Bronchopulmonary Dysplasia: Symptoms, Types, Causes and Treatment

Bronchopulmonary dysplasia (BPD) stands as one of the most common and impactful chronic lung diseases in infancy, predominantly affecting premature newborns. With advances in neonatal care, both the presentation and understanding of BPD have evolved, but the condition continues to pose significant clinical challenges for affected families and healthcare providers. In this article, we explore the key symptoms, types, causes, and modern approaches to treatment, drawing on up-to-date research.

Symptoms of Bronchopulmonary Dysplasia

Understanding the symptoms of BPD is crucial for early recognition and long-term management. The clinical presentation can range from mild to severe, and may change as affected children grow.

Symptom	Description	Age Group	Source(s)
Chronic cough	Persistent cough that may be worse at night	Infancy–adulthood	2 3 4 7
Wheezing	Whistling sound when breathing	Infancy–adulthood	2 3 4 7
Exercise intolerance	Shortness of breath or fatigue with activity	Childhood–adult	1 2 4 7
Respiratory distress	Rapid breathing, retractions, grunting	Infancy	4 6 8
Frequent infections	Recurrent lower respiratory tract infections	Childhood	2 4 8
Hypoxemia	Low blood oxygen, may need supplemental O₂	Infancy–childhood	4 8
Pulmonary hypertension	High blood pressure in the lungs	Any (esp. severe)	4 5 7

Table 1: Key Symptoms

Chronic Respiratory Symptoms

Children with BPD often exhibit chronic symptoms such as cough and wheezing. These symptoms can persist into adolescence and even adulthood, although they often become less severe over time. Some patients may develop asthma-like symptoms, with airway hyperreactivity and reversible airway obstruction, which can impact daily life and physical activities 2 4 7.

Exercise Intolerance and Activity Limitation

Exercise intolerance is a hallmark of BPD, particularly in children and adults who survived severe cases in infancy. Even after hospital discharge, many individuals experience shortness of breath or fatigue during exertion. This is often exacerbated by underlying airway obstruction and lung hyperinflation 1 2 4.

Acute Respiratory Distress

In infancy, BPD may present with signs of respiratory distress, such as rapid breathing (tachypnea), chest retractions, grunting, or nasal flaring. These symptoms often necessitate prolonged respiratory support and frequent hospitalizations, especially in the first years of life 4 6 8.

Increased Risk of Infections

Children with BPD are more prone to recurrent lower respiratory tract infections, which can lead to exacerbations and further decline in lung function. Hospital readmissions due to respiratory illnesses are common, particularly during early childhood 2 4 8.

Hypoxemia and Oxygen Dependence

A defining feature of BPD is prolonged oxygen requirement beyond the neonatal period. Some children may continue to need supplemental oxygen to maintain adequate blood oxygen levels for months or years, especially those with severe disease 4 8.

Pulmonary Hypertension

In more severe cases, the development of pulmonary hypertension—a form of high blood pressure within the lungs—can occur. This complication increases the risk of right heart failure and is associated with worse long-term outcomes 4 5 7.

Types of Bronchopulmonary Dysplasia

BPD is not a uniform disease; rather, it encompasses a spectrum of clinical and pathological subtypes shaped by advances in neonatal care and the evolving understanding of its pathophysiology.

Type	Defining Features	Typical Era	Source(s)
"Old" BPD	Fibrosis, scarring, emphysema, hyperinflation	Pre-surfactant era	4 6 7 9
"New" BPD	Arrested lung development, alveolar simplification	Modern era	4 7 9 10 12
Phenotypic Subtypes	Parenchymal, airway, vascular disease	Any (esp. severe)	5 7
Severity Grading	Mild, moderate, severe (by O₂/ventilation need)	Modern era	4 14

Table 2: Types and Subtypes of BPD

"Old" vs. "New" BPD

Historically, "old" BPD was described in preterm infants who developed lung injury after mechanical ventilation and prolonged high-concentration oxygen therapy. It was characterized by marked fibrosis, scarring, emphysema, and hyperinflation of the lungs 4 6 7 9. With the introduction of antenatal steroids and surfactant therapy, a "new" BPD emerged. This form is less about scarring and more about disrupted growth—particularly an arrest in alveolar and vascular development, leading to simplified lung structure and impaired gas exchange 4 7 9 10 12.

Phenotypic Subtypes

Recent research has identified that BPD can present with different pathological emphases:

• Parenchymal Disease: Involving the lung tissue itself, often with impaired alveolar growth.
• Airway Disease: Such as tracheomalacia or bronchomalacia, characterized by airway weakness or collapse.
• Pulmonary Vascular Disease: Including pulmonary hypertension due to abnormal vascular development 5 7.

Many infants with severe BPD may simultaneously have more than one of these components, and the presence of multiple types increases the risk of worse outcomes 5.

Severity Grading

Modern definitions of BPD rely on the degree and type of respiratory support needed at a corrected gestational age (typically 36 weeks), categorizing BPD as mild, moderate, or severe. This grading informs prognosis and guides management 4 14.

Causes of Bronchopulmonary Dysplasia

BPD develops from a complex interplay of prenatal and postnatal factors, all converging on the vulnerable, immature lungs of preterm infants.

