What timepoint to consider to make an accurate prognosis after pediatric ARDS and ARDS onset?

Oxygenation measured at PARDS (pediatric acute respiratory distress syndrome) and ARDS (acute respiratory distress syndrome) onset poorly predicts the risk of death of both syndromes. Villar and coworkers suggested a categorization based on both PaO2/FiO2 and PEEP (positive end-expiratory pressure) values, measured 24 hours after the initial diagnosis of ARDS, for a better hospital mortality prediction (1).