We have demonstrated that as compared with median-nerve-type motor response, injection performed after a radial-nerve-type motor response promoted reproducible and remarkable ultrasound spread characteristics associated with complete sensory block of the 3 cords at 30 minutes.

The present study showed that the ultrasound approaches were less painful and more comfortable than neurostimulation to place axillary blocks. We also showed that, although pain intensity resulting from blocks placement was similar with the ultrasound approaches, very comfortable procedures were more frequent with the out-of-plane than with the in-plane approach.