Pulmonary surfactant

Pulmonary surfactant is a complex mixture of lipids and proteins that, by modulating surface tension during breathing, prevents alveolar collapse at exhalation and overdistention at inspiration. Surfactant is synthesized by type II pneumocytes, assembled in lamellar bodies and secreted at the air-liquid interface of the alveolus. This surface-active material is re-uptaken by alveolar type II cells and eliminated by macrophages. Deficiency or dysfunction of pulmonary surfactant contributes to several respiratory pathologies, such as among other respiratory distress syndrome (RDS) in newborns and acute respiratory distress syndrome (ARDS) in children and adults. Surfactant replacement therapy in the treatment and prophylaxis of RDS substantially reduces mortality and morbidity in preterm infants. However, ARDS treatment trials involving adult patients have not brought about good results. The aim of the paper is to present structure, function and metabolism of pulmonary surfactant as well as an overview of publications on the use of exogenous surfactants in RDS and ARDS treatment.