The orthogonal two-needle technique: a new axillary approach to the brachial plexus

Ninety-eight patients scheduled for elbow, forearm, wrist or hand surgery were allocated randomly to one of two different techniques of brachial plexus block, both using the axillary approach. The blocks were all performed at the level of the insertion of the lateral margin of the pectoralis major muscle on the humerus. The same mixture and volume of anaesthetic solution (30 mL of a mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200 000 and 2% lignocaine) was injected through two needles positioned above and below the axillary artery, in the fascial compartments containing the median and ulnar nerves, respectively. Confirmation of correct needle placement was obtained by elicitation of paraesthesias. In one group of patients (n = 40) the needles were inserted parallel to the axillary artery pathway and the anaesthetic solution was injected toward the apex of the axilla. In a second group (n = 58) the needles were inserted orthogonally with respect to the neurovascular bundle pathway, aimed towards the posterior fascial compartment containing the radial nerve. Using the second technique, all the terminal branches of the brachial plexus were more frequently involved in the block, including the distribution of the musculocutaneous nerve. It seems likely that the inclination of the needles causes a preferential spread of the anaesthetic solution which follows the direction of the needle shaft.