Premature Baby-Bronchopulmonary Dysplasia
Babies who are born prematurely or who experience respiratory problems shortly after birth are at risk for bronchopulmonary dysplasia (BPD), sometimes called chronic lung disease. Although most premature babies fully recover from BPD and have few long-term health problems as a result, BPD can be a serious condition requiring intensive medical care.
A child is not born with BPD. It is something that develops as a consequence of prematurity and progressive lung inflammation.
What Is BPD?
Bronchopulmonary dysplasia involves abnormal development of lung tissue. It is characterized by inflammation and scarring in the lungs. It develops most often in a premature baby, who are born with underdeveloped lungs.
"Broncho" refers to the airways (the bronchial tubes) through which the oxygen we breathe travels into the lungs. "Pulmonary" refers to the lungs' tiny air sacs (alveoli), where oxygen and carbon dioxide are exchanged. "Dysplasia" means abnormal changes in the structure or organization of a group of cells. The cell changes in BPD take place in the smaller airways and lung alveoli, making breathing difficult and causing problems with lung function.
Along with asthma and cystic fibrosis, BPD is one of the most common chronic lung diseases in a premature baby and children. According to the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH), between 5,000 and 10,000 cases of BPD occur every year in the United States. Premature babies with extremely low birth weight (less than 2.2 pounds or 1,000 grams) are most at risk for developing BPD. Although most of these premature babies eventually outgrow the more serious symptoms, in rare cases BPD - in combination with other complications of prematurity - can be fatal.
What Causes BPD?
The majority of BPD cases occur in a premature baby, usually those who are born at 34 weeks' gestation or before and weigh less than 4.5 pounds (2,000 grams). These premature babies are more likely to be affected by a condition known as infant respiratory distress syndrome (RDS) or hyaline membrane disease, which occurs as a result of tissue damage to the lungs from being on a mechanical ventilator for a significant amount of time.
Mechanical ventilators do the breathing for a premature baby whose lungs are too immature to allow them to breathe on their own. The ventilators also supply necessary oxygen to the lungs of these premature babies. Oxygen is delivered through a tube that has been inserted into the premature baby's trachea (windpipe) and is given under pressure from the machine to properly move air into stiff, underdeveloped lungs. Sometimes, for these premature babies to survive, the amount of oxygen given must be higher than the oxygen concentration in the air we commonly breathe.
Although mechanical ventilation is essential to their survival, over time the pressure from the ventilation and excess oxygen intake can injure a newborn's delicate lungs, leading to RDS. Almost half of all extremely low birth weight infants will develop some form of RDS. If symptoms of RDS persist, then the condition will be considered BPD if a premature baby is oxygen dependent at 36 weeks' postconceptional age.
BPD also can arise from other adverse conditions that a newborn's fragile lungs have difficulty coping with, such as trauma, pneumonia, and other infections. All of these can cause the inflammation and scarring associated with BPD, even in a full-term newborn or, very rarely, in older infants and children.
Among babies who are premature and have a low birth weight, white male premature babies seem to be at greater risk for developing BPD, for reasons unknown to doctors. Genetics may contribute to some cases of BPD as well.
Diagnosis and Treatment of BPD
Important factors in diagnosing BPD are prematurity, infection, mechanical ventilator dependence, and oxygen exposure.
BPD is typically diagnosed if a premature baby still requires additional oxygen and continues to show signs of respiratory problems after 28 days of age (or past 36 weeks' postconceptional age). Chest X-rays may be helpful in making the diagnosis. In babies with RDS, the X-rays may show lungs that look like ground glass. In babies with BPD, the X-rays may show lungs that appear spongy.
No available medical treatment can immediately cure bronchopulmonary dysplasia. Treatment is geared to support the breathing and oxygen needs of infants with BPD and to enable them to grow and thrive. Premature babies first diagnosed with BPD receive intense supportive care in the hospital, usually in a newborn intensive care unit (NICU) until they are able to breathe well enough on their own without the support of a mechanical ventilator. Some premature babies also may receive jet ventilation, a continuous low-pressure ventilation that is used to minimize the lung damage from ventilation that contributes to BPD. Not all hospitals use this procedure to treat BPD, but some hospitals with large NICUs do.
Infants with BPD are also treated with different kinds of medications that help to support lung function. These include bronchodilators (such as albuterol) to help keep the airways open and diuretics (such as furosemide) to reduce the buildup of fluid in the lungs.
