Respiratory Distress Syndrome (RDS)

What is RDS?

If a baby is born before his lungs have matured, he will develop respiratory distress syndrome (RDS). A baby with RDS tries to cry and breathe at birth, but within minutes to hours he starts working hard to breathe because his lungs tend to collapse with each breath.

A baby with RDS:

• breathes faster than 60 breaths a minute
• makes a grunting sound when he breathes out
• pulls in the chest wall and the spaces between the ribs when he tries to breathe (these movements during breathing are called retractions)
• has flaring of the nostrils
• has a bluish color around the lips, which means that he needs more oxygen.

Two other possible causes of breathing problems in babies are infection in the lungs (pneumonia) and extra fluid in the lungs.

What causes RDS?

Before birth a baby does not use his lungs because the placenta delivers oxygen from the mother to the baby's bloodstream. Once the baby is born, the baby's lungs fill with air and begin delivering oxygen to the blood. To prepare the lungs to work properly after birth, a baby produces a substance called surfactant.

Surfactant is a material that lines the air sacs of the lungs and helps keep the lungs open when breathing out. Babies usually start making surfactant sometime between the 30th and 36th weeks of the pregnancy. Nearly all babies have made surfactant by the 35th week of pregnancy. Certain events, such as the mother's water breaking early or preterm labor, may cause a baby to start making surfactant early. Without surfactant, the lungs tend to collapse with each breath. A lack of surfactant causes RDS.

How is it diagnosed?

Certain laboratory tests are done to help determine the cause of the breathing problems. These tests include:

• Blood culture: Because the cause of a breathing problem may not be known right away, all babies are treated for the possibility of infection with antibiotics. Before starting the antibiotics, a sample of the baby's blood is tested for infection. The test is called a blood culture. If the baby does not have an infection, the test will be negative and the antibiotics will be stopped in 3 days. Antibiotics are safe and do not cause any long-term problems. Your health care provider will probably take the blood sample from a vein or artery.
• Blood gas test: Blood gas tests show how much oxygen is in the bloodstream. This information helps your doctor know how much oxygen the baby needs. It also tells how hard the baby is working to breathe and whether he needs help to keep breathing.
• Chest x-ray: X-rays for babies use very little radiation and do not cause the baby any problems later in life.

What is the treatment?

Many babies develop RDS. Usually the babies who have RDS are more than 6 weeks premature, but occasionally more mature babies have RDS. There are many effective treatments for babies with RDS, and most infants recover completely within the first weeks of life.

• The special care nursery (SCN)

  A baby who has breathing difficulties is placed on a warming bed in the special care nursery (SCN). He is attached to a monitor that continuously measures his heart rate and respiratory (breathing) rate. This monitor is called a cardiorespiratory monitor. The baby is also attached to a monitor that records the amount of oxygen in his skin. It is called a pulse oximeter.

• IV fluids

  A baby with RDS breathes fast and uses all of his energy to breathe. He does not have any energy left for eating and cannot coordinate sucking with the fast breathing rate. An intravenous (IV) line is inserted into the veins of the baby's hands, feet, or scalp. The IV provides fluid to prevent dehydration and gives the baby sugar for energy. The baby will be able to take milk after the lungs have improved.

• Oxygen

  A baby with RDS needs extra oxygen to keep the level of oxygen in his blood in the normal range. If tests show that a baby needs extra oxygen, he is placed in a plastic hood into which extra oxygen is blown. The level of oxygen a baby breathes is called FiO2. The level of oxygen in the blood is called pO2.

• Umbilical artery catheter

  If a baby needs more than 40 percent oxygen or a ventilator to breathe, the blood gases are checked frequently. So the baby does not have to be stuck with a needle each time a sample of blood is needed, an IV line may be inserted into an artery. The IV is often placed in the artery in the umbilical cord and passed into the aorta, the largest artery in the body. This umbilical artery catheter allows blood to be taken painlessly from the baby. The catheter can also be used to give fluids and medications to the baby. Arteries in the hands and feet may also be used for the IV.

• Assisting the baby's breathing

  If the work of breathing becomes too difficult for the baby, he will begin to tire. There are two ways to help his breathing: nasal CPAP and a ventilator.

