A randomized controlled study on the effects of different doses of intrathecal morphine on the postoperative recovery quality of patients undergoing laparoscopic abdominal surgery

INTERVENTION: 100µg group:Intrathecal injection of 100 µg morphine (diluted with normal saline to 5 mL);150µg group:Intrathecal injection of 150 µg morphine (diluted with normal saline to 5 mL);200µg group:Intrathecal injection of 200 µg morphine (diluted with normal saline to 5 mL);Placebo group:Intrathecal injection of an equal volume of 0.9% normal saline (5 mL); CONDITION: colorectal diseases PRIMARY OUTCOME: Postoperative 24‐hour Quality of Life Scale (QoR‐15) score; SECONDARY OUTCOME: Quality of Recovery‐15 Score at 48 and 72 hours postoperatively;Numerical Rating Scale pain score at rest and during activity at 24, 48, and 72 hours postoperatively;Cumulative opioid consumption (measured in Morphine Milligram Equivalents, MME) at 24, 48, and 72 hours postoperatively;Frequency of rescue analgesia, total dose of rescue medication, and rescue analgesia utilization rate at each time interval;Time to first flatus and time to first ambulation postoperatively;Postoperative length of hospital stay (days);Incidence of adverse events (including nausea, vomiting, pruritus, hypotension, headache, dizziness, etc.) at 24, 48, and 72 hours postoperatively;Patient‐Controlled Intravenous Analgesia (PCIA) pressing count and rescue analgesia utilization rate; INCLUSION CRITERIA: 1. Age: 18 ‐ 75 years old, gender not restricted; 2. American Society of Anesthesiologists (ASA) physical condition classification: I ‐ III; 3. Scheduled for laparoscopic abdominal surgery (laparoscopic colorectal surgery), with an expected operation time of >= 60 minutes and an insufflation time of >= 40 minutes; 4. Signed a written informed consent form before the operation, and able to cooperate with postoperative follow‐up and scale scoring; 5. Preoperative Numerical Rating Scale (NRS) for pain <= 3 points, and no history of long‐term use of opioid drugs before the operation.