Institutional members access full text with Ovid®

Saccadic Eye Movement Metrics Reflect Surgical Residents' Fatigue

Di Stasi, Leandro L. PhD*,†,‡; McCamy, Michael B. PhD*; Macknik, Stephen L. PhD§,*; Mankin, James A. MD; Hooft, Nicole MD; Catena, Andrés PhD; Martinez-Conde, Susana PhD*

doi: 10.1097/SLA.0000000000000260
Original Articles

Objective: Little is known about the effects of surgical residents' fatigue on patient safety. We monitored surgical residents' fatigue levels during their call day using (1) eye movement metrics, (2) objective measures of laparoscopic surgical performance, and (3) subjective reports based on standardized questionnaires.

Background: Prior attempts to investigate the effects of fatigue on surgical performance have suffered from methodological limitations, including inconsistent definitions and lack of objective measures of fatigue, and nonstandardized measures of surgical performance. Recent research has shown that fatigue can affect the characteristics of saccadic (fast ballistic) eye movements in nonsurgical scenarios. Here we asked whether fatigue induced by time-on-duty (∼24 hours) might affect saccadic metrics in surgical residents. Because saccadic velocity is not under voluntary control, a fatigue index based on saccadic velocity has the potential to provide an accurate and unbiased measure of the resident's fatigue level.

Methods: We measured the eye movements of members of the general surgery resident team at St. Joseph's Hospital and Medical Center (Phoenix, AZ) (6 males and 6 females), using a head-mounted video eye tracker (similar configuration to a surgical headlight), during the performance of 3 tasks: 2 simulated laparoscopic surgery tasks (peg transfer and precision cutting) and a guided saccade task, before and after their call day. Residents rated their perceived fatigue level every 3 hours throughout their 24-hour shift, using a standardized scale.

Results: Time-on-duty decreased saccadic velocity and increased subjective fatigue but did not affect laparoscopic performance. These results support the hypothesis that saccadic indices reflect graded changes in fatigue. They also indicate that fatigue due to prolonged time-on-duty does not result necessarily in medical error, highlighting the complicated relationship among continuity of care, patient safety, and fatigued providers.

Conclusions: Our data show, for the first time, that saccadic velocity is a reliable indicator of the subjective fatigue of health care professionals during prolonged time-on-duty. These findings have potential impacts for the development of neuroergonomic tools to detect fatigue among health professionals and in the specifications of future guidelines regarding residents' duty hours.

We monitored the fatigue levels of surgical residents, using eye movement metrics, objective measures of laparoscopic surgical performance, and subjective reports. Time-on-duty decreased the velocity of saccadic eye movements and increased subjective fatigue but did not affect laparoscopic performance. Our data show, for the first time, that saccadic velocity is a reliable indicator of the subjective fatigue of health care professionals and, moreover, indicate that fatigue due to prolonged time-on-duty does not result necessarily in impaired surgical performance.

*Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ

Cognitive Ergonomics Group, Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Granada, Spain

Joint Center University of Granada-Spanish Army Training and Doctrine Command, Spain

§Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ

St. Joseph's Hospital and Medical Center, Phoenix, AZ

Learning, Emotion and Decision Group, Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Granada, Spain.

Reprints: Susana Martinez-Conde, PhD, Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Rd, Phoenix, AZ 85013. E-mail: smart@neuralcorrelate.com.

Supported by the Barrow Neurological Foundation (to S.L.M. and S.M.-C.), the St. Joseph's Foundation (to J. M.), the National Science Foundation (awards 0852636 and 1153786 to S.M.-C), the Spanish Ministry of Economy and Finance (project PSI2012-39292 to A. C.), and the MEC-Fulbright Postdoctoral Fellowship program (grant PS-2010-0667 to L.L.D.S.).

Disclosure: The authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest, or nonfinancial interest in the subject matter or materials discussed in this manuscript. The authors declare no conflicts of interest.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.annalsofsurgery.com).

© 2014 by Lippincott Williams & Wilkins.