Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia is the chronic lung disease of prematurity, defined by a prolonged need for supplemental oxygen or respiratory support in preterm infants whose lungs were injured and whose development was disrupted during a critical phase of growth. First described in ventilated infants with hyaline membrane disease, it has become the most common chronic respiratory complication of extreme prematurity.

Definition

Bronchopulmonary dysplasia is a chronic lung disease of preterm infants characterized by persistent need for supplemental oxygen or respiratory support, typically assessed at 36 weeks postmenstrual age, arising from disrupted lung development together with injury from oxygen, ventilation, and inflammation.

Scope

The entry covers the concept of bronchopulmonary dysplasia as arrested lung development plus injury, the shift from the original ventilator-injury picture to the modern "new" form, and the oxygen- and support-based definitions used to classify it. It is a reference description of the disorder and not a treatment guide.

Core questions

• How do injury and arrested development combine to produce chronic lung disease in the preterm infant?
• How does the modern "new" bronchopulmonary dysplasia differ from the original form described in the 1960s?
• How is the disorder defined and graded, and why do definitions matter for diagnosis and research?
• What are the long-term respiratory consequences for affected children?

Key concepts

• Arrested alveolar and vascular development
• Oxygen toxicity and volutrauma
• Inflammation in the immature lung
• "Old" versus "new" bronchopulmonary dysplasia
• Postmenstrual-age-based definition
• Severity grading by oxygen and support need

Mechanisms

In the very preterm infant the lung is still in the saccular or early alveolar stage of development. Exposure to mechanical ventilation, supplemental oxygen, and inflammation injures the immature lung and disrupts the orderly formation of alveoli and the pulmonary microvasculature. Northway and colleagues (1967) first described the severe fibrotic injury seen in ventilated infants. With gentler ventilation, surfactant, and antenatal steroids, the dominant picture shifted to a "new" bronchopulmonary dysplasia marked less by fibrosis than by fewer, larger, simplified alveoli and abnormal vascular growth (Jobe & Bancalari, 2001). The result is a lung with reduced gas-exchange surface area and persistent need for respiratory support.

Clinical relevance

Bronchopulmonary dysplasia is a major determinant of long-term respiratory and developmental outcomes after extreme prematurity. This entry describes the disorder for reference and education and does not provide guidance for managing an individual infant.

Epidemiology

The disorder is largely confined to very and extremely preterm infants, and its frequency increases with decreasing gestational age and birth weight. As survival of the most immature infants has improved, the population at risk has grown, so that bronchopulmonary dysplasia remains common despite advances in care (Jensen et al., 2019).

Evidence & guidelines

Consensus workshops and cohort studies have refined how bronchopulmonary dysplasia is defined and graded, including severity classification by the degree of respiratory support at 36 weeks postmenstrual age (Jobe & Bancalari, 2001; Jensen et al., 2019). European guidelines on neonatal respiratory care address strategies relevant to reducing lung injury (Sweet et al., 2023). These sources are summarized for orientation only.

History

Northway, Rosan, and Porter named bronchopulmonary dysplasia in 1967 to describe a severe chronic lung injury in infants who had survived mechanical ventilation for hyaline membrane disease. Over the following decades, as surfactant, antenatal steroids, and gentler ventilation changed neonatal care, the typical pathology shifted toward developmental arrest, prompting the concept of a "new" bronchopulmonary dysplasia and successive efforts to standardize its definition (Jobe & Bancalari, 2001; Jensen et al., 2019).

Debates

How should bronchopulmonary dysplasia be defined?

Definitions based on oxygen use at 28 days versus 36 weeks postmenstrual age, and grading by the type of respiratory support, identify different infants and predict outcomes differently; the best definition for clinical and research use remains debated.

Key figures

• William Northway
• Alan Jobe
• Eduardo Bancalari
• Erik Jensen

Seminal works

• northway-1967
• jobe-bancalari-2001
• jensen-2019

Frequently asked questions

What is bronchopulmonary dysplasia?

It is the chronic lung disease of prematurity, in which a preterm infant continues to need supplemental oxygen or respiratory support because the immature lung was injured and its development was disrupted; it is commonly assessed around 36 weeks postmenstrual age.

How is "new" bronchopulmonary dysplasia different from the original description?

The original form described by Northway in 1967 featured severe airway injury and fibrosis from aggressive ventilation. The modern "new" form, seen in more immature infants treated with gentler ventilation and surfactant, is characterized mainly by fewer, simplified alveoli and abnormal lung vascular development.