Study on the Effects of Multimodal Analgesia Regimens on Postoperative Analgesia and Gastrointestinal Function Recovery After Laparoscopic Abdominal Surgery

Study design：This is a prospective, randomized, comparative, double-blind study designed to assess the superiority and non-inferiority of four analgesic techniques: epidural analgesia (EA), paravertebral block (PB), transversus abdominis plane block (TAP), and patient-controlled intravenous analgesia (PCIA). The study will evaluate the effectiveness of these methods for pain management in patients undergoing laparoscopic abdominal surgery. Patients will be recruited at Baogang Hospital in Inner Mongolia. This study was approved by the Medical Ethics Committee of Baogang Hospital, Inner Mongolia, and adhered to the Declaration of Helsinki and the Consolidated Standards of Reporting Trials (CONSORT) guidelines. All participants provided informed consent voluntarily.

Patients：A total of 120 patients undergoing laparoscopic abdominal surgery, classified as American Society of Anesthesiologists (ASA) physical status I-III, will be recruited between February and May 2025. These patients will be randomly assigned to one of four groups, with 30 patients in each group. Randomization and Blinding：This study employed block randomization to generate the random allocation sequence. A block size of 6 was set, and the random sequence was generated using dedicated software (the blockrand package in R version 4.3.2). The allocation of the random sequence was performed by an independent third party, and allocation concealment was implemented using sequentially numbered, sealed, opaque envelopes. The research team remained blinded throughout the randomization process and was not involved in the generation or allocation of the random sequence.

Intervention： General anesthesia and monitoring Upon arrival in the operating room, patients were monitored for pulse oximetry (SPO2), electrocardiogram (ECG), bispectral index (BIS), and non-invasive arterial blood pressure. Pain threshold (PTh, mA) and pain tolerance threshold (PTTh, mA) were measured and recorded. Patients received pre-operative administration of Penehyclidine Hydrochloride Injection (Lot H20051948, Chengdu List Pharmaceutical Co., Ltd., China) (0.01 mg kg-1 i.v.). Induction was achieved with propofol (1.5-2 mg kg-1 i.v.), rocuronium bromide (1-2 mg kg-1 i.v.), and fentanyl (1-2 μg kg-1 i.v.). Anesthesia was maintained with inhaled sevoflurane or desflurane, with the inhaled concentration adjusted according to BIS values. Remifentanil (0.05-0.2 μg kg-1 min-1 i.v.) was continuously infused to maintain blood pressure and heart rate within ±20% of baseline values. Mechanical ventilation was initiated in pressure-regulated volume control (PRVC) mode after induction. Ventilator settings (Aestiva; GE Healthcare, Waukesha, Wisconsin, USA) were as follows: tidal volume 6-8 ml kg-1, positive end-expiratory pressure (PEEP) 0 cmH2O, inspiratory-to-expiratory ratio 1:2, respiratory rate 16 beats per minute (BPM), and inspired oxygen concentration 41%. The patient was positioned in the Trendelenburg position, with the operating table tilted 20-25° head down. Carbon dioxide pneumoperitoneum was established at an intra-abdominal pressure of 10-15 mmHg.

Postoperative care Vital signs were monitored in the Post Anesthesia Care Unit (PACU), with supplemental oxygen provided via facemask. For hypotension, ephedrine (6-10 mg) was administered, and fluid administration was increased. Atropine (0.3-0.5 mg) was given for bradycardia. For pain, sufentanil (0.1-0.2 μg/kg) was administered.

Data collection Upon arrival in the operating room, heart rate (HR, bpm), mean arterial pressure (MAP, mmHg) (calculated as MAP = diastolic pressure + 1/3 pulse pressure), BIS, remifentanil dosage (mg), ephedrine dosage (mg), duration of surgery (minutes), and duration of anesthesia (minutes) were recorded for all patients.

In the PACU, the following data were recorded: number of patients requiring sufentanil (μg), number of patients experiencing respiratory depression (n), number of hypotension events requiring intervention (n), ephedrine dosage (mg), intravenous fluid volume (ml), number of patients experiencing bradycardia (n), atropine dosage (mg), Bromage score, and time spent in the PACU (min). For patients transferred to the high dependency unit, the number of patients (n) and length of stay (h) were recorded.

Postoperatively, rest pain (Numerical Rating Scale, NRS), dynamic pain (NRS), morphine equivalent (mg), quality of sleep on the first night (Likert scale, 1-5), functional recovery (return of bowel function, h, recommencement of oral intake, h, and time to first mobilization, h), quality of recovery (QoR, 0-15) on postoperative day 1, and hospital stay (days) were recorded at 4, 8, 12, and 24 hours. Ketorolac dosage (mg), hydromorphone dosage (mg), oral medications, number of episodes of PONV (n), antiemetic dosage (mg), number of episodes of pruritus (n), and Comprehensive Complication Index (CCI) were recorded over 24 hours.

Outcomes and measures：Patient follow-up was conducted in the ward by two specially trained nurses who were blinded to patient group assignment. Assessments, including those for postoperative day 1 and length of hospital stay, were performed in person at 4, 8, 12, and 24 hours post-procedure.