Bronchopulmonary Dysplasia

Molly K. Ball, MD, FAAP

Introduction/Etiology/Epidemiology

•Despite meaningful advances in fetal and neonatal care, bronchopulmonary dysplasia (BPD) continues to represent the major respiratory morbidity in preterm infants.

•With improved survival of increasingly preterm neonates, the pathophysiology, affected population, and definitions of BPD have evolved.

•BPD incidence remains stable, with diagnosis and severity inversely proportional to birth weight and gestational age.

•The high-risk population includes patients who weigh <1,200–1,500 g and/or are <30 weeks’ gestational age at birth.

•Patients with BPD who are released from the neonatal intensive care unit (NICU) represent a high-risk population with multisystem complications and clinically significant post-NICU health care needs. For these children, primary care providers play a pivotal role.

Pathophysiology

•The immature lung is subjected to injurious environmental factors that result in the arrest of normal lung and pulmonary vascular development.

•Risk factors for development of BPD include

—Antenatal infection

—Increasing lung immaturity

—Exposure to supplemental oxygen (oxidative stress injury)

—Exposure to mechanical ventilation (ventilator-induced lung injury)

—Postnatal infection

—Immature inflammatory regulation

—Genetic susceptibility

Clinical Features

•Clinically, infants and children with BPD display respiratory symptoms that include tachypnea, retractions, increased work of breathing, and decreased oxygen saturation levels (hypoxemia).

•Functionally, lung volumes are reduced and develop bronchoreactivity, as well as airway obstruction with air trapping (hyperinflation).

Differential Diagnosis

•Recurrent pneumonia and/or pulmonary infection

•Chronic aspiration pneumonitis

•Airway malformations (including subglottic stenosis and tracheobron chomalacia)

•Alveolar capillary dysplasia

•Pulmonary interstitial lung disease

•Pulmonary hypoplasia

•Congenital lobar emphysema

•Wilson-Mikity syndrome (pulmonary dysmaturity syndrome)

•Congenital neuromuscular disorders

Diagnostic Considerations

•The diagnosis of BPD is established in the NICU, prior to discharging the patient to go home.

•BPD is a complex, heterogeneous, and multifactorial disease. Current definitions remain limited by poor prognostic ability for short- and long-term morbidities and outcomes.

•Current definitions of BPD are clinically derived and serve to stratify disease severity.

•The 2000 National Institutes of Health, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Heart, Lung, and Blood Institute Workshop definition

•The early NICU approach to BPD prevention is as follows.

—The goal is (a) to support respiratory insufficiency while avoiding ventilator- and oxygen-induced lung injury and (b) early extubation.

—Surfactant therapy has revolutionized neonatal lung disease through improved pulmonary mechanics and early survival. However, as with antenatal corticosteroids, a direct effect on BPD prevention has been difficult to establish.

—Data support the avoidance of fluid overload, while the role of the ductus arteriosus remains controversial.

Evolving BPD

•NICU management of BPD is aimed at minimizing ongoing lung injury (oxygen and ventilator induced), avoiding infection, and optimizing nutrition and growth.

•The routine use of systemic steroids has been limited by adverse neurodevelopmental outcomes.

Established BPD

•Long-term management of BPD and its comorbidities remains challenging but is optimized by a longitudinal multidisciplinary care team.

•Oxygen and ventilation

—Home oxygen therapy may be necessary to support tissue oxygen delivery during waking hours, feeding, and sleeping. These infants may require a home pulse oximeter monitor.

—For severe BPD, chronic ventilation via tracheostomy tube may be required to support respiratory needs.

—Chronic hypoxia is associated with pulmonary hypertension and poorer growth and neurodevelopment. However, optimal oxygen saturations and weaning parameters remain areas of research.

•Pulmonary medication

—Mainstays of symptomatic treatment include bronchodilators, inhaled corticosteroids, and diuretics.

—The chronic use of these medications should be approached with caution and in conjunction with a BPD or pulmonary team, because data supporting the effectiveness of widespread use are lacking.

•Routine prophylaxis should be used against respiratory infections (see the Prevention of Respiratory Morbidities section in this chapter).

•Nutrition continues to play a key role in the growth and maturation of the lungs and brain. Growth should be assessed monthly, with increased frequency if concerns arise.

•The treatment of associated conditions should occur with a focus on neurodevelopmental optimization (see the next section).