The role of surfactant in neonatal adaptation.

The fetal lung has complex mechanisms for surfactant accumulation and secretion that prepare the fetus for an uncomplicated transition to air breathing. Recent experiments indicate that this transition is not just a process of secretion of accumulated stores, but involves dynamic processes of mobilization of intracellular pools, alveolar surfactant reuptake, and complex changes in alveolar surfactant fractions. The intricacies of these processes and the relative importance of the various proposed secretagogues remain to be further explored. Surfactant is necessary, but not sufficient for normal neonatal pulmonary adaptation. Without adequate central respiratory drive, respiratory muscles, and lung structural maturation, normal respiratory adaptation will not occur.