Ultrasound-Guided Block of the Axillary Nerve: A Prospective, Randomized, Single-Blind Study Comparing Interfascial and Perivascular Injections

Abstract

Background: The ultrasound-guided block of the axillary nerve may be complicated in cases in which the posterior circumflex humeral artery (PCHA) follows an abnormal course. Objectives: To develop a new technique that does not rely on direct visualization of the PCHA or the axillary nerve, and to compare interfascial injection and conventional perivascular injection for a block of the axillary nerve. Study Design: A prospective randomized study. Setting: An interventional pain-management practice in a university hospital. Methods: A total of 56 patients received ultrasound-guided block of the axillary nerve with either interfascial injection (IF Group) or perivascular injection with nerve stimulation (PV Group). The primary outcome was procedure duration, defined as the time interval from when the transducer contacted the skin to when the needle was removed from the skin. Results: The mean procedure time was significantly shorter in the IF Group than in the PV Group (64 seconds [SD 28.3] vs. 135 seconds [50.3], difference of −71.4 seconds; 95% confidence interval, −93.2 to −49.5) (P < 0.001). There were no differences in secondary outcomes, including the quality of blocks, between the 2 groups. Limitations: The practitioner was not blinded to the group to which the patients belonged. Conclusions: Ultrasound-guided block of the axillary nerve with interfascial injection can be performed without placing the needle near the PCHA. Key words: Block of axillary nerve, ultrasound-guided block, posterior circumflex humeral artery, interfascial injection