Virtual Reality as an Affirmative Spin-Off to Laparoscopic Training: An Updated Review

Latest advancements in science lead to drastic improvements in patient health care. Techniques and technology evolved in surgery over the years have resulted in the improvement of patient outcomes by leaps and bounds. Open surgeries previously done for procedures like appendectomy and cholecystectomy evolved into laparoscopic minimally invasive procedures. Such procedures pose few challenges to the surgeons, like lack of tissue feedback and fulcrum effect of the abdominal wall. But training surgeons for such an advanced skill is still following conventional methods. These procedures can be effectively trained using Virtual Reality (VR), which can simulate operations outside the operating room (OR). To maximize the outcomes of VR training, knowledge on various strategies affecting the skills acquisition and retention in VR training is essential. This review collected information from PubMed, EMBASE, Cochrane Library (CENTRAL) databases. Data from the previous ten years are included in the review. This included documents, clinical trials, meta-analysis, randomized controlled trials, reviews, systematic reviews, letters to editors, and grey literature. After an advanced Medical Subject Headings (MeSH) search, we got 59,532 results, and after the application of filters, 189 results showed up. Out of these, studies that were not exclusively relevant to the use of VR in laparoscopic surgery were manually excluded, and a total of 35 articles were included in the study. VR is found to be an excellent training modality with promising outcomes. It helps the surgeons perform the surgery accurately at a faster pace and improves confidence and multitasking ability in OR. Instructor feedback from mentors and deliberate practice of trainees, and early introduction of haptics in VR resulted in the most effective outcomes of the VR training. Box trainers are also compared with VR trainers as they are the cheaper modalities of training. However, this area needs more research to conclude if box trainers can act as a cheaper alternative to VR training providing similar outcomes.


Introduction And Background
Virtual Reality (VR) is a simulated system generated by a computer to provide an experience similar to or completely different from the real world. It has many applications in gaming, military training, and astronaut training, among others. Many studies have been published to determine the effectiveness of VR in the surgical training field [1]. Minimally invasive surgery gained widespread importance in recent times. Laparoscopy requires unique skills which are non-transferable from open surgery [2]. For this type of surgery, psychomotor and hand-eye coordination are essential. However, it is widely accepted that training for laparoscopic surgery can be done in virtual laboratories before performing in the OR as it is a safe, controlled, standardized, and repeatable environment [2,3].
The traditional surgical training system advocating "see one, do one, teach one" is slowly losing importance. VR training ensures safer health care systems and a reduction in the number of surgical errors [4]. Virtual reality simulators used in laparoscopic training include Minimally Invasive Surgical Trainer Virtual Reality (MIST VR), LapSim®, SimSurgery, Lap Mentor TM , Sinergia [5]. "Out of OR" training is possible with the use of VR for laparoscopic procedures like appendectomy, cholecystectomy, etc., which is found to make a profound difference in their performances in OR and shortens their learning curve [6,7]. During their laparoscopic training, the major challenges faced by trainee surgeons are their limited time available for training, fulcrum effect of the abdominal wall, and lack of haptic feedback. VR laparoscopic training is found 1 , 2  3  4  3  1  5   3  1  6  1, 7, 8, 9 1, 10 1, 11 1 12, 13 to be an effective method to address all these challenges and enables them to learn the skills in a risk-free environment [8,9]. It has been a long while since the introduction of VR systems in training laparoscopic surgeons. However, there is a scarcity of long-term review literature targeting the efficacy of VR in laparoscopic training and the variety of factors playing a role in improving or depreciating the performance of laparoscopic surgeons in VR. Hence this standard review article aims to bridge the literature gap by reviewing the articles of the past ten years related to the use of VR in laparoscopic training.

Review Methods
A traditional review was carried out until June 1, 2021. Databases used for the search were MEDLINE (PubMed), EMBASE (Ovid), Cochrane Library (CENTRAL). The Medical Subject Headings (MeSH) terms used for the search in PubMed are MeSH "Virtual Reality" AND MeSH "Laparoscopy" AND MeSH "Surgery" AND MeSH "Training." Articles of the previous ten years and only those in English, including books and documents, clinical trials, meta-analysis, randomized controlled trials (RCT), reviews, systematic reviews, letters to editors, were taken into study. Articles that are not exclusively related to 'laparoscopic surgical training,' including the use of VR in other surgical and medical training, augmented and mixed reality, and VR for rehabilitation, were excluded. Articles on other forms of training were also excluded.

Result
After an advanced MeSH search, we got 59,532 results, and after the application of filters, 189 results showed up. Out of these, papers that were not exclusively relevant to the use of VR in laparoscopic surgery were manually excluded, and a total of 35 papers were included in the study.

