Factors influencing surfactant composition in the newborn infant.

In order to evaluate the surfactant maturation of the neonate, tracheal aspirates were analyzed in 84 newborn infants with 12h of birth. Using 2-dimensional thin-layer chromatography, 9 different phospholipids were identified. Dynamic surface tension measurements were performed with a modified Wilhelmy balance. Five different groups of infants with typical phospholipid patterns were characterized: i.e., 1. Normal term newborn. 2. RDS in the preterm infant. 3. Acceleration of lung maturity in preterm infants without RDS. 4. Retardation in term infants with RDS. 5. Therapeutic induction of pulmonary maturity in preterm infants following maternal glucocorticoid administration. Mature lung effluent contains high concentrations of phosphatidylcholine (PC) and phsophatidylglycerol (PG). In infants with RDS, PC is low and PG absent. Accelerated lung maturity was observed after chronic prenatal stress, such as prolonged rupture of the membranes, chronic vaginal bleeding, and maternal hepatitis or drug addiction. Retardation of pulmonary maturity was seen in infants with alpha-1-AT-deficiency, maternal diabetes and maternal hypothyroidism. Administration of methylprednisolone to the mother 24 h to 72h before birth induced both the synthesis of PC and PG in the preterm infants, resulting in an almost full-term phospholipid pattern as early as 31 weeks of gestation. The significance of these factors on the pathogenesis of RDS is discussed.