Review Question - QID 101919

This infant's presentation is consistent with neonatal respiratory distress syndrome (NRDS), also known as hyaline membrane disease. NRDS can be prevented with administration of a corticosteroid such as dexamethasone to the mother between 24 and 34 weeks gestation.

In a healthy lung, surfactant prevents atelectasis (collapse) of alveoli. In NRDS, a lack of surfactant production results in atelectasis and intrapulmonary shunting. NRDS may be caused by premature birth, C-section, or maternal diabetes. It presents in the first hours of life with dyspnea and hypoxemia that are unresponsive to O2. Both fetal and maternal cortisol stimulate the production of surfactant and contribute to the maturation of the fetal lungs. The lecithin-sphingomyelin ratio may be measured in the amniotic fluid as a marker of fetal lung maturity. An L-S ratio above 1.9 indicates that the fetal lungs are mature.

Image A shows a chest X-ray with the typical bilateral diffuse ground glass appearance of NRDS. Illustration A shows another case of NRDS with the same bilateral diffuse ground-glass appearance. Note additionally the left-sided tension pneumothorax and pneumomediastinum, likely secondary to ventilator barotrauma.

Incorrect answers:
Answer 1: Administration of oxygen to the mother does not prevent NRDS. Newborns with NRDS can be treated with concentrated oxygen therapy, but it must be given carefully in order to avoid retinopathy of prematurity.
Answer 2-3: Lecithin and sphingomyelin are components of surfactant secreted from the fetal lung and are present in the amniotic fluid.
Answer 4: Insulin decreases surfactant production. A mother with high levels of insulin (e.g. with diabetes) therefore puts her fetus at risk for NRDS.