Single versus triple injection ultrasound-guided infraclavicular block: confirmation of the effectiveness of the single injection technique.

BACKGROUND The optimal site for local anesthetic placement during ultrasound-guided infraclavicular block remains controversial. METHODS Patients were randomized to receive lidocaine 2% 30 mL as a single injection posterior to the axillary artery (n = 51) or a triple injection ideally adjacent to each brachial plexus cord (n = 49). Pinprick sensory and motor block (3 = no block, 0 = complete block) were assessed to 20 minutes in the 4 distal nerve territories. RESULTS The single injection group was not significantly inferior (single versus triple injection median [interquartile range] 20-minute aggregate block score: 5 [2-9] vs 7 [3.5-11]) but also demonstrated superiority (2-tailed test, P = 0.043). The single injection technique was associated with a small reduction in procedural time. CONCLUSIONS The optimal site for local anesthetic placement during ultrasound-guided infraclavicular block is a single point injection posterior to the axillary artery.