Effects of quadratus lumborum block regional anesthesia on postoperative pain after colorectal resection: a randomized controlled trial.

Introduction: Postoperative pain following colorectal surgery is associated with a significant use of opioids. Recently, regional anesthesia, such as the posterior quadratus lumborum block (QL2), has been proposed to improve pain relief and reduce opioid use. However, the benefit of the QL2 on postoperative pain control remains controversial.

Methods: We conducted a randomized controlled trial of patients undergoing colorectal surgery at the CHU de Québec-Université Laval. Patients were randomized to regional QL2 anesthesia with 150 mg of ropivacaine combined with standard analgesia or to QL2 with a sham intervention and standard analgesia. Our primary outcome was postoperative opioid administration at 24 h. Secondary outcomes included opioid administration in the post-anesthesia care unit (PACU), at 48 h and at hospital discharge, postoperative pain scores, delay in resumption of intestinal transit, nausea and vomiting, and hospital length of stay.

Results: A total of 62 patients were enrolled from November 2017 to February 2018. QL2 regional anesthesia compared with a sham intervention was not associated with a reduction in postoperative morphine dose equivalent (100.2 mg, 95% CI 68.9-131.5 versus 88.7 mg, 95% CI 59.3-118.0, p = 0.81, respectively). Compared to QL2 regional anesthesia, postoperative pain scores in the control group were lower although statistical significance was not consistent for all postoperative time points. Other secondary outcomes were comparable between both groups.

Conclusion: We did not observe a reduction in postoperative opioid administration at 24 h with a posterior quadratus lumborum block regional anesthesia in patients undergoing elective colorectal surgery.