Achieving Interface and Environment Fidelity in the Virtual Basic Laparoscopic Surgical Trainer

Virtual reality trainers are educational tools with great potential for laparoscopic surgery. They can provide basic skills training in a controlled environment and free of risks for patients. They can also offer objective performance assessment without the need for proctors. However, designing effective user interfaces that allow the acquisition of the appropriate technical skills on these systems remains a challenge. This paper aims to examine a process for achieving interface and environment fidelity during the development of the Virtual Basic Laparoscopic Surgical Trainer (VBLaST). Two iterations of the design process were conducted and evaluated. For that purpose, a total of 42 subjects participated in two experimental studies in which two versions of the VBLaST were compared to the accepted standard in the surgical community for training and assessing basic laparoscopic skills in North America, the FLS box-trainer. Participants performed 10 trials of the peg transfer task on each trainer. The assessment of task performance was based on the validated FLS scoring method. Moreover, a subjective evaluation questionnaire was used to assess the fidelity aspects of the VBLaST relative to the FLS trainer. Finally, a focus group session with expert surgeons was conducted as a comparative situated evaluation after the first design iteration. This session aimed to assess the fidelity aspects of the early VBLaST prototype as compared to the FLS trainer. The results indicate that user performance on the earlier version of the VBLaST resulting from the first design iteration was significantly lower than the performance on the standard FLS box-trainer. The comparative situated evaluation with domain experts permitted us to identify some issues related to the visual, haptic and interface fidelity on this early prototype. Results of the second experiment indicate that the performance on the second generation VBLaST was significantly improved as compared to the first generation and not significantly different from that of the standard FLS box-trainer. Furthermore, the subjects rated the fidelity features of the modified VBLaST version higher than the early version. These findings demonstrate the value of the comparative situated evaluation sessions entailing hands on reflection by domain experts to achieve the environment and interface fidelity and training objectives when designing a virtual reality laparoscopic trainer. This suggests that this method could be used successfully in the future to enhance the value of VR systems as an alternative to physical trainers for laparoscopic surgery skills. Some recommendations on how to use this method to achieve the environment and interface fidelity of a VR laparoscopic surgical trainer are identified.

Haptic Communication in Collaborative Virtual Environments

OBJECTIVE

To understand the interaction between haptic and verbal communication, we quantified the relative effect of verbal, haptic, and haptic-plus-verbal feedback in a collaborative virtual pointing task.

BACKGROUND

Collaborative virtual environments (CVEs) provide a medium for interaction among remote participants. Better understanding of the role of haptic feedback as a supplement to verbalization can improve the design of CVEs.

METHODS

Thirty-six participants were randomly paired into 18 dyads to complete a 2-D pointing task in a CVE. In a mixed experimental design, participants completed the task in three communication conditions: haptic only (H), verbal only (V), and haptic plus verbal (HV). The order of the conditions presented to the participants was counterbalanced.

RESULTS

The time to task completion, path length, overshoot, and root mean square error were analyzed. Overall, performance in the V and HV conditions was significantly better than in the H condition. H was the least efficient communication channel but elicited response with the shortest reaction time. When verbalization was not available, the use of the haptic device was more likely to be exaggerated to ensure information transmission. When verbalization was used, participants converged on the use of a Cartesian coordinate system for communicating spatial information.

CONCLUSION

Haptic communication can be used to complete a collaborative virtual task but is less efficient than verbal communication. A training period may help to improve the efficiency of haptic communication.

APPLICATION

These results can be used to design remote collaboration tasks incorporating haptic components and for improving the design of CVEs that support haptic communication.

Validation of the VBLaST: A Virtual Peg Transfer Task in Gynecologic Surgeons

STUDY OBJECTIVE

To validate the Virtual Basic Laparoscopic Skill Trainer (VBLaST-PT; the peg transfer task) for concurrent validity based on its ability to differentiate between novice, intermediate, and expert groups of gynecologists, and the gynecologists' subjective preference between the physical Fundamentals of Laparoscopic Surgery (FLS) system and the virtual reality system.

DESIGN

Prospective study (Canadian Task Force II-2).

SETTING

Academic medical center.

PARTICIPANTS

Obstetrics and gynecology residents (n = 18) and attending gynecologists (n = 9).

