Comparative study of two different doses of dexmedetomidine as an adjuvant to bupivacaine in the peripheral nerve block

Abstract

Background: The duration of analgesia in the brachial plexus block (BPB) with local anesthetics (LAs) only is not sufficient to avoid the requirement of analgesia for breakthrough pain. Dexmedetomidine (DEX) is an upcoming adjuvant with long-acting LA to reduce the requirement of analgesics in the postoperative period. However, there is no documented consensus about the dose of DEX in this regard. Aim: We compared two doses of DEX with LA in the BPB to find out the effectiveness of analgesia and other effects. Materials and Methods: All patients were separated into two groups, namely Group A (0.5 μg/kg DEX added to 20 mL of 0.25% bupivacaine) and Group B (1.0 μg/kg DEX added to 20 mL of 0.25% bupivacaine). Thirty patients in each group were analyzed. The sample size was estimated with a type I error of 0.05 and a power of the study as 80%. Statistical analysis was performed using SPSS (version 13.0) software. Rescue analgesia was decided as injection morphine (0.05–0.15 mg/kg) intramuscularly as indicated. Results: The mean time of onset of sensory analgesia (18.04 ± 3.195 vs. 12.20 ± 1.848 min) and motor blockade (23.7 ± 2.8 vs. 17.3 ± 1.7 min) were comparable (P < 0.05); however, the duration for the motor (668.0 ± 22.7 vs. 702.0 ± 111.6 min) and sensory blockade (734.8 ± 47.9 vs. 755.6 ± 126.8 min) and time to first demand of analgesics were insignificant. Conclusion: A dose of 1.0 μg/kg DEX has no added benefit when compared with a lower dose of 0.5 μg/kg DEX as an adjuvant to LA.

Keywords

• adjuvant
• analgesia
• bupivacaine
• dexmedetomidine
• nerve block