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

Successful resuscitation of a fetus and a smooth transition to air breathing is a complex process that requires the orchestration of numerous events. The ability of the newborn to establish adequate ventilation and oxygenation is critically dependent on alveolar expansion and clearing of lung fluid. This transition is aided by changes, including a decrease in lung fluid production, that occur in the immediate period prior to birth. In neonates who face difficulty in establishing air exchange after birth, failure of adequate clearance of lung fluid is an important factor. Such infants are likely to benefit from efforts directed at increasing lung epithelial sodium reabsorption, which in turn will drive water out of the alveolar spaces. We are beginning to understand how these physiologic events occur and some of the factors that can speed up the process. Therapeutic modalities aimed at rescuing infants whose lungs continue to stay flooded are likely to reduce pulmonary morbidity and improve outcome.