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Neonatal respiratory distress syndrome
Definition
Neonatal respiratory distress syndrome (RDS) is most commonly seen in premature infants. The condition makes it difficult to breathe.
Alternative Names
Hyaline membrane disease; Infant respiratory distress syndrome (IRDS); Respiratory distress syndrome in infants; RDS - infants
Causes
Neonatal RDS occurs in infants whose lungs have not yet fully developed.
The disease is mainly caused by a lack of a slippery, protective substance called surfactant, which helps the lungs inflate with air and keeps the air sacs from collapsing. This substance normally appears in fully developed lungs.
Neonatal RDS can also be the result of genetic problems with lung development.
The earlier a baby is born, the less developed the lungs are and the higher the chance of neonatal RDS. Most cases are seen in babies born before 28 weeks. It is very uncommon in infants born full-term (at 40 weeks).
In addition to prematurity, the following increase the risk of neonatal RDS:
- A brother or sister who had RDS
- Diabetes in the mother
- Cesarean delivery
- Delivery complications that reduce blood flow to the baby
- Multiple pregnancy (twins or more)
- Rapid labor
The risk of neonatal RDS may be decreased if the pregnant mother has chronic, pregnancy-related high blood pressure or prolonged rupture of membranes, because the stress of these situations can cause the infant's lungs to mature sooner.
Symptoms
The symptoms usually appear within minutes of birth, although they may not be seen for several hours. Symptoms may include:
- Bluish color of the skin and mucus membranes (cyanosis)
- Brief stop in breathing (apnea)
- Decreased urine output
- Grunting
- Nasal flaring
- Rapid breathing
- Shallow breathing
- Shortness of breath and grunting sounds while breathing
- Unusual breathing movement -- drawing back of the chest muscles with breathing
Exams and Tests
A blood gas analysis shows low oxygen and excess acid in the body fluids.
A chest x-ray shows the lungs have a characteristic "ground glass" appearance, which often develops 6 to 12 hours after birth.
Lab tests are done to rule out infection and sepsis as a cause of the respiratory distress.
Treatment
High-risk and premature infants require prompt attention by a neonatal resuscitation team.
Despite greatly improved RDS treatment in recent years, many controversies still exist. Delivering artificial surfactant directly to the infant's lungs can be enormously important, but how much should be given and who should receive it and when is still under investigation.
Infants will be given warm, moist oxygen. This is critically important, but needs to be given carefully to reduce the side effects associated with too much oxygen.
A breathing machine can be lifesaving, especially for babies with the following:
- High levels of carbon dioxide in the arteries
- Low blood oxygen in the arteries
- Low blood pH (acidity)
It can also be lifesaving for infants with repeated breathing pauses. There are a number of different types of breathing machines available. However, the devices can damage fragile lung tissues, and breathing machines should be avoided or limited when possible.
A treatment called continuous positive airway pressure (CPAP) that delivers slightly pressurized air through the nose can help keep the airways open and may prevent the need for a breathing machine for many babies. Even with CPAP, oxygen and pressure will be reduced as soon as possible to prevent side effects associated with excessive oxygen or pressure.
A variety of other treatments may be used, including:
- Extracorporeal membrane oxygenation (ECMO) to directly put oxygen in the blood if a breathing machine can't be used
- Inhaled nitric oxide to improve oxygen levels
It is important that all babies with RDS receive excellent supportive care, including the following, which help reduce the infant's oxygen needs:
- Few disturbances
- Gentle handling
- Maintaining ideal body temperature
Infants with RDS also need careful fluid management and close attention to other situations, such as infections, if they develop.
Outlook (Prognosis)
The condition often worsens for 2 to 4 days after birth with slow improvement thereafter. Some infants with severe respiratory distress syndrome will die, although this is rare on the first day of life. If it occurs, it usually happens between days 2 and 7.
Long-term complications may develop as a result of too much oxygen, high pressures delivered to the lungs, the severity of the condition itself, or periods when the brain or other organs did not receive enough oxygen.
Possible Complications
Air or gas may build up in:
- The space surrounding the lungs (pneumothorax)
- The space in the chest between two lungs (pneumomediastinum)
- The area between the heart and the thin sac that surrounds the heart (pneumopericardium)
Other complications may include:
- Bleeding into the brain (intraventricular hemorrhage of the newborn)
- Bleeding into the lung (sometimes associated with surfactant use)
- Blood clots due to an umbilical arterial catheter
- Bronchopulmonary dysplasia
- Delayed mental development and mental retardation associated with brain damage or bleeding
- Retinopathy of prematurity and blindness
When to Contact a Medical Professional
This disorder usually develops shortly after birth while the baby is still in the hospital. If you have given birth at home or outside a medical center, seek emergency attention if your baby develops any difficulty breathing.
Prevention
Preventing prematurity is the most important way to prevent neonatal RDS. Ideally, this effort begins with the first prenatal visit, which should be scheduled as soon as a mother discovers that she is pregnant. Good prenatal care results in larger, healthier babies and fewer premature births.
Avoiding unnecessary or poorly timed cesarean sections can also reduce the risk of RDS.
If a mother does go into labor early, a lab test will be done to determine the maturity of the infant's lungs. When possible, labor is usually halted until the test shows that the baby's lungs have matured. This decreases the chances of developing RDS.
In some cases, medicines called corticosteroids may be given to help speed up lung maturity in the developing baby. They are often given to pregnant women between 24 and 34 weeks of pregnancy who seem likely to delivery in the next week. The therapy can reduce the rate and severity of RDS, as well as the rate of other complications of prematurity, such as intraventricular hemorrhage, patent ductus arteriosus, and necrotizing enterocolitis. It is not clear if additional doses of corticosteroids are safe or effective.
References
Cloherty J, Stark A, Eichenwald E. Manual of Neonatal Care. 6th ed. Lippincott, Wilkins and Williams; 2008.
Reviewed By: Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
