Double- vs. single-injection infraclavicular plexus block in the emergency setting: higher success rate with lower volume of local anaesthetic

Background and objectives: Infraclavicular plexus block has many advantages of particular interest in the emergency setting. However, the number of nerve stimulations needed to optimize the technique remains unclear. We evaluated both the local anaesthetic requirement and the success rate of Sim's derived infraclavcular plexus block performed with a nerve stimulator when either one or two responses were sought. Methods: In this prospective study, 50 patients who presented for distal upper limb surgery were randomized into two groups: in Group 1, ropivacaine 0.75% 40 mL was injected when nerve stimulation elicited a distal motor response (median, ulnar or radial). In Group 2, only 30 mL of the same local anaesthetic was injected, 7 mL to the musculocutaneous nerve and 23 mL to the median, ulnar or radial nerves. Sensory and motor blocks were tested at 5-min intervals over 30 min. Results: The time to perform the block was similar in both groups. The success rate of the block increased from 80% in the single-stimulation group to 92% in the double-stimulation group (not significant). The onset time of sensory and motor block was shorter and block extension was greater in ulnar, antebrachial cutaneous and brachial cutaneous nerve distributions in the multistimulation group (P < 0.05). Conclusions: We conclude that only 30 mL of local anaesthetic seems to be sufficient to ensure a high level of success when performing an infraclavicular block with stimulation of both the musculocutaneous nerve and median, ulnar or radial nerve.