Bronchopulmonary Dysplasia (BPD)
Bronchopulmonary Dysplasia (BPD)
What Is BPD?
BPD is a serious, chronic lung disease of infants. The dictionary defines BPD as abnormal development or growth (dysplasia) of the lungs and air passages.
BPD was first described in 1967 by William Northway, a radiologist at Stanford University, as a chronic lung disease that occurred in premature babies who needed intensive oxygen therapy to survive respiratory distress syndrome (RDS). Northway noted that the symptoms and chest x-rays of these babies were different than those seen in newborns with other lung diseases.
BPD develops most commonly during the first 4 weeks after birth. Although it is seen most often in premature babies, it can also occur in full-term babies who have respiratory problems during their first days of life. Babies who are still dependent on a respirator for oxygen at 28 days of age and whose chest x-rays are typical of BPD are considered to have the disorder.
BPD can occur when a baby's lungs which have not fully developed at birth have to begin breathing immediately and also adjust to adverse conditions outside the mother's womb. Among the adverse conditions which injure the lungs and cause BPD are oxygen under high pressure and infectious agents such as bacteria or viruses.
How Common Is BPD?
BPD is a worldwide problem. BPD and RDS together are probably responsible for most of the infant morbidity and mortality in developed countries. BPD ranks with cystic fibrosis and asthma among the most common chronic lung diseases in infants in the United States. Approximately 5,000 to 10,000 new cases of BPD (20 to 30 percent of infants surviving RDS) occur each year.
Development of BPD is not limited to RDS survivors. Any newborn infant who has serious respiratory problems in its first few days after birth is at risk of developing BPD. Although BPD is most common in premature babies, it can occur in full-term infants who need mechanical ventilation and oxygen under pressure for problems such as neonatal pulmonary hypertension.
Ninety percent of the infants who develop BPD are premature and weigh less than 1500 grams (3.5 pounds). In very premature infants (weighing 1 to 1.5 pounds or born after less than 22 weeks of gestation) BPD sometimes develops even in the absence of acute respiratory problems.
The risk of BPD increases with decreasing birth weight and gestation period. BPD occurs in 5 percent of infants whose birth weight is over 1,500 grams; the incidence rises to 85 percent in surviving newborns weighing between 500 and 700 grams (1 to 1.5 pounds). Male gender and non-African ethnicity seem to be additional risk factors. Genetic factors also may have a role.
In the late 1960s, infants with BPD who survived past 4 weeks of age were an average of 6 weeks premature and their average weight was 2,234 grams (a little more than 4.5 pounds). Improved and more sophisticated neonatal critical care now makes it possible for the majority of infants weighing at least 500 grams to survive. This increased survival of very low birth weight infants is a major factor contributing to the growing incidence of BPD.
What Causes BPD?
BPD does not develop in all infants for the same reason. When it was first described, doctors thought that BPD was a result of lung injury from the mechanical ventilation and supplemental oxygen provided as therapy for RDS.
Today the specialists who treat BPD believe that, although RDS and premature birth play a role in the development of the disorder, these are not the only factors. Rather, BPD appears to reflect the limited ability of the baby's lungs during its first hours and days after birth to respond to adverse situations. These challenges may include oxygen toxicity, mechanical lung trauma, infections, or pneumonia. The state of immaturity of the lung at birth and the type of lung injury probably determine how the newborn's lungs respond and whether or not BPD actually develops.
What Are the Signs And Symptoms of BPD?
The signs and symptoms of BPD and how severe they are vary from infant to infant. They reflect differences in lung maturity and in the severity of disease. Respiratory signs include:
- rapid shallow breathing (tachypnea), sucked-in ribs and chest (retraction), and cough;
- movement of the chest and abdomen in opposite directions with every breath (paradoxical or see-saw respiration); and
The BPD infant's struggle to breathe is reflected in an abnormal posture of its neck, shoulders, and trunk. These babies also crane their necks as they use their neck muscles to try to get as much air as possible into their lungs.
Many of the symptoms of BPD are seen with other breathing problems, for example, severe asthma. If an infant shows any of these symptoms, the doctor will conduct tests to find the cause.
