Fig. 2

Plots of cumulative checksums (CUSUM analysis). Intubation: passing the bronchoscope through the vocal folds into the trachea. When the CUSUM curve is directed upward it indicates inadequate performance (less than 80% of procedures were scored with a standardized score ≥ 80/100), when the curve stabilizes indicates that between 80 and 90% of the procedures were rated with a standardized score ≥ 80/100, when the curve is directed downwards indicates that more than 90% of the procedures were scored with a standardized score ≥ 80/100. The assembly of the equipment and the quality of aspiration obtained standardized scores ≥ 80/100 from the first procedure. Intubation ease obtained standardized scores ≥ 80/100 in more than 80% of cases since the 3rd procedure, the ease of maneuver obtained standardized scores ≥ 80/100 in more than 80% of cases since the 4th procedure, the image quality obtained standardized scores ≥ 80/100 in more than 80% of cases since the 9th procedure