Comparing Continuous Bilateral Quadratus Lumborum Block with Continuous Epidural Block for Analgesia and Perioperative Outcomes in Colorectal Cancer Surgery: A Noninferiority Randomized Controlled Trial

Background and Aims: Managing acute postsurgical pain following midline exploratory laparotomy in colorectal cancer patients involves various approaches, such as central neuraxial blockade, patient-controlled intravenous analgesia with opioids, and bilateral continuous paravertebral block. However, each of these modalities carries its disadvantages. The Quadratus Lumborum Block’s role in delivering adequate analgesia in abdominal surgical cases has recently gained prominence across different patient populations, including adults, pediatrics, and pregnant patients. This study aims to compare the analgesic and perioperative effects of continuous bilateral quadratus lumborum block [CQL (II)] (using the QL2 approach) with continuous epidural block [Epi]. Material and Methods: In this noninferiority randomized controlled trial, all eligible patients, aged 18 to 80 undergoing exploratory laparotomy for colorectal cancer surgery, falling within the American Society of Anesthesiologists (ASA) Physical Status Class I, II, and III, who voluntarily provided written informed consent were randomly assigned to the CQL (II) or the Epi group using computer-generated randomization. Due to the presence of invasive catheters, both patients and investigators could not be masked regarding group allocation. Separate anesthesiologists performed the block procedures, operating room anaesthesia management, and postoperative pain follow-up. Results: No significant disparities in age, height, weight, BMI, gender, and ASA physical status between the two groups. The upper limit of the 95% confidence interval (1.63) crosses the noninferiority margin (1.0), indicating that the NRS score at rest after 24 hours of surgery is inferior in the CQLII group compared to the Epi group. Among other postoperative outcomes, sleep quality (P value = 0.0015), patient satisfaction score (P value = 0.0000), total postoperative rescue fentanyl use (P value = 0.0005), and postoperative time for first activity out of bed (P value = 0.016) were significantly better in the Epi group. Conclusions: The continuous bilateral quadratus lumborum block failed to demonstrate noninferiority to the epidural block in providing similar NRS scores at rest at 24 hours and other postoperative outcomes.