  Nasal CPAP: Nasal CPAP is a device that blows oxygen under pressure in through the nose. It helps inflate the lungs. A strap placed around the baby's head holds the CPAP prongs in the nose. The baby does all the breathing but the CPAP delivers oxygen at a pressure that keeps the lungs inflated. Nasal CPAP is used for the bigger and stronger babies or babies who have mild disease and need just a little help.

  Ventilator: When a baby gets too tired to breathe effectively, a ventilator may be used to give the baby extra breaths. A tube is placed through the baby's mouth and into the windpipe (trachea). The tube is kept in place with tape across the baby's upper lip. The ventilator blows oxygen under pressure through the tube and into the baby's lungs. The baby breathes on his own, but the ventilator gives extra breaths.

  Babies usually get used to the ventilator and actually feel more comfortable because they don't have to work so hard to breathe. Occasionally a baby may be irritated by the ventilator. If this happens the baby may be given a mild sedative to help him relax and sleep.

• Artificial surfactant

  Babies who need a ventilator may be given 2 to 4 doses of artificial surfactant during their first 24 to 48 hours of life. If artificial surfactant is given, not as much oxygen or pressure on the ventilator will have to be used, and the baby will get better faster. The baby will still need the ventilator for about 3 days and then will begin to get better as his lungs make his own surfactant.

How long does recovery take?

A baby with RDS is sick for about 3 days. In the first 3 days his need for oxygen will increase or stay the same. When the baby starts needing less oxygen, it is a sign that the baby is getting better. If your baby is on a ventilator, the amount of oxygen and breaths he is given will be reduced until he can finally breathe on his own. At this time the breathing tube can be removed.

When the baby is able to breathe easily at a normal rate and does not need extra oxygen, he can begin feedings. If the baby is strong and mature enough to suck, he can begin to breast-feed or bottle-feed. However, often a baby is weak because his lungs are still recovering. A weak baby can be fed by passing a tube through his mouth and into his stomach. Milk is dripped through the tube into the baby's stomach. This is called gavage feeding. This way the baby can be fed without using a lot of energy to suck. Soon he will be able to breast- or bottle-feed vigorously.

All babies can go 4 or more days on IV fluids without eating and be perfectly fine. Don't worry if your baby can't eat at first and loses weight. Once he is well, he will make up for lost time. Even a healthy baby who eats immediately after birth loses weight in the first week of life.

Are there complications?

Most babies recover completely from RDS with no short-or long-term problems. The most common complication occurring shortly after birth is a pneumothorax. Long-term problems, such as chronic lung problems or neurologic problems (brain damage), are usually related to how premature the baby is rather than to the RDS.

• Pneumothorax

  Sometimes the air sacs of a baby's lungs tear. The air that should be inside the air sacs escapes outside the lungs but remains inside the chest. The accumulated air then presses on the lung and makes it even more difficult for the baby to breathe. This is called an air leak, or pneumothorax. A pneumothorax may occur at any time with no apparent cause, or it may happen when the baby is receiving oxygen under pressure (on CPAP or a ventilator).

  A small pneumothorax does not require treatment. A larger one is treated by drawing the air out through a needle. For the largest or most persistent air leaks, a tube is inserted into the chest and the air is drained out continuously. Over time (hours to days), the air sacs heal themselves and the tube can be removed.

• Chronic lung disease

  Babies who have unusually severe lung disease or are very premature may require a lot of oxygen and pressure from the ventilator to survive. This can scar the lungs. Some of these babies may need to be on the ventilator for several weeks and may need oxygen for several months. These babies may be given diuretics to get rid of extra water in the lungs.

  Most babies outgrow these problems in the first few months. They grow new lung tissue, which replaces the scarred lung tissue. However, during the first few years of life they may have more bouts of wheezing and may get pneumonia when they have upper respiratory infections (colds). These problems will occur less often as the children grow older.

Virtually all babies who have respiratory distress syndrome grow up to be healthy, normal children. RDS does not cause brain damage or long-term developmental problems.

Can RDS be prevented?

If the doctor knows that the baby is going to be premature, drugs can be given to the mother to help the baby start producing surfactant before birth. The most frequently used drug is betamethasone.

By testing the amniotic fluid, doctor's can check if a baby has made surfactant. Amniotic fluid is collected by doing a procedure called an amniocentesis. The fluid can also be sampled right after the mother's water breaks. If the baby has not yet made surfactant, the mother may be given betamethasone and may also be given other drugs to try to stop labor and delay the birth.