Quantifying Mental Workload of Surgeons Performing NOTES Procedures

Bin Zheng, MD PhD, Erwin Rieder, MD, Maria A Cassera, BS, Danny V Martinec, BS, Lee L Swanström, MD. Department of Surgery, University of British Columbia, Canada; Minimally Invasive Surgery Program, Legacy Health, Portland, Oregon

INTRODUCTION: During Natural Orifice Transluminal Endoscopic Surgery (NOTES), surgeons often have difficulties orienting the surgical view and manipulating instruments accurately, which increases surgeons’ mental and physical fatigues. Overloaded surgeons may have problems making logical decisions and maintaining dexterity during an operation. Therefore, quantifying surgeons’ mental workload provides an opportunity to understand surgeons’ response to the challenges posed by NOTES, and it is an essential step for developing an effective strategy to ensure safe performance of NOTES procedures. We took initiative to quantify mental workload by measuring spared mental resources of surgeons while performing NOTES training tasks. We hypothesized that surgeons would require more mental resources while performing NOTES procedures than during laparoscopic procedures; thus, leaving less spared mental resources for effective performance of a secondary task.

METHODS: Assessment was conducted in two stages. First, NOTES training tasks were performed in a human mannequin bench-top model, and second, in a hybrid animate model. In the bench-top model, surgeons were required to complete a ring transfer task, passing a ring as many times as possible between two graspers placed through a dual channel endoscope in a time period of 6 minutes. In the hybrid animate model, a pig liver and gall-bladder were placed inside a standard laparoscopic training box. Surgeons were required to dissect the gall-bladder from the liver-bed using cautery and graspers placed through an NOTES operating platform. While performing the NOTES task in either the bench-top or the hybrid model, a secondary visual detection task was introduced to assess mental workload. The surgeon was required to identify 60 true visual signals among 300 false signals that were displayed randomly on an adjacent monitor placed 15 degrees off axis to the surgical monitor. Surgeons were asked to repeat the trials using laparoscopy. Surgeons’ performance of the primary and secondary tasks using both the NOTES and laparoscopic approaches were compared.

RESULTS: Of the 9 surgeons who completed trials in the bench-top model, a mean of 13.0 ± 4.0 rings were successfully transferred between targets using laparoscopy, in contrast to a mean of 1.2 ± 1.0 rings when performing the task using the NOTES platform (P <0.001). While transferring rings by laparoscopy, surgeons were able to detect 74% of true visual signals presented on the side monitor, which is significantly higher than the 54% detection rate when performed using the NOTES platform (P = 0.005). In the hybrid model, 10 surgeons were able to detect 56% of true visual signals displayed on the side monitor while performing the cholecystectomy task. This was found to be significantly higher (P = 0.006) than when the task was performed using the NOTES platform (39%).

CONCLUSION: Results support our hypothesis that performance of a task using the NOTES platform increases surgeons’ mental workload, when compared to task performance using standard laparoscopy. Since difficulty in performing NOTES is associated with flexible endoscopy, we expect that new operating systems providing stable platforms would help to decrease the mental workload of surgeons and enhance the safety in performing NOTES.

Session: SS11
Program Number: S055

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