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Last updated:
8/23/2023
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NORD gratefully acknowledges Steven H. Abman, MD, Professor, Department of Pediatrics, University of Colorado School of Medicine and Director, Pediatric Heart Lung Center, The Children’s Hospital, for assistance in the preparation of this report.
Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease that most often occurs in low-birthweight or premature infants who have received supplemental oxygen or have spent long periods of time on a breathing machine (mechanical ventilation), such as infants who have acute respiratory distress syndrome. BPD can also occur in older infants who experience abnormal lung development or some infants that have had an infection before birth (antenatal infection) or placental abnormalities (such as preeclampsia). Antenatal steroid treatment prior to preterm birth and early treatment with surfactant have reduced the need for high levels of respiratory support after birth.
Affected infants may have rapid, labored breathing and bluish discoloration of the skin due to low levels of oxygen in the blood (cyanosis). Infants are not born with BPD and the condition results from damage to the lungs due to the extremely fragile nature of the underdeveloped, immature lungs. Although most infants fully recover from BPD, some have sustained abnormalities of lung function and structure throughout adolescence and into adulthood. However, the condition can cause serious complications during infancy and often requires hospitalization and intensive medical care, especially during the first 2 years after birth.
The survival of low-birth-weight infants has improved steadily over the past few decades. Many infants diagnosed with BPD today are born at far earlier gestational ages than in the past. Researchers think that these cases of BPD are less associated with injury and repair to the lungs and more likely represent an underlying disruption or abnormality affecting the development of the lungs. These infants may require chronic oxygen supplementation even without developing acute respiratory distress syndrome. These cases are sometimes referred to as “new” BPD.
Some infants who develop BPD have a condition called respiratory distress syndrome (RSD), which is a breathing disorder that affects some premature infants immediately after birth. It is characterized by rapid, shallow breathing and leads to the need for oxygen and respiratory support in the first days of life. Affected infants may also exhibit fast breathing with signs of shortness of breath, a chronic cough or wheezing, flaring of the nostrils when breathing and bluish discoloration of the skin due to low levels of oxygen in the blood (cyanosis). Some infants may grunt when breathing out (exhaling). Additional symptoms may include abnormally fast breathing (tachypnea), wheezing or a “crackling” or “rattling” sound that is heard in the lungs when inhaling.
Most infants with BPD recover fully and damage to the lungs progressively improves with growth. In a few rare cases, BPD can cause life-threatening complications during infancy such as high blood pressure of the main artery of the lungs (pulmonary hypertension) and failure of the right side of the heart (cor pulmonale).
As affected infants and children grow, they may be at a greater risk than the general population of developing asthma, respiratory infections or viral pneumonia.
BPD is caused by damage to the delicate tissue of the lungs, usually related to the degree of prematurity. This damage most often occurs in infants who have required extended treatment with supplemental oxygen or breathing assistance with a machine (mechanical ventilation) such as infants who are born prematurely and have acute respiratory distress syndrome.
When infants receive mechanical ventilation to help support their breathing, a tube is inserted through the windpipe and the machine pushes air into the lungs, which are often underdeveloped in premature infants. In some cases, the levels of oxygen required for an affected infant to survive are higher than normally would be found in the air we breathe. Over time, the constant pressure from the ventilator and the excess oxygen levels can damage the delicate tissues of an infant’s lungs causing inflammation and scarring.
Although many cases of BPD are associated with mechanical ventilation or excess oxygen levels, BPD can arise from other conditions that affect the development of the lungs such as infection that occurs before birth (antenatal infection) or other maternal complications such as smoking, drug use, placental abnormalities (preeclampsia) and inflammation of the fetal membranes (chorioamnionitis). In rare cases, some older infants who are born closer to term gestation can have abnormal lung development and develop BPD.
Infants who have patent ductus arteriosus are at a greater risk than other infants of developing BPD. Patent ductus arteriosus (PDA) is a large vascular structure that is open in every fetus before birth and usually closes shortly after birth in babies who are not born prematurely. In premature infants, however, the PDA remains open after birth, and can be a passage between the blood vessel that leads to the lungs (the pulmonary artery) and the major artery of the body (the aorta). As the PDA fails to close after birth, the higher flow of blood into the lungs may increase the need for higher levels of supplemental oxygen or support with mechanical ventilation. If open too long, the PDA may contribute to the risk for BPD and may require specific medications or other treatments to close the PDA.
