Determining the Learning Curve for Acquiring Core Sonographic Skills for Ultrasound-Guided Axillary Brachial Plexus Block.

Background And Objectives: The objectives of this study were to determine the learning curve for capturing sonograms and identifying anatomical structures relevant to ultrasound-guided axillary brachial plexus block and to determine if massed was superior to distributed practice for this core sonographic skill.

Methods: Ten University of Melbourne, third- or fourth-year Doctor of Medicine students were randomized to massed or distributed practice. Participants performed 15 supervised learning sessions comprising scanning followed by feedback. A "sonographic proficiency score" was calculated by summing parameters in acquiring and interpreting the sonogram, and identifying relevant anatomical structures.

Results: Between the 1st and 10th sessions, the proficiency scores increased (P = 0.043). Except for one, all participants had relatively rapid increases in their "sonographic proficiency scores." There was no difference in proficiency scores between the 15th and 10th sessions (P > 0.05). There was no difference in scores between groups for the first session, (P = 0.40), 15th session (P = 0.10), or at any time. There was no difference in the slope of the increase in "sonographic proficiency score" over the first 10 scanning sessions between groups [massed, 1.1 (0.32); distributed, 0.90 (0.15); P = 0.22) presented as mean (SD)]. The 95% confidence interval for the difference in slopes between massed and distributed groups was -0.15 to 0.56.

Conclusions: The proficiency of participants in capturing sonograms and identifying anatomical structures improved significantly over 8 to 10 learning sessions. Because of sample size issues, we cannot make a firm conclusion regarding massed versus distributed practice for this core sonographic skill.