Perineural dexmedetomidine as an adjuvant to axillary plexus block for wrist surgery

Various adjuvants are used to prolong the duration of plexus block. Dexmedetomidine, an α2 adrenergic agonist, could be evaluated as an adjuvant to regional anesthesia. We aim to evaluate the effect of perineural dexmedetomidine on the duration of sensory and motor block and side effects during axillary plexus brachialis block. The study included 84 patients undergoing wrist surgery under axillary plexus brachialis block. Patients were divided in 2 groups - control group (CG; N=42) and dexmedetomidine group (DG; N=42). Axillary plexus brachialis block was provided with 0.5% 20 mL bupivacaine and 1% 10 mL lidocaine. Patients in the DG group also received 100 mcg of dexmedetomidine perineurally in addition to local anesthetic. Depth of sedation was assessed using Ramsay sedation scale (RSS). Postoperative pain intensity was assessed using VAS. In the DG group, sensory block occurred within 10.1 minutes and motor block within 13.1 minutes. In the CG group, sensory block occurred within 15.4 minutes and motor block within 20.8 minutes (p <0.001). The duration of sensory block in the DG group was 12.74 h, duration of motor block was 13.67 h. In the CG group, sensory block lasted 7.35 h, motor block lasted 8.06 h (p <0.001). In the DG group 71.42% had an RSS score of 4 during surgery. Bradycardia and hypotension were not observed in CG group. Two patients had bradycardia and three patients had hypotension during surgery in the DG group. No postoperative adverse effects were observed in both groups. Perineural administration of dexmedetomidine alongside local anesthetics for wrist surgery increases the speed of onset and nearly doubles the duration of sensory and motor block. Perineural dexmedetomidine allows a faster initiation of surgery, prolongs postoperative analgesia, and provides a sedative effect. Postoperative adverse effects of dexmedetomidine administration were not observed and intraoperative adverse effects were rare.