Balance as a Measurement of Fatigue in Postcall Residents

Objectives/Hypothesis: To determine the degree to which balance is impaired by fatigue in postcall medical residents and to assess the validity of posturography in quantifying that impairment. Study Design: Prospective study. Methods: Medical residents underwent the following tests before and immediately after overnight call: 1) computerized dynamic posturography (CDP) using the Equitest force platform (Natus Medical Inc., Clackamas, OR); 2) Clinical Test of Sensory Interaction and Balance, in which the residents stood on a compliant foam mat with closed eyes and flexed and extended their necks; 3) a computerized reaction time test (available at www.humanbenchmark.com). All tests were performed before and after call at approximately the same time of day to exclude circadian rhythm influence on fatigue. The residents also completed questionnaires, including the Stanford Sleepiness Scale, describing their level of fatigue before and after call. Results: A statistically significant difference was found between a resident's pre- and postcall test with regard to reaction time (P=.01), Stanford Sleepiness Scale score (P=.001), and preference for the visual system as measured by CDP (P=.05). Linear regression analysis showed a statistically significant relationship between sleep deprivation and multiple performance variables measured by CDP. Conclusions: With the growing attention paid to resident duty hours, there is an increasing need for research involving fatigue and practical ways to measure it. This study shows that residents who are measurably fatigued (both objectively and subjectively) may have difficulty utilizing vestibular input during quiet standing but can compensate by means of somatosensory and visual input.