Effect of Liposomal Bupivacaine TAPB Combined With Oxycodone PCIA on Postoperative Gastrointestinal Recovery in Patients Undergoing Major Abdominal Surgery

Effect of Liposomal Bupivacaine TAPB Combined With Oxycodone PCIA on Postoperative Gastrointestinal Function in Patients Undergoing Major Abdominal Surgery: A Randomized Controlled Trial

Rationale and Objective:

The purpose of this study is to evaluate the clinical efficacy and safety of a novel multimodal analgesia regimen, combining transversus abdominis plane block (TAPB) with patient-controlled intravenous analgesia (PCIA), in improving postoperative gastrointestinal function recovery in patients undergoing major abdominal surgery.

Study Design and Interventions:

This is a prospective, single-center, randomized, double-blind, parallel-controlled trial. A total of 132 eligible patients (aged 18-80 years, ASA I-III, scheduled for elective small bowel or colorectal surgery) will be randomly allocated to one of three groups (n = 44 per group) to receive distinct postoperative analgesia regimens:

Group R-S: 0.375% Ropivacaine TAPB + Sufentanil PCIA; Group LB-S: 266 mg Liposomal Bupivacaine TAPB + Sufentanil PCIA; Group LB-O: 266 mg Liposomal Bupivacaine TAPB + Oxycodone PCIA.

Primary Outcome:

The primary outcome is the area under the curve (AUC) of the I-FEED scoring system within the first 7 postoperative days, which comprehensively reflects the overall trajectory of gastrointestinal function recovery.

Hypothesis:

The investigators hypothesize that the combination of long-acting Liposomal Bupivacaine TAPB (for prolonged somatic pain relief) and Oxycodone PCIA (for precise visceral pain control via dual u and k receptor agonism) will synergistically attenuate the perioperative stress-inflammatory response. Consequently, this regimen is expected to significantly mitigate postoperative ileus (POI) and accelerate the recovery of gastrointestinal motility

Inclusion Criteria:

• Patients scheduled to undergo elective major abdominal surgery, specifically small bowel or colorectal resections.
• Aged between 18 and 80 years (inclusive).
• American Society of Anesthesiologists (ASA) physical status I, II, or III.
• Capable of understanding the study procedures, cooperating with postoperative pain/recovery assessments (e.g., VAS, QoR-15, I-FEED), and providing written informed consent prior to surgery.

Exclusion Criteria:

• History of significant neuropsychiatric disorders, including schizophrenia, epilepsy, Parkinson's disease, or myasthenia gravis, that may interfere with pain perception or cognitive evaluation.
• History of alcohol abuse or chronic opioid/analgesic dependence.
• Severe, uncontrolled hypertension (defined as systolic blood pressure ≥ 180 mmHg or diastolic blood pressure ≥ 110 mmHg).
• Severe cardiac, hepatic, renal, or pulmonary dysfunction that poses a high surgical/anesthetic risk or alters drug metabolism.
• Pregnant or lactating women.
• Known allergy, hypersensitivity, or contraindications to any of the study medications, including local anesthetics (ropivacaine, bupivacaine) or opioids (sufentanil, oxycodone).