[Ultrasound-guided axillary brachial plexus block: learning curve and results]

Abstract

Background and objective: The use of ultrasound in regional anesthesia requires the acquisition of new knowledge and skills not only by anesthesiologists in training but also by anesthesiologists experienced in neurostimulation-guided peripheral nerve blocks. We studied the effect of training on 2 anesthesiologists who were skilled in neurostimulation-guided regional anesthesia.

Patients and methods: Observational, controlled study of the first 45 ultrasound-guided axillary blocks of the brachial plexus performed by two anesthesiologists with expertise in the neurostimulation-guided axillary procedure. For analysis of results, groups of 15 patients from each anesthesiologist were assigned consecutively (G15, G30 and G45). We assessed the duration of the block procedure, the incidence of vascular puncture and effectiveness of the block.

Results: The mean (SD) duration of the procedure was 547 (16) seconds in G15. It was significantly lower in G30 and G45 (893 [104] seconds and 397 [111] seconds). The incidence of vascular puncture dropped significantly after completion of the first 15 blocks, from 20% in 615 to 3% in G30 and 0% in G45. The results of the block procedure also significantly improved after the first 15 blocks: 89% effectiveness in 615, 93% in G30, and 100% in G45. The variables assessed were similar for the 2 anesthesiologists.

Conclusions: For an anesthesiologist with experience establishing a conventional axillary brachial plexus block using a nerve stimulator, 15 ultrasound-guided axillary blocks are required before good results can be expected with the new procedure.