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 ۶۰ patients who underwent colorectal surgery with the American Society of Anesthesiologists (ASA) I–III were included and randomized into ۲ groups; the study group received QL block (QL group), whereas the control group received epidural analgesia (EP group). Postoperative analgesia was assessed using a ۱۰-point visual analog scale (VAS), time to first morphine requirement, and ۲۴-hour morphine consumption. Postoperative renal function was compared with preoperative values using laboratory and renal Doppler indices. Results: The age range was ۳۵ to ۶۵ years with ۴۱ male patients, showing no significant difference between the two groups (P-value = ۰.۷۹۶ for age and ۰.۷۸۱ for sex). There was no significant difference between the QL block and the epidural analgesia regarding postoperative VAS pain score (P-value ranging from ۰.۰۶۶ to ۰.۸۶۹). The morphine analgesia parameters were statistically insignificant between the two groups. Nineteen patients required morphine among the QL group compared to ۱۵ patients among the EP (P-value = ۰.۲۹۷), the mean cumulative dose was almost similar in both groups ۳.۱±۱.۲ mg (P-value = ۰.۹۷۳), and first-time use of morphine was ۹.۵±۷.۳ hours in the QL group compared to ۵.۹±۶.۰ hours in the EP group (P-value = ۰.۱۳۲). There was no significant difference between the ۲ 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 ۰.۶۱±۰.۰۵ preoperatively compared to ۰.۵۸±۰.۰۵ postoperatively in the QL group (P-value = <۰.۰۰۱) compared to ۰.۶۲±۰.۰۵ preoperatively and ۰.۶۱±۰.۰۵ postoperatively in the EP group (P-value = ۰.۱۵۸). 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.