How is BPD Diagnosed?
Although BPD may begin as early as 1 week of age, it is difficult to diagnose until a baby is 14 to 30 days old. A diagnosis of BPD is based on:
- a history of lung injury in the first days after birth, (Pulmonary injury can result when a respirator must be used to provide oxygen under pressure for a minimum of 3 days during the first 2 weeks of life.)
- a continuing need for supplemental oxygen at age 28 days, and
- persistence of the clinical signs of respiratory difficulty beyond 28 days of age.
An x-ray of the infant's chest is also taken to help diagnose BPD. However, the most important functional criterion for the diagnosis of BPD is the need for supplemental oxygen beyond the 28th day of life.
The criteria used for a diagnosis of BPD vary among neonatologists. They include how long respiratory distress exists and how long the baby needs to be on a respirator. Many doctors make a diagnosis of BPD in the second or third week of life. However, some doctors defer a diagnosis until the baby is at least 28 days old.
What is the Outcome for Babies with BPD?
Most infants over 1,500 grams birth weight (3.5 pounds) who develop BPD have severe respiratory failure in the first week of life which may continue for several weeks. Extremely premature infants (those weighing less than 1,500 grams at birth, and especially those weighing less than 1,000 grams), seem to have minimal lung disease or acute lung disease that has apparently resolved, and then symptoms of BPD begin in the second week of life.
As BPD develops and progresses, the infants become increasingly dependent on oxygen and artificial ventilation. They typically display recurrent blueing or cyanotic episodes, and asthma-like symptoms. They may develop life-threatening bronchiolitis and other pulmonary complications. They may also develop serious medical complications of the heart, kidney, gastrointestinal tract, brain, or retina. In severe cases, the baby may die. Most of these deaths occur during the baby's first hospital stay. They are due to progressive respiratory failure, or its complications.
Most BPD infants will show continued slow improvement, but some may require extra weeks and months of care in the neonatal intensive care unit (NICU). It is estimated that infants with BPD require intensive in-hospital care for an average of 120 days.
At 36 weeks after conception (4 weeks before the baby's original due date), nearly a third of the infants with BPD no longer require supplemental oxygen therapy. Those who continue to require supplemental oxygen are usually otherwise growing and improving. Even if they continue to require supplemental oxygen, BPD infants may be discharged from the hospital if they are in stable condition on medication and if the family and the baby's doctor agree that providing continuing care at home is best for the baby.
How Is BPD Treated?
There is no treatment that is specific for BPD. In the NICU supportive measures and symptomatic treatment are provided to help BPD babies breathe and give their lungs time to mature. The baby's lungs improve gradually through normal repair processes.
The treatment of BPD includes three components: therapy for RDS before BPD is confirmed, therapy after BPD is diagnosed, and home care. For infants who show signs and symptoms of RDS but who are not yet diagnosed with BPD treatment may include:
- surfactant administration to improve lung aeration,
- mechanical ventilators to make up for respiratory failure,
- supplemental oxygen to insure that the baby has enough oxygen in its blood,
- careful control of fluids to avoid pulmonary edema (accumulation of fluid in the lungs),
- treatment for patent ductus arteriosus, a circulatory problem sometimes found in premature infants.
- giving the baby medicines that improve air flow in and out of the lungs, and
- feedings and appropriate supplemental formula to prevent malnutrition.
Once the diagnosis of BPD is confirmed the following treatments are continued in the NICU:
- continued mechanical ventilation and supplemental oxygen to overcome respiratory failure and maintain blood oxygen levels,
- bronchodilator medications to improve airflow in the lungs,
- corticosteroids and other medicines to reduce swelling and inflammation of airways,
- fluid restriction and diuretics to decrease water accumulation in the lungs
- antibiotics to control infections,
- intravenous feeding of needed nutrients, and
- physical therapy to improve muscle performance and to help the lungs expel mucus.
Scientists are working to develop new drugs and methods to prevent, lessen, or repair the lung injury that is seen with BPD. Some of the areas of research include:
- improving respirators so that fewer complications of positive pressure ventilation occur,
- using drugs to protect premature lungs from injury, or speed healing, and
- developing new drugs that improve lung function.
