The Effects of Viewing Axis On Laparoscopic Performance: A Comparison of Non-expert and Expert Laparoscopic Surgeons.

Rebecca J Rhee, MD, Gladys Fernandez, MD, Ron Bush, BS, Neal E Seymour, MD. Baystate Medical Center-Western Campus Tufts University School of Medicine


Introduction: While the ideal relationship of telescope viewing axis and instrument working axis in laparoscopic surgery is co-axial, it is often necessary to deviate the view of the surgical field from the direction of the working instruments with potentially negative implications to performance. The objectives of this study are to 1) characterize the 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 and Procedures: Baystate Medical Center surgical residents between PGY 1 and PGY 5 clinical training years (N=9) and expert laparoscopic surgeons (>250 basic and >50 advanced laparoscopic cases, N=8) performed a standard laparoscopic task (FLS peg transfer) on the Szabo-Berci-Sackier Laparoscopic Trainer using a 0 degree Olympus laparoscope inserted at 0, 45, 90, 135, and 180 degree viewing angles relative to axis of the working instruments (and surgeon position). Scope angles were varied in random order for each participant. Two sequences of the task were completed by all participants at all viewing angles. Performance measures included: a) time to task completion (seconds), b) errors (# dropped objects), and c) task completion rate (% completed transfers). Task time was capped at 300 seconds. Time data were analyzed using a linear mixed model accounting for repeated measures (iterations nested within angle nested within subject). Percent completion data were modeled as a proportion using generalized linear models with a logit link and binomial family. Drops were modeled as counts using a generalized linear model with a log link and Poisson family. These two models clustered on subject (resulting robust standard errors) to account for repeated measures. For all models, trends were assessed using linear contrasts for trend. Differences between experts and non-experts were evaluated using an interaction term in the model. All data analysis was conducted using Stata version 12.0 (StataCorp, College Station TX).

Results: Overall there was a trend towards increased time to completion, increased number of dropped pegs, and decreased percentage of completion as the degree of working off axis of working instruments increased from 0 to 180 degrees. Expert laparoscopic surgeons demonstrated significantly shorter time to completion (p<0.016) Figure 1, higher percentage of completed peg transfers (p<0.001) Figure 2, and fewer dropped pegs (p<0.001) Figure 3 at all angles compared to non-expert surgeons.

Figure 1.
Figure 2.
Figure 3.

Handedness, sex, and previous history of experience performing the FLS peg transfer task did not affect level of performance.

Conclusions: Ability to perform degrades as the viewing axis increases relative to working instruments, with the major decrement occurring beyond the 90 degree viewing angle. Expert laparoscopic surgeons have superior performance compared to non-expert surgeons working off the viewing axis.


Session Number: SS05 – Education
Program Number: S030

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