Loss of muscle thickness in critically-ill children.

A. Percent change in muscle thickness between the first two ultrasound assessments in the entire study cohort. Dashed red line indicates a 10% decrease. Gray line at zero is shown for clarity. Box boundaries represent 25th and 75th percentiles, whiskers– 5th and 95th percentiles. B. Percent of patients experiencing muscle atrophy, defined as >10% loss of muscle thickness. C. Frequency distribution of patients by the number of muscle groups showing atrophy.