Surfactant Replacement

Normal lung function depends on the presence of an alveolar lining layer with properties that permit a decrease in surface tension at end-expiration and an increase in surface tension on lung expansion, thus preventing atelectasis at the end of expiration and facilitating elastic recoil at the end of inspiration. The principal ingredients of this lining layer, which is called pulmonary surfactant, are dipalmitoyl phos-phatidylcholine and other phospholipids, as well as at least two groups of non-serum surfactant-associated proteins. Surfactant deficiency due to “immaturity” with respect to synthesis is characteristic of the respiratory distress syndrome in premature infants. Surfactant replacement is.