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Objective evaluation of minimally invasive surgical skills for transplantation surgeons using a virtual reality simulator

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Objective evaluation of minimally invasive surgical skills for transplantation surgeons using a virtual reality simulator

R. Dãnilã, B. Gerdes, H. Ulrike, E. Domínguez Fernández, I. Hassan
Original article, no. 2, 2009
* Department of Visceral-Thoracic- and Vascular Surgery, Philipps-University of Marburg, Germany
* Department of Visceral-Thoracic- and Vascular Surgery


Introduction and objective
 The introduction of laparoscopic donor surgery in 1995 heralded a new era, offering reduced postoperative pain and improved cosmetic results. It was hoped that these benefits may counter some disincentives and thereby increase donation rates (1). Like all other new techniques, laparos-copic live donor nephrectomy should be developed and improved at a few centers of excellence to avoid the loss of a donor or a graft (2).
It is well known that different types of operations need to be performed 15–100 times before reaching a low plateau of complications (3-5). Medical educators know that such learning curves are longer for endoscopic surgery compared to open surgery (6). For such purposes, several computer simulation programs have been established as assessment and training tools. Such simulations make it possible to offer a wide range of repeatable surgical situations, and thus, enable assessments based on direct observation of performance (7, 8).
However, it remains unclear, which physician can achieve the most benefit through training with a virtual laparoscopy simulator. The answer to this question is important for the educators, since they should become more involved in the structured residency program as previously suggested (9,11).
The purpose of this study was to investigate if the performance level in a virtual reality training session corelates with the actual skill of consultants in transplantations surgery, compared to advanced trainees with varying general laparos-copic experience.

Subjects and Methods
 The simulator used in this study (LapSim®, Surgical Science Ltd., Goeteborg/Sweden) creates a virtual endoscopic system using a computer (Windows XP®), a video monitor and endoscopic interface containing two pistol-grip instruments and a diathermy pedal without haptic feedback. The LapSim® software contains the basic modules referred to as “clip-and-cutting task”, in which the level of complexity and difficulty can be adjusted as previously described (9). The clip-and-cutting modules in the LapSim® skills set represent a surgical manoeuvre during laparoscopic living donor nephrectomy. For the purpose of this study, the clip-and-cutting task was adjusted to a high level of difficulty to determine the existing laparoscopic skills on the simulator. This task was chosen for several reasons. Firstly, it is likely to be one of the most essential stages of laparoscopic procedures that must be performed safely to avoid possible bleeding or damage the important length of the vein and artery during laparoscopic living donor nephrectomy. Secondly, by selective assessment of the clip-and-cut scenario, technical skills can be assessed independently of other factors influencing outcome variation. Thirdly, it is likely to be a good predictor of overall performance (12). For each individual, as well as for the entire group the following parameters were calculated as previously described (13): time needed to complete the task (min); blood loss (ml); dropped clips (n); badly placed clips (n); incomplete target areas (n) as well as economy of motion [instrument path length (m) and angular path (°)].

The study groups
 The study group included 16 surgeons, 8 women and 8 men, with ages ranging from 25 to 45 years. None of the participants had extended experience with a virtual reality simulator. All participants were briefly instructed regarding the virtual reality technique of coordination, clip application, dissection and cutting. The use of the laparoscopic instruments was demonstrated and the participants were given time to practice until they felt comfortable. Then they completed the training program specified above. The participants of the study had various degrees of experience in laparoscopic surgery and were divided into two groups: 1) experts in transplantation surgery: 5 transplantation surgeons, who had performed challenging laparoscopic procedure such as laparoscopic donor nephrec-tomy, laparoscopic adrenalectomy, laparoscopic fundoplication and laparoscopic colonic resection; and 2) 11 advanced residents who had performed several simple laparoscopic operations such as cholecystectomy and appendectomy. In this study both groups performed the clip application task at the same level as endpoint.

Statistics
 The data were transported directly into MS Excel®. The data were descriptively analyzed using the statistical program (SPSS®, version 12.0). The difference in the parameters of performance between the groups was analyzed using the non-parametric Mann-Whitney U- test. The comparison of means was performed using the two-independent t-tests. The level of statistical significance was set at p < 0.05.

Results
 Subject characteristics
 All 16 participants completed the study as described previously. There was no significant correlation between performance parameters and gender or age in the entire group.
Comparison of performance of both groups
 The comparison of the performance between experts and advanced residents showed that transplantation surgeons completed the task faster, with less errors and better economy of motion than advanced residents.
Reviewing parameters in Table 1 it seems obvious that transplantation surgeons needed to complete the task aproximately half of the total mean time spent by trainees, the difference being also statistically significant (p = 0,029), as shown in Fig. 1.
Regarding the error score, a far more accurate performance of senior surgeons was noticed, concerning the above mentioned parameters, with striking differences in the mean number of incomplete target areas (1 vs 55), badly placed / dropped clips (0 vs18 / 0 vs 64) and blood loss (0,7 vs 1,7 ml).
Statistically significant differences were recorded both for path length (p=0,020) and angular path lenth (p= 0,038) but interestingly, only for the right instrument (Fig. 2 a, b).
Figure 1
Figure 2A
Figure 2B

Discussion
 Surgery is a dynamic, constantly changing field. Newer approaches to specific problems often require advanced training and expensive technology (14). In order to increase the number of renal donors, laparoscopic live-donor nephrectomy (LLDN) was first performed 8 years ago. Today, LLDN is a routine procedure in many centres worldwide. For the donor, LLDN has numerous advantages, while graft and recipient outcome are the same as with the open approach. The learning curve on the way to performing this operation safely is long, and surgeons planning to integrate LLDN into their programme must be trained thoroughly. It is expected that with LLDN the number of donors willing to donate a kidney can be increased (15).
Surgical simulators were developed to help trainees overcome the learning curve of endoscopic surgery outside the operating room in order to reduce the risks for patients. A further advantage of computer simulation is that it is free of ethical considerations. A virtual training programme can provide an objective evaluation of performance (8-11).
We hypothesized that transplantation surgeons with special experience in LLDN should perform better on the simulator than advanced residents with limited experience in transplantation but adequate experience in laparoscopy, as a result of the subtle laparoscopic technique of transplantation surgeons by performing during LLDN.
Herein, we were able to show that after a short training course on a laparoscopy simulator, the transplantations surgeon performed the clip application task of the LapSim® faster, with a greater economy of motion than that demonstrated by advanced residents (fig. 1 and 2).
To time, there is some evidence that training with virtual reality improves endoscopic skills in different fields. Most studies were undertaken to evaluate the improvement of laparoscopic skills after training with virtual reality simulators. Two previous randomized studies, as those from Seymour (16) and Grantcharov (17) showed that surgeons who received training on virtual reality simulator had significantly greater improvement in performance in the operating room compared to those in the control group.
Improvement of performance in gastrointestinal endoscopy is the second field, which has been extensively studied. To this topic, Grantcharov et al. showed that novices and intermediate surgeons showed the greatest benefit from training in a virtual environment when using a virtual reality endoscopy trainer for coloscopy (GI Mentor II) (18).
The need for effective training and assessment tools for endoscopic surgery is evident. At present, the technical skills in the field of transplantation surgery have been commonly taught using the apprenticeship model. Virtual reality simulations make it possible to offer a wide range of repeatable surgical situations and thus to make assessments based on direct observation of the performance.
In conclusion, the current study has demonstrated the construct validity of the LapSim® virtual reality simulator, since the experts in transplantation surgery performed, at the first exposure to the Lapsim®, significantly better compared to advanced residents. This implicates that virtual reality simulation is beneficial and should obligatory be a part of the surgical training.

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