What is BPD today and In the next 50 years?

摘要

WHAT IS BPD TODAY: After more than 50 years from its original description, bronchopulmonary dysplasia (BPD) continues to be one of the most common and devastating consequences of extreme preterm birth. Although the clinical presentation today is quite different and milder from that described originally by Northway and collaborators (1), it still occurs in ~40% of the infants born under 28 wk of gestation, and it is associated with longer hospitalization and increased medical costs. It is also associated with increased mortality and other comor-bidities such as pulmonary hypertension and abnormal neu-rodevelopmental outcome (2, 3). Although the original form of BPD occurred in more mature infants who had severe respiratory distress syndrome (RDS) requiring aggressive respiratory support with high oxygen, which caused severe disruption of lung morphology and function, today BPD occurs in more immature infants who because of antenatal steroids and surfactant use have only mild initial respiratory failure and receive noninvasive or less aggressive respiratory support. The disruption in lung architecture and function in most of these infants is much less striking and is characterized by decreased alveolarization and abnormal vascular development and by milder respiratory failure. This milder phenotype has made obsolete many of the original diagnostic criteria that applied mainly to severe cases and has created confusion among clinicians and researchers who have difficulty classifying these milder forms of BPD. It has also frustrated researchers who are now faced with a much more complex task of preserving normal lung development rather than just preventing lung injury. The abnormal lung development may be an inevitable consequence of prematurity, and quite independent of BPD (4). Today, it is not a question of whether an extremely premature infant has BPD or not, but what is the degree of alteration of their lung development that will define their long-term pulmonary outcome. Dichotomizing infants in those with and without BPD is clearly not the best approach but we need to understand the multiple variables contributing to abnormal lung development, and how they interact during fetal life and postnatal care resulting in different degrees of lung disruption and poor long-term outcomes. There is clear evidence in the literature that many ex-preterm infants without the diagnosis of BPD still have abnormal lung function later in life (5). Identifying these infants early will require new, more precise tools to determine the degree of abnormality in their lung morphology and function (6-9).