Effect of patient-controlled analgesia on development of postoperative nausea and vomiting in patients undergoing microvascular decompression: a prospective randomized controlled trial

OBJECTIVE Postoperative nausea and vomiting (PONV) occurs frequently after microvascular decompression (MVD). Fentanyl, an opioid, is strongly related to the development of PONV, and ketorolac, a nonsteroidal anti-inflammatory drug, has been approved for postoperative pain management. However, how ketorolac-based patient-controlled analgesia (PCA) causes PONV or how its efficacy differs from that of fentanyl-based PCA after MVD is unclear. In this study, the authors compared ketorolac-based with fentanyl-based PCA in terms of the incidence and severity of PONV and analgesia after MVD. METHODS This prospective, double-blind, single-center, randomized controlled trial conducted from December 2021 to February 2023 included patients with MVD who were randomly allocated to the ketorolac- or fentanyl-based PCA group postoperatively. The incidence (primary outcome) and severity of PONV and rescue antiemetic requirements were determined during the first 48 hours postoperatively. Additionally, postoperative pain scores, rescue analgesic requirement, PCA usage, and satisfaction scores were assessed during the study period. PONV severity and postoperative pain scores were assessed using an 11-point numeric rating scale (0 = none, 10 = extremely). Satisfaction scores for PONV and pain were determined (0 = very dissatisfied, 10 = very satisfied). Categorical variables were analyzed using the chi-square or Fisher's exact test. Continuous variables were analyzed using the Student t-test or Mann-Whitney U-test based on normal distribution. RESULTS Of 185 screened patients, 91 were excluded based on predetermined exclusion criteria; 87 patients (43 in the ketorolac group and 44 in the fentanyl group) were analyzed and showed no significant differences in demographic data between groups. PONV incidence (48.8% vs 79.5%, p = 0.003) and severity (p = 0.004) were lower in the ketorolacbased PCA group than in the fentanyl-based PCA group. In the ketorolac group, there was a significant reduction in rescue antiemetic requirements compared with the fentanyl group (p = 0.049). The number of discontinuations was lower in the ketorolac-based PCA group than in the fentanyl-based PCA group (p = 0.001), whereas no significant differences in postoperative pain were found between the two groups. CONCLUSIONS In patients with MVD, ketorolac-based PCA resulted in a decrease in PONV incidence and severity compared with fentanyl-based PCA, with analgesic effects similar to those of fentanyl-based PCA. This study provides clinical evidence that ketorolac-based PCA may be a valid alternative to fentanyl-based PCA in postoperative care.