Fig. 1

The learning curves were constructed for six anesthesiologist trainees using CUSUM method. a total of 20 ultrasound scans of the neck were performed by each trainee. Four out of six trainees. a-d achieved competency and two trainees did not reach competency. e, f Each downward point represents a correct identification of the cricothyroid membrane. Each upward point represents an incorrect identification of the cricothyroid membrane. Competency is defined as when the CUSUM score reaches two lines (dashed horizontal line) in the downward direction. Failure to reach competency is defined as when the CUSUM score reaches two lines in the upward direction