This study is designed to assess the direct effects of sleep deprivation on medical residents by measuring the level of exhaled nitric oxide (FeNO), a marker of systemic inflammation. Given that other pro-inflammatory markers are elevated in sleep deprivation, we hypothesized that FeNO will be increased in sleep deprived subjects.
Medical residents at our institution were notified of the study via email. A screening questionnaire included clinical predictors for obstructive sleep apnea (OSA) and Epworth scale. Using a parallel cross-over design, residents were assigned randomly to either the non-call group or the call group. Both groups were screened for exclusionary criteria. Call group participants required two sequential FeNO measurements, one while on-call and the next 24 hours following.
Seventeen residents responded with the initial screening questionnaire. None had more than a 7% pre-test probability for OSA as determined by previously established clinical prediction formulas. Average Epworth 7.1 (±SD 4.1). Eleven residents were eligible and underwent complete testing. Two residents were excluded for recent NSAID use, 1 for cold symptoms, 1 for not completing the questionnaire, 1 for test administered incorrectly, and 1 for not following-up with the post-call FeNO measurement. The length of time spent sleeping by the non-call (n=8), immediately pre-call (n=5), and immediately post-call (n=5) groups were 6.4 (±SD 0.8) hours, 6.7 (±1.2) hours, and 3.7 (±3.3) hours, respectively. Mean FeNO in the non-call, pre-call and post-call groups were 12.3 ±0.8 ppm, 18.3 ±8.6 ppm, and 19.2 ±9.9 ppm, respectively (ANOVA, p<0.05).
FeNo levels are elevated in residents engaged in regular in-house overnight call in as little as two weeks when compared to their non-call counterparts. The greater FeNO level on the day of call when compared to the non-call group in spite of greater average sleep time the night prior suggests that the inflammatory state lingers for at least 72 hours after call.
FeNO is increased in sleep-deprived medical residents, supporting the concept that sleep deprivation gives rise to a pro-inflammatory state.
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