Effect of esketamine as an adjuvant of ropivacaine on the efficacy of supraclavicular brachial plexus block in radius fracture surgery: a randomized controlled trial

BACKGROUND: Adding adjuvants to local anesthetics can improve the efficacy of peripheral nerve blocks. However, the literature supporting the advantages of esketamine on peripheral nerve blocks remains limited. This study aims to assess whether adjunctive esketamine enhances the duration of postoperative analgesia when added to ropivacaine in supraclavicular brachial plexus block (SBPB). METHODS: In this randomized controlled trial, 117 adult patients scheduled for distal radius fracture surgery received either 30 mL of 0.4% ropivacaine alone or 30 mL of 0.4% ropivacaine with 25 mg of esketamine in the SBPB. The primary outcome was the analgesic duration of SBPB, defined as the first time a patient experienced pain postoperatively. Secondary outcomes included the SBPB onset time, motor block duration, and pain scores 48 h after surgery. The incidence of adverse events was recorded. RESULTS: No significant difference in analgesic duration was found between the two groups (11.3 [10.1, 12.4] h vs. 10.8 [9.4, 12.2] h, median difference = 0.3, 95% confidence interval, -0.4-1.0, P=0.344). Meanwhile, no significant differences were found in SBPB onset time, motor block duration, or pain scores between the groups. The incidences of Horner syndrome, hoarseness, postoperative nausea and vomiting were comparable between the groups. CONCLUSIONS: Adding 25 mg esketamine to 30 mL of 0.4% ropivacaine did not improve the analgesic efficacy of SBPB in patients undergoing distal radius fracture surgery. These findings suggest that the limited benefits of esketamine in peripheral nerve blocks such as SBPB warrant further investigation to optimize agent design.