What causes infant respiratory distress syndrome?Infant respiratory distress syndrome is caused by lack of surfactant in the lungs of premature infants. This surfactant is chemically di-palmitoul-lecithin. This lack of surfactant leads to the collapse of lung alveoli. Surfactant is produced by the type II pneumocytes, which also help generate type I pneumocytes. Tiny air sacs called alveoli are located at the tips of the
body’s smallest breathing tubes, called the bronchi. The alveoli are responsible for passing oxygen into the blood. In the last stages of pregnancy, from 34 to 37 weeks, the cells in the alveoli normally produce a substance called surfactant. Surfacant reduces the surface tension of fluids that coat the lungs so the air sacs can expand at birth and the infant can breathe normally.
It is usually seen in premature infants less than 28 weeks of gestation. The lecithin-sphingomyelin ratio is used as a test for lung maturity. The availability of synthetic surfactant since the late 1980s revolutionised its treatment. However premature infants often still require mechanical ventilation until their lungs mature. The mortality rate lies around 30%. Another management option is corticosteroid therapy for the mother. When an infant is born prematurely, the cells in the alveoli do not yet have enough surfacant formed and the alveoli cannot expand. Very premature babies may have lungs that are so stiff they cannot breathe on their own. Or, the baby may be able to start breathing, but the "airless" lungs collapse and cause respiratory distress.