Fig. 3
From: Ultrasound and non-ultrasound imaging techniques in the assessment of diaphragmatic dysfunction
Reproduced with permission from The American Physiological Society: Wait et al. J Appl Physiol 1989;67(4):1560–1568
Diaphragmatic thickening fraction. (Upper panel) Schematic representation of the points used to measure diaphragm thickness and formula used to calculate thickening fraction (TF). (Lower panels) Relationship of thickening fraction to lung volume expressed as a percent of inspiratory capacity (IC) in two healthy subjects. Each point represents the mean of three measurements taken from one breath. The slope of the relationship between thickening fraction and lung volume has high interindividual variability.