Loading dose of 7.5 mcg IV at dural closure. PCIA pump: Sufentanil 2 mcg/kg diluted to 100 ml with normal saline. Settings: background infusion 1 ml/h, bolus dose 0.5 ml, lockout time 6 min. Duration: 48h.

Frequency and/or dose of administered rescue antiemetics (e.g., 5HT-3 receptor antagonists, metoclopramide).

Time from end of surgery to first passage of flatus, as self-reported by the patient or directly observed and documented by nursing or study staff.

Time from end of surgery to first bowel movement, as self-reported by the patient or directly observed and documented by nursing or study staff.

Presence of constipation, defined as meeting Rome IV criteria for functional constipation in postoperative period, assessed by clinical staff or patient self-report.

Assessment of gastrointestinal symptoms using the Gastrointestinal Symptom Rating Scale (GSRS). The scale consists of 15 items rated on a 7-point Likert scale (1 = no discomfort, 7 = severe discomfort). The total score ranges from 15 to 105, with higher scores indicating worse gastrointestinal symptom severity.

Assessment of postoperative gastrointestinal intolerance using the Intake, Feeling nauseated, Emesis, Exam, and Duration (I-FEED) scoring system. The scale includes 5 domains (intake, nausea, emesis, physical exam findings, symptom duration) with a total score range of 0-14 points. Higher scores indicate worse gastrointestinal function: 0-2 = normal, 3-5 = postoperative gastrointestinal intolerance (POGI), ≥6 = postoperative gastrointestinal dysfunction (POGD).

Changes in levels of Pepsinogen I, Pepsinogen II, Gastrin-17, and Serotonin (5-HT).

Total amount of study drug used via PCIA pump, converted to morphine milligram equivalents (MME).

Number of effective demands and total number of demands.

Frequency and/or dose of administered rescue analgesics (e.g., NSAIDs).

Assessment of subjective sleep quality using the Richards-Campbell Sleep Questionnaire (RCSQ). The scale consists of 5 items (sleep depth, sleep latency, awakenings, sleep quality, return to sleep after awakening) rated on a 100-mm visual analog scale, with a total score range of 0-100 points. Higher scores indicate better subjective sleep quality (scores ≥70 are generally considered indicative of good sleep quality).

Defined as respiratory rate < 10 breaths/min or SpO₂ < 90% for >1 min, or PaCO₂ > 50 mmHg.

Assessment of level of sedation and agitation using the Richmond Agitation-Sedation Scale (RASS). The scale ranges from -5 (unarousable) to +4 (combative/agitated), with a score of 0 (alert and calm) representing the optimal clinical state. Positive scores indicate increasing agitation, while negative scores indicate increasing sedation

Incidence of urinary retention, defined as patient-reported difficulty voiding or a post-void residual urine volume ≥150 mL (measured via bladder scan) within 48 hours after urinary catheter removal. This will be assessed by counting the number of participants meeting the above criteria.

Assessed using a Visual Analogue Scale (VAS, 0-10).

Assessment of dizziness severity using the Dizziness Handicap Inventory (DHI) scale. The scale consists of 25 items rated on a 3-point scale (0 = no handicap, 2 = occasional handicap, 4 = severe handicap), with a total score range of 0-100 points. Higher scores indicate greater dizziness-related functional handicap (scores 0-30 = mild, 31-60 = moderate, 61-100 = severe handicap).

Total number of days from the end of surgery to hospital discharge.

Binary assessment (yes/no) of whether the patient required admission to the intensive care unit (ICU) during the postoperative period.

Total number of days spent in the ICU, if ICU admission occurred.

Total direct medical costs incurred during the entire hospital stay (including surgery, ward care, ICU, medications, and laboratory tests).