Comparative Evaluation of Dexmedetomidine and Clonidine as Adjuvants to Ropivacaine in Ultrasound-Guided Supraclavicular Brachial Plexus Block: A Prospective Double-Blind Randomized Controlled Trial

Abstract

Background: Ultrasound-guided supraclavicular brachial plexus block is a widely used regional anaesthetic technique for upper limb surgeries. The addition of α₂-adrenergic agonists to local anaesthetics has been shown to improve block characteristics and postoperative analgesia. Dexmedetomidine and clonidine are commonly used adjuvants; however, evidence comparing their efficacy with ropivacaine remains limited. Aim: To compare the efficacy and safety of dexmedetomidine and clonidine as adjuvants to 0.5% ropivacaine in ultrasound-guided supraclavicular brachial plexus block. Materials and Methods: This prospective, randomised, double-blind controlled study was conducted in the Department of Anaesthesiology, CSI Redfern Memorial Hospital, Hassan, Karnataka, over a period of two years. A total of 100 adult patients (ASA physical status I–II) undergoing elective upper limb surgeries were randomly allocated into two groups of 50 each. Group D received 29 mL of 0.5% ropivacaine with dexmedetomidine (1 µg/kg), diluted with normal saline to a final volume of 30 mL, whereas Group C received 29 mL of 0.5% ropivacaine with clonidine (1 µg/kg), also diluted to a total volume of 30 mL. The primary outcome was duration of postoperative analgesia. Secondary outcomes included onset and duration of sensory and motor block, postoperative Visual Analogue Scale (VAS) scores, rescue analgesic requirement, hemodynamic parameters, sedation score, and adverse events. Results: Baseline demographic characteristics and laboratory parameters were comparable between the two groups. Dexmedetomidine produced a significantly faster onset of sensory block (8.2 ± 1.3 vs. 10.5 ± 1.6 minutes; p<0.001) and motor block (11.1 ± 1.8 vs. 13.7 ± 2.1 minutes; p<0.001). The duration of sensory block (846.8 ± 81.3 vs. 684.5 ± 74.1 minutes), motor block (764.2 ± 72.5 vs. 616.4 ± 68.3 minutes), and postoperative analgesia (921.6 ± 88.2 vs. 748.9 ± 79.5 minutes) was significantly longer in Group D (p<0.001 for all). Patients receiving dexmedetomidine had significantly lower postoperative VAS scores, delayed first rescue analgesia, fewer analgesic requirements, and better sedation scores. Hemodynamic parameters remained stable in both groups, and no significant difference in adverse events was observed. Conclusion: Dexmedetomidine is a superior adjuvant to 0.5% ropivacaine compared with clonidine for ultrasound-guided supraclavicular brachial plexus block. It provides faster onset, prolonged sensory and motor blockade, extended postoperative analgesia, improved postoperative pain control, reduced rescue analgesic requirements, and satisfactory sedation while maintaining a favourable safety profile. These findings support the routine use of dexmedetomidine as an effective adjuvant for upper limb surgeries performed under ultrasound-guided supraclavicular brachial plexus block.

Keywords: Dexmedetomidine, Clonidine, Ropivacaine, Supraclavicular brachial plexus block, Ultrasound-guided regional anaesthesia, Postoperative analgesia, Peripheral nerve block.