The role of phosphatidylglycerol in phospholipid analysis of tracheal and gastric aspirate in premature infants.

Tracheal and gastric aspirates from premature infants simultaneously sampled shortly after birth were analyzed for their phospholipid composition using 2-dimensional thin layer chromatography. The results were related to clinical outcome. The L/S ratio was higher in infants without than in infants with hyaline membrane disease (HMD). The L/S values and the concentrations of phosphatidylglycerol (PG) were higher in tracheal compared with gastric aspirates (table I). This resulted in different L/S cutoff points with respect to lung maturity. In both aspirates, the predictive value of a "mature" (but not of an "immature") L/S ratio was improved by PG determination (table II). Only one out of 22 infants with HMD had a completely "mature" phospholipid profile in its tracheal aspirate. Two vaginally delivered premature infants without HMD had an "immature" phospholipid pattern in their gastric aspirates, but a "mature" one in their tracheal aspirates. The results indicate that phospholipid analysis of tracheal and gastric aspirates shortly after birth is useful in the biochemical diagnosis of HMD if proper cutoff points for the L/S ratio are used and the determination of PG is included. It may prove to be important in establishing criteria for a therapeutic trial of surfactant substitution.