Analgesic efficacy of continuous wound infiltration compared with continuous intravenous fentanyl after gynaecological surgery: a non‐inferiority, randomised controlled trial

The present trial aimed to prove the non-inferiority of the analgesic efficacy of continuous wound infiltration (CWI) to that of continuous intravenous fentanyl (IV) and to compare the safety of the two methods.This trial was a prospective, single-centre, two-arm, non-inferiority, randomised controlled trial. Patients participating in the trial were randomised to a CWI group or an IV group. The VAS (visual analogue scale), additional analgesic usage and side effects were then compared between the groups.In total, 61 patients were enrolled; two in CWI were excluded, leaving 59 (30 in the CWI group and 29 in the IV group) for analysis. The difference in the VAS score at 24 h (CWI group - IV group) was -3.2 (95% confidence interval [CI] -14.7 to 8.2), which was less than the non-inferiority margin of 15. The mean amount of total fentanyl use at postoperative hour 48 was 1395 (95% CI 886-1903) µg in the CWI group and 3186 (95% CI 2716-3658) µg in the IV group. The amount of other analgesics and the incidence of adverse effects did not differ significantly between the groups.CWI was non-inferior to IV in terms of its analgesic effect, and has an opioid sparing effect in open gynaecological surgery.