Usual care ECMO Cohort

The cohort will be comprised of 550 patients, aged 14 days to 20 years, who go on extracorporeal membrane oxygenation (ECMO) support due to pediatric acute respiratory distress syndrome (PARDS) at physician discretion. Patients with qualifying PARDS must have one oxygenation index (OI) ≥ 16 or two OIs 12 ≥ to \< 16 (at least 4 hours apart) or two oxygenation saturation indexes (OSIs) ≥ 10 (at least 4 hours apart) or one OI 12 ≥ to \< 16 and one OSI \> 10 (at least 4 hours apart) Subjects must be on mechanical ventilation for less than 240 hours (10 days) prior to cannulation. These measures must be after endotracheal intubation and before ECMO start. Chest radiograph prior to ECMO must show bilateral lung disease.~Subjects cannulated on ECMO for no more than 96 hours prior to gaining consent.

PROSpect protocolized therapies cohort

The cohort will be comprised of 1000 patients, aged 14 days to 20 years, who are endotracheally intubated for PARDS. Patients with qualifying PARDS must have one oxygenation index (OI) ≥ 16 or two OIs 12 ≥ to \< 16 (at least 4 hours apart) or two oxygenation saturation indexes (OSIs) ≥ 10 (at least 4 hours apart) or one OI 12 ≥ to \< 16 and one OSI \> 10 (at least 4 hours apart). These measures must be after endotracheal intubation. Chest radiograph must show bilateral lung disease. Patient must be enrolled in a clinical trial Prone and Oscillation Pediatric Clinical Trial (PROSpect) NCT01515787 which is distinct from ASCEND.~PROSpect is a response adaptive randomized clinical trial, testing the impact of supine/prone positioning and conventional mechanical ventilation/high-frequency oscillatory ventilation on short and long-term clinical outcomes in children with severe PARDS. PROSpect manages severe PARDS subjects using a rigorous protocol that reserves ECMO for protocol failure.