Brief reports: nerve stimulator evoked motor response predicting a successful supraclavicular brachial plexus block

We examined the success rate of supraclavicular brachial plexus block after the different evoked motor responses to nerve stimulation.

This multicenter observational study included 377 patients. For each block, the evoked motor response elicited at 0.25 mA for 2 milliseconds was recorded, 30 mL bupivacaine 0.25% was injected, and the block was observed for success or failure.

Complete anesthesia occurred in 317 cases (84.1%). The success rate was 100% when the evoked motor response was simultaneous flexion of the third and fourth digits or flexion of all 4 digits (digits 2-5) with or without thumb opposition.

Simultaneous flexion of the third and fourth digits with or without other digits is associated with the highest success rate of supraclavicular brachial plexus block.