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 bronchopulmonary dysplasia, often due to prolonged intubation. Such infants often display oral-tactile hypersensitivity (also known as oral aversion). Physical findings: hypoxemia; hypercapnia; crackles, wheezing, & decreased breath sounds; increased bronchial secretions; hyperinflation; frequent lower respiratory infections; delayed growth & development; cor pulmonale; CXR shows with hyperinflation, low diaphragm, atelectasis, cystic changes. 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: Positive pressure ventilation during the first 2 weeks of life for a minimum of 3 days. Clinical signs of abnormal respiratory function. Requirements for supplemental oxygen for longer than 28 days of age to maintain PaO2 above 50 mm Hg. Chest radiograph with diffuse abnormal findings characteristic of BPD. Newer criteria The 2006 National Institute of Health (US) criteria for BPD (for neonates treated with more than 21% oxygen for at least 28 days) is as follows:, Mild Breathing room air at