Surfactant and Inhaled Nitric Oxide in Acute Lung Injury

Received June 28, 2000 Pulmonary surfactant is routinely used in immature newborns for the prevention and treatment of respiratory distress syndrome (RDS). Inhaled nitric oxide (INO) is a new respiratory therapy, recently approved by the Food and Drug Administration, for selective pulmonary vasodilation in persistent pulmonary hypertension of the newborns (PPHN) and in hypoxic respiratory failure in neonates and infants. It is noteworthy that these two most eminent therapies, developed in 80's and 90's, respectively, revolutionized neonatal respiratory care, and are still the foci of basic and clinical investigation for infants, children and adults with acute lung injury (ALI) and acute (or adult type) RDS (ARDS), the pathogenesis of which differs from primary surfactant deficiency in RDS and primary or secondary PPHN, but is related to, among other mechanisms, surfactant dysfunction and abnormal metabolism, and impairment of pulmonary vasodilatation due to hypoxic vasoconstriction. Pulmonary surfactant is a phospholipid-protein complex produced by the type II alveolar epithelial cells. Theoratically, in a normal adult lung, about 0.3 μg of tightly packed dipalmitoylphosphatidylcholine (DPPC) monolayer is needed to cover 1 cm of alveolar inner Abstract Surfactant replacement and inhaled nitric oxide are two important respiratory therapies for neonatal respiratory distress and persistent pulmonary hypertension. However, limitation of each therapy alone in various respiratory disorders raised questions as to whether we should use them in a combined manner, or in combination with other effective treatment modalities, so that the problems in both alveolar space and intrapulmonary vasculature may well be dealt with simultaneously. In recent years, a number of experimental and clinical studies have demonstrated that combined surfactant and inhaled nitric oxide consistently showed better effects than that of the independent therapy, suggesting that the adequate use of these two therapies may have a potential to improve clinical management of severe respiratory problems in infants and children.