Lung surfactant phospholipids in the foetus, newborn, and in the adult; evidence of abnormality in respiratory failure.

The surface active material on the peripheral airway lining prevents atelectasis and its consequences. Abnormalities in lung surfactant can be diagnosed by analysis of the amniotic fluid in the foetus, tracheal aspirate in the newborn, and segmental bronchoalveolar lavage in children or adults. In the respiratory distress syndrome in the newborn (RDS) surfactant phospholipids are immature. This is a major cause of respiratory failure in RDS. In acute respiratory failure in adults and in children (ARF) alveolar phospholipids are abnormal. There are three main types of surfactant abnormalities; 1) Immature surfactant in RDS, 2) defective surfactant phospholipids in ARF, and 3) inhibition of surfactant function by proteins (mostly due to increased alveolar permeability) in RDS, ARF, and in alveolar proteinosis. The importance of myoinositol in surfactant metabolism is discussed.