Comparison of low dose dexmedetomidine and clonidine as additives to bupivacaine in ultrasound directed supraclavicular blocks

Introduction: Ultrasound guidance has resulted in a renewal of interest in supra clavicular approach of brachial plexus block for surgeries below the shoulder. There is a necessity for an additive that increase the duration of local anaesthetics providing effective postoperative analgesia also after one shot injections. Dexmedetomidine and clonidine are the common adjuvants used, but in higher doses. The aim of this study was to see which among them is a better analgesic additive in lower doses. Materials and Methods: Sixty patients, aged 18-55 years, posted for hand and forearm surgeries under Ultrasound directed supraclavicular brachial block were divided randomly in to 2 groups using computer generated tables. Group C: Clonidine 0.5 ?g /kg added to 25ml of 0.375% bupivacaine. Group D: Dexmedetomidine 0.5 ?g /kg and 25ml of 0.375% bupivacaine. The onset and the duration of analgesia, motor block and sedation scores were noted. Results: Onset of sensory block was 11.6 +/-3.4 minutes in group C, 14.4 +/-4.5 minutes in group D. The onset of motor block was 17.6 +/-4.9 in group C, 20.6+/-5.9 in group D. The mean time of sensory block in Group C was 9.7+/-1.6 hours, 13.3+/-1.9 hours in Group D. Motor blockade (hrs) was for 9.1+/-1.7 in Group C, 12.1+/-2.0 in Group D. Analgesia and motor blockade were longer in dexmedetomidine group. Rescue analgesic was given at 10.5 ± 1.7 hrs in clonidine category and at 15 ± 2.2 hrs in dexmedetomidine category. 10% of subjects in Dexmedetomidine category had adverse reactions, it was not there in clonidine. Conclusions: Dexmedetomidine showed features of a superior additive compared to clonidine as it enhanced the quality and duration of analgesia with lesser complications at lower doses.