Ultrasound diaphragmatic manual and semi-automated motion measurements: Application in simulated and in vivo data of critically ill subjects

•Diaphragmatic muscle motion characteristics may provide useful information about diaphragmatic function.•Diaphragmatic motion semi-automated and manual measurements are not statistically significantly different.•The diaphragmatic excursion derived in this study for the subjects investigated at risk or had presumed diaphragmatic weakness was significantly lower than that of normal subjects based on published literature.•Diaphragmatic ultrasound video recorded in the course of a B-mode examination can be used to generate an M-mode image where diaphragmatic motion measurements can be performed.•The usefulness of the proposed system still remains to be evaluated in the clinical practice in the assessment and follow up of patients with diaphragmatic weakness or paralysis.