Monitor height affects surgeons' stress level and performance on minimally invasive surgery tasks

This study investigated the effect of monitor height on surgeons' workload and performance during simulated minimally invasive surgery (MIS). Fourteen volunteer subjects (7 experienced, 7 inexperienced) performed a cutting task in a training box at a standard MIS station with the video monitor positioned in random order at, below (-35 degrees), and above (+15 degrees) the subject's eye level. Task time and error, difficulty and discomfort, head orientation, trapezius and neck muscle activity, and skin conductance were recorded. The experienced subjects performed the task faster, with less error, and with less difficulty than did the inexperienced subjects. For the experienced subjects, error decreased when the monitor was lowered. Difficulty and discomfort increased at the high monitor position. As the monitor was lowered, the head pitched forward, and paraspinal cervical muscle activity increased. Variability in sternocleidomastoid activity increased both at the low and high monitor positions. The results show that monitor height affects both performance and workload. The monitor should be lowered to reduce error and task difficulty but not so low as to produce excessive neck flexion.