Postoperative Opioid-Free Multistep Opiranserin Infusion Versus Fentanyl Patient-Controlled Analgesia After Breast or Minimally Invasive Gynecologic Surgery: A Retrospective Cohort Study.
Kim Yeojung Y, Park Mia M, Choi Sungho S, Kim Juyeon J et al.
Background/Objectives: Women undergoing breast or gynecologic surgery face high postoperative nausea and vomiting (PONV) risk, which often prompts discontinuation of opioid patient-controlled analgesia (PCA). Since anticipated opioid use is an Apfel risk factor, we examined a postoperative opioid-free analgesic regimen using opiranserin, previously evaluated only as an adjunct. Methods: In this single-center retrospective cohort study, 150 women undergoing breast or minimally invasive gynecologic surgery received a multistep opiranserin infusion via a PCA pump without demand boluses (n = 77) or fentanyl demand bolus PCA (n = 73). The opiranserin infusion ended at 10 h; fentanyl PCA remained connected throughout. The primary outcome was resting numeric rating scale (NRS, 0-10) at 24 h, by which time the infusion had been complete for 14-15 h; secondary outcomes were post-anesthesia care unit (PACU) and 6 h NRS, PONV, and early discontinuation. Results: Resting NRS did not differ significantly during the infusion (PACU p = 0.965; 6 h p = 0.675), with a larger difference at 24 h. The adjusted 24 h difference was 0.58 points higher with opiranserin (95% CI, 0.04 to 1.12; p = 0.036) by covariance analysis on pre-treatment covariates and 0.55 (0.02 to 1.09) by inverse-probability-of-treatment weighting; the point estimates were below the minimal clinically important difference of 1 point, but the confidence intervals do not exclude a clinically relevant increase in pain, and the estimate was nonsignificant after adjusting for non-opioid adjuncts (p = 0.177). Moderate or severe pain at 24 h was more frequent with opiranserin (19.5% vs. 8.2%; adjusted odds ratio, 3.76; 95% CI, 1.34 to 11.82). PONV (9.1% vs. 11.0%), rescue analgesia (26.0% vs. 17.8%), and early discontinuation (10.4% vs. 9.6%) were similar. Rescue opioids were available to both groups but used by one fentanyl-group patient and by none receiving opiranserin. Conclusions: The regimen eliminated postoperative opioid exposure, with resting pain scores that differed by less than 1 NRS point on average, although a clinically relevant increase cannot be excluded. With coverage fixed at 10 h, the 24 h difference cannot be separated into a shortfall of the agent and a shortfall of coverage. The anticipated PONV reduction was not observed, possibly in the context of low event rates and routine antiemetic prophylaxis.