From a recent paper:
Guidelines recommend teaching of lung ultrasound for critical care, though little information exists on how much training is required for independent practice, especially for non-physician trainees. We thus aimed to elucidate a threshold number of cases above which competency for independent practice may be attained for respiratory therapists (Rts)...
Eleven ultrasound-naïve RTs scanned an average of 15 patients each (170 patients in total)...
After trainees performed at least ten scans, less than 2 % of images required assistance with acquisition and less than 5 % were wrongly interpreted.
Our training method allowed RTs to independently perform lung ultrasound after at least ten directly supervised scans. Given that RTs are likely to have less ultrasound knowledge and less clinical know-how compared to physicians, we believe that the same threshold number of scans may be also safely applied to the latter.