Background and Objectives: This prospective, randomized, observer-blinded study compared single- and double-injection, ultrasound-guided supraclavicular brachial plexus block for upper extremity surgery.

Methods: Ninety-two patients were randomly allocated to receive a single-injection (n = 46) or double-injection (n = 46), ultrasound-guided supraclavicular block. Performance time (defined as the sum of imaging and needling times) and the number of needle passes were recorded during the performance of the block. Subsequently, a blinded observer recorded the onset time, block-related pain scores, success rate (surgical anesthesia), and the incidence of complications. The total anesthesia-related time was defined as the sum of the performance and onset times. The main outcome variable was the onset time.

Results: The onset time was shorter with the 2-injection technique (17.5 mins [SD, 8.4 mins] vs 21.7 mins [SD, 7.2 mins]; P = 0.021); however, performance time was also longer (7.2 mins [SD, 2.7 mins] vs 6.0 mins [SD, 2.4 mins]; P = 0.037). Thus, no differences were observed in terms of total anesthesia-related time (23.4-24.3 mins). Success rates (95.7%), block-related pain scores, and complication rates were also similar between the 2 groups. As expected, the 2-injection technique required a greater number of needle passes (3.5 [SD, 1.2] vs 1.9 [SD, 1.1]; P < 0.001). In return, it provided a faster onset for sensory and motor block of the musculocutaneous nerve and a faster sensory block of the radial nerve. However, at 30 mins, no differences were observed.

Conclusion: The double-injection, ultrasound-guided supraclavicular block provides no significant advantages compared with its single-injection counterpart.