Surfactant Lecithin Fatty Acid Composition and Its Relationship to the Infantile Respiratory Distress Syndrome

Abstract

Summary: In order to evaluate the role of surfactant lecithin composition in the development of the infantile respiratory distress syndrome (IRDS) we have examined lecithin fatty acid composition from gastric aspirates obtained at the time of delivery from 14 full term healthy infants, 9 control premature infants without respiratory distress, and 16 premature infants who developed IRDS. The latter had significantly reduced concentrations of palmitic acid (48.4 ± 1.8% vs. 65.3 ± 1.5% in fullterm and 59.5 ± 0.8% in control premature infants, P < 0.001). None of the infants in whom palmitic acid was more than 60% of total lecithin fatty acids developed IRDS, whereas 10 of 11 infants with values below 50% did develop this complication. Lecithin from gastric aspirate was shown to be similar in fatty acid composition to lecithins from tracheal washings and amniotic fluid. Palmitic acid concentrations in lecithins of serial tracheal washings paralleled the clinical course of eight infants with IRDS. Speculation: The enzyme systems involved in the biosynthesis of pulmonary surfactant are complex. Failure of maturation of these systems can result in inadequate synthesis of total lecithins or in a selective deficiency of dipalmitoyl lecithin, an essential component of surfactant. Therefore, studies directed to determining the composition of surfactant lecithins may result in better diagnosis, understanding, and management of IRDS.