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NEONATAL RESPIRATORY DISTRESS SYNDROME

Neonatal respiratory distress syndrome (RDS) is a problem often seen in premature babies. The condition makes it hard for the baby to breathe.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that prevents enough oxygen from getting to the lungs and into the blood.

Causes Of Acute respiratory distress syndrome

ARDS can be caused by any major direct or indirect injury to the lung. Common causes include:

Breathing vomit into the lungs (aspiration)
Inhaling chemicals
Lung transplant
Pneumonia
Septic shock (infection throughout the body)
Trauma

ARDS leads to a buildup of fluid in the air sacs (alveoli). This fluid prevents enough oxygen from passing into the bloodstream.

The fluid buildup also makes the lungs heavy and stiff, which decreases the lungs' ability to expand. The level of oxygen in the blood can stay dangerously low, even if the person receives oxygen from a breathing machine (ventilator) through a breathing tube (endotracheal tube).

ARDS often occurs along with the failure of other organ systems, such as the liver or kidneys. Cigarette smoking and heavy alcohol use may be risk factors.

Causes Of Neonatal Respiratory Distress Syndrome

Neonatal RDS occurs in infants whose lungs have not yet fully developed. The disease is mainly caused by a lack of a slippery substance in the lungs called surfactant. This substance helps the lungs fill with air and keeps the air sacs from deflating. Surfactant is present when the lungs are fully developed.

Neonatal RDS can also be due to genetic problems with lung development.

Most cases of RDS occur in babies born before 37 to 39 weeks. The more premature the baby is, the higher the chance of RDS after birth. The problem is uncommon in babies born full-term (after 39 weeks).

Other factors that can increase the risk of RDS include:

A brother or sister who had RDS
Diabetes in the mother
Cesarean delivery or induction of labor before the baby is full-term
Problems with delivery that reduce blood flow to the baby
Multiple pregnancy (twins or more)
Rapid labor

Symptoms

Most of the time, symptoms appear within minutes of birth. However, 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
Nasal flaring
Rapid breathing
Shallow breathing
Shortness of breath and grunting sounds while breathing
Unusual breathing movement (such as drawing back of the chest muscles with breathing)

Exams and Tests The following tests are used to detect the condition:

Blood gas analysis -- shows low oxygen and excess acid in the body fluids
Chest x-ray -- shows a "ground glass" appearance to the lungs that is typical of the disease. This often develops 6 to 12 hours after birth.

Lab tests -- help to rule out infection as a cause of breathing problem

Treatment

Babies who are premature or have other conditions that make them at high risk for the problem need to be treated at birth by a medical team that specializes in newborn breathing problems.

Infants will be given warm, moist oxygen. However, this treatment needs to be monitored carefully to avoid side effects from too much oxygen.

Giving extra surfactant to a sick infant has been shown to be helpful. However, the surfactant is delivered directly into the baby's airway, so some risk is involved. More research still needs to be done on which babies should get this treatment and how much to use.

Assisted ventilation with a ventilator (breathing machine) can be lifesaving for some babies. However, use of a breathing machine can damage the lung tissue, so this treatment should be avoided if possible. Babies may need this treatment if they have:

High level of carbon dioxide in the blood
Low blood oxygen
Low blood pH (acidity)
Repeated pauses in breathing

A treatment called continuous positive airway pressure (CPAP) may prevent the need for assisted ventilation or surfactant in many babies. CPAP sends air into the nose to help keep the airways open. It can be given by a ventilator (while the baby is breathing independently) or with a separate CPAP device.

Babies with RDS need close care. This includes:

Having a calm setting
Gentle handling
Staying at an ideal body temperature
Carefully managing fluids and nutrition
Treating infections right away

Outlook (Prognosis)

The condition often gets worse for 2 to 4 days after birth and improves slowly after that. Some infants with severe respiratory distress syndrome will die. This most often occurs between days 2 and 7.

Long-term complications may develop due to:

Too much oxygen.
High pressure delivered to the lungs.
More severe disease or immaturity. RDS can be associated with inflammation that causes lung or brain damage.
Periods when the brain or other organs did not get 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 conditions associated with RDS or extreme prematurity may include:

Bleeding into the brain (intraventricular hemorrhage of the newborn)
Bleeding into the lung (pulmonary hemorrhage; sometimes associated with surfactant use)
Problems with lung development and growth (bronchopulmonary dysplasia)
Delayed development or intellectual disability associated with brain damage or bleeding
Problems with eye development (retinopathy of prematurity) and blindness

Prevention

Taking steps to prevent premature birth can help prevent neonatal RDS. Good prenatal care and regular checkups beginning as soon as a woman discovers she is pregnant can help avoid premature birth.

The risk of RDS can also be lessened by the proper timing of delivery. An induced delivery or cesarean may be needed. A lab test can be done before delivery to check the readiness of the baby's lungs. Unless medically necessary, induced or cesarean deliveries should be delayed until at least 39 weeks or until tests show that the baby's lungs have matured.

Medicines called corticosteroids can help speed up lung development before a baby is born. They are often given to pregnant women between 24 and 34 weeks of pregnancy who seem likely to deliver in the next week. More research is needed to determine if corticosteroids may also benefit babies who are younger than 24 or older than 34 weeks.

At times, it may be possible to give other medicines to delay labor and delivery until the steroid medicine has time to work. This treatment may reduce the severity of RDS. It may also help prevent other complications of prematurity. However, it will not totally remove the risks.

References

Wambach JA, Hamvas A. Respiratory distress syndrome in the neonate. In Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap. 72.

Bersten AD. Acute respiratory distress syndrome. In: Berstein AD, Soni N, eds. Oh's Intensive Care Manual. 7th ed. Philadelphia, PA: Elsevier; 2014:chap 33.

Lee WL, Slutsky AS. Acute hypoxemic respiratory failure and ARDS. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 100.