Surfactant Supplementation

Abstract

Not until late in gestation does surfactant (SA) synthesis become adequate, allowing a smooth transition from intra- to extrauterine life. If delivery is too early, there would be an SA deficiency, which quite likely would result in the development of the respiratory distress syndrome (RDS). The first breath would then meet excessive resistance, but if the lungs became expanded in spite of this, air distribution would be uneven and the airways would tend to close again during expiration. The neonate obviously would never encounter these difficulties if the SA deficiency were compensated for by an instillation of pulmonary SA before the first attempt to aerate the lungs. This concept of supplementing the SA the instant before it is needed was not put to the test until 1972. Enhorning and Robertson (1) reported that lung compliance in rabbits delivered on the 27th day of gestation, when SA synthesis is still very inadequate, improved dramatically following instillation of SA into the trachea. This was the first in a series of animal experiments (2–6) demonstrating the efficacy of SA supplementation prior to the first breath.