Clinical and radiological comparison of perivascular and transarterial techniques of axillary brachial plexus block.

The perivascular technique of axillary brachial plexus block results in incomplete block of radial and musculocutaneous nerves in 10-20% of patients. With the transarterial technique and a large dose of mepivacaine, success rates of 99% have been reported. We have compared the clinical efficacy of these techniques in 50 patients using 1% mepivacaine 45 ml with adrenaline. If required, the block was supplemented with additional blocks of single nerves or i.v. alfentanil. Additionally, eight patients in each group were studied with computed tomography after contrast medium was added to 0.5% bupivacaine 40 ml. There were no statistically significant differences in sensory or motor block between the groups at 20 min or in the plasma concentrations of mepivacaine measured 0-45 min after injection. In the CT scans, both proximal and distal spread of the contrast medium were more common after perivascular than after transarterial block. The distribution of the contrast medium was not related to the efficacy of the block.