The biochemistry of fetal lung development.

Surfactant therapy for RDS is likely to become widespread in the near future. Animal data indicate that this will not preclude a role for hormonal acceleration of lung maturation. In studies with prematurely delivered and ventilated fetal rabbits, Fiascone et al. have shown that the administration of betamethasone antenatally improves lung compliance, as does intratracheal administration of excess amounts of adult rabbit natural surfactant. If the two therapies are combined, however, an additive effect is observed. This suggests that some of the effects of glucocorticoids on lung compliance are not related to surfactant. Prior glucocorticoid therapy may provide a benefit that differs from that of surfactant therapy because steroids mature the lungs anatomically and enhance nonsurfactant-related tissue compliance. It is also possible that surfactant therapy itself may be more effective in the presence of larger and increased numbers of alveoli. It thus seems likely that in the future both hormonal enhancement of lung maturation and surfactant therapy may be used in combination to further reduce the morbidity and mortality from RDS.