Bronchopulmonary dysplasia (BPD) is one of the few diseases in neonatal medicine that has continued to evolve since its first description about 50 years ago. Over these years, advancements in neonatal medicine such as antenatal steroids and exogenous surfactant therapy have significantly reduced neonatal mortality and lowered the limits of viability for preterm infants. Although the incidence of BPD continues to be high, especially in extremely low birth weight infants, the clinical picture has evolved into a milder disease with low mortality or significant morbidities. This new BPD is the result of complex interactions between altered alveolar and vascular development, injury by ante- and postnatal pathogenic factors, and reparative processes in the lung. There has been significant progress in our understanding of risk factors for BPD, but challenges persist in its definition, and in finding effective preventive strategies. There are promising developments with newer preventive interventions such as mesenchymal stem cells, exosomes, immunomodulators, and growth factors, but they are still in preclinical stage. The future challenges include finding ways to define BPD based on the severity of lung pathology, which can better predict long-term outcomes, development of early predictors of lung disease, and finding innovative and evidence-based preventive and management strategies.
Since Northway's original description of BPD almost 45 years ago, the clinical presentation of BPD has evolved into a disease process, which mostly involves extremely premature infants. This new form of BPD is the result of multiple antenatal and postnatal factors that can cause injury to the developing lung leading to altered alveolar and vascular development. Over the years, there has been considerable increase in knowledge of factors that contribute to the development of BPD. This has led to different strategies for prevention as well as management of BPD. Some of these strategies have been successful and have withstood the test of clinical trials, such as vitamin A supplementation, post-natal steroids, caffeine, and volume targeted ventilation. The evidence for other interventions has been weak or negative. With better understanding of the complex and multifactorial pathogenesis of BPD, it is quite clear that any single therapy is very unlikely to eliminate this problem unless it reduces prematurity. Further development in prevention and treatment of BPD will likely need a multi-pronged strategy with novel therapeutic agents acting at various stages of the disease process.
The evolution of neonatal respiratory support has been one of the cornerstones for the advancements in neonatal–perinatal medicine, allowing survival of infants previously considered not viable. There is an increasing focus on developing strategies which are not only lifesaving but also minimize lung and other organ systems injury, thereby reducing long-term morbidities. Respiratory support immediately after birth is an area that had lagged behind in terms of evidence base and technological advancements until recently. Some of these advancements include use of a respiratory function monitors for measuring flow and tidal volume, new evidence for oxygen supplementation and monitoring, and the efforts to formulate an ideal strategy for establishing functional residual capacity after birth. Increasing evidence for the benefits of avoiding invasive ventilation on reduction of bronchopulmonary dysplasia has resulted in efforts to further reduce the need for endotracheal intubation by applying newer strategies such as less invasive surfactant instillation, noninvasive high-frequency oscillatory ventilation, or use of high flow nasal cannula oxygen. For infants requiring mechanical ventilation, newer strategies such as volume targeted ventilation or neurally adjusted ventilation are being evaluated to reduce ventilator induced lung injury. Despite these advances, there are significant challenges, including lack of conclusive evidence base for many of currently used respiratory strategies, no reduction in the incidence of bronchopulmonary dysplasia in the last decade, and difficulties in defining outcome measures that better reflect long-term respiratory health.
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