Background Posterior quadratus lumborum block (QLB) and intrathecal morphine are accepted analgesic strategies in laparoscopic liver resection, but their effects have not been compared after laparoscopic donor hepatectomy. This study was planned to perform this comparison.

Methods Fifty-six donors were randomized to receive bilateral posterior (QLB2, 20 mL of 0.375% ropivacaine on each side, 150 mg total) or preoperative injection of 0.4 mg morphine sulfate intrathecally. Primary outcome was resting pain score at 24 hour postsurgery. Secondary outcomes included cumulative opioid consumption and recovery parameters. Serial plasma ropivacaine concentrations were measured in QLB group. Only the outcome assessor was properly blinded.

Results Mean resting pain score at 24-hour postsurgery was 4.19±1.66 in QLB group (n=27) and 3.07±1.41 in intrathecal morphine group (n=27, p=0.04). Mean difference (QLB group-intrathecal morphine group) was 1.11 (95% CI 0.27 to 1.95), and the upper limit of CI was higher than prespecified non-inferiority margin (δ=1), indicating an inferior effect of QLB. Cumulative opioid consumption was significantly higher in QLB group at 24 hours and 48 hours postsurgery. QLB group exhibited lower incidence of postoperative pruritus at all time points, and there were no differences in other recovery outcomes. All measured ropivacaine concentrations were below the threshold for systemic toxicity (4.3 µg/mL).

Conclusions Bilateral posterior QLB elicited higher resting pain scores at 24-hour after laparoscopic donor hepatectomy than intrathecal morphine and did not meet the definition of non-inferiority.

Trial registration number KCT0005360.