Influence or perioperative dexmedetomidine on the incidence of postoperative delirium in adult patients undergoing cardiac surgery

Background: Delirium is a common neurocognitive complication after cardiac surgery. The aim of this systematic review was to determine whether the administration of dexmedetomidine in the perioperative period decreases the incidence of postoperative delirium in adult patients undergoing cardiac surgery. Methods: Central, CINAHL, Ovid Embase, Ovid Medline, and Web of Science databases were searched for RCTs of adult patients undergoing cardiac surgery where participants received i.v. dexmedetomidine or control in the perioperative period. The methods included systematic review, meta-analysis, and trial sequential analysis. The primary outcome was the incidence of postoperative delirium. Dichotomous outcomes were presented as risk ratio (RR) using the Mantel-Haenszel method, and continuous variables were presented as mean difference with the inverse variance method. Results: Thirty trials, comprising 4090 patients, were included. With unselected inclusion of trials, dexmedetomidine vs control was associated with decreased incidence of postoperative delirium (12.4% vs 16.2%; RR=0.62; 95% confidence interval 0.44-0.86; P=0.005; I-2=61%). If trials at high risk of bias were excluded, the incidence of postoperative delirium was not significantly different between groups (RR=0.71; 95% confidence interval 0.49-1.03; P=0.070; I-2=58%). Postoperative delirium was not a reliably determined outcome across trials because of methodological and reporting limitations, including the heterogeneity of delirium diagnostic approach. Trial sequential analysis revealed that the optimal information size was not reached, and the Z-curve did not cross the trial sequential boundaries for benefit or futility. With respect to safety concerns, dexmedetomidine was not significantly associated with incident bradycardia or hypotension, or with the duration of mechanical ventilation. Conclusions: When trials at high risk of bias were excluded, the use of perioperative dexmedetomidine was not associated with decreased incidence of postoperative delirium.