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Fatigue effects during the night shift should be considered when designing work-rest schedules for clinicians

To reduce fatigue-related medical errors, medical resident work hours are now restricted to 80 hours per week. Nevertheless, fatigue from sleep deprivation and working through the night remains common for many physician residents. For example, a new study found that anesthesiology residents had lower task performance and mood than colleagues working similar cases on the day shift.

Because night shift residents had been awake and working for more than 16 hours, the observed differences in task performance and mood may have been due to fatigue, note Matthew B. Weinger, M.D., of Vanderbilt University Medical Center, and colleagues. They suggest that fatigue effects during night shifts be considered when designing work-rest schedules for clinicians. They looked at the impact of day and night shift on task times, workload ratings, response to an alarm light, and mood for 13 pairs of day-night matched anesthesia cases.

The residents took significantly more breaks during the day than night cases (1.3 vs. 0.5) and total break time per case (27 vs. 9 minutes). Overall, day and night shift residents spent the same amount of time on clinical tasks, except manual tasks and observation tasks. During night shift cases, residents spent significantly less time on manual tasks, but significantly more time on observing tasks. These differences were most notable during the maintenance phases of anesthesia (the longest of the three phases: induction, maintenance, and emergence), when night shift residents spent more time observing physiological monitors, the patient's airway, and intravenous fluids, perhaps to compensate for fatigue.

Observers' workload ratings of residents during maintenance were significantly lower in the night cases than in the day cases (7.9 vs. 8.6). Night shift residents did not perceive a higher workload or respond slower to the alarm light, but did report more negative mood both pre- and post-surgery.

The study was supported in part by the Agency for Healthcare Research and Quality (HS11375 and HS11521).

See "Differences in day and night shift clinical performance in anesthesiology," by Caroline G.L. Cao, Ph.D., Dr. Weinger, Jason Slagle, Ph.D., and others, in the April 2008 Human Factors 50(2), pp. 276-290.

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