Bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD; part of the spectrum of chronic lung disease of infancy) is a chronic lung disease in which premature infants, usually those who were treated with supplemental oxygen, require long-term oxygen. The alveoli that are present tend to not be mature enough to function normally. It is more common in infants with low birth weight (LBW) and those who receive prolonged mechanical ventilation to treat respiratory distress syndrome (RDS). It results in significant morbidity and mortality. The definition of BPD has continued to evolve primarily due to changes in the population, such as more survivors at earlier gestational ages, and improved neonatal management including surfactant, antenatal glucocorticoid therapy, and less aggressive mechanical ventilation.
Currently the description of BPD includes the grading of its severity into mild, moderate and severe. This correlates with the infant's maturity, growth and overall severity of illness. The new system offers a better description of underlying pulmonary disease and its severity.
Presentation.
Complications.
Feeding problems are common in infants with BPD, often due to prolonged intubation. Such infants often display oral-tactile hypersensitivity (also known as oral aversion).
Physical findings:
Cause.
Prolonged high oxygen delivery in premature infants causes necrotizing bronchiolitis and alveolar septal injury, with inflammation and scarring. This results in hypoxemia. Today, with the advent of surfactant therapy and high frequency ventilation and oxygen supplementation, infants with BPD experience much milder injury without necrotizing bronchiolitis or alveolar septal fibrosis. Instead, there are usually uniformly dilated acini with thin alveolar septa and little or no interstitial fibrosis. It develops most commonly in the first 4 weeks after birth.
Diagnosis.
Earlier criteria.
The classic diagnosis of BPD may be assigned at 28 days of life if the following criteria are met:
Newer criteria.
The newer National Institute of Health (US) criteria for BPD (for neonates treated with more than 21% oxygen for at least 28 days) is as follows:,
Management.
Infants with bronchopulmonary dysplasia are often treated with diuretics that decrease fluid in the alveoli where gas exchange occurs and bronchodilators that relax the airway muscles to facilitate breathing. Viral immunization is also important for these children who have a higher risk of infections in the respiratory tract. 
There is evidence to show that steroids given to babies less than 8 days old can prevent bronchopulmonary dysplasia. However, the risks of neurodevelopmental sequelae may outweigh the benefits. It is unclear if starting steroids more than 7 days after birth is harmful or beneficial. It is thus recommended that they only be used in those who cannot be taken off of a ventilator. Evidence suggests that vitamin A in LBW babies is associated with a reduction in mortality and bronchopulmonary dysplasia.Oxygen therapy at home is recommended in those with significant low oxygen levels.
Hypercarbia (too much carbon dioxide in the blood) may contribute to the development of bronchopulmonary dysplasia. Monitoring the level of carbon dioxide in neonatal infants to ensure that the level is not too high or too low (hypocarbia) is important for improving outcomes for neonates in intensive care. Carbon dioxide can be monitored by taking a blood sample (arterial blood gas), through the breath (exhalation), and it can be measured continuously through the skin by using a minimally invasive transcutaneous device. The most effective and safest approach for measuring carbon dioxide in newborn infants is not clear. 
Epidemiology.
The rate of BPD varies among institutions, which may reflect neonatal risk factors, care practices (e.g., target levels for acceptable oxygen saturation), and differences in the clinical definitions of BPD.