Cause	Mechanism/Description	Modifiability	Source(s)
Prematurity	Immature lungs, incomplete development	No	4 8 9 11 12 15
Mechanical ventilation	Barotrauma, volutrauma	Partial	4 6 9 10 12 15
Oxygen toxicity	Oxidative injury to lung tissue	Partial	4 6 9 10 15
Infection/Inflammation	Prenatal (chorioamnionitis), postnatal sepsis	Partial	10 12 15
Genetic susceptibility	Genetic predisposition to lung injury	No	12
Environmental exposures	Indoor pollution, secondhand smoke	Yes	3

Table 3: Main Causes and Risk Factors

The Role of Prematurity

Prematurity is the single greatest risk factor for BPD. The earlier a baby is born, the less developed their lungs are, making them highly susceptible to injury from even routine neonatal care 4 8 9 11 12 15. The incidence of BPD rises sharply with decreasing gestational age and birth weight.

Mechanical Ventilation and Oxygen Therapy

To survive, many preterm infants require mechanical ventilation and supplemental oxygen. While life-saving, these interventions can also cause lung injury. Mechanical ventilation leads to physical stress (barotrauma, volutrauma), while high concentrations of oxygen result in oxidative damage to delicate pulmonary tissues 4 6 9 10 12 15.

Inflammation and Infection

A growing body of evidence highlights inflammation as central to the development of BPD. Both prenatal exposures (such as chorioamnionitis) and postnatal infections (sepsis, pneumonia) trigger inflammatory cascades that damage lung structure and impair normal repair processes. Persistent inflammation leads to abnormal healing, alveolar simplification, and vascular dysregulation 10 12 15.

Genetic and Environmental Factors

Some infants may have a genetic predisposition that increases their vulnerability to lung injury and dysregulated healing 12. Environmental exposures, including indoor air pollution and secondhand smoke, have been shown to worsen respiratory outcomes in infants with BPD. These modifiable factors can increase the risk of hospitalizations and chronic symptoms, highlighting the importance of a smoke-free and clean home environment 3.

Treatment of Bronchopulmonary Dysplasia

Treating BPD involves a multifaceted approach aimed at minimizing further lung injury, supporting growth and development, and managing complications as they arise.

Treatment	Purpose/Use	Indication/Stage	Source(s)
Oxygen supplementation	Maintain adequate blood oxygen levels	Infancy–childhood	4 8 14
Diuretics	Reduce lung fluid, ease breathing	Acute/chronic stages	4 14
Bronchodilators	Relieve airway obstruction, wheeze	Subgroup (e.g., asthma-like symptoms)	4 14
Steroids (systemic/inhaled)	Reduce inflammation	Cautious/limited use	4 13 14
Pulmonary hypertension meds	Lower pulmonary vascular resistance	When indicated	4 5
Multidisciplinary care	Address nutrition, development, overall health	All stages	8 14
Environmental control	Minimize smoke/pollutant exposure	All stages	3
Experimental therapies	Stem cell therapy, targeted molecular treatments	Research/selected cases	15 16

Table 4: Treatments and Interventions

Oxygen Supplementation and Respiratory Support

Maintaining adequate oxygenation is a cornerstone of BPD management. Most infants require supplemental oxygen, often for weeks or months, with gradual weaning as lung function improves. Invasive or noninvasive respiratory support may be necessary in severe cases 4 8 14.

Diuretics and Fluid Management

Diuretic medications help reduce excess fluid in the lungs, improving breathing and gas exchange. However, long-term use is approached cautiously, with gradual reduction as children grow 4 14.

Bronchodilators and Steroids

Bronchodilators are considered for children who exhibit reversible airway obstruction or asthma-like symptoms, but are not recommended for all patients. The use of inhaled or systemic steroids is controversial: while they can reduce inflammation and facilitate extubation, concerns remain regarding side effects and long-term neurodevelopmental outcomes, especially with early systemic corticosteroid use 4 13 14.

Management of Pulmonary Hypertension

For children who develop pulmonary hypertension, targeted therapies to lower pulmonary vascular resistance may be required. This is a serious complication that demands specialized care and often additional diagnostic monitoring 4 5.

Environmental and Supportive Measures

Mitigating exposure to indoor air pollution and secondhand smoke is crucial for respiratory health in BPD. Home air purifiers may help reduce some negative effects 3. Nutritional support, growth monitoring, and developmental assessments are integral to comprehensive care 8 14.

Multidisciplinary and Long-Term Care

Given the complexity of BPD, especially in severe cases, a multidisciplinary team—including pulmonologists, nutritionists, physical therapists, and developmental specialists—is essential for optimizing outcomes. Long-term follow-up into adolescence and adulthood is needed, as some individuals may develop chronic obstructive pulmonary disease (COPD) or other late consequences 8 14.

Experimental and Emerging Therapies

Research is ongoing into novel therapies such as stem cell transplantation, which has shown some promise in early-phase trials but is not yet standard care 15 16. Other potential treatments target molecular pathways involved in inflammation and lung growth, but more evidence is needed before widespread adoption 15.

Conclusion

Bronchopulmonary dysplasia is a complex, evolving disorder with lifelong consequences for many affected individuals and families. Advances in neonatal care have changed its face, but challenges remain.

Main points:

• Symptoms: Range from chronic cough and wheezing to exercise intolerance, frequent infections, and, in severe cases, pulmonary hypertension.
• Types: The disease has shifted from "old" (fibrotic, scarred) forms to "new" (arrested development) types, with subtyping based on parenchymal, airway, and vascular involvement.
• Causes: Multifactorial, including prematurity, oxygen/ventilator-induced injury, inflammation, infection, genetic predisposition, and environmental exposures.
• Treatment: Multidisciplinary, focusing on oxygen therapy, diuretics, bronchodilators (for some), cautious steroid use, management of complications, and minimizing environmental risks. Experimental therapies are under investigation.

With ongoing research and coordinated care, the prognosis for children with BPD continues to improve, but vigilance for late complications and a holistic approach to management remain essential.