The prevention of hyaline membrane disease: new concepts and approaches to therapy.

New approaches to hyaline membrane disease have emerged in recent years. These developments are principally attributable to advances in our understanding of the following: (1) the pathophysiology and pathogenesis of HMD in relationship to pulmonary surfactant, (2) fundamental aspects of fetal lung development, including the movement of surfactant phospholipids from fetal pulmonary fluid to the amniotic space, (3) mechanisms for accelerating lung maturation, particularly with maternally administered prenatal glucocorticoids, and (4) ventilatory techniques effective in protecting and conserving alveolar surfactant by the continuous application of end expiratory pressure. Prenatal assessment of the risk for developing hyaline membrane disease is now routinely possible by amniocentesis and analysis of the ratio of lecithin to sphingomyelin in amniotic fluid. Such predictability, coupled with the ability to postpone delviery, allows the perinatologist in some instances to provide the fetus with ample opportunity for lung development in utero. Recent clinical trials around the world with pregnant women in premature labor document a significantly lower incidence of hyaline membrane disease after antenatal glucocorticoid treatment. In neonates with the disease weighing more than 1500 gm, it is now established that reduced mortality rates accrue from the use of end expiratory positive pressure. These clinical advances offer great promise in changing the nature of HMD management from procedures that are largely supportive to approaches that are truly preventative.