Scatterplot showing the results of regression analysis of diaphragm volume and patient weight (A), (B) height, and (C) body mass index. Correlation was calculated for the entire sample (critically ill and controls). There was a linear correlation between total diaphragm volume and weight, height, and body mass index. Scatterplot showing the result of regression analysis of psoas volume and intensive care unit patient weight (D), height (E), and body mass index (F). There was a linear correlation between total psoas volume and weight, height, and body surface area.