The learning curve associated with a simulated ultrasound-guided interventional task by inexperienced anesthesia residents

Abstract

Background and objective: Ultrasound has become an increasingly popular modality in facilitating the performance of peripheral nerve blocks. There exists no literature that examines the learning curve of the ultrasound novice. In this prospective series, we evaluated the learning curve of inexperienced anesthesia residents in performing a simulated ultrasound-guided interventional procedure. In doing so, we hoped to identify reproducible patterns of human errors, which could potentially aid in the prevention of real-life iatrogenic injuries.

Methods: Ten subjects were prospectively enrolled. After a brief introduction to the ultrasound system, the subjects were asked to perform 6 sequential trials of a simulated breast cyst aspiration. For the first 3 trials, each subject attempted to place a 22-gauge b-bevel needle into any aspect of an olive buried inside the turkey breast. After completion of these 3 trials, the subjects were asked to place the needle into the exact midpoint of the olive wall closest to the transducer. Trials were videotaped and analyzed for task performance in terms of speed and accuracy.

Results: All subjects successfully completed the 6 interventional trials. The mean time to perform the task was reduced by 38% and 48%, respectively, for the second and third trials. A composite score of accuracy showed an improvement of 36% and 59%, respectively, for the second and third trials. The most common committed error, which occurred in 7 of 10 subjects, was the failure to accurately image the needle while advancing. This resulted in excessive depth of penetration and inadvertent transfixation of the olive in 5 of these subjects.

Conclusions: Anesthesiology residents, with little or no ultrasound experience, can rapidly learn and improve their speed and accuracy in performing a simulated interventional ultrasound procedure. A concerning novice pattern was identified where the subjects advanced the needle even though it was not appropriately visualized in the ultrasound beam. This resulted in needle placement error, which could cause iatrogenic injury in the clinical setting.