Comparison of the Onset Time between 0.25% Bupivacaine and 0.5% Bupivacaine for Ultrasound‑Guided Infraclavicular Brachial Plexus Block: A Randomized Clinical Trial

Background: Infraclavicular brachial plexus block is a suitable regional anaesthesia technique for hand, wrist and elbow operations and it is usually performed in conjunction with nerve stimulation. We aimed to compare the onset times of sensory block with equipotential 0.25% bupivacaine and 0.5% bupivacaine. Methods: This prospective double-blinded randomized controlled study was conducted on 60 patients, aged > 18 years, with ASA physical status I–III, and scheduled for upper extremity surgery with infraclavicular brachial plexus block. The participants were randomized into two equal groups; group I in which ICB performed with 0.25%, 20 mL bupivacaine and group II in which ICB performed with 0.5% 20 mL bupivacaine. Results: Regarding the block performance, group II showed earlier onset time and longer duration of sensory and motor blocks compared to group I (P<0.05) and the performance time was significantly shorter in in group II compared to group I (P=0.015). Number of patients required analgesia was significantly lower in group II compared to group I (P=0.003) was significantly lower in group II compared to group I (P=0.003) and the first rescue analgesic requirement was significantly delayed in group II compared to group I (P<0.001). Conclusions: We found that 0.5% bupivacaine showed earlier onset time and longer duration of sensory and motor blocks compared to 0.25% bupivacaine in infraclavicular block. Thus, when a quicker block onset is required, 0.5% bupivacaine is a better choice than 0.25% bupivacaine.