The first successful clinical pilot studies of
surfactant replacement were published about 20 years ago as a logical extension of experimental studies showing beneficial effects in pre-term animals. The efficacy of this
therapy for immature new-borns has been confirmed in various controlled trials and
surfactant therapy is now part of the routine management of the infant
respiratory distress syndrome. During the last decade there has been growing insight into the functional role of
surfactant components and the mechanisms by which exogenous
surfactant exerts its
therapeutic effects on lung mechanics, gas exchange and host defence. Of particular interest in this context is the essential role that
surfactant-associated
proteins play in the surface tension-limiting ability of
surfactant, as well as their contribution to pulmonary defence. Indications for
surfactant replacement have widened in recent years and promising results have been obtained for adult conditions such as the
acute respiratory distress syndrome (ARDS),
pneumonia, chronic obstructive and allergic
lung diseases. This review outlines the complexity of the
surfactant system and describes its basic biophysics, physiology and biochemistry. Problems related to the development of exogenous
surfactant preparations, the exploration of clinical targets for
surfactant therapy and pathophysiological mechanisms interfering with
surfactant function in various forms of
lung disease will be discussed.