Perioperative dexmedetomidine reduces delirium after cardiac surgery: A meta-analysis of randomized controlled trials

Study objective: To evaluate the efficiency of dexmedetomidine on the incidence of delirium in patients after cardiac surgery. Design: Meta-analysis of randomized controlled trials. Setting: Operating room and Intensive Care Unit (ICU). Patients: Ten trials with a total of 1387 patients undergoing cardiac surgery met the inclusion criteria. Intervention: Randomized controlled trials (RCTs) comparing the effect of dexmedetomidine versus non-treatment of dexmedetomidine (normal saline (NS), propofol and other anesthetic drugs) on delirium in patients undergoing cardiac surgery were retrieved from PubMed/Medline, Embase, the Cochrane Library and Web of science. The primary outcome was the incidence of delirium. The secondary outcomes were the rate of bradycardia and hypotension, the duration of mechanical ventilation and the length of ICU and hospital stay. Main results: Compared with the control group, Dexmedetomidine significantly decreased the incidence of postoperative delirium, (risk ratio 0.46; 95% confidence intervals, 0.34 to 0.62; P < 0.00001), while the incidence of bradycardia was increased in dexmedetomidine group (risk ratio 1.86; 95% confidence intervals, 1.16 to 2,99; P = 0.01). There was no significant difference between groups with regarding to the occurrence of hypotension (risk ratio 0.90; 95% confidence intervals, 0.59 to 1.38; P = 0.63), the duration of mechanical ventilation (Mean Difference 0.21; 95% confidence intervals, -0.70 to 1.12; P = 0.65), and the length of ICU (Standard Mean Difference -0.07; 95% confidence intervals, 0.19 to 0.06; P = 0.3) and hospital stay (Mean Difference -0.13; 95% confidence intervals, -0.56 to 0.30; P = 0.56). Conclusion: Perioperative dexmedetomidine administration decreased the incidence of delirium in patients after cardiac surgery, but might increase the rate of bradycardia. Furthermore, we did not observe significant differences in the incidence of hypotension, the duration of mechanical ventilation and length of ICU and hospital stay between groups. Future studies are needed to ascertain the effect of dexmedetomidine on the incidence of delirium after coronary artery bypass grafting (CABG) and in patient with cognitive disorder at baseline, whether intraoperative dexmedetomidine infusion could reduce postoperative delirium and the optimal dose of dexmedetomidine.