Axillary Block by "Selective" Injections at the Nerves Involved in Surgery Using a Peripheral Nerve Stimulator

Background and Objectives: A triple-injection technique (injections at the median, musculocutaneous, and radial nerves) for axillary block affords a high incidence of complete block (all the nerves below the elbow). However, in certain surgeries, only 1 or 2 nerves are involved in the surgical field. The aim of this prospective randomized study was to test the effectiveness of surgical anesthesia of a Bselective[ approach in which only the nerves involved in surgery were electrically located and injected. Methods: Three types of surgery were selected. Type 1 included surgery on the fifth finger, type 2 included superficial surgery (without bone involvement) on the palm or on the dorsum of the hand, and type 3 included any surgery on the first 3 fingers. For each type, 138 patients were enrolled and divided into 2 groups: group SEL in which only the nerves involved in the surgical field (1 or 2) were located and injected and group TNS in which a standard triple-nerve stimulation technique was used. Results: A lower rate of surgical anesthesia (84% vs 92%; P G 0.05) was recorded in group SEL considered as a whole: this was mainly due to the significant difference recorded in type 2 surgery (75% vs 93%; P G 0.05). More patients needed intravenous administration of fentanyl for tourniquet pain (18% vs 8%; P G 0.005) and of midazolam for intraoperative anxiety (20% vs 8%; P G 0.005) in group SEL considered as a whole. In type 1, improved patient comfort at block performance (P G 0.05), a 7-min saving on total anesthetic time (P G 0.001), and a higher need for midazolam administration (P G 0.05) were recorded in group SEL. In type 2, a higher need for midazolam administration (P G 0.05) was recorded in group SEL. In type 3, no clinically significant differences between the groups were recorded. Conclusions: A standard triple-nerve stimulation technique seems to be preferable to the selective approach even when a limited number of nerves are involved in the surgical field