Basic diaphragm ultrasound training: Curriculum implementation and learning trajectory among diaphragm ultrasound naive trainees

BACKGROUND: Little information exists on the amount or type of training required for diaphragm ultrasound (DUS) competency. AIM: To determine the number of directly-supervised DUS cases required for DUS-naive trainees to achieve competency for independent practice. METHODS: A prospective observational study was conducted in the intensive care unit, among trainees without prior DUS experience. Trainees completed a theoretical module and questionnaire, then performed a standardized DUS protocol on both right and left hemi-diaphragms under supervision. Trainees were tasked to determine: (1) Diaphragm thickening fraction (DTF), as a percentage difference of the diaphragm thickness at end-inspiration compared to thickness at end-expiration; and (2) Amount of diaphragm excursion (DE). DTF was evaluated at the zone of apposition and mid-axillary line on both sides. Both DTF and DE were calculated using the mean of measurements from three consecutive breaths. Trainee measurements and interpretation were compared with trainers, according to pre-defined criteria. Need for assistance was also recorded. RESULTS: Thirteen trainees (mean age 29.5 years; 7 females) scanned 5 patients each, whereby each trainee would have acquired 150 hemi-diaphragm images for 20 sets of DTF measurements and 10 sets of DE measurements. Across 65 supervised assessments on 52 patients, measurement agreement improved with repeated attempts, particularly for DTF, reaching near 100% by the fifth attempt. Interpretation agreement was consistently high (> 80%) from the start and also approached 100% with training. However, some trainees still required assistance with left diaphragm assessments, especially excursion. CONCLUSION: Our training approach allowed DUS-naive trainees to achieve adequate skills to perform unsupervised DUS evaluation of the right hemi-diaphragm after at least 5 patient encounters. For left DTF and DE, some trainees require more supervised scans to achieve competency for independent practice.