Alveolar fluid clearance in developing lungs and its role in neonatal transition

This article reviews the process of alveolar fluid clearance at birth and its relevance to successful transition from placental to pulmonary gas exchange. Although mechanical factors contribute to the fluid shift from developing air spaces, the bulk of fluid movement is secondary to transepithelial sodium reabsorption through amiloride sensitive sodium channels. Disruptions of this process can lead to retention of fluid in the air spaces resulting in "wet lungs" and may play a role in the pathogenesis of diseases like hyaline membrane disease and transient tachypnea of the newborn. The kev factors that stimulate lung fluid clearance in the perinatal period are also discussed.