Respiratory distress syndrome (RDS)

Respiratory distress syndrome (RDS) of the newborn is an acute lung disease caused by surfactant deficiency. It is seen primarily in neonates younger than 36-38 weeks' gestational age and weighing less than 2500 g. In comparison, hyaline membrane disease (HMD) tends to occur in neonates younger than 32 weeks' gestational age and weighing less than 1200 g. The radiographic features of respiratory distress syndrome are seen in the images below.

Classic respiratory distress syndrome (RDS). Bell-shaped thorax is due to generalized underaeration. Lung volume is reduced, the lung parenchyma has a diffused reticulogranular pattern, and peripherally extending air bronchograms are present.

Moderately severe respiratory distress syndrome (RDS). The reticulogranular pattern is more prominent and uniformly distributed than usual. The lungs are hypoaerated. Increased air bronchograms are observed.

Severe respiratory distress syndrome (RDS). Reticulogranular opacities are present throughout both lungs, with prominent air bronchograms and total obscuration of the cardiac silhouette. Cystic areas in the right lung may represent dilated alveoli or early pulmonary interstitial emphysema (PIE).



The incidence and severity of RDS is inversely related to gestational age. RDS is the most common cause of respiratory failure during the first days after birth. In addition to prematurity, other factors contributing to the development of RDS are maternal diabetes, cesarean delivery without preceding labor,1 fetal asphyxia, and being the second born of twins.2,3



The outcome of patients with RDS has improved with the increased use of antenatal steroids to improve pulmonary maturity, early postnatal surfactant therapy to replace surfactant deficiency, and gentle techniques of ventilation to reduce barotrauma to the immature lungs.



Randomized, controlled trials have shown surfactant therapy to be efficacious in treating infants with, or at risk for, respiratory distress syndrome. A study by Soll et al demonstrated that multiple doses of animal-derived surfactant extract provided greater improvement than single-dose therapy did with regard to oxygenation and ventilatory requirements, reduced risk of pneumothorax, and improved survival.4



Lahra et al found that maternal and fetal intrauterine inflammatory responses (chorioamnionitis and umbilical vasculitis) are protective for RDS. In this study, chorioamnionitis with umbilical vasculitis was found to provide a markedly greater reduction of RDS than the presence of chorioamnionitis alone.5



Preferred examination



Respiratory distress syndrome is usually diagnosed with a combination of clinical signs and/or symptoms, chest radiographic findings, and arterial blood gas results.