Effect of atypical-sleep EEG patterns on weaning from prolonged mechanical ventilation

BACKGROUND:Approximately one-third of acute ICU patients display atypical sleep patterns that cannot be interpreted using standard EEG criteria for sleep. Atypical sleep patterns have been associated with poor weaning outcomes in acute ICUs. RESEARCH QUESTION:Do patients weaning from prolonged mechanical ventilation experience atypical-sleep EEG patterns, and are these patterns linked with weaning outcomes? STUDY DESIGN AND METHODS:EEG power-spectral analysis during wakefulness and overnight polysomnogram (PSG) were performed on alert, non-delirious patients at a long-term acute care facility (LTACH). RESULTS:Forty-four patients ventilated for a median duration of 38 days at the time of PSG were studied. Eleven patients (25%) demonstrated atypical-sleep EEG. During wakefulness, relative EEG power-spectral analysis revealed higher relative delta power in patients with atypical sleep than in patients with usual sleep - 53% v. 41%, p <0.001- and a higher slow-to-fast power ratio during wakefulness: 4.39 v. 2.17, p < 0.001. Patients with atypical sleep demonstrated more subsyndromal delirium (36% vs 6%, p = 0.027) and less REM sleep (4% vs 11% total sleep time p <0.02). Weaning failure was more common in the atypical-sleep group than in the usual-sleep group: 91% vs. 45% (p = 0.013). INTERPRETATION:Our study provides the first evidence that LTACH patients being weaned from prolonged ventilation exhibit atypical-sleep EEG patterns which were associated with weaning failure. Patients with atypical-sleep EEG patterns had higher rates of subsyndromal delirium and slowing of the wakeful EEG, suggesting that these two findings represent a biological signal for brain dysfunction.