Lung Superimposed Pressure in Pediatric Acute Respiratory Distress Syndrome: Single-Center Study, 2014–2024

OBJECTIVES: Superimposed pressure (SP) is the hydrostatic pressure compressing dependent lung regions and is a major determinant of dorsal collapse in adult patients with acute respiratory distress syndrome (ARDS). CT studies clarify its role in determining the need for positive end-expiratory pressure (PEEP) in ARDS. We therefore aimed to describe SP in pediatric ARDS (pARDS) and assess its associations with anthropometric, clinical, and quantitative CT parameters. DESIGN: Retrospective cohort study. SETTING: Urban academic tertiary care children's hospital in Italy. PATIENTS: All children with pARDS undergoing noncontrast chest CT between 2014 and 2024 compared with age-matched control patients with normal lung findings undergoing chest CT. MEASUREMENTS AND MAIN RESULTS: We included 12 pARDS patients and 24 controls. Quantitative CT analysis was used to measure lung aeration and the SP in 10 ventral-to-dorsal regions. The median (interquartile range [IQR]) SP increased from ventral to dorsal in both groups but was higher in pARDS patients: (dorsal SP, 5.9 cm H2O [IQR, 4.4-7.5 cm H2O] vs. 3.0 cm H2O [IQR, 2.4-4.0 cm H2O]; p < 0.001). Compared with controls, we found that pARDS patients had higher lung weight, lower gas/tissue ratio, and less normally aerated tissue. In pARDS patients, SP correlated with chest circumference (ρ = 0.60; p = 0.043), lung weight (ρ = 0.76; p = 0.006) and inversely with normally aerated tissue (ρ = -0.72; p = 0.011). We failed to identify a relationship between SP and oxygenation indices. INTERVENTIONS: None. CONCLUSIONS: SP in pARDS is lower and more variable compared with descriptions in adult patients with ARDS and is both affected by disease severity and chest size. We failed to identify an association between oxygenation indices and SP, which raises concerns about titrating PEEP based on oxygenation targets alone. Further studies are needed to confirm and integrate these in pARDS.