166 - BENZODIAZEPINE-FREE CARDIAC ANESTHESIA FOR REDUCTION OF POSTOPERATIVE DELIRIUM: A PRAGMATIC CLUSTER-RANDOMIZED CROSSOVER TRIAL

Background: Delirium is common after cardiac surgery and associated with increased morbidity, mortality, and healthcare costs. Intraoperative benzodiazepines may increase postoperative delirium rates. We sought to determine whether an institutional policy of restricted intraoperative benzodiazepine administration would reduce the incidence of postoperative delirium when compared to a policy of liberal use.

METHODS AND RESULTS: We conducted a pragmatic, multiple-period, patient and assessor blinded, cluster-randomised, crossover trial comparing institutional policies of restricted versus liberal intraoperative benzodiazepine administration in patients undergoing cardiac surgery at 20 hospitals. During 12 to 18 four-week crossover periods, hospitals were randomized to use one of two policies, with crossover to the other policy at random. The primary outcome was the incidence of delirium within 72-hours of surgery as detected in routine clinical care using a validated delirium scale. We assessed intraoperative awareness by patient report as an adverse event. During the trial, 19,768 patients underwent cardiac surgery: 9,827 during restricted benzodiazepine periods and 9,941 during liberal benzodiazepine periods. Overall, adherence to both policies was 18,196/19,768 (92.0%). Delirium occurred in 1,373 patients (14.0%) during restricted periods and 1,485 (14.9%) patients during liberal periods (adjusted odds ratio [aOR] 0.92; 95% confidence interval [CI], 0.84-1.01; P=0.07). When considering only patients managed according to policy, delirium occurred in 1,219/8,928 (13.7%) patients in restricted periods and 1,372/9,268 (14.8%) patients in liberal periods (aOR 0.90; 95% CI 0.82-0.99). No patient reported intraoperative awareness.


Conclusion: The odds of postoperative delirium ranged from 16% lower to 1% higher (based on a 95% CI) with a policy of restricted compared to liberal benzodiazepine use during cardiac surgery, with no demonstration of an increase in intraoperative awareness. Restricting benzodiazepines during cardiac surgery should be considered.