Surfactant replacement in the management of the neonatal respiratory distress syndrome.

Several recent reports have documented the efficacy of surfactants replacement therapy in the neonatal respiratory distress syndrome (RDS). The surfactants tested in these trials were obtained from animal lungs or human amniotic fluid. In general, such natural preparations seem to be superior to entirely synthetic surfactants, although promising results have recently been obtained in animal experiments with artificial surfactant based on isolated apoproteins and synthetic phospholipids. Furthermore, surfactant replacement therapy seems to be more effective when the exogenous material is administered at birth, before the first breath, than when surfactant is instilled into the airways after a period of ventilation. This discrepancy may be due to maldistribution of the exogenous material, or to the rapid development of epithelial lesions in the immature lung, with leakage of surfactant-inhibiting proteins into the airspaces. A transient beneficial response to surfactant replacement may also be due to circulatory problems, especially reversal of the shunt through a patent ductus arteriosus, with overloading of the lung circulation leading to pulmonary oedema and recurrent respiratory failure. Additional, properly randomized clinical trials are required to evaluate the benefits and potential hazards of surfactant replacement therapy in neonatal RDS.