Analgesic Outcomes of Ultrasound-Guided QLB vs TAP Block in Midline Laparotomy

Midline laparotomy is associated with significant postoperative pain that can limitmobilization, impair respiratory function, and increase opioid‐related side effects.Abdominal wall blocks such as the transversus abdominis plane (TAP) block and quadratuslumborum block (QLB) are used as part of multimodal analgesia. TAP primarily targetssomatic afferents of the anterior abdominal wall, while QLB may provide broader coverageincluding potential paravertebral spread via the thoracolumbar fascia, potentiallyoffering longer‐lasting analgesia.This single‐center, prospective, randomized controlled trial will enroll 100 adults (50per group) aged 18‐65 years, ASA physical status I‐III, scheduled for elective midlinelaparotomy under general anesthesia. Participants will be randomized 1:1 usingsequentially numbered, opaque, sealed envelopes prepared by an independent researchassistant. Both blocks will be performed after induction of general anesthesia and beforesurgical incision by an experienced anesthesiologist under ultrasound guidance and strictaseptic precautions.Group A (QLB): Bilateral lateral quadratus lumborum (QL1) block with 20 mL of 0.25%bupivacaine per side (total 40 mL / 100 mg, not exceeding 2 mg/kg).Group B (TAP): Bilateral TAP block with 20 mL of 0.25% bupivacaine per side (total 40 mL/ 100 mg, not exceeding 2 mg/kg).Postoperative analgesia will be standardized with intravenous paracetamol 1 g every 6hours. Pain will be assessed using the Numerical Rating Scale (NRS 0‐10) at 6, 12, and 24hours by an independent, blinded outcome assessor. Rescue analgesia (intravenous morphineor tramadol) will be given for NRS ≥4. Primary and secondary analgesic outcomes includeNRS scores, time to first rescue analgesia, proportion requiring rescue analgesia within24 hours, and total opioid consumption in the first 24 hours. Block‐related complicationswill also be recorded.Statistical analysis will use SPSS version 26. Normality will be assessed by Shapiro‐Wilktest. Continuous variables will be compared with independent‐samples t‐test orMann‐Whitney U test; categorical variables with Chi‐square or Fisher's exact test.Potential confounders will be addressed by stratification. A two‐sided p‐value ≤0.05 willbe considered statistically significant.