A prospective randomized comparative study of dexmedetomidine versus clonidine as an adjunct to 0.75% ropivacaine in ultrasound-guided supraclavicular brachial plexus block

Abstract

Introduction Alpha-2 agonists are popular adjuvants used in neuraxial anesthesia like spinal, epidural, caudal anesthesia, and peripheral nerve blocks. The authors compared the efficacy of clonidine with dexmedetomidine as an adjuvant to ultrasound (US)-guided supraclavicular brachial plexus block in adult patients undergoing elective upper limb surgeries. Materials and methods After obtaining Ethics Committee approval, 60 American Society of Anesthesiologists’- physical status (ASA-PS) I/II patients were randomized into two groups. Group Clonidine-Ropivacaine (CR) received 1 μg/kg clonidine as an adjuvant and group Dexmedetomidine-Ropivacaine (DR) received 1 μg/kg dexmedetomidine. Patients received an ipsilateral US-guided supraclavicular brachial plexus block with 0.75% ropivacaine (total volume of 20 ml). Demographic data, hemodynamics, the onset of block (sensory, motor), the duration of block (sensory, motor), duration of analgesia and surgery, total number of rescue analgesics, numerical rating scores, and Ramsay sedation score were compared between both groups using appropriate statistical tests. Results Heart rates at 30 min, 60 min, 2 h, and 3 h were lower in group DR compared with group CR, which was statistically significant (P=0.0001, 0.0001, 0.021, and 0.026, respectively). The onset of sensory and motor block, duration of sensory and motor block, and duration of analgesia were better in group DR compared with CR, which was statistically significant (P=0.00). The number of rescue analgesics required in group CR in both groups was comparable (P=0.057). Numeric rating scale scores at 12, 18, and 24 h were significantly better in group DR compared with group CR (P=0.0001, 0.039, and 0.036, respectively). Conclusion When added as an adjuvant to 0.75% ropivacaine in the US-guided supraclavicular brachial plexus, dexmedetomidine block produced faster onset of sensory and motor blockade, prolonged the duration of sensory and motor blockade, and also prolonged the duration of analgesia, when compared with clonidine.