Prevalence, risk factors, and outcomes of delirium in mechanically ventilated adults.

Mehta, Sangeeta; Cook, Deborah; Devlin, John W; Skrobik, Yoanna; Meade, Maureen; Fergusson, Dean; Herridge, Margaret; Steinberg, Marilyn; Granton, John; Ferguson, Niall; Tanios, Maged; Dodek, Peter; Fowler, Robert; Burns, Karen; Jacka, Michael; Olafson, Kendiss; Mallick, Ranjeeta; Reynolds, Steven; Keenan, Sean; Burry, Lisa

OBJECTIVE Delirium is common during critical illness and associated with adverse outcomes. We compared characteristics and outcomes of delirious and nondelirious patients enrolled in a multicenter trial comparing protocolized sedation with protocolized sedation plus daily sedation interruption. DESIGN Randomized trial. SETTING Sixteen North American medical and surgical ICUs. PATIENTS Four hundred thirty critically ill, mechanically ventilated adults. INTERVENTIONS All patients had hourly titration of opioid and benzodiazepine infusions using a validated sedation scale. For patients in the interruption group, infusions were resumed, if indicated, at half of previous doses. Delirium screening occurred daily; positive screening was defined as an Intensive Care Delirium Screening Checklist score of 4 or more at any time. MEASUREMENTS AND MAIN RESULTS Delirium was diagnosed in 226 of 420 assessed patients (53.8%). Coma was identified in 32.7% of delirious compared with 22.7% of nondelirious patients (p = 0.03). The median time to onset of delirium was 3.5 days (interquartile range, 2-7), and the median duration of delirium was 2 days (interquartile range, 1-4). Delirious patients were more likely to be male (61.1% vs 46.6%; p = 0.005), have a surgical/trauma diagnosis (21.2% vs 11.0%; p = 0.030), and history of tobacco (31.5% vs 16.2%; p = 0.002) or alcohol use (34.6% vs 20.9%; p = 0.009). Patients with positive delirium screening had longer duration of ventilation (13 vs 7 d; p < 0.001), ICU stay (12 vs 8 d; p < 0.0001), and hospital stay (24 vs 15 d; p < 0.0001). Delirious patients were more likely to be physically restrained (86.3% vs 76.7%; p = 0.014) and undergo tracheostomy (34.6% vs 15.5%; p < 0.0001). Antecedent factors independently associated with delirium onset were restraint use (hazard ratio, 1.87; 95% CI, 1.33-2.63; p = 0.0003), antipsychotic administration (hazard ratio, 1.67; 95% CI, 1.005-2.767; p = 0.047), and midazolam dose (hazard ratio, 0.998; 95% CI, 0.997-1.0; p = 0.049). There was no difference in delirium prevalence or duration between the interruption and control groups. CONCLUSION In mechanically ventilated adults, delirium was common and associated with longer duration of ventilation and hospitalization. Physical restraint was most strongly associated with delirium.