Subjective sleep assessment compared to polysomnography in mechanically ventilated critically ill ICU patients.

Abstract

Sleep deprivation is expected in the intensive care unit (ICU) and is associated with delirium and increased mortality. Polysomnography (PSG) is the gold standard for sleep assessment, but practical issues limit the method. Hence many ICUs worldwide use subjective sleep assessment (SSA) for sleep monitoring, but the agreement between SSA and PSG is unknown. The hypothesis was that the level of agreement between SSA and PSG was low and that total sleep time (TST) assessed with SSA would be overestimated compared to PSG in this existing cohort database. In this sub-analysis thirty consecutive study participants underwent 15-hour PSG recordings during two consecutive nights. The attending nurse performed an hourly subjective observer rating of sleep quantity during both nights, and the agreement between SSA and PSG was determined along with mean TST. The level of agreement between SSA and PSG determined by Bland-Altman analysis. 1) The overall mean TST estimated by SSA compared to PSG in all study participants enrolled in the main study during both study nights, 2) TST for all study participants evaluated hourly during both study nights, 3) TST assessed with SSA compared to PSG in study participants sedated with dexmedetomidine during the second night and for study participants treated with placebo or non-sedation the first and second nights. The level of agreement between SSA and PSG was low. Mean TST estimated by SSA during the time interval 4.00 pm to 7.00 am was 481 minutes (428;534, 95% CI) vs. PSG at 437 minutes (386;488, 95% CI) (p=0.05). When sedated with dexmedetomidine, TST estimated using SSA was 650 minutes (571;729, 95% CI) vs. PSG which was 588 minutes (531;645, 95% CI) (p=0.56). For participants treated with placebo or non-sedation TST estimated with SSA was 397 minutes (343;450, 95% CI) vs. PSG at 362 minutes (302;422, 95% CI) vs. (p=0.17). In mechanically ventilated critically ill ICU patients, the level of agreement between SSA and PSG was low, and there was a significant overestimation of mean TST. SSA should only be used under awareness that it is imprecise and overestimates TST. This article is protected by copyright. All rights reserved.