Effect of Opioid-free Anaesthesia on Postoperative Delirium in Elderly Patients Undergoing Gastrointestinal Surgery

Continuous infusion at 0.5-1.0 μg/kg/h during surgery

Induction dose 0.3-0.5 mg/kg; maintenance 0.2-0.5 mg/kg/h; 0.02 mg/kg at closure; PCIA: 1.5 mg/kg in 100 mL saline

Maintenance 20-100 μg/kg/min during surgery

0.3-0.5 μg/kg induction; 0.15 μg/kg at closure; 2 μg/kg in 100 mL for PCIA

0.2-1.0 μg/kg/min maintenance