INTERVENTIONS

Twenty-seven subjects were divided into 3 groups: novices (n = 9), intermediates (n = 9), and experts (n = 9). All subjects performed 10 trials of the peg transfer on each simulator. Assessment of laparoscopic performance was based on FLS scoring, whereas a questionnaire was used for subjective evaluation.

MEASUREMENTS AND MAIN RESULTS

The performance scores in the 2 simulators were nearly identical. Experts performed better than intermediates and novices in both the FLS trainer and the VBLAST, and intermediates performed better than novices in both simulators. The results also show a significant learning effect on both trainers for all subgroups; however, the greatest learning effect was in the novice group for both trainers. Subjectively, 74% participants preferred the FLS over the VBLaST for training laparoscopic surgical skills.

CONCLUSION

This study demonstrates that the peg transfer task was reproduced well in the VBLaST in gynecologic surgeons and trainees. The VBLaST has the potential to be a valuable tool in laparoscopic training for gynecologic surgeons.

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.

The Impact of New Instruments on Surgical Performance in Natural Orifice Translumenal Endoscopic Surgery

Natural Orifice Translumenal Endoscopic Surgery (NOTES) is a recent emerging technique for performing general surgery procedures such as cholecystectomy (gallbladder removal). However, the advantages of NOTES over conventional laparoscopic surgery, the current gold standard, are still questionable. The aim of this study was to show the impact of introducing new surgical instruments in the NOTES technique on surgical performance in a cholecystectomy as compared to conventional laparoscopic surgery. A set of videos from real cholecystectomy cases performed using these two different techniques were analyzed. Hierarchical task decomposition and timeline analysis were conducted for each technique. A comparison to show variations between the two techniques at the task level is presented to highlight the technical issues, and their effects on performance, associated with the use of current endoscopic tools in the NOTES technique. The results show a longer procedural time in the NOTES technique than in the laparoscopic technique with the highest increase in surgical time for dissection tasks. The tools used for dissection were also shown to be inadequate for the task based on the motion analysis. Using this systematic method of analysis, new surgical techniques can be assessed based on performance measures, while areas of design improvement in surgical tools can be identified and related to the performance assessment.

Face and construct validation of a virtual peg transfer simulator

BACKGROUND

The Fundamentals of Laparoscopic Surgery (FLS) trainer box is now established as a standard for evaluating minimally invasive surgical skills. A particularly simple task in this trainer box is the peg transfer task which is aimed at testing the surgeon's bimanual dexterity, hand-eye coordination, speed, and precision. The Virtual Basic Laparoscopic Skill Trainer (VBLaST) is a virtual version of the FLS tasks which allows automatic scoring and real-time, subjective quantification of performance without the need of a human proctor. In this article we report validation studies of the VBLaST peg transfer (VBLaST-PT) simulator.

METHODS

Thirty-five subjects with medical background were divided into two groups: experts (PGY 4-5, fellows, and practicing surgeons) and novices (PGY 1-3). The subjects were asked to perform the peg transfer task on both the FLS trainer box and the VBLaST-PT simulator; their performance was evaluated based on established metrics of error and time. A new length of trajectory (LOT) metric has also been introduced for offline analysis. A questionnaire was used to rate the realism of the virtual system on a 5-point Likert scale.

RESULTS

Preliminary face validation of the VBLaST-PT with 34 subjects rated on a 5-point Likert scale questionnaire revealed high scores for all aspects of simulation, with 3.53 being the lowest mean score across all questions. A two-tailed Mann-Whitney test performed on the total scores showed significant (p = 0.001) difference between the groups. A similar test performed on the task time (p = 0.002) and the LOT (p = 0.004) separately showed statistically significant differences between the experts and the novices (p < 0.05). The experts appear to be traversing shorter overall trajectories in less time than the novices.

CONCLUSION

VBLaST-PT showed both face and construct validity and has promise as a substitute for the FLS for training peg transfer skills.

Development and validation of VBLaST-PT© : a virtual peg transfer simulator

Peg transfer is one of the five tasks in the Fundamentals of Laparoscopic Surgery (FLS), which is now established as a standard for training minimally invasive surgery. In this paper we report development and preliminary validation of Virtual Basic Laparoscopic Skill Trainer-peg transfer (VBLaST-PT© simulator. Face validation of the VBLaST-PT© with 34 subjects revealed high scores for all aspects of simulation. A two-tailed Mann-Whitney performed on the total scores on VBLaST-PT© showed significant (p=0.001) difference between the skill groups.