A Randomised Controlled Study of Two Different Doses of Bupivacaine in Ultrasound Guided Axillary Brachial Plexus Block

Abstract

Introduction: The use of Ultrasound (USG) for needle precision aids in reduction of local anaesthetic volume needed for peripheral nerve blockade. Conventional dosages of 30 to 40 mL of local anaesthetic mixture have been used in peripheral nerve blockades but using a lesser volume will reduce the incidence of local anaesthesia associated systemic toxicity. Aim: To assess the efficacy of two different doses 20 mL and 25 mL of Bupivacaine in USG guided axillary plexus block. Materials and Methods: Sixty patients requiring forearm and hand surgeries were randomised into two groups. Group A received low volume (20 mL of 0.375% bupivacaine) and group B received intermediate volume (25 mL of 0.375% bupivacaine). The quality of anaesthesia in regards to sensory and motor blockade, duration of analgesia, haemodynamic variability and complications were evaluated. Successful block was defined by Vester Anderson’s criteria. Duration of analgesia was measured using Visual Analogue Scale (VAS). Statistical comparison of all continuous variables were assessed utilising Student’s t-test and Mann-Whitney U-test as applicable. Results: No significant difference in onset times were observed as far as sensory and motor blockade was concerned between the two groups A and B with p-values of 0.69 and 0.40, respectively. Group B had significantly longer duration of block in comparison with Group A (p<0.001). Two patients in group A and one patient in Group B required supplemental analgesia with fentanyl boluses. Haemodynamics were stable and no complications were seen in both the groups. Conclusion: Lower volume of Bupivacaine is convincingly prudent for regional blockade under USG guidance than suggested in literature.