGROUND: Many laparoscopic simulation training systems exist and have been shown to transfer learning of surgical skills to the operating room. The manner in which the training is structured to maximize learning has not been examined. There are many aspects to the acquisition of laparoscopic skills during training, one of which is the availability of knowledge of results (KR). Knowledge of results is information about the outcome of motor skill execution, usually provided to individuals at the end of the execution. The timing and nature of KR can affect how well people learn new motor skills. In addition, detailed instruction during learning can also affect skill acquisition. We studied the effects of KR and instruction on the learning curve of a suturing and knot-tying task. We hypothesized that KR was necessary for skill acquisition, and that detailed instruction would help trainees to learn to perform the task more correctly and reach a performance plateau earlier. In addition, the overall workload of a trainee during training would decrease as skills improved, especially when KR and coaching were provided. METHODS: Nine medical students with no previous laparoscopic surgical experience were randomly and evenly divided into three groups with different KR conditions: (1) no KR, (2) KR, (3) KR + instruction. Each subject attended a training session for 1 h each day, 6 days a week for 4 consecutive weeks. Performance measures such as task time, smoothness of instrument, and path length were recorded for each trial. Workload was assessed using the NASA-TLX questionnaire. RESULTS: While KR was necessary for learning to suture, continual instruction had limited additional benefits. However, KR + instruction did reduce subjects' perceived overall workload. CONCLUSIONS: Surgical training could be carried out effectively with only knowledge of results. These results have implications for the staffing of surgical skills laboratories.

Guiding navigation in colonoscopy.

BACKGROUND: Nonrigid environments such as the human colon present unique challenges for the navigator in maintaining spatial orientation. Conventional wisdom suggests that a navigational aid, similar to a map, that provides critical shape information would be useful. This article presents a design concept for a colonoscopy navigational aid and the results of an experiment conducted to evaluate the display for supporting navigation and spatial orientation in simulated colonoscopy. METHODS: A navigational aid was designed to present shape information in an augmented reality display. A total of 14 untrained subjects performed a colonoscopy procedure in rigid and nonrigid colon models, with and without the navigational aid display, in a Latin square design. Performance measures such as time, distance or efficiency of travel, and location and direction error were recorded, together with subjective measures of confidence and workload. RESULTS: The results showed that, unlike navigating in rigid environments, the subjects spent more time navigating in the nonrigid environment (p < 0.01) and traveled a longer total distance (p = 0.01). The navigational aid had no effect on performance, as compared with the no aid condition. However, subjective measures showed that the subjects were more confident about their determination of location and direction (p < 0.01). They also preferred having the aid during navigation. CONCLUSION: A navigational aid or map that provides shape information does not seem to improve performance in colonoscopy. In fact, it may lead to a false sense of security about location and orientation in the colon. The value of a map for training purposes remains to be examined.

Comparison of the sensitivity of physical and virtual laparoscopic surgical training simulators to the user's level of experience.

BACKGROUND: The recent focus on quality of care and patient safety has been accompanied by increased interest in standardizing the training for laparoscopic surgeons. Studies have shown that laparoscopic simulators can be used to train surgical skills. Therefore, we designed an experiment to compare the effectiveness of two popular training systems. One system was based on a physical model, whereas the other used a virtual reality model. METHODS: A total of 32 medical students and residents were tested on both simulators. Time required for task completion and number of errors committed were recorded and compared. RESULTS: The physical training system differentiated among experience levels on three of the five tasks when time was used as a measure and four of five tasks when score was used, whereas the virtual reality system yielded statistically significant results in eight of 13 tasks for time and in five of 13 tasks for score. CONCLUSION: The physical model is more sensitive than the virtual reality one in detecting differences in levels of laparoscopic surgical experience.