The Analgesic Effect of Bilateral Quadratus Lumborum Block and its Postoperative Implication On Kidney Function in Colorectal Surgery: A Comparative Randomized Control Trial Study With Epidural Anesthesia

Background: Pain management in major abdominal surgery is an essential clinical task. Epidural analgesia alternatives have become popular; for instance, the quadratus lumborum (QL) block. Acute kidney injury (AKI) is one of the main complications encountered during major surgery. We aimed to assess the postoperative analgesic efficacy of the QL block compared to epidural analgesia as well as the effect on the postoperative kidney functions. Materials and Methods: A total of 60 patients who underwent colorectal surgery with the American Society of Anesthesiologists (ASA) I?III were included and randomized into 2 groups; the study group received QL block (QL group), whereas the control group received epidural analgesia (EP group). Postoperative analgesia was assessed using a 10-point visual analog scale (VAS), time to first morphine requirement, and 24-hour morphine consumption. Postoperative renal function was compared with preoperative values using laboratory and renal Doppler indices. Results: The age range was 35 to 65 years with 41 male patients, showing no significant difference between the two groups (P-value = 0.796 for age and 0.781 for sex). There was no significant difference between the QL block and the epidural analgesia regarding postoperative VAS pain score (P-value ranging from 0.066 to 0.869). The morphine analgesia parameters were statistically insignificant between the two groups. Nineteen patients required morphine among the QL group compared to 15 patients among the EP (P-value = 0.297), the mean cumulative dose was almost similar in both groups 3.1?1.2 mg (P-value = 0.973), and first-time use of morphine was 9.5?7.3 hours in the QL group compared to 5.9?6.0 hours in the EP group (P-value = 0.132). There was no significant difference between the 2 groups regarding blood urea nitrogen (BUN) and serum creatinine. However, QL showed significantly lower postoperative values in the renal resistive index (RI) than preoperative values. The mean RI value was 0.61?0.05 preoperatively compared to 0.58?0.05 postoperatively in the QL group (P-value = <0.001) compared to 0.62?0.05 preoperatively and 0.61?0.05 postoperatively in the EP group (P-value = 0.158). Conclusion: QL block produced comparable analgesia with epidural anesthesia and was associated with improved postoperative renal artery flow, reflecting a better kidney performance; QL block may be the choice for patients with borderline kidney function or suspected AKI.