Bilateral single-injection erector spinae plane block versus intrathecal morphine for postoperative analgesia in living donor laparoscopic hepatectomy: a randomized non-inferiority trial.

Background: Intrathecal morphine (ITM) provides effective postoperative analgesia in living donor hepatectomy but has significant adverse effects. Studies support the efficacy of erector spinae plane (ESP) blocks in laparoscopic abdominal surgery; we therefore hypothesized that they would provide non-inferior postoperative analgesia compared with ITM and reduce postoperative nausea/vomiting and pruritus. We conducted a randomized, controlled, non-inferiority trial to compare the analgesic efficacy of ITM and bilateral single-injection ESP blocks in laparoscopic donor hepatectomy.

Methods: Fifty-four donors were randomized to receive bilateral ESP blocks with 20 mL 0.5% ropivacaine (n=27) or 400 µg ITM (n=27). Primary outcome was resting pain score 24 hours postoperatively measured on an 11-point numeric rating scale. The prespecified non-inferiority limit was 1. Incidences of postoperative nausea/vomiting and pruritus were assessed.

Results: The mean treatment difference (ESP-ITM) in the primary outcome was 1.2 (95% CI 0.7 to 1.8). The 95% CI upper limit exceeded the non-inferiority limit. Opioid consumption and all other pain measurements were similar between groups up to 72 hours postoperatively. The ESP group had significantly lower incidences of postoperative vomiting (p=0.002) and pruritus (p<0.001).

Conclusions: Bilateral single-injection ESP blocks resulted in higher resting pain scores 24 hours postoperatively compared with ITM and thus did not meet the study definition of non-inferiority. However, the pain intensity with ESP blocks was mild (mean pain scores <3/10) and associated with reduced incidence of postoperative vomiting and pruritus. It warrants further investigation as an analgesic option after laparoscopic living donor hepatectomy.

Trial Registration Number: KCT0003191.