Respiratory distress syndrome is a lung disorder in premature newborns in which the air sacs in their lungs do not remain open because a substance that coats the air sacs, called surfactant, is insufficient or not functioning properly.
Premature newborns are at increased risk of developing respiratory distress syndrome.
Affected newborns have severe difficulty breathing and may appear blue or gray because of a lack of oxygen in the blood.
The diagnosis is based on breathing trouble, oxygen levels in the blood, and chest x-ray results.
Oxygen is given, continuous positive airway pressure can be used to keep the air sacs open, and a ventilator may be necessary if breathing becomes too difficult for the newborn.
Sometimes surfactant is given until newborns start producing enough of their own surfactant.
If low oxygen levels in the blood cannot be improved with treatment, the syndrome may cause brain damage or death.
If the fetus is going to be born prematurely, the mother may be injected with a steroid that speeds up the fetus’s production of surfactant.
(See also Overview of General Problems in Newborns.)
Respiratory distress is trouble breathing. For newborns to be able to breathe easily, the air sacs (alveoli) in the lungs must be able to remain open and filled with air. Normally, the lungs produce a substance called surfactant. Surfactant coats the surface of the air sacs, where it lowers the surface tension. Low surface tension allows the air sacs to remain open throughout the respiratory cycle.
Usually, the fetus begins producing surfactant at around 24 weeks of pregnancy. By between 34 weeks and 36 weeks of pregnancy, there is enough surfactant in the fetus' lungs to allow the air sacs to remain open. Thus, the more premature the newborn, the less surfactant is available, and the greater the likelihood that respiratory distress syndrome will develop after birth.
Respiratory distress syndrome occurs almost exclusively in premature newborns but may also occur in newborns whose mother is older or had diabetes while pregnant. Other risk factors include cesarean delivery (C-section) and being male.
Rarely, this syndrome is caused by a mutation in certain genes that causes a deficiency of surfactant. This genetically caused type of respiratory distress syndrome may occur in full-term babies as well.
Symptoms of Respiratory Distress Syndrome in Newborns
In affected newborns, the lungs are stiff and the air sacs tend to collapse completely, emptying the lungs of air. In some very premature newborns, the lungs may be so stiff that the newborns are unable to begin breathing at birth. More commonly, newborns try to breathe, but because the lungs are so stiff, severe trouble breathing (respiratory distress) occurs. Symptoms of respiratory distress include:
Visibly labored and rapid breathing
Retractions (pulling in of the chest muscles attached to the ribs and below the ribs during rapid breathing)
Flaring of the nostrils during breathing in
Grunting while breathing out
Because the lung does not fill normally with air, newborns with respiratory distress syndrome have low levels of oxygen in their blood, which causes a bluish discoloration to the skin and/or lips (cyanosis). In newborns with dark skin, the skin may appear blue, gray, or whitish, and these changes may be more easily seen in the mucous membranes lining the inside of the mouth, nose, and eyelids.
Over a period of hours, the respiratory distress tends to become more severe as the muscles used for breathing tire, the small amount of surfactant in the lungs is used up, and increasing numbers of air sacs collapse. Some very premature and small infants (weighing less than about 2 pounds [1 kilogram]) may not be able to start breathing at all without help. If the low oxygen levels are not treated, newborns may have damage to their brain and other organs and may die.
Diagnosis of Respiratory Distress Syndrome in Newborns
Signs of respiratory distress
Blood tests
Chest x-ray
Cultures of blood and sometimes of cerebrospinal fluid
The diagnosis of respiratory distress syndrome is based on signs of respiratory distress, levels of oxygen in the blood, and abnormal chest x-ray results.
Respiratory distress syndrome can sometimes accompany or have similar symptoms to other disorders, such as infection in the blood (sepsis) or transient tachypnea of the newborn. Therefore, doctors may do other tests to look for these disorders. Cultures of blood and sometimes cerebrospinal fluid may be done to look for certain kinds of infections.
Treatment of Respiratory Distress Syndrome in Newborns
Sometimes surfactant therapy
Oxygen and measures to support breathing
Doctors give surfactant to newborns who have respiratory distress syndrome. Surfactant treatments may be repeated several times during the first days of life if respiratory distress continues. There are a variety of ways to administer surfactant, and doctors prefer methods that do not require a breathing tube.
After delivery, affected newborns may require only supplemental oxygen or may require oxygen delivered by continuous positive airway pressure (CPAP) or by noninvasive (also called nasal intermittent) positive pressure ventilation (NIPPV). In CPAP, supplemental oxygen is given through prongs placed in the newborn’s nostrils, and in NIPPV, oxygen is given through a face mask or nasal prongs. CPAP and NIPPV allow newborns to breathe on their own while being given slightly pressurized oxygen.
However, in some newborns with respiratory distress syndrome, a breathing tube may need to be passed into the windpipe after delivery. The tube is attached to a ventilator (a machine that helps air get in and out of the lungs) to support the newborn’s breathing.
Prognosis for Respiratory Distress Syndrome in Newborns
With treatment, most newborns survive. Natural production of surfactant increases after birth. With continued breathing support, newborns start producing surfactant on their own. Once this process begins, respiratory distress syndrome usually resolves over time. However, severely low oxygen levels in infants who are waiting for treatment to take effect or in infants who do not have access to treatment can cause damage to the brain or other organs and can be fatal.
Newborns who are very premature are at increased risk of developing bronchopulmonary dysplasia.
Prevention of Respiratory Distress Syndrome in Newborns
The risk of respiratory distress syndrome is greatly reduced if delivery can be safely delayed until the fetus’s lungs have produced sufficient surfactant.
When premature delivery cannot be avoided, obstetricians may give the mother injections of the steroid (sometimes called glucocorticoids or corticosteroids) betamethasone or dexamethasone. The medication enters the fetus's bloodstream through the placenta and accelerates the fetus's production of surfactant. Within 48 hours after the injections are started, the fetus's lungs may mature to the point that respiratory distress syndrome is less likely to develop after delivery or, if it does develop, is likely to be milder.When premature delivery cannot be avoided, obstetricians may give the mother injections of the steroid (sometimes called glucocorticoids or corticosteroids) betamethasone or dexamethasone. The medication enters the fetus's bloodstream through the placenta and accelerates the fetus's production of surfactant. Within 48 hours after the injections are started, the fetus's lungs may mature to the point that respiratory distress syndrome is less likely to develop after delivery or, if it does develop, is likely to be milder.
After delivery, doctors may give a surfactant preparation to newborns who are at high risk of developing respiratory distress syndrome. At-risk newborns are those who were delivered before 30 weeks of gestational age, especially those whose mother did not receive steroid injections. The surfactant preparation can be lifesaving and reduces the risk of some complications, such as collapse of the lung (pneumothorax). The surfactant preparation acts in the same way that natural surfactant does.
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