The best place for the baby's growth and development is at home with the family. It is important that the parents be loving and well-informed about the symptoms and treatment of BPD. These babies continue to have some respiratory symptoms for varying periods after leaving the hospital, and they remain in fragile health. A primary care pediatrician should be available to provide acute, long-term, and preventive health care. In addition, nurses, respiratory and physical therapists, and social services may be needed.
What Are the Short- And Long-Term Consequences of BPD?
The symptoms that persist after the infant is discharged from the hospital vary. Babies with a history of BPD are more susceptible to respiratory infections and may continue to need low levels of supplemental oxygen. Some may remain dependent on a mechanical ventilator throughout early childhood.
BPD survivors are at higher risk of complications after the usual childhood infections. As a precaution, hospital care may be recommended when a BPD baby becomes ill with a respiratory infection.
Babies who survive BPD grow more slowly than normal. This delayed growth continues into their second year of life. They usually remain smaller than normal children of the same age. Their lung growth is almost complete at 8 years of age as in all children, but they may continue to have some problems with their lung function even when they are adults.
The outlook for growth and development of babies with BPD varies. It depends more on the effects of prematurity and acute respiratory failure, rather than BPD itself. In very severe cases there may be some long-term limitations. These might include abnormalities in coordination, gait and muscle tone, inability to tolerate exercise, vision and hearing problems, and learning disabilities. The risk of these problems varies greatly among individual patients but is actually quite small. Parents of BPD infants need not assume that their child has a high risk of such developmental handicaps. If they should occur, however, parents and families can obtain information about these problems from their baby's doctors.
Living with BPD
An infant with BPD may spend several weeks or months in the NICU. This is a stressful period for the parents and the family. While the baby remains in the hospital the parents should visit as frequently as possible, to bond with the baby and help the infant recognize the voices and touch of its parents.
Social service agency personnel may be needed to teach parents of a baby with BPD how to play with and care for their infant. It is not uncommon for concern about the baby's medical condition to interfere with the parents care-giving abilities. Continued monitoring of the BPD survivor's growth and nutritional needs throughout infancy and childhood by a pediatric nutritionist can be reassuring to parents.
The parents of BPD infants can take a number of other steps to help their infants recover and grow as normally as possible. These include:
- seeking medical help when the child shows any signs of respiratory infection, for example, irritability, fever, nasal congestion, cough, changes in breathing pattern, wheezing;
- limiting the exposure of the infant to infections by avoiding the use of large day-care settings and crowds;
- protecting the baby from exposure to cigarette smoke and other respiratory irritants in the air; and
- making sure that the baby and its siblings receive all routine immunizations. Some doctors now recommend shots to protect against infection with RSV (respiratory syncytial virus) which causes bronchiolitis.
Can BPD Be Prevented?
At present, the only practical way to prevent BPD is to eliminate high risk pregnancies that result in low birth weight babies. Programs of regular prenatal care for women at high risk of early delivery have been shown to lower the incidence of premature babies.
Scientists are studying ways to better understand the processes involved in premature labor and its prevention. In addition, research is being conducted on how to prevent or lessen the adverse effects that result when birth occurs before the lungs are mature. Ways are being sought to accelerate the process of lung maturation in infants at high risk of developing RDS and BPD. Providing corticosteroids to women at risk of premature delivery reduces infant mortality and decreases the incidence of RDS.
What Are the Healthcare Costs of BPD?
Infants with BPD need intensive hospital care for an average of 120 days. In 1990, the cost of caring for these infants was more than $170,000. These infants may also require home oxygen therapy for an average of 92 days. This cost is estimated to be more than $5,000 per child per year (1990 costs). However, if the infant were hospitalized during this period, the comparable cost would be $45,000 to $50,000. The overall costs of treating infants with BPD in the United States are estimated to be $2.4 billion. This amount is second only to the costs for treating asthma and far exceeds the cost of treating cystic fibrosis.
National Institutes of Health
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