Interventions
The infusion process was performed at Beijing Anding Hospital, Capital Medical University. All participants were admitted to the research ward the day before infusion and started 6 hours preoperative fasting and water deprivation. On the infusion day, 0.2 mg/kg esketamine or 0.045 mg/kg midazolam was administered intravenously according to randomization group. Both medications were dissolved in 50 mL of normal saline and administered for 40 minutes using a syringe pump. Safety checks were performed before, during, and after infusion. Detailed information on the safety check procedure is presented in the trial protocol in 