Effect of VR on Mental Workload in Novice Laparoscopic Surgeons
Surgery is one of the demanding branches which puts its trainees to extreme mental and physical workload. A prospective controlled simulation study was conducted by Barré [11]. RCT performed by Larsen et al. and Nagendran et al. also proved that skills learned in VR trainers can be successfully transferred to real operations and also a reduction in operating time [12,13]. RCT conducted by Torkington et al. also proved the same [14]. Considering the ethical issues involved in using animals and cadavers for laparoscopic simulation, VR can act as an effective method to develop curriculum-based training taking advantage of its repeatability in a safe environment. VR trainer is shown in Figure 1.

FIGURE 1: Virtual Reality (VR) trainer
Original figure, made by the author KK

Factors Affecting VR Laparoscopic Training Outcomes
It is important to understand the factors affecting skills acquisition and retention to develop a VR training program.
Instructor feedback: An RCT was performed by Bjerrum et al. to assess skill retention after VR training after six months using LapSim for laparoscopic salpingectomy. The author noted that skills decay started after 6-18 months without practice. This study also showed that, however, instructor feedback during VR improved the efficiency of initial VR training, though it has no effect on skills retention [7]. Also, in a study conducted by Paschold et al., the trainees were divided into low performer group (LPG) and high performer group (HPG) based on their initial performance of procedural tasks on VR simulator. Then tailored verbal instructor feedback (VIF) was given only to LPG. After completion of training, a post-test (clip applying task) was conducted on LapSim VR trainer to both the groups. It was found that with VIF, LPG performance equalled HPG [15]. A similar study to assess the effect of instructor feedback on virtual reality was also conducted by Oestergaard et al., but the results have not been published by the time of completion of this study [16].
Multitask training: Distraction can harm laparoscopic performance. One of such distractions is insufflator problems in the OR. An RCT conducted by Bongers et al. evaluated the use of VR training to improve multitasking in OR to overcome distraction. The intervention group was trained using both VR laparoscopic trainer and a laparoscopic insufflator trainer. Scenarios such as intra-abdominal pressure build-up problems, tube obstruction, gas supply problems were simulated and trained. The intervention group was successfully able to "task switch," and solve the insufflator problems and complete the surgery early in the post-test. This showed that two modules, when combined trained in VR, can enable multitasking [4].
Warmup before VR: Several warmup strategies have emerged intending to improve laparoscopic performance. In a study conducted by Brönnimann et al., few participants were given hands-on warmup (playing table soccer), few were given cognitive warmup (playing tablet 3D game on iPad) and others were control group with no warmup. Then all of them were subjected to laparoscopy training in VR. The hands-on warmup group didn't show any performance improvement, whereas the iPad group showed improved performance in camera navigation but no significant improvement in hand-eye coordination and two-handed maneuvers [17].
Competitive training: The competition had led to improved performance in sports. The same was tried with VR laparoscopic training. In an RCT conducted by Hashimoto et al., 20 surgical novices were randomized into competitive training (CT) group and control group to perform 10 VR laparoscopic cholecystectomies (LC). CT group were told that they were under competition to win a prize. Performance was assessed using the Objective Structured Assessment of Technical Skills Global Rating Scale (OSATS GRS) score. It was expected that the CT group would show significant improvement than the control group. But surprisingly, it was found that there was no significant difference in OSATS GRS score between the two groups; however, the CT group showed greater dexterity [18].
