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
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.
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.
Parallel
ropivacaine hydrochloride
Drug0.375% solution for transversus abdominis plane (TAP) local injection during surgery for postoperative analgesia.
Liposomal bupivacaine (LB)
Drug266mg single dose for TAP block local injection for postoperative pain control after abdominal surgery.
Sufentanil citrate
DrugFormulated into PCIA pump for continuous intravenous infusion for postoperative patient-controlled analgesia.
oxycodone
DrugPrepared in PCIA pump for intravenous patient-controlled analgesia after abdominal operation.
Area Under Curve (AUC) of I-FEED Score within Postoperative 7 Days
The I-FEED score was recorded daily on days 1 through 7; the area under the curve (AUC) of the consecutive I-FEED scores within 7 days postoperatively was calculated to comprehensively assess the recovery of postoperative gastrointestinal function. A higher score indicates poorer recovery of gastrointestinal function. An I-FEED score \> 6 indicates severe gastrointestinal dysfunction.
Time-Weighted Average (TWA) of Rest & Movement NRS Pain Score within 72h Postoperatively
Postoperative 6h,12h,24h,48h,72h
TWA of Short-form McGill Pain Questionnaire 2 (SF-MPQ-2) Score within Postoperative 72h
The Short-form McGill Pain Questionnaire 2 (SF-MPQ-2) Score (consisting of 22 items, each scored on a scale of 0-10, with higher scores indicating more severe pain) was used to distinguish between somatic pain and visceral pain; the weighted average (TWA) of the visceral pain subscale scores was calculated.
Total opioid dose (morphine equivalent) within 72 hours postoperatively
The cumulative doses of sufentanil or oxycodone administered via the PCIA pump within 72 hours postoperatively, as well as the doses of opioid rescue analgesics, were converted to morphine equivalents to facilitate intergroup comparisons.
Incidence of Prolonged Postoperative Ileus (PPOI)
PPOI defined as patients without mechanical bowel obstruction who meet ≥2 of 5 criteria after postoperative 72h: persistent PONV, intolerance to solid diet, no flatus/stool, obvious abdominal distension, daily I-FEED\>6 points。
Serum IL-6 and Cortisol Concentrations
Serum levels of interleukin-6 and cortisol were measured at three time points to assess perioperative inflammatory and surgical stress response.
Serum Motilin and Gastrin Concentrations
Detect serum motilin and gastrin to explore the effect of analgesic regimens on gastrointestinal endocrine function.
Plasma β-Endorphin Concentration
Determine plasma β-endorphin level to explore central pain modulation mechanism of multimodal analgesia.
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