Assessment of sleep in ventilator-supported critically III patients.

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 (kappa = 0.52 +/- 0.23) was worse than that for control patients (kappa = 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 (kappa = 0.19), but detection of rapid eye movement sleep revealed good agreement (kappa = 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.