An investigation of the pulmonary surfactant system in children with severe respiratory syncytial virus infection

Severe infection with Respiratory Syncytial Virus (RSV) is an important cause of respiratory failure in infants and young children. Pulmonary surfactant is a surface-active complex of phospholipids and proteins which lines the alveolar surface of the lung. Clinical similarities of severe RSV infection to Respiratory Distress Syndrome of the newborn (RDS) and Adult Respiratory Distress Syndrome (ARDS) suggest that surfactant abnormalities may be involved in the pathogenesis of the disease. The hypothesis tested in this study is that the pulmonary surfactant system is dysfunctional in severe RSV infection, due to deficiency, abnormal composition, damage or inhibition. Non-bronchoscopic bronchoalveolar lavage was performed on 18 children ventilated for severe RSV infection and 16 children ventilated for surgical procedures and post operative care. It was concluded that in children with severe RSV infection, surfactant was dysfunctional. There was evidence that two mechanisms contributed to this: 1. Pulmonary surfactant proteins and phospholipids were deficient. 2. Surfactant surface activity was inhibited. Surfactant phospholipid and fatty acid composition was abnormal, and surfactant damage was present. However, the surface active properties of an organic extract of BAL fluid were intact. This indicated that damage to surfactant and change in composition did not reduce surface activity. There was minimal damage to lipids by peroxidation. In conclusion, the pulmonary surfactant system is abnormal in children with severe RSV infection. Surfactant abnormality may be an important factor leading to respiratory failure in these children. (Abstract shortened by ProQuest.)