Integrated lung-diaphragm ultrasound in pediatric weaning assessment: a mini review

Weaning from mechanical ventilation remains a major challenge in pediatric critical care. Diaphragm ultrasound has emerged as a promising bedside, radiation-free tool for assessing respiratory muscle function. However, the value of diaphragm thickening fraction (DTF) in neonates and children remains heterogeneous rather than definitive. While several pediatric studies have reported potentially useful DTF thresholds, often around 20%-25%, other cohorts and physiological validation studies have shown weak or inconsistent associations with extubation outcomes or inspiratory effort. These discrepancies likely stem from developmental differences in diaphragm structure and function, high chest wall compliance in children, disease heterogeneity, varying ventilator settings, and technical challenges in obtaining reliable measurements in small patients. Importantly, DTF reflects only one aspect of the respiratory pump and does not evaluate pulmonary factors that increase breathing workload, such as atelectasis, pulmonary edema, consolidation, or poor lung aeration. Lung ultrasound can complement diaphragm assessment by identifying these sources of increased respiratory load during spontaneous breathing trials and after extubation. This mini-review summarizes the current evidence on diaphragm and lung ultrasound for pediatric weaning assessment and proposes an integrated PUMP-LOAD framework: diaphragm ultrasound to evaluate respiratory pump function and lung ultrasound to assess pulmonary load. Although physiologically sound and clinically feasible, this combined approach requires standardized pediatric protocols, age-specific reference values, and prospective multicenter validation before it can reliably guide extubation decisions.