Surfactant content in children with inflammatory lung disease

Objective: To determine surfactant profiles of tracheal secretions in mechanically ventilated children with respiratory failure secondary to bacterial pneumonia, viral pneumonitis, adult respiratory distress syndrome (ARDs), and cardiopulmonary bypass. Design: Prospective, cohort study. Setting: Tertiary, multidisciplinary, pediatric intensive unit. Patients: One hundred twenty pediatric patients with respiratory failure requiring mechanical ventilation. Interventions: Routine tracheal aspirates were collected from children with bacterial pneumonia, viral pneumonitis, ARDS, postcardiopulmonary bypass, and a postsurgical control group, Samples were obtained on days 1, 2, 3, after every week of intubation and on the day of extubation. Measurements and Main Results: The tracheal aspirates were: analyzed by high-performance liquid chromatography for lecithin/sphingomyelin ratios and by enzyme-linked immunosorbent assay for surfactant proteins A and B, Lung compliance and the oxygenation index were measured on each day of sample collection, Ore day 1, patients with bacterial pneumonia, viral pneumonitis, and ARDS had decreased lecithin/sphingomyelin ratios (p < .001), and those patients with bacterial pneumonia and viral pneumonitis had decreased surfactant protein A/protein concentration (p < .001), The lecithin/sphingomyelin ratios and surfactant protein A/protein concentration were significantly different among the groups (p < .001), with the bacterial pneumonia and viral pneumonitis groups having higher lecithin/sphingomyelin ratios and increased surfactant protein concentrations before extubation. Pulmonary compliance was lower and the oxygenation index was higher than controls (p < .001) in patients with bacterial pneumonia, viral pneumonitis, and ARDS, Pulmonary compliance was correlated weakly with lecithin/sphingomyelin ratio (r(2) = .11, p < .001) and surfactant protein A/protein concentration (r(2) = .03, p < .05). Surfactant protein B was similar in the diagnostic groups. surfactant content in tracheal secretions from cardiopulmonary bypass patients was equivalent to controls. Conclusion: Abnormal tracheal aspirate surfactant phospholipids and surfactant protein A were noted in children with bacterial pneumonia, viral pneumonitis, and ARDS, but not in children on cardiopulmonary bypass.