IntroductionYour baby has been diagnosed with
bronchopulmonary dysplasia (BPD). BPD is a chronic lung disease of
newborn infants marked by inflammation of the airways. The lungs of
babies with BPD are immature or have not developed normally. Their lungs are
therefore unable to perform gas exchange. Gas exchange is the primary
function of the lungs. This term is used for the process by which lungs transfer
oxygen from inhaled air into the bloodstream in exchange for carbon
dioxide from the blood to be exhaled.
Inhaled air travels to the alveoli (tiny air sacs
located at the end of the conducting airways of the lungs) where it comes in
contact with blood containing carbon dioxide. The blood travels through a fine
network of pulmonary vessels called capillaries. Gas exchange
occurs instantaneously in normal infants as the red blood cells pass through the
capillaries. It does not occur adequately in BPD infants because their alveoli
and capillaries are not fully developed.
This booklet explains what BPD is, its signs and symptoms, how it is treated,
and what parents might expect as an infant with a history of BPD grows. Words
that may not be familiar are in italic and are explained when they first appear;
they also are defined in the glossary at the end of the booklet. The centerfold
presents a more technical discussion of BPD. Also in the centerfold is a
description of highlights of the National Heart, Lung, and Blood Institute's
research programs in 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.
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.
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.
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
- wheezing.
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.
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.
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.
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.
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.
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.
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.
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.
Keeping on Top of Your Condition
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