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Respiratory Distress Syndrome

What is respiratory distress syndrome?

Respiratory distress syndrome (RDS), which used to be called hyaline membrane disease, is one of the most common problems of premature babies. It can cause babies to need extra oxygen and help breathing. The course of illness with respiratory distress syndrome depends on the size and gestational age of the baby, the severity of the disease, the presence of infection, whether or not a baby has a patent ductus arteriosus (a heart condition), and whether or not the baby needs mechanical help to breathe. RDS typically worsens over the first 48 to 72 hours, then improves with treatment.

What causes RDS?

RDS occurs when there is not enough of a substance in the lungs called surfactant. Surfactant is a liquid produced by the lungs that keeps the airways (called alveoli) open, making it possible for babies to breathe in air after delivery. It begins to be produced in the fetus at about 26 weeks of pregnancy.

When there is not enough surfactant, the tiny alveoli collapse with each breath. As the alveoli collapse, damaged cells collect in the airways and further affect breathing ability. The baby works harder and harder at breathing, trying to reinflate the collapsed airways.

As the baby's lung function decreases, less oxygen is taken in and more carbon dioxide builds up in the blood. This can lead to increased acid in the blood called acidosis, a condition that can affect other body organs. Without treatment, the baby becomes exhausted trying to breathe and eventually gives up. A mechanical ventilator (breathing machine) must do the work of breathing instead.

Who is affected by RDS?

RDS occurs most often in babies born before 28 weeks gestation. Some premature babies develop RDS severe enough to need a mechanical ventilator (breathing machine). The more premature the baby, the higher the risk and the more severe the RDS.

Although most babies with RDS are premature, other factors can influence the chances of developing the disease. These include the following:

  • White or male babies

  • Previous birth of baby with RDS

  • Cesarean delivery

  • Perinatal asphyxia

  • Cold stress (a condition that suppresses surfactant production)

  • Perinatal infection

  • Multiple births (multiple birth babies are often premature)

  • Infants of diabetic mothers (too much insulin in a baby's system due to maternal diabetes can delay surfactant production)

  • Babies with patent ductus arteriosus

What are the symptoms of RDS?

The following are the most common symptoms of RDS. However, each baby may experience symptoms differently. Symptoms may include:

  • Respiratory difficulty at birth that gets progressively worse

  • Cyanosis (blue coloring)

  • Flaring of the nostrils

  • Tachypnea (rapid breathing)

  • Grunting sounds with breathing

  • Chest retractions (pulling in at the ribs and sternum during breathing)

The symptoms of RDS usually peak by the third day, and may resolve quickly when the baby begins to diurese (excrete excess water in urine). When a baby improves, he or she begins to need less oxygen and mechanical help to breathe.

The symptoms of RDS may resemble other conditions or medical problems. Always consult your baby's doctor for a diagnosis.

How is RDS diagnosed?

RDS is usually diagnosed by a combination of assessments, including the following:

  • Appearance, color, and breathing efforts (indicate a baby's need for oxygen).

  • Chest X-rays of lungs. X-rays are electromagnetic energy used to produce images of bones and internal organs onto film.

  • Blood gases (tests for oxygen, carbon dioxide and acid in arterial blood). These often show lowered amounts of oxygen and increased carbon dioxide.

  • Echocardiography. Sometimes used to rule out heart problems that might cause symptoms similar to RDS. Echocardiography is a type of ultrasound that looks specifically at the structure and function of the heart.

Treatment for RDS

Specific treatment for RDS will be determined by your baby's doctor based on:

  • Your baby's gestational age, overall health, and medical history

  • Extent of the condition

  • Your baby's tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the condition

  • Your opinion or preference

Treatment for RDS may include:

  • Placing an endotracheal (ET) tube into the baby's windpipe

  • Mechanical breathing machine (to do the work of breathing for the baby)

  • Supplemental oxygen (extra amounts of oxygen)

  • Continuous positive airway pressure (CPAP). A mechanical breathing machine that pushes a continuous flow of air or oxygen to the airways to help keep tiny air passages in the lungs open.

  • Surfactant replacement with artificial surfactant. This is most effective if started in the first six hours of birth. Surfactant replacement has been shown to reduce the severity of RDS. Surfactant is given as prophylactic (preventive) treatment for some babies at very high risk for RDS. For others it is used as a "rescue" method. The drug comes as a powder to be mixed with sterile water and then is given through the ET tube (breathing tube). Surfactant is usually given in several doses.

  • Medications (to help sedate and ease pain in babies during treatment)

Complications of RDS

Babies with RDS sometimes develop complications of the disease or problems as side effects of treatment. As with any disease, more severe cases often have greater risks for complications. Some complications associated with RDS include the following:

  • Air leaks of the lung tissues, such as:

    • Pneumomediastinum. Air leaks into the mediastinum (the space in the thoracic cavity behind the sternum and between the two pleural sacs containing the lungs).

    • Pneumothorax. Air leaks into the space between the chest wall and the outer tissues of the lungs.

    • Pneumopericardium. Air leaks into the sac surrounding the heart.

    • Pulmonary interstitial emphysema (PIE). Air leaks and becomes trapped between the alveoli, the tiny air sacs of the lungs.

  • Chronic lung disease, sometimes called bronchopulmonary dysplasia

Prevention of RDS

Preventing a preterm birth is the primary means of preventing RDS. When a preterm birth cannot be prevented, giving the mother medications called corticosteroids before delivery has been shown to dramatically lower the risk and severity of RDS in the baby. These steroids are often given to women between 24 and 34 weeks gestation who are at risk of early delivery. However, if the delivery is very quick or unexpected, there may not be time to give the steroids, or they may not have a chance to begin working.   

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