Low-dose Dexmedetomidine and Postoperative Delirium After Cardiac Surgery

Dexmedetomidine infusion is administered from 16:00 to 08:00 during the night of surgery in the intensive care unit; and will repeated for a maximum of 5 consecutive nights. For patients with mechanical ventilation, the infusion rate is 0.2-0.7 ug/kg/h; for those without mechanical ventilation, the infusion rate is 0.05-0.2 ug/kg/h. The target depth of sedation is Richmond Agitation-Sedation Scale (RASS) -1.

Placebo (normal saline) infusion is administered in the same rate for the same duration as in the dexmedetomidine group. The conventional sedation is provided when necessary with propofol and/or midazolam by intravenous infusion/injection. The target depth of sedation depth is RASS -1.