BACKGROUND: Although ultrasound-guided supraclavicular block has a good success rate, it remains unclear whether multiple injections are superior to single injection (SI). We compared the sensory block success rate of SI versus triple injection (TI).
METHODS: In this randomized double-blind study, 96 end-stage renal disease patients undergoing arteriovenous fistula creation or superficialization were randomly allocated to receive either SI or TI. The primary outcome was the combined score of sensory blockade of the 5 nerves (median, ulnar, radial, medial cutaneous nerve of the forearm, and musculocutaneous) measured at 5, 10, 15, and 20 minutes after injection. Secondary outcome variables were the time to onset of the blockade, performance time (time to do the block), separate success rate for each of the above nerves, success rate of surgical anesthesia, and the complication rate.
RESULTS: The combined success of the sensory block was 20% to 31% higher in the TI group than in the SI group at 10, 15, and 20 minutes after injection (all P < 0.035). The block of the musculocutaneous nerve in the TI group was faster and more successful than in the SI group, at all time points (all P < 0.026). The average time needed to perform the block was significantly longer in the TI than the SI group (6.5 ± 2.1 vs 4.7 ± 2.1 minutes, P = 0.001). The overall success of surgical anesthesia measured at 30 minutes did not differ significantly between the 2 groups (96% in TI vs 87% in SI, P = 0.253).
CONCLUSIONS: Although the performance time of the SI technique was shorter, TI had a faster onset and resulted in a more successful block of all nerves in the first 20 minutes.