Sequential changes of surfactant phosphatidylcholine in hyaline-membrane disease of the newborn.

Although reduced levels of lung surfactant are known to predispose to hyaline-membrane disease, the role of biochemical changes in surfactant composition has not been defined. We found that surfactant isolated from pharyngeal and tracheal aspirates of newborns with hyaline-membrane disease had a distinctly different phosphatidylcholine fatty acid composition from surfactant of control infants. Surfactant phosphatidylcholine from newborns with hyaline-membrane disease had a lower percentage of palmitic acid and higher percentages of the 18-carbon and 20-carbon fatty acids, irrespective of gestational age. Evaluation of serial aspirates for 18 days revealed that in hyaline-membrane disease the surfactant phosphatidylcholine fatty acids followed a predictable pattern of change, gradually becoming similar to those of the control group. Evaluation of surfactant from tracheal and pharyngeal aspirates effectively monitors the biochemical maturation of the surfactant system in hyaline-membrane disease.