Infraclavicular brachial plexus block effects on respiratory function and extent of the block

Background and Objectives. Axillary block is devoid of severe respiratory complications. However, incomplete anesthesia of the upper limb is the main disadvantage of the technique. Theoretically, the more proximal infraclavicular approach would produce a more extensive block without the risk of pneumothorax. However, neither its effects on respiratory function nor a detailed characterization of the extent of neural block has been assessed. The goal of this study was to evaluate the possible changes in respiratory function and also the extent of the block after infraclavicular block. Methods. We performed an infraclavicular block with a mixture of 40 mL 1.5% plain mepivacaine and 4 mL 8.4% sodium bicarbonate in 20 patients. Forced expiratory volumes were measured before and 15 minutes after the injection of local anesthetic, and sensory and motor block were evaluated at 10 and 20 minutes. Results. We did not find significant differences from baseline in the forced expiratory volumes in any of the patients. Axillary and musculocutaneous nerve distributions had the lowest rate of sensory block at 20 minutes. Conclusions. Infraclavicular block does not produce a reduction in respiratory function.