Deliberate practice: Deliberate practice involves individuals repeatedly practicing on tasks and getting immediate feedback so that they can focus on training to overcome their weaknesses while also working on refining other aspects of performance. RCT conducted by Hashimoto et al. randomized 20 laparoscopic novices into deliberate practice (DP) group and control group. Both the groups were subjected to 10 VR sessions comprising a total of 20 VR laparoscopic cholecystectomies (LC) on the Lap Mentor TM VR laparoscopic simulator, and their performances were continuously assessed using OSATS GRS score. The DP group was constantly given feedback on their weaknesses by the qualified observer after each session based on their scores and methods to improve them. Then they were subjected to 30 min of deliberate practice on Lap Mentor TM VR trainer or LapSim® VR trainer to improve on their weaknesses while the control group spent 30 minutes watching Ted talks or reading journals. After these VR sessions, both the groups were subjected to LC on a cadaveric porcine model using real surgical instruments and rated on OSATS GRS score. DP group people scored significantly higher scores than the control group. The author also mentioned that DP could lead to improved performance to the level of an expert. However, lapses in practice can cause "arrested development" and premature plateauing of performance [19]. Similar findings were also observed in RCT conducted by Palter et al., further strengthening the evidence [20].
Skill transfer from other procedural training: Yang et al. conducted an RCT with surgical novices who were randomized into group 1 (trainees underwent appendectomy VR training and then cholecystectomy VR training) and group 2 (trainees underwent cholecystectomy VR training directly). Both the groups underwent basic training of five laparoscopic tasks (clipping and grasping, cutting, electrocautery, peg transfer, and pattern cutting) in VR and were then subjected to post-test on laparoscopic cholecystectomy (LC) on VR simulator. It was found that there was no improved performance on VR LC with prior practice of VR appendectomy. However, the movements of group 1 participants were more economical. Hence, this shows that though the participants may benefit from the transfer of motor skills, the procedures need to be trained separately [21].
Multimodality training: In the RCT conducted by Kowalewski et al., participants were randomized into multimodality training (MMT) group and control group. Pretest (LC on the porcine liver) was performed for both groups. Then MMT group was trained for basic skills on box trainer for six hours and the procedure of laparoscopic cholecystectomy on VR trainer for another six hours. Then both these groups were subjected to a post-test on a VR trainer. Their performance was assessed using the Global Operative Assessment of Laparoscopic Skills (GOALS) score. MMT group scored significantly higher than the control group. It was also found that after MMT the expertise of junior residents matched that of senior residents, thus showing that MMT is beneficial to achieve better outcomes in VR training [22]. RCT conducted by Sumitani et al. also showed the same results [3]. Also, in the study conducted by Lesch et al., where candidates were randomized into a video training group and VR laparoscopic cholecystectomy training group, the post-training questionnaire showed that video training is easy to use than VR training. However, VR training showed improved confidence than video training. So the participants suggested that the trainees should get to read the steps of the procedure first; they should be trained with a video trainer and then with a VR trainer for best outcomes [23].
Paired team training: When trainees are teamed up in pairs during training sessions, this leads to the exchange of knowledge, discussions, reduction of stress through intraoperative breaks. An interesting study conducted by Nickel et al. randomized surgical novices into group A (multimodality training alone), group B (multimodality training in pairs), group C (no training). Group B candidates got lesser repetitions at a trainer as they had to take turns to train at the same time as that provided to other groups. Post-test was conducted to all the groups on VR trainer and porcine cadaveric LC, and OSATS score was used for the assessment. However, the trial has not been completed by the time of publication of this study [24]. Hence the effect of team training on VR outcomes is still questionable.
Haptic feedback: One of the crucial things that VR trainers lack is the haptic feedback of the tissue. Introducing haptic feedback into VR trainers can lead to the use of different senses of the surgeon and may further lead to better and faster performance. In the RCT conducted by Ström et al., 38 surgical residents were randomized into the early haptic (EH) group and late haptic (LH) group. EH group were trained in VR trainer with haptic feedback for one hour and then without haptics for another hour. LH group started training without haptics first and then with haptics. Then both groups were subjected to the BasIQ general cognitive ability test and Mental Rotation Test A (MRT-A). It was observed that early haptic group performance was significantly higher in manipulating and diathermy (MD) tasks and point diathermy (PD) tasks in the tests. Hence the early introduction of haptic feedback results in improved VR outcomes [25]. All the RCTs mentioned above are summarized in Table 1.

