Meta-analysis of trials of surfactant in children with acute respiratory failure: Duration of PICU stay Meta-analysis of trials of surfactant in children with acute respiratory failure: Duration of PICU stay. ALI, acute lung injury; ARDS, acute respiratory distress syndrome; 95% CI, 95% confidence interval; PICU, paediatric intensive care unit; RSV, respiratory syncytial virus; SD, standard deviation; WMD, weighted mean difference.