Many infants now diagnosed with BPD are born at an earlier gestational age than in the past. These cases are sometimes referred to as “new BPD.” These cases generally have less inflammation and scarring than in classic BPD. These cases are believed to be less associated with mechanical ventilation and damage to the lungs and more likely due to disrupted or abnormal lung development. Researchers theorize that the formation of new blood vessels (angiogenesis) is abnormal or disrupted in infants with “new” BPD. Lung angiogenesis plays a key role in the development of the lung’s alveoli, which are thin, capillary-rich sacs in the lungs where the exchange of oxygen and carbon dioxide takes place. Capillaries are very small blood vessels. Researchers think that disrupted lung angiogenesis impairs the proper development of the alveoli, which contributes to the development of BPD in some cases.
The exact, underlying mechanisms that cause classic or new BPD are complex and not fully understood. The causes of BPD in one infant may be different from the causes in another. Most likely, multiple different environmental and genetic factors all play a role in the development of the disorder. Some individuals may have a genetic predisposition to developing BPD. A person who is genetically predisposed to a disorder carries a gene variant (or variants) for the disease, but it may not be expressed unless it is triggered or “activated” under certain circumstances, such as due to particular environmental factors (multifactorial inheritance). More research is necessary to determine the exact causes and underlying mechanisms involved in the development of the BPD.
Bronchopulmonary dysplasia can affect both males and females. The exact incidence of BPD is unknown but is highest in infants born with extreme prematurity. The National Institutes of Health estimates that 10,000-15,000 babies born in the United States develop BPD each year. The risk of developing BPD increases the earlier a baby is born (gestational age) and the lower the birth weight. Infants born weighing less than 2.2 pounds are at the greatest risk for developing BPD. The number of cases of BPD has been increasing, most likely because of modern advances in medicine, which have enabled doctors to keep more low birth weight, premature babies alive than in the past. BPD was first described in the medical literature in 1967.
A diagnosis of BPD is made based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests including blood tests, chest x-rays and echocardiograms. Blood tests may show low levels of oxygen in the blood that require treatment with higher levels of oxygen or respiratory support. Chest x-rays may show distinctive changes in the lungs including abnormal development of the lungs. An echocardiogram is used to rule out other conditions that can cause breathing difficulties in infants such as congenital heart defects and helps show how the heart is working and the presence of a large PDA. During an echocardiogram, sound waves are directed toward the heart, enabling doctors to study cardiac function and motion.
Prevention
The lungs of infants with respiratory distress syndrome and underdeveloped and cannot produce enough surfactant, which is a substance secreted by the tiny air sacs (alveoli) of the lungs that serves to reduce the tension of pulmonary fluids. These infants may be treated with surfactant-replacement therapy, which may be able to prevent the development of BPD in some cases. Most importantly, maternal steroid treatments prior to birth reduce the risk for BPD in preterm infants.
Infants with respiratory distress syndrome are also treated with mechanical ventilation and oxygen supplementation. Continued medical advances, including the use of surfactant, different types of breathing machines and earlier nutrition have lessened the risk of damage to infants’ lungs during these therapies and lowered the risk of these infants’ developing BPD.
Treatment
The treatment for infants with BPD is geared toward minimizing damage to the lungs and providing enough support to allow an affected infant’s lungs heal and grow. The specific therapies used may change as an affected infant grows and the clinical picture changes.
Newborns with BPD initially require care in the hospital. Treatment may include mechanical ventilation. Ventilators are only used when necessary to help sustain effective breathing and oxygen for the baby and affected infants are taken off the breathing machine as early as possible but only when the infant has clearly shown the ability to breathe effectively and without distress. Many infants still require supplemental oxygen after being taken off mechanical ventilation, and the amount of oxygen is progressively reduced by close monitoring of the body’s oxygen level by serial measurements with a pulse oximeter. Proper nutritional management is also necessary to ensure the proper growth and development of the lungs. Some affected infants may require the insertion of a gastrointestinal (GI) tube directly into the stomach to ensure a sufficient intake of calories and nutrients. Because infants with BPD are at risk for the accumulation of excess fluid in the lungs, daily fluid intake may be monitored and adjusted.
