Background: The awkward visual and physical interface of video-endoscopic surgery (VES) has been shown to increase the physical workload of the surgeon, yet there is a lack of objective information on the mental effort and stress demanded by VES techniques. This study addresses the hypothesis that VES is more stressful than open surgery using an ergonomic analysis of surgical tasks in a laboratory setting.
Methods: A portable ergonomic work station was developed using a software Virtual Instrument (VI) interfaced with electronic hardware to compare the mental workload of 28 surgeons. The task was knot tying. The independent variable was work condition: rest, open technique, or VES technique. Dependent variables were tonic skin conductance level (SCL), electrooculogram (EOG), and subjective reports of concentration (CON) and stress (STR). Statistical analysis used nonparametric methods.
Results: Subjects tied fewer knots using the VES technique (p < 0.05). The SCL increased progressively from rest to the open task to the VES task (p < 0.05), correlating with the subjects' reported increase in mental stress level (p < 0.05). Eye blinks decreased from rest to the open task (p < 0.05), consistent with the subjects' reported increase in level of mental concentration. From the open to the VES task, eye blinks increased (p < 0.05), as would be expected given the greater demands of the VES task. Experienced subjects demonstrated less variability in SCL levels across tasks.
Conclusions: VES technique requires greater concentration and places greater mental stress on surgeons than to open surgery. More experience with VES may decrease this effect. Studies are needed to improve the human-technology interface the stress.