Mistri S, Dhochak N, Jana M, et al. - Researchers conducted this observational cohort study to estimate changes in ultrasound measurements of diaphragmatic thickness over the first week of mechanical ventilation and to evaluate magnitude and risk factors of diaphragmatic atrophy. The sample consisted of children, aged 1 to 18 years, requiring mechanical ventilation. Ultrasound measurements of diaphragmatic thickness at end‐expiration (DTe) and end‐inspiration (DTi), and diaphragmatic thickening fraction (DTF) were conducted daily during the first week of admission, and pre‐ and post‐extubation. Of 55 children (74.6% boys) recruited, 20 (36.4%) died. In extubation success vs failure, there was no difference in diaphragmatic parameters (atrophy rate, and peri‐extubation DTe and DTF). During the first week of mechanical ventilation, the diaphragm undergoes progressive atrophy in critically ill children. Future research should determine ventilation strategies to minimise the diaphragmatic atrophy.