FiO₂ predicts outcome in infants with respiratory syncytial virus-induced acute respiratory distress syndrome

Objective: Respiratory syncytial virus (RSV) infection can progress to acute respiratory distress syndrome (ARDS) in infants. ARDS is a life-threatening condition that is characterized by severe hypoxemia, defined as PaO₂/FiO₂ ratio <300 mmHg. This ratio is used in many trials as the sole oxygenation criterion for ARDS. Recently, however, it has been shown in adults with ARDS that FiO₂, independently of the PaO₂/FiO₂ ratio predicts mortality. Because epidemiology and outcome of ARDS differ strongly between children and adults, we determined if FiO₂ on admission (baseline FiO₂) independently predicted the duration of mechanical ventilation (MV) and length of stay (LOS) in the pediatric intensive care unit (PICU) in infants with RSV-induced ARDS. Design: Retrospective observational study. Setting: A 14-bed pediatric intensive care unit. Patients: One hundred twenty-nine mechanically ventilated infants with RSV-induced ARDS. Interventions: None. Measurements and main results: Independent predictors for outcome, including baseline FiO₂ and PEEP, were analyzed using the cox regression model. Endpoints were duration of MV and LOS in the PICU. A higher baseline FiO₂ was independently associated with a longer duration of MV (HR 0.12, CI 0.02–0.87, P = 0.036) and increased LOS in the PICU (HR 0.09, CI 0.01–0.57, P = 0.023). Neither baseline PEEP nor PaO₂/FiO₂ ratio correlated with outcome. Conclusions: FiO₂ level independently predicted outcome in infants with RSV-induced ARDS, whereas both PEEP and the PaO₂/FiO₂ ratio did not. This suggests that FiO₂ should be taken into account in defining disease severity in infants with RSV-induced ARDS. Pediatr Pulmonol. 2014; 49:1138–1144.