Fetal lung maturity testing.

Hyaline membrane disease (HMD) is a disorder primarily affecting premature infants and is a significant cause of morbidity and mortality in this population. The disorder is characterized by widespread atelectasis and an inability of the neonate to expand his or her lungs. Secondary hemor rhage, edema and desquamation of alveolar lining cells then occur which further compromise respira tory function. Surfactant is a combination of several phospholipid compounds including phosphatidyl choline (lecithin), phosphatidyl glycerol, sphingomyelin and phosphatidyl ethanolamine. Approximate percen tages for "mature" surfactant are shown in Table 1. These phospholipids are associated with several apoprotein moieties whose functions are only beginning to be understood. It appears, however, that these proteins are critical for proper surfactant function.