Symposium on the Newborn Respiratory Distress Syndrome - Update 1982 Mikko Hallman, M.D.,* and Louis Gluck, M.D. t Respiratory distress syndrome (hyaline membrane disease, RDS) re- mains the major pulmonary problem of the newborn, despite the many advances in therapy. RDS is characterized by failure of pulmonary gas exchange following birth, with progressive expiratory atelectasis. A defi- ciency of surfactant is the principal cause for the atelectasis. Besides surfactant deficiency, other factors, including inadequate and self-deflating chest wall mechanics and patent ductus arteriosus (PDA), prevent clearing of lung fluid, interfere with normal neonatal cardiopulmonary transition, and cause the well-known symptoms and signs of progressive respiratory insufficiency. Advances in therapy that can compensate for deficient pulmonary ventilation and gas exchange have markedly increased survival, but some- times at the expense of severe secondary lung damage resulting from the therapy, and from the immaturity of the airways and cardiovascular system, and particularly from the failure of closure of the PDA. Attempts to reduce the incidence of RDS have met with some success, but a truly dramatic decrease is prevented by the continuing high rates of prematurity. In the following discussion recent progress in the understanding of the pathogenesis and prevention of RDS is summarized, and some new trials of treatment of RDS are discussed. DEVELOPMENTAL ASPECTS Lung Surfactant Lung surfactant decreases the surface tension of the peripheral airways. The biosynthesis of surfactant takes place in microsomal membranes and *Associate Professor of Pediatrics, University of California, San Diego, Division of Perinatal Medicine, La Jolla, California tProfessor of Pediatrics and Reproductive Medicine, University of California, San Diego, Division of Perinatal Medicine, La Jolla, California Pediatric Clinics of North America-Yo!. 29, No. 5, October 1982 1057