0841 Feasibility of Actigraphy during a Daytime Bright Pilot Study in the Medical ICU

Abstract Introduction Medical intensive care unit (MICU) light patterns are inadequate for proper circadian alignment. Sleep disruption and circadian misalignment are observed in MICU patients and adversely impact patient outcomes. We sought to establish the feasibility of using longitudinal actigraphy to measure diurnal rest-activity patterns, as a in the context of a pilot study evaluating daytime bright light (DBL). In an exploratory manner, we analyzed diurnal rest-activity characteristics. Methods Patients >50 years admitted to the MICU without pre-existing circadian disruption were enrolled. An actigraph was placed (wrist) on study day 1 (D1) and remained for up to 5 days. DBL exposure (>1200 lux, 5000K) began at 09:00 on D2 and continued until D5 (varied lengths of exposure among patients). Actigraphy feasibility was assessed via (1) total recording duration and (2) proportion of total recording with activity data (e.g., proportion of epochs on wrist with data capture). In an exploratory analysis, we evaluated rest-activity characteristics from D1 and D2 for fit with gamma distribution cosinor analysis. Characteristics included ratio of day/total activity, mesor (midline estimation statistic of circadian rhythm), and circadian quotient (normalized amplitude/mesor). Results Thirteen of fourteen enrolled patients completed actigraphy. Mean (SD) age was 74 (11) years. Mean APACHE II illness severity score was 21 (4). Patients had a mean 3.7 (1.3) days of actigraphy recording and a mean activity data proportion of 92% (16%). There were only two reports of temporary actigraph removal related to patient care. All actigraphy patients had fit using cosinor analysis. D1 median (IQR) day/total ratio was 0.76 (0.68,0.82), mesor was 10.31 (6.36,13.00), and circadian quotient was 0.82 (0.48,0.99). D2 (after DBL start) median (IQR) day/total ratio was 0.76 (0.64,0.78), mesor was 11.90 (8.97,15.83), and circadian quotient was 0.89 (0.65,0.95). Conclusion Here we demonstrate the feasibility of actigraphy as a measure of diurnal rest-activity patterns in MICU patients based on successful collection and analysis of data in all patients. While cohort size remains a limitation of this study, Actigraphic rest-activity patterns are being explored in an ongoing RCT evaluating the impact of DBL versus usual light exposure on circadian rhythms in critical illness. Support (if any) K23HL138229, AASM Foundation