The effects of viewing axis on laparoscopic performance: a comparison of non-expert and expert laparoscopic surgeons.

BACKGROUND

While the ideal relationship of telescope viewing axis and instrument working axis in laparoscopic surgery is co-axial, it is often necessary to deviate view of the surgical field from the direction of working instruments with potentially negative implications to performance. The objectives of this study are to (1) characterize performance effects of working progressively further off telescope viewing axis and (2) compare the ability of expert laparoscopic surgeons and non-expert surgeons to compensate for the psychomotor problems imposed by off-axis viewing.

METHODS

Subjects included Baystate Medical Center surgical residents between PGY 1 and PGY 5 training years and attending surgeons. Expert subjects (>250 basic and >50 advanced laparoscopic cases, N = 6) and non-expert subjects (N = 11) performed the FLS peg transfer task in a box trainer configured to accept a laparoscope inserted at 0°, 45°, 90°, 135°, and 180° viewing angles relative to axis of working instruments. Performance measures included time to task completion (seconds), errors (# dropped objects), and percent completed transfers. Statistical analysis took into account repeated measures within each subject for each performance measure. Trends were assessed using linear contrasts for trend (p-trend). Differences between experts and non-experts were evaluated using an interaction term (p-interaction).

RESULTS

Overall there was increased time to completion (p < 0.001), increased number of dropped pegs (p < 0.001), and decreased percentage of completed transfers (<0.001) as the viewing axis relative to working instruments increased from 0° to 180°. Overall, expert laparoscopic surgeons demonstrated significantly shorter time to completion (p < 0.0027), fewer dropped pegs (p < 0.001), and higher percentage of completed peg transfers (p < 0.0001) compared to non-expert surgeons.

CONCLUSIONS

Surgeon performance degrades as viewing axis increases from 0° to 180° relative to working instruments. Expert laparoscopic surgeons perform better than non-expert surgeons when working off the laparoscope viewing axis.