The Effect of Shift Length on Fatigue and Cognitive Performance in Air Medical Providers

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Abstract
Objective. To employ a battery of previously validated surveys and neuropsychological tests to compare changes in fatigue and cognitive abilities of air medical providers after 12- and 24-hour shifts. Methods. A convenience sample of 34 flight nurses and flight paramedics employed by one air medical service completed the Pittsburgh Sleep Quality Index (PSQI) and the Chalder Fatigue Questionnaire (CFQ) to determine fatigue before and after 12-hour (n = 16) and 24-hour (n = 19) shifts. A battery of neuropsychological tests, including the University of Southern California Repeatable Episodic Memory Test (USC-REMT), Paced Auditory Serial Addition Test (PASAT), Trail Making Test (TMT), and Stroop Color–Word Test were administered before and after the shift to measure changes in cognition. We compared the change in scores stratified by shift length using t-tests, Wilcoxon signed-rank test, and Fisher's exact test. Results. Participants in the 12- and 24-hour shift groups were aged 36 ± 8 years (12-hour shifts) and 39 ± 6 years (24-hour shifts) (mean ± standard deviation) and were preponderantly male (62% 12-hour shifts; 63%, 24 hour shifts). The PSQI scores identified 50% of both 12-hour and 24-hour shift subjects as having poor sleep quality. Preshift fatigue was described as a median 2/10 (interquartile range [IQR] = 2–4) and fatigue declined by the end of the shift to a median 1/10 [IQR = 1–2], p = 0.006. Providers averaged 6.8 hours of sleep during 24-hour shifts and 1 hour of sleep during 12-hour shifts. Changes in cognitive scores did not differ between groups. Conclusions. This study identified no changes in cognitive performance following 12- and 24-hour shifts in air medical providers. This suggests that 24-hour shifts in an air medical service with low to moderate utilization do not have a detrimental effect on cognition as measured by this test battery, and are comparable to 12-hour shifts in terms of impact on cognitive function.