Fig. 4.
Lung density histograms. Value are provided for COVID− (n = 10 patients, panel a), type H (n = 5 patients, panel b) and type L (n = 8 patients, panel c) ARDS patients. Histograms represents the volume of all the voxels belonging to each interval of 100 Hounsfield units width, normalized by total lung volume. Bars are mean values and error bars are standard deviations. Red bars represent intervals within the over inflation range, blue bars intervals within the normal inflation range, yellow intervals within the poor inflation range, and green intervals within the non-aeration range. Panel d represent the fitted values in each group, with R2 of the general additive mixed model (red, green and blue lines refer to COVID−, Type H and type L groups, respectively). Grey shade areas represent 95% confidence interval of the fitted values. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)