Assessment of Sleep in Ventilator-Supported Critically Ill Patients

ABSTRACT

Ambrogio C; Koebnick J; Quan SF; Ranieri VM; Parthasarathy

Objectives: In critically ill patients, sleep derangements are reported to be severe using Rechtschaffen and Kales (R&K) methodology; however, whether such methodology can reliably assess sleep during critical illness is unknown. We set out to determine the reproducibility of 4 different sleep-assessment methods (3 manual and 1 computer-based) for ventilator-supported critically ill patients and also to quantify the extent to which the reproducibility of the manual methods for measuring sleep differed between critically ill and ambulatory (control) patients.

Design: Observational methodologic study.

Setting: Academic center.

Patients: Critically ill patients receiving mechanical ventilation and age-matched controls underwent polysomnography.

Interventions: None.

Measurements and Results: Reproducibility for the computer-based method (spectral analysis of electroencephalography [EEG]) was better than that for the manual methods: R&K methodology and sleep-wakefulness organization pattern (P = 0.03). In critically ill patients, the proportion of misclassifications for measurements using spectral analysis, sleep-wakefulness organization pattern, and R&K methodology were 0%, 36%, and 53%, respectively (P < 0.0001). The EEG pattern of burst suppression was not observed. Interobserver and intraobserver reliability of the manual sleep-assessment methods for critically ill patients (κ = 0.52 ± 0.23) was worse than that for control patients (κ = 0.89 ± 0.13; P = 0.03). In critically ill patients, the overall reliability of the R&K methodology was relatively low for assessing sleep (κ = 0.19), but detection of rapid eye movement sleep revealed good agreement (κ = 0.70).

Conclusions: Reproducibility for spectral analysis of EEG was better than that for the manual methods: R&K methodology and sleep-wakefulness organization pattern. For assessment of sleep in critically ill patients, the use of spectral analysis, sleep-wakefulness organization state, or rapid eye movement sleep alone may be preferred over the R&K methodology. (SLEEP 2008;31(11):1559–1568)

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