To determine whether benzodiazepine and propofol doses are increased at night and whether daytime and nighttime sedative doses are associated with delirium, coma, and delayed liberation from mechanical ventilation.
Single-center, prospective cohort study nested within the Awakening and Breathing Controlled randomized trial
Saint Thomas Hospital in Nashville, TN from 2004–2006
Adult patients receiving mechanical ventilation for greater than 12 hours with continuous recording of hourly sedation dosing
We measured hourly doses of benzodiazepine and propofol exposure during the daytime (7am–11pm) and nighttime (11pm–7am) for five days. We quantified nighttime dose increases by subtracting the average hourly daytime dose on the preceding day from subsequent average hourly nighttime dose. We used multivariable logistic regression to determine if daytime and nighttime dose increases were independently associated with delirium, coma, and delayed liberation from mechanical ventilation.
Measurements and main results
Among 140 patients, the median APACHE II score was 27 [IQR: 22, 33]. Among those receiving the sedatives, benzodiazepine and propofol doses were increased at night on 40% and 41% of patient-days, respectively. Of 485 patient-days, delirium was present on 160 (33%) and coma on 206 (42%). In adjusted models, greater daytime benzodiazepine dose was independently associated with failed SBT and extubation, and subsequent delirium (p<0.02 for all). Nighttime increase in benzodiazepine dose was associated with failed SBT (p<0.01) and delirium (p=0.05). Daytime propofol dose was marginally associated with subsequent delirium (p=0.06).
Nearly half of mechanically ventilated ICU patients received greater doses of sedation at night, a practice associated with failed SBTs, coma, and delirium. Over the first five days in our study, patients spent 75% of their time in coma or delirium, outcomes that may be reduced by efforts to decrease sedative exposure during both daytime and nighttime hours in the ICU.