Effect of Intravenous Esketamine on Rebound Pain Following Single-Shot Brachial Plexus Block in Patients Undergoing Shoulder Arthroscopic Surgery: A Prospective, Randomized, Placebo-Controlled Study

Patients undergoing arthroscopic rotator cuff repair under combined single-shot interscalene brachial plexus block and general anesthesia exhibit a rebound pain incidence of approximately 25%. Intravenous administration of esketamine (0.5 mg/kg bolus followed by continuous infusion at 0.25 mg/kg/h) during the operation failed to significantly reduce the incidence of rebound pain post-block (<i>P</i>>0.05). However, it demonstrated significant reductions in pain scores at 8h, 12h, and 24h postoperatively (<i>P</i><0.05), with enhanced hemodynamic stability observed from anesthetic induction to pre-incision periods. No severe adverse events were reported.