Alternate Names: Hyaline membrane disease; Infant respiratory distress syndrome (IRDS)

Causes and Risks: Respiratory distress syndrome affects 10% of all premature infants. A full-term infant rarely will be affected. The disease is caused by a lack of pulmonary surfactant, a chemical that normally appears in mature lungs. Pulmonary surfactant reduces the surface tension within the air sacs of the lungs, preventing a collapse of these air sacs and allowing them to inflate more easily. In respiratory distress syndrome, there is atelectasis, or collapse of these air sacs with a decrease in lung volume, and an inability to exchange oxygen and carbon dioxide within the lung. The symptoms usually appear shortly after birth and become progressively more severe. Risk factors are prematurity, diabetes mellitus in the mother, and stress during delivery that produces acidosis in the newborn at the time of delivery.

Prevention: Since RDS usually occurs as a result of prematurity, every effort is usually made to help the mother carry the baby to term. This begins with the first prenatal visit that should be made as soon as the mother discovers she is pregnant. Statistics clearly show that good prenatal care results in larger healthier babies and fewer premature births. If the mother goes into labor prematurely every effort is made to stop the labor and allow the pregnancy to continue to full term. A lab test called the L/S ratio (a measurement of the fetus’ lung maturity) is made and labor is usually halted until the L/S ratio shows that the lungs have matured. The infant’s chance of not developing RDS, if not 100 precent, is at least improved.

When it appears that premature delivery is unavoidable, administration of corticosteroids to the mother two to three days prior to delivery may help the fetal lung tissue mature in certain cases.

Symptoms:

• rapid breathing (tachypnea)
• unusual breathing movement -- drawing back of the chest muscles with breathing (see intercostal retractions)
• shortness of breath, and grunting sounds while breathing
• nasal flaring
• cessation of breathing (apneic episode)
• bluish coloration of the skin and mucus membranes (cyanosis)
• extremities puffy or swollen (edematous)

Signs and Tests:

• A blood gas analysis shows low oxygen and acidosis.
• A chest X-ray shows findings consistent with respiratory distress (the lungs develop a characteristic "ground glass" appearance).
• Pulmonary function studies may be necessary.
• blood cultures and a sepsis work-up are usually done to rule out infection and sepsis as a cause of the respiratory distress.

Treatment:
The treatment is prompt resuscitation of all high-risk and premature infants by a pediatric resuscitation team. High oxygen and humidity concentrations are given initially. Those infants with mild symptoms of the disease will be given supplemental oxygen. Those with severe symptoms will be managed on a ventilator to deliver both oxygen and pressure to keep the lungs inflated. Oxygen and pressure will be decreased as soon as possible to prevent side effects associated with oxygen toxicity and high pressures.

Artificial surfactant is sometimes instilled through an endotracheal tube into the lungs of an infant at high risk for respiratory distress syndrome immediately after birth (see lung surfactant). This treatment has been associated with preventing or improving the course of respiratory distress syndrome. Enough information now has been gathered regarding surfactants to show that they reduce mortality from RDS.

Prognosis: The condition may persist or worsen for two to four days after birth with improvement thereafter. Some infants with severe respiratory distress syndrome will die. Sometimes long-term complications will develop as a result of oxygen toxicity, high pressures delivered to the lungs, or the severity of the disease.

Complications:

• pneumothorax
• pneumomediastinum
• pneumopericardium
• bronchopulmonary dysplasia
• hemorrhage into the brain (intraventricular bleed)
• hemorrhage into the lung (sometimes associated with surfactant use)
• thrombotic events associated with an umbilical arterial catheter
• retrolental fibroplasia and blindness
• delayed mental development and mental retardation associated with anoxic brain damage or hemorrhage

This disorder usually develops shortly after birth while the baby is still in the hospital.