Effect of addition of dexamethasone to low volumes of local anaesthetics for ultrasound-guided supraclavicular brachial plexus block

Abstract

Objectives We examined the efficacy of dexamethasone as an adjuvant to low volumes of local anaesthetics in an ultrasound-guided supraclavicular brachial plexus block (SBPB). Background SBPB is an effective nerve block for use during upper limb surgery as an alternative to general anaesthesia. In addition, this block has a beneficial postoperative analgesic effect for these surgeries. Materials and methods We compared three groups of patients; each group included 30 patients scheduled for forearm and hand orthopaedic surgeries and anaesthetized by SBPB. Group A was anaesthetized by an injection of 15 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone, group B was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 8 mg (2 ml) dexamethasone and group C was anaesthetized by an injection of 20 ml of bupivacaine 0.5% mixed with 2 ml normal saline. All groups were assessed for efficacy of the block by assessment of the onset and duration of sensory and motor block and assessment of the quality and duration of postoperative analgesia. All groups were assessed for the incidence of complications. Results The addition of dexamethasone to low volumes of bupivacaine in SBPB significantly hastened the onset and prolonged the duration of sensory and motor block. Dexamethasone yielded better quality of postoperative analgesia with lower levels of the visual analogue scale; also, it led to a statistically significantly longer duration of postoperative analgesia with lower analgesic consumption, and these effects were more prominent in group B with a slightly higher volume of bupivacaine. There were very few incidences of complications among the three groups. Conclusion The addition of dexamethasone to low volumes of bupivacaine in ultrasound-guided SBPB significantly decreased the onset time and prolonged the duration of sensory and motor blockade; also, it prolonged the duration and improved the quality of postoperative analgesia, with very few incidences of complications.