VR Trainer is Superior or Inferior to Other Trainers?
Other alternatives to VR trainers are: box trainer, hybrid simulator, augmented reality simulator, porcine model, and pulsating organ perfusion (POP) trainer [5].
VR trainer versus video trainer: RCT conducted by Hamilton et al. randomized junior surgical residents (n=50) into video trainer (VT) group and VR trainer group (MIST VR). Baseline skill-testing was done for both VR and VT groups. Then they were given training in their respective training groups, and both groups were subjected to post-test in both VT and MIST VR. To assess the correlation of practice in either of the systems with improved OR performance, all the second-year residents (n=19) performed laparoscopic cholecystectomies for symptomatic cholelithiasis before and after the training period and were assessed using GOALS score. In the post-test conducted on MIST VR, the task performance improved significantly in both VT and VR groups. However, the VR group showed more improvement in task performance than the VT group. Similarly, in the post-test conducted on video trainers, the VT group showed more improvement than the VR group. There was a significant overall improvement in the GOALS score of the VR group but no significant improvement in the VT group. This study shows that skills learned on one trainer are transferrable to another and also highlights the fact that VR training is more efficient than VT training [26].

VR trainer versus box trainer:
A study conducted by Brinkmann et al. randomized surgical novices into VR training group and box trainer group. Both were trained for five days and were subjected to a post-test (Laparoscopic cholecystectomy on the porcine gallbladder). Their performance was evaluated using the GOALS score. Both the groups showed improved performance after simulation training. Surprisingly, the box trainer group achieved a significantly higher GOALS score. There is a possibility that the box group performed better because their assessment was in box trainer too. And box training group also had the advantage of training with the same instruments as used in the OR and getting real haptic feedback [27]. However, a meta-analysis conducted by Guedes et al. showed that VR training was better than box training, considering the scores while performing minimally invasive surgery and time to complete (TTC) basic peg transfer task, though no significant difference was observed in TTC of other basic tasks and advanced tasks. Although this meta-analysis had its limitations (publication bias and unblinded reviewers), it widely studied different randomized controlled trials performed in various countries and is more reliable. The author also mentioned in his literature review the views of other authors who opined that VR trainers had better outcomes than box trainers [28]. RCT conducted by Khan et al. showed that skills retained through fundamentals of laparoscopic surgery simulator (FLS) lasted longer than LapSim® VR trainer. The author suggested that VR refresher courses should be conducted shortly after the initial VR training course. Hence, we can summarize that skills are efficiently acquired during VR training but poorly retained as compared to box trainers [29]. But the RCT conducted by Oussi et al. using box trainer and Lap Mentor TM VR trainer showed that the performance of the box training group matched with the VR training group. Hence the author suggests a low-cost box trainer as an effective alternative to the expensive VR trainer [30]. This is also supported by the RCT of Yiasemidou et al., where the box trainer group showed significant improvement in GOALS score compared to the VR trainer group during post-training VR Laparoscopic cholecystectomy post-test in all other metrics except for time taken to complete [31]. The question of the usage of box trainers or VR trainers for laparoscopic training is still debatable and needs further studies considering all other factors.
VR versus low-cost blended learning: VR being an expensive method of training, the use of multiple affordable alternatives for training was tried. RCT was conducted by Nickel et al. randomized surgical novices into the VR group and blended learning (BL) group. VR group received 12 hours of training using Lap Mentor II and the BL group received 10 hours of basic skills training in box trainer and two hours of e-learning for laparoscopic cholecystectomy training. Then all the participants were subjected to multiple-choice questions (MCQs) post-test for knowledge assessment and POP trainer for assessment of surgical skills. Their performance was rated using the OSATS score. VR group operated faster than BL group and BL group scored higher in MCQ test than VR group. However, the OSATS score was nearly equal for the VR group and BL group. Hence it can be concluded that VR training and BL training are equally effective in training laparoscopic surgeons [32]. RCTs comparing VR trainers and other trainers are summarized in Table 2.

Barriers to Implementation of VR Training in Surgery
It is an expensive mode of training that totally increases the cost of laparoscopic training, leading to restricted availability. It lacks haptic feedback of tissue. The operative field is visualized on a separate screen away from the patient's axis [33]. VR also has side effects like cybersickness (nausea, vomiting, eye fatigue, dizziness, ataxia), etc. [34]. Another major drawback is using the simulators only for courses and improper maintenance & protection. An effective solution to this is to make them available out of office hours for practice to students under closed-circuit television (CCTV) surveillance instead of locking the doors of the simulation room. VR training program must be a part of the regular surgical laparoscopic training program. Benchmarks to proficiency should be set rather than subjecting them to VR training for a stipulated time.
Once these are achieved, they are obliged to provide the operating opportunity to others [35].

Limitations of the study
Most of the studies included in this review are RCTs, and many of them had small sample sizes. The review included literature only from the past ten years (2010-2021). In one of the RCTs taken into consideration, participants felt VR trainers were difficult to use because of the technical difficulties that occurred during the trial. In one of the reviews taken into the study, all the RCTs included in that review had a high risk of bias [13]. Few of the RCTs included in this review did not complete their trial by the time of their publication [16,24]. There are few dropouts in a few RCTs, which may have affected the study.

Conclusions
The primary objective of this study is to study the effect of VR in training laparoscopic surgeons and various factors affecting the outcomes of VR training. Laparoscopy is a key procedure that itself poses few challenges to surgeons while operating. Hence it is recommended that laparoscopic procedures need to be simulated and trained before they are performed in the OR. VR can be successfully used for laparoscopic training curriculum as it not only helps to reduce the physical and mental workload on surgeons but also improves their surgical performance in operation theatres. It can also be used to train surgeons to cope up with other technical problems encountered during surgery simultaneously. Competitive training and warmup exercises before VR training can improve few aspects of VR training, but it can be concluded that instructor feedback from mentors, deliberate practice of trainees, and early introduction of haptics in VR can maximize the effect of VR training. This review carefully assessed various factors affecting VR training so that an effective structured VR curriculum can be developed considering all these factors due to the high cost involved in introducing VR into training. Our review also assessed cheaper modalities of simulation like box trainers to see if they are equally effective and can act as a cost-effective replacement to VR trainers. However, we are unable to conclude the same due to variation in results from different studies. This is an area that warrants more amount of research in future studies.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.