Infraclavicular brachial plexus block by the coracoid approach:a comparison of the effectiveness between single-and dual-injection techniques

Objective To evaluate the hypothesis that dual injection technique in infraclavicular brachial plexus block by the coracoid approach might enhance sensory block for anesthesia of the upper limb compared with a single-injection technique.Methods Fifty-seven patients scheduled for surgery below the elbow were randomly assigned to receive the infraclavicular brachial plexus block by the coracoid approach guided by nerve stimulator with either single-injection technique(Group Single,n=29)or dual-injection technique(Group Dual,n=28).In group single,30 mL 0.5% ropivacaine was injected after eliciting one distal extensive motor response in the upper limb with a nerve stimulator for block.In group dual,the musculocutaneus nerve of brachial plexus was also located,the same volume of anesthetic was injected in separate doses of 10 mL and 20mL after elicitation of two different motor responses(flection of the elbow and extensive of the wrist or fingers).Sensory block was assessed in the upper limb every 10 minutes after the end of injection of the local anesthetic.The time that needed to complete the block and the side effects were also recorded.Results Ten minutes after blockade,higher rates of sensory block in the dermatome of musculocutaneus nerve was read in group dual than in group single.Thirty minutes after blockade,significantly higher rates of sensory block to pinprick on the distributions of musculocutaneous nerve(89.3% vs 62.1%,P0.05)and medial antebrachial cutaneous nerve(85.7% vs 58.6%,P0.05)were found in group dual than in group single.No difference was observed in global scores between the two groups(P0.05).Conclusions Dual-injection technique guided by nerve stimulator increases the efficacy for infraclavicular brachial plexus block by the coracoid approach compared with a single injection technique with the same dose of local anesthetic.