2.3. Interventions

In the DEX group, patients received continuous infusion of dexmedetomidine without loading dose at a rate of 0.2-0.7 μg/kg/h to achieve RASS score in the target range on the night of surgery. The target of sedation scores on the Richmond Agitation and Sedation Scale was −2 to +1 (lightly sedated to restless), on which scores range from −5 [unresponsive] to +4 [combative], as assessed at least every 2 hours. The saline group received equivalent volumes of saline. If bradycardia occurred which was defined as heart rate < 50 beats·min⁻¹, the infusion of dexmedetomidine was terminated and the patient was excluded from the study.