Infants with BPD may receive different medications including bronchodilators, diuretics and antibiotics. Bronchodilators are medications that widen the airway tubes and improve the flow of air through the lungs. Diuretics are medications that reduce the amount of water in the body and may be administered to help remove excess fluid in the lungs. Antibiotics are used to help control infections and prevent pneumonia. In addition, intermittent use of steroids may reduce lung inflammation and congestion, reducing the need for high levels of respiratory support and oxygen. However, early and high doses of steroids may have adverse effects on neurocognitive and developmental outcomes. As a result, steroids are used selectively later in the clinical course, and for shorter periods of time.
Infants with BPD may spend several weeks or even months in the hospital, depending on the rate of improvement in lung function as well as other medical problems that may be present. In most cases, lung function and development gradually improve, although it is often a slow process. After leaving the hospital, infants require proper nutrition, should avoid cigarette smoke and should receive regular follow up checkups from their pediatrician. Some infants may require supplemental oxygen, nutritional supplementation and ongoing use of other medicines after returning home. After discharge to home, babies with BPD are often seen frequently by their healthcare provider to closely monitor progress related to lung disease, growth and nutrition, vaccinations, development and for general pediatric health care.
Infants with BPD remain at a greater risk of developing respiratory infections and pneumonia than the general population. They should avoid individuals who have upper respiratory infections. In some cases, affected infants may receive preventive therapy with palivizumab, an antibody that protects against respiratory syncytial virus (RSV) infection. RSV is a common and contagious winter infection that can potentially cause pneumonia.
In infants with severe forms of BPD, treatment with a short course of steroids may be necessary. Steroids may also be used in infants at risk of developing BPD. Steroids are powerfully anti-inflammatory drugs. Studies have shown that low-dose, short-term therapy with steroids has improved lung function and neurodevelopmental outcomes. However, steroid therapy can be associated with a variety of side effects. More research is necessary to determine the safest and most effective dose, timing and length of steroid therapy for infants with BPD. More research is necessary to determine the long-term consequences of steroid therapy as well. The use of caffeine has been shown to reduce BPD in preterm infants, but the mechanism underlying this effect is uncertain.
Inhaled nitric oxide therapy is being studied to determine what role, if any, it may play in preventing the development of BPD in at-risk infants. Nitric oxide is a vasodilator, a drug that relaxes the smooth muscles of blood vessels causing the vessels to widen. Inhaled nitric oxide may be able to improve ventilation and decrease inflammation in children at risk for BPD. Currently, the effects of inhaled NO in preventing BPD have been inconsistent. More research is necessary to determine the long-term safety and effectiveness of inhaled nitric oxide as a potential preventive therapy for infants at risk of developing BPD.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
TEXTBOOKS
Abman, SH. Bronchopulmonay Dysplasia. New York, NY: Informa Healthcare USA, Inc. 2010.
The Merck Manual, 15th Ed.: R. Berkow, ed.-in-chief; Merck & Co., Inc. 1987. Pp. 1870-71.
Pulmonary Disease And Disorders. 2nd Ed.: Alfred P. Fishman, M.D., et al.; Editors; McGraw-Hill Book Company. 1988. Pp. 2261-62.
JOURNAL ARTICLES
Northway WH Jr, Moss RB, Carlisle KB, et al. Late pulmonary sequelae of bronchopulmonary dysplasia. N Engl J Med. 1990;323(26):1793-1799. doi:10.1056/NEJM199012273232603
Brudno DS, Parker DH, Slaton G. Response of pulmonary mechanics to terbutaline in patients with bronchopulmonary dysplasia. Am J Med Sci. 1989;297(3):166-168. doi:10.1097/00000441-198903000-00007
Edwards DK 3rd, Hilton SW. Flat chest in chronic bronchopulmonary dysplasia [published correction appears in AJR Am J Roentgenol 1988 Feb;150(2):375]. AJR Am J Roentgenol. 1987;149(6):1213-1216. doi:10.2214/ajr.149.6.1213
Giuffre RM, Rubin S, Mitchell I. Antireflux surgery in infants with bronchopulmonary dysplasia. Am J Dis Child. 1987;141(6):648-651. doi:10.1001/archpedi.1987.04460060064035
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