Background: 

Postoperative delirium (POD) is a common complication in cardiac surgery especially in elderly population which can lead to a delay of weaning from ventilator and extubation. Cardiopulmonary bypass (CPB)-induced inflammation is related to POD. Anti-inflammatory effect of anesthetic agent might attenuate POD.

Aims: 

The present study was primarily aimed to compare within-24-h POD between ketamine-based anesthesia and propofol-based anesthesia during CPB. The secondary objective was to identify risk factors associated with within-24-h POD.

Setting and Design: 

Our study was a randomized controlled trial in patients undergoing cardiac surgery with CPB. Enrolling patients were aged >65 years, and able to comprehensive communication. Exclusion criteria were aortic surgery, cognitive disorders, cerebrovascular and carotid disease, and positive result of preoperative CAM-ICU.

Materials and Methods: 

Patients were randomly assigned to group Ketamine infusion of 1 mg/kg/h and group Propofol infusion of 1.5-6 mg/kg/h during CPB. POD was evaluated by validated Thai version CAM-ICU at 8-24 hour after ICU arrival.

Statistics:

 Chi-square, Fisher exact and t-test tests, univariate analysis and multivariate logistic regression were utilized. Results: Total 82 patients entered this study and 64 patients remained after exclusion (Group Ketamine = 32 and Group Propofol = 32). Within-24-h POD were 31.25% and 56.25% (P = 0.04) and mean arterial pressure (MAP) were 71.45 and 65.53 mmHg (P = 0.01) respectively in Ketamine and Propofol group. Postoperative leukocytosis was a significant risk to POD (adjusted OR 124.5).

Conclusion:

 With limitations of the study, prevention of 24-h POD in general by ketamine was inconclusive. In comparison with propofol, ketamine leaded to less events of 24-h POD and kept higher MAP. Severity of postoperative inflammation was a significant prediction of 24-h POD.