Bronchiolitis Obliterans

Key Features

Essentials of Diagnosis

• Persistent symptoms of airway obstruction 8 weeks after the resolution of a lower respiratory tract infection

• Chest CT shows a mosaic pattern of hyperinflation and vascular attenuation

General Considerations

• Rare chronic obstructive lung disease

• Characