Elsevier

Journal of Surgical Education

Volume 73, Issue 5, September–October 2016, Pages 858-869
Journal of Surgical Education

Original Reports
Objective Assessment of Laparoscopic Force and Psychomotor Skills in a Novel Virtual Reality-Based Haptic Simulator

https://doi.org/10.1016/j.jsurg.2016.04.009Get rights and content

Background

Most of the commercially available virtual reality-based laparoscopic simulators do not effectively evaluate combined psychomotor and force-based laparoscopic skills. Consequently, the lack of training on these critical skills leads to intraoperative errors.

Objectives

To assess the effectiveness of the novel virtual reality-based simulator, this study analyzed the combined psychomotor (i.e., motion or movement) and force skills of residents and expert surgeons. The study also examined the effectiveness of real-time visual force feedback and tool motion during training.

Design

Bimanual fundamental (i.e., probing, pulling, sweeping, grasping, and twisting) and complex tasks (i.e., tissue dissection) were evaluated. In both tasks, visual feedback on applied force and tool motion were provided. The skills of the participants while performing the early tasks were assessed with and without visual feedback. Participants performed 5 repetitions of fundamental and complex tasks. Reaction force and instrument acceleration were used as metrics.

Setting

Surgical Gastroenterology, Government Stanley Medical College and Hospital; Institute of Surgical Gastroenterology, Madras Medical College and Rajiv Gandhi Government General Hospital.

Participants

Residents (N = 25; postgraduates and surgeons with <2 years of laparoscopic surgery) and expert surgeons (N = 25; surgeons with >4 and ≤10 years of laparoscopic surgery).

Results

Residents applied large forces compared with expert surgeons and performed abrupt tool movements (p < 0.001). However, visual + haptic feedback improved the performance of residents (p < 0.001). In complex tasks, visual + haptic feedback did not influence the applied force of expert surgeons, but influenced their tool motion (p < 0.001). Furthermore, in complex tissue sweeping task, expert surgeons applied more force, but were within the tissue damage limits. In both groups, exertion of large forces and abrupt tool motion were observed during grasping, probing or pulling, and tissue sweeping maneuvers (p < 0.001).

Conclusions

Modern day curriculum-based training should evaluate the skills of residents with robust force and psychomotor-based exercises for proficient laparoscopy. Visual feedback on force and motion during training has the potential to enhance the learning curve of residents.

Introduction

Laparoscopic surgery has widely replaced open surgery because of the advantages it has for patients during surgery and postsurgery recovery. Owing to the inversion and the distant entry to the surgical site, haptic feedback is altered with laparoscopic surgical instruments.1 This leads to an excessive exertion of force.2 Many intraoperative errors, such as tissue injury, are because of the exertion of large forces and abrupt tool motion.2, 3, 4, 5 Therefore, to apply precise and accurate forces with economized tool movements, laparoscopic residents should be trained in both fundamental and complex skills. Virtual reality (VR)-based training with haptic feedback has been demonstrated to impart fundamental and core laparoscopic skills to residents and expert surgeons.6, 7, 8 However, modern day VR-based laparoscopic training curricula do not effectively teach combined psychomotor and force-based laparoscopic skills because most of the skill assessment metrics are based on instrument motion and task completion time.9, 10, 11 Additionally, prior research on VR-based fundamental and complex skills assessments have focused on objectively evaluating psychomotor skills alone.12, 13, 14, 15

To avoid excessive force exertion and abrupt tool movements, it is important to enhance both the force perception and psychomotor skills of residents and expert surgeons. This could be achieved by imparting combined psychomotor and force-based training. Furthermore, the force and motion skills of expert surgeons and residents vary significantly. These skills are highly dependent on the nature of the task (i.e., either fundamental or complex tasks). In the past, several studies on laparoscopic force skills have shown that in certain tasks, residents apply large forces compared with expert surgeons16, 17, 18, 19 and that in other tasks, expert surgeons applied higher forces.12, 20 This shows that the force perception of residents and expert surgeons is diminished in laparoscopic surgery. Therefore, in addition to psychomotor skills, there is a pressing need to enhance force-based laparoscopic skills. In our study, we used combined force and motion metrics to quantify laparoscopic skills using a novel custom-built haptic-based VR laparoscopic simulator. Applied force is considered to be a crucial metric of skill evaluation in laparoscopic surgery.18, 21, 22 This is because past studies have demonstrated that visual cues alone cannot provide all of the necessary information related to the force parameters or haptic properties of tissues during tissue manipulation23, 24, 25 and that position or motion metrics alone cannot effectively characterize the skill levels of residents and expert surgeons.21, 26, 27

In the current study, our primary objective was to use combined force and psychomotor metrics to analyze the effect of experience on fundamental and complex laparoscopic tasks. The secondary objective was to examine whether real-time active visual feedback on applied force and instrument motion data improves performance during fundamental and complex training tasks. The third objective was to evaluate the effectiveness of our custom-built VR-based laparoscopic simulator in differentiating the force and psychomotor signatures of residents from those of expert surgeons.

Section snippets

Subjects

In total, 50 healthy subjects with no previous history of musculoskeletal, cognitive, or psychomotor impairment voluntarily participated in the experiments. Subjects were divided equally into 2 groups, namely, residents and expert surgeons (Table 1). Subjects had no prior knowledge of the nature of the experiment. Demographic information of all of the subjects was obtained through a questionnaire. All subjects signed a letter of informed consent before participating in the study. Subjects were

Data Analysis and Statistics

Force and acceleration are considered as standard metrics to evaluate the tissue handling skills.21, 22, 26, 28, 29, 30 The force metric was computed using the reaction force (F) generated by the bimanual haptic device during active tool-object collision or interaction. This metric was termed the maximum absolute reaction force (MARF) and was computed using eq. (1).17, 28 Figure 3 depicts the distribution and orientation of forces. The MARF was derived from first principles based on the

Demographic Characteristics

The average age of subjects was 38.5 years. Of 50 subjects, 17 were left handed and 33 were right handed. There were 35 males and 15 females. The demographic characteristics of residents vs. expert surgeons are described in Table 3. Significant differences between residents and expert surgeons were observed for the following parameters: (1) age (p < 0.001), (2) sex (p = 0.021), (3) laparoscopic surgeries performed (p < 0.001), (4) intraoperative errors caused because of excessive exertion of

Discussion

A novel laparoscopic simulator was developed to quantify the force and psychomotor skills of residents and expert surgeons. To our knowledge, this is the first study to evaluate the effect of visual feedback (i.e., applied force and acceleration) on force and psychomotor skills. The major findings of our work are as follows: (1) visual + haptic feedback improved the performance of residents in both fundamental and complex tasks; (2) in a complex tissue sweeping task, expert surgeons exerted

Conclusion

This study can be considered a first step toward critical laparoscopic skills assessment on VR-based simulators, as past studies on VR-based simulator studies have focused on evaluating psychomotor skills alone. Visual feedback on the magnitude of the force exerted and tool movement improved the force and motion skills of residents as they progressed through the training tasks. However, visual force feedback was not very effective for expert surgeons, as there was no major difference observed

Acknowledgments

The authors thank all of the residents and expert surgeons of Government Stanley Medical College and hospital, Rajiv Gandhi General Hospital, and Madras Medical College, Chennai, who willingly participated in the experiments. The authors also extend their thanks to all of the expert surgeons and residents who visited the haptics laboratory and voluntarily participated in the experiments. The authors also acknowledge the immense support and cooperation of Prof. Suresh Devsahyam, Bioengineering

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    Medical Electronics and Health Informatics Division, Department of Electronics and Information Technology (Deity) from the Ministry of Communications and Information Technology, Government of India. Grant No: APM/09-10/082/DITX/MANI.

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