The Effects of Midazolam, Dexmedetomidine, and Esketamine on Bispectral Index and Raw Electroencephalogram in Patients Under Propofol-Remifentanil Baseline Anesthesia

Inclusion Criteria: 1. ASA physical status I-II; 2. BMI 18-28 kg/m²; 3. Scheduled for elective laparoscopic cholecystectomy, with an expected surgical duration from skin incision to completion of wound closure of ≥45 min; 4. Planned to receive propofol-remifentanil total intravenous anesthesia, with routine intraoperative BIS monitoring and simultaneous acquisition of raw EEG signals; 5. Voluntarily agrees to participate in this study, has signed the informed consent form, and is able to cooperate with the intervention and assessment procedures. Exclusion Criteria: 1. A confirmed history of psychiatric or neurological disorders, or use of antipsychotics, antidepressants, benzodiazepines, or other sedative-hypnotic drugs within 4 weeks before surgery; 2. Cognitive impairment identified by Mini-Cog screening; 3. Poorly controlled or untreated hypertension, sinus bradycardia, or severe cardiac conduction block; 4. Acute angle-closure glaucoma; 5. Known allergy to any required anesthetic drug; 6. Difficulty in electrode placement or any condition that may interfere with EEG monitoring.