Effect of Low-dose EsketaMine on dElirium in High-risk Elderly Patients uNdergoing elecTive Surgery (ELEMENT)

Esketamine (1mg/ml) will be administered at a loading dose of 0.2 mg/kg, namely at a infusion rate of 1.2ml/kg/h over 10 minutes after induction, then a maintenance infusion rate of 0.1 mg/kg/h until 40 minutes before the end of the surgery. For postoperative analgesia, patient-controlled intravenous analgesia (PCIA) is prepared with a formulation consisting of esketamine 50mg and sufentanil 200 μg, diluted to a total volume of 200 ml. The background dose is set at 2 ml/h, with a bolus dose of 2 ml and a lockout interval of 15 minutes.

Normal saline will be administered at a infusion rate of 1.2ml/kg/h over 10 minutes after induction, then a maintenance infusion rate of 0.1 mg/kg/h until 40 minutes before the end of the surgery. For postoperative analgesia, patient-controlled intravenous analgesia (PCIA) is prepared with sufentanil 200μg, diluted to a total volume of 200 ml. The background dose is set at 2 ml/h, with a bolus dose of 2 ml and a lockout interval of 15 minutes.