Chronic Lung Disease

Chronic lung disease (CLD), also known as bronchopulmonary dysplasia, occurs when a newborn's lungs have been injured. Damaged tissue inside the baby's lungs becomes inflamed and may break down, causing scarring. This scarring can make it difficult for a newborn to breathe, in which case the baby will need oxygen therapy.

In the past, the condition was thought to only affect premature babies with a breathing problem called respiratory distress syndrome, who were treated with oxygen through a ventilator. However, with the development of new therapies and improved ventilation techniques, CLD rarely affects larger premature babies. It's now seen primarily in very premature newborns, both those who have been treated for respiratory distress syndrome and those who have not.

Most babies with CLD survive, and many outgrow their lung problems. While they have CLD, it's important for them to receive good nutrition to prevent problems with growth and development and complications of the condition.

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Causes of CLD

Factors that may increase a newborn's chances of developing CLD include:

  • Immature lungs — Babies born prematurely often have immature lungs. As many as 70 to 75 percent of babies born before 26 weeks of gestation develop CLD because their lungs haven't developed completely. A full-term pregnancy is considered 40 weeks.
  • Exposure to high concentrations of oxygen — The air we breathe normally is a blend of nitrogen, oxygen, carbon dioxide and other gases. Oxygen normally makes up about 21 percent of the blend of gases we call "room air." One way to deliver more oxygen to a baby with immature lungs is to increase the fraction of oxygen in that blend, sometimes up to 100 percent. However, oxygen itself can injure lung tissue. When a newborn is treated with oxygen for prolonged periods, especially high levels of oxygen, it can cause lung damage.
  • Forced breathing — Some premature babies don't produce enough of a special lung fluid called surfactant, first identified by Dr. John Clements at UCSF Benioff Children's Hospital. Surfactant fluids lubricate the small airways of the lungs, preventing them from collapsing with each breath. Because surfactant isn't produced in adequate amounts until later in pregnancy, very premature infants may be unable to inflate their own lungs, leading to respiratory distress syndrome. These babies may need help to force open their lungs, which can include the use of a ventilator and surfactant replacement therapy. Lung damage due to increased air pressure from the ventilator can lead to CLD.
  • Irritation of the lung tissue — Inflammation in the lung tissues is associated with immature lungs, infection, and exposure to oxygen or the use of a ventilator. The inflammation leads to more irritation and injury in the tissues of the newborn's lungs, which can later affect lung development or lead to scarring.
  • Fluid in the lungs — Fluid can build up in a newborn's lungs, usually due to a heart defect or being born by Caesarean section; other causes include premature birth and lung inflammation after prolonged mechanical ventilation.
  • Genetics — Newborns can inherit lungs that aren't fully mature at birth, which puts them at risk for developing CLD. Also, a family history of asthma or similar types of lung disease, such as reactive lung diseases, increases a newborn's chances of developing CLD.
  • Insufficient nutrition — Premature newborns who are undernourished or don't get enough vitamin A or certain other nutrients may be more likely to develop CLD.
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Babies with chronic lung disease will have trouble breathing normally. Signs of this may include:

  • Grunting or rapid breathing
  • Flaring nostrils
  • Using the neck, chest and abdominal muscles to breath, causing a "sucking in" between or under the ribs, called retractions
  • Wheezing, a high-pitched sound when breathing
  • Tiring during and after feeding
  • Pale, gray or mottled skin, especially the tongue, lips, earlobes and nail beds

Chronic lung disease (CLD) is usually diagnosed with a chest X-ray that shows scar tissues in the lungs, a characteristic of the condition.

Treatment for chronic lung disease depends on the severity of the condition. Therapy involves vaccinations to ward off infections, and oxygen to help babies breathe normally until their lungs improve. Some babies may need a medicine, called a diuretic, which makes them pass more urine to remove extra fluid from around their lungs.

Some babies may not need oxygen therapy by the time they go home, but others will need continued treatment after they've left the hospital. Before going home, your doctors and nurses will teach you how to give your baby oxygen therapy and other medications, such as inhaled treatments.

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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