Antibiotics are sometimes needed to fight bacterial infections because babies with BPD are more likely to develop pneumonia. Part of a premature baby's treatment may involve the administration of surfactant, a natural lubricant that improves breathing function. Babies with RDS who have not yet been diagnosed with BPD may have disrupted surfactant production, so administering natural or synthetic surfactant may reduce the chance that BPD develops.
In addition, babies sick enough to be hospitalized with BPD may need feedings of high-calorie formulas through a gastric tube inserted into the stomach to ensure they get enough calories and nutrients and start to grow.
In severe cases, babies with BPD cannot use their gastrointestinal systems to digest food. These premature babies require intravenous (IV) feedings - called TPN, or total parenteral nutrition - made up of fats, proteins, sugars, and nutrients. These are given through a small tube that is inserted into a large vein through the baby's skin.
The time spent in the NICU for infants with BPD can range from several weeks to a few months. The NIH estimates that the average length of intensive in-hospital care for babies with BPD is 120 days. Even after a premature baby leaves the hospital, he or she may require continued medication, breathing treatments, or even oxygen at home. Although most children are weaned from supplemental oxygen by the end of their first year, a few with serious cases may need a ventilator for several years or even their entire lives (although this is rare).
Improvement for any baby with BPD is gradual. Some premature babies will be slow to improve; others may not recover from the condition if their lung disease is very severe. Lungs continue to grow for 5-7 years, and there can be subtle abnormal lung function even at school age, although the majority of children function well. Many premature babies diagnosed with BPD will recover close to normal lung function, but this takes time. Scarred, stiffened lung tissue will always have poor function. However, as infants with BPD grow, new healthy lung tissue can form and grow, and may eventually take over much of the work of breathing for diseased lung tissue.
Complications of BPD
After coming through the more critical stages of BPD, some premature babies still have longer-term complications. They are often more susceptible to respiratory infections such as influenza, respiratory syncytial virus (RSV), and pneumonia. When they come down with an infection, they tend to get sicker than most children do.
Another respiratory complication of BPD includes excess fluid buildup in the lungs, known as pulmonary edema, which makes it more difficult for air to travel through the airways.
Occasionally, kids with a history of BPD may also develop complications of the circulatory system, such as pulmonary hypertension in which the pulmonary arteries - the vessels that carry blood from the heart to the lungs - become narrowed and cause high blood pressure. However, this is relatively uncommon and a late complication.
Effects of the medications they may need to take include dehydration and low sodium levels from diuretics. Kidney stones, hearing problems, and low potassium and calcium levels can result from long-term furosemide use.
A premature baby with BPD often grow more slowly than other babies and have difficulty gaining weight. They tend to lose weight when they are sick. Premature infants with severe BPD also have a higher incidence of cerebral palsy.
Overall, though, the risk of serious permanent complications from BPD is fairly small.
Caring for Your Child
As with any child, parents have a critical role in the care of an infant with BPD. One important precaution you can take is to reduce your premature baby's exposure to potential respiratory infections. Limit visits from people who are sick, and if your child needs day care, pick a small center, where there will be less exposure to infectious agents. Ensuring that your child receives all the recommended vaccinations can help ward off problems as well. And keep your child away from tobacco smoke, particularly in your home, as it is a serious respiratory irritant.
If your premature baby requires oxygen at home, your baby's health care providers will show you how to work the tube and check oxygen levels.
Children with asthma-type symptoms may need bronchodilators to relieve asthma-like attacks. You can give this medication to your premature baby with a puffer or nebulizer, which produces a fine spray of medicine that your child then breathes in.
Because infants with BPD sometimes have trouble growing due to breathing problems, you may also need to feed your baby a high-calorie formula. Sometimes, babies with BPD who are slower to gain weight will go home from the intensive care nursery on gastric tube feedings. Formula feedings may be given alone or as a supplement to breastfeeding.
When to Call Your Child's Doctor
Once a premature baby comes home from the hospital, parents still need to watch for signs of respiratory distress or BPD emergencies, instances in which a child has serious trouble breathing. Signs that an infant might need immediate care include: faster breathing than normal.
working much harder than usual to breathe:
belly sinking in with breathing
pulling in of the skin between the ribs with each breath
growing tired or lethargic from working to breathe
more coughing than usual
panting or grunting
pale, dusky, or blue skin color that may start around the lips or nail beds
trouble feeding or excess spitting up or vomiting of feedings
If you notice any of these symptoms in your child, call your child's doctor or seek emergency medical attention.
Reviewed by: Michael Spear, M.D.
Clinical Director, NICU
Medical Director, Infant Apnea Team
Division of Neonatology
Alfred I. duPont Hospital for Children
Clinical Professor of Pediatrics
Jefferson Medical College