0583 Tolerance and feasibility of daytime bright light in medical intensive care unit patients

Abstract

Abstract Introduction Sleep and circadian disruption in critical illness are associated with poor outcomes. Normal circadian entrainment requires bright light exposure during the day and dim or no light during the night. Disruption of this diurnal light pattern can cause circadian abnormalities. To leverage this highly influential circadian entrainment cue, our study investigates the tolerance and feasibility of a daytime bright light (DBL) intervention in the medical ICU (MICU). We hypothesize that DBL is tolerable and has high fidelity and sustainability (i.e., feasibility). Methods Here we present the findings of a pilot randomized control trial of DBL in MICU patients. Patients were randomized to receive light for either 4 hours, 8 hours, or no light (usual care). For DBL groups, the light was turned on at 09:00 daily for 4 consecutive days. Metrics of tolerability (percentage of days patient agreed to light), fidelity (percentage of intended hours light was delivered), and sustainability (percentage of days light delivered out of days patients allowed light) were collected. Results Sixteen patients were enrolled; 5 were assigned to 8 hours of DBL, 9 were assigned to 4 hours of DBL, and 2 were assigned to usual care. Mean (standard deviation) patient age was 73 (10) and mean severity of illness, as determined by Acute Physiology and Chronic Health Evaluation II score, was 21(5). Patients who received 4 hours of DBL averaged 69% tolerability, 55% fidelity, and 94% sustainability. Patients who received 8 hours of DBL averaged 70% tolerability, 57% fidelity, and 90% sustainability. Further analysis of light delivery data showed that the 8-hour group was subject to a higher number of requests to delay light start or end light early and more care related breaks versus the 4-hour group. Conclusion Our study demonstrates the feasibility of a DBL intervention for MICU patients. While fidelity was lower than expected, the findings support that DBL is tolerable and sustainable in critically-ill patients. These findings have influenced the design of our ongoing randomized control trial further evaluating the impact of daytime bright light on circadian phase in critical illness. Support (If Any) This work was supported by the NHLBI (K23 HL138229), the Academy of Sleep Medicine Foundation, and the Fund to Retain Clinical Scientists at Yale sponsored by the Doris Duke Charitable Foundation award #2015216 and the Yale Center for Clinical Investigation.