Background
When the axillary nerves are difficult to image sonographically using conventional technique, interfascial injection can be feasible alternative to local anesthetic injection and nerve stimulation technique with the needle tip being directly beside the nerve itself. The purpose of this study was therefore to develop the new technique to perform an axillary nerve block, and to compare interfascial injection and conventional perivascular injection.

Method
In this prospective, randomized study, 56 patients received ultrasound-guided axillary nerve blocks with either interfascial injection (Group IF), or perivascular injection with nerve stimulation (Group PV). Primary outcome was procedure time defined as the time interval between from when the transducer contacted the skin to when the needle was removed from the skin.

Results
The procedure time in the Group IF was significantly shorter than Group PV. There were no differentiations in secondary outcomes including the quality of blocks between two groups.

Conclusion
Ultrasound-guided interfascial injection for axillary nerve block can be performed without placing the needle near the posterior circumflex humeral artery.

Fig. 1. Ultrasound-guided axillary nerve block with interfascial injection.