Comparative Evaluation of Two Different Doses of Dexmedetomidine as an Adjuvant to 0.5% Bupivacaine in Ultrasound-Guided Supraclavicular Brachial Plexus Block: A Randomized Double-Blind Study

Background: Dexmedetomidine is widely used as an adjuvant to local anesthetics in brachial plexus blocks to improve block quality and prolong postoperative analgesia. While its efficacy is established, the optimal perineural dose that balances block enhancement with hemodynamic stability remains unclear. Objectives: (1). To compare the efficacy of 25 µg vs 50 µg dexmedetomidine as an adjuvant to 0.5% bupivacaine in supraclavicular brachial plexus block. (2). To assess the quality of postoperative analgesia using pain scores and rescue analgesic consumption. (3). To evaluate sedation levels and patient satisfaction. (4). To compare incidence of adverse effects between the two doses. Methods: Sixty ASA I–II patients undergoing elective upper limb surgery were randomized into two groups. Group D25 received 20 mL 0.5% bupivacaine + 25 µg dexmedetomidine, while Group D50 received 20 mL 0.5% bupivacaine + 50 µg dexmedetomidine. Sensory and motor block characteristics, duration of analgesia, VAS pain scores, sedation score, hemodynamic parameters, and adverse effects were recorded. Results: Group D50 demonstrated significantly longer analgesia compared to Group D25 (p < 0.05). However, Group D50 had a higher incidence of bradycardia and deeper sedation. Postoperative pain scores and rescue analgesic requirement were lower in Group D50. Conclusion: Both doses are effective, but 25 µg provides a safer hemodynamic profile, whereas 50 µg offers superior and longer analgesia. Dose selection should be individualized based on patient comorbidities and surgical duration.