Radial plus musculocutaneous nerve stimulation for axillary block is inferior to triple nerve stimulation with 2% mepivacaine.

STUDY OBJECTIVE: To compare the extent of sensory and motor block with two different nerve stimulation techniques in axillary blocks. DESIGN: Prospective, randomized, investigator-blinded study. SETTING: Ambulatory surgery unit of a university hospital. PATIENTS: 60 ASA physical status I, II, and III patients undergoing surgery at or below the elbow. INTERVENTIONS: Patients receiving axillary block were randomized into two nerve stimulation groups with either radial plus musculocutaneous or triple nerve stimulation (radial, median, and musculocutaneous nerves). Thirty milliliters of plain 2% mepivacaine was given to all patients either in a single or fractionated dosing for radial or for radial and median nerves, according to group assignment. Five milliliters of plain 1% mepivacaine for the musculocutaneous nerve was given to all patients. MEASUREMENTS: Blocks were assessed at 10, 20, and 30 minutes. Rates of supplementation given as a result of insufficient surgical anesthesia were also noted. MAIN RESULTS: Statistically significantly higher rates of anesthesia at the cutaneous distributions of median and medial cutaneous of the arm nerves with multiple nerve stimulation at 30 minutes were found as compared with radial plus musculocutaneous nerve stimulation. The rate of supplementation was lower with multiple nerve stimulation. CONCLUSIONS: Radial plus musculocutaneous nerve stimulation showed lower efficacy of axillary block than did triple nerve stimulation when using 2% mepivacaine.