Background and Objectives It has recently been proposed that an infraclavicular brachial plexus block (BPB) at the costoclavicular (CC) space may overcome some of the limitations of the lateral sagittal (LS) approach. In this study, we hypothesized that the CC approach will produce faster onset of sensory blockade of the 4 major terminal nerves of the brachial plexus than the LS approach.

Methods Forty patients undergoing elective upper extremity surgery under a BPB were randomized to receive either the LS (Gp-LS, n = 20) or CC approach (Gp-CC, n = 20) for infraclavicular BPB. Twenty-five milliliters of 0.5% ropivacaine was used for the BPB in both study groups. Sensory-motor blockade of the ipsilateral median, radial, ulnar, and musculocutaneous nerves was assessed by a blinded observer at regular intervals for 45 minutes after the block. Sensory block was assessed using a verbal rating scale (0–100) and motor block using a 3-point qualitative scale (0–2). Onset of sensory (primary outcome variable) and motor blockade was defined as the time it took to achieve a sensory verbal rating scale of 30 or less and motor grade of 1 or less, respectively. Time to readiness for surgery was defined as the time it took to achieve a sensory score of 30 or less and motor grade of 1 or less in all the 4 nerves tested.

Results The overall sensory onset time (median [interquartile range]) was significantly faster (P = 0.004) in Gp-CC (10 [10–26.25] minutes) than in Gp-LS (20 [15–30] minutes). The overall sensory score was significantly lower in Gp-CC than in Gp-LS at 5 (P < 0.001), 10 (P = 001), 15 (P = 0.001), and 20 (P = 0.04) minutes after the BPB. The overall motor score was significantly lower (P = 0.009) in Gp-CC than in Gp-LS at 10 minutes after the BPB. There were more (P = 0.04) patients with complete sensory-motor blockade at 20 minutes after the BPB in Gp-CC (25%) than in Gp-LS (0%). Time to readiness for surgery was also significantly faster (P = 0.002) in Gp-CC (10 [10–26.5] minutes) than in Gp-LS (20 [15–30] minutes).

Conclusions The CC approach for infraclavicular BPB produces faster onset of sensory blockade and earlier readiness for surgery than the LS approach.

Clinical Trial Registration This study was registered at the Centre for Clinical Trials of The Chinese University of Hong Kong, identifier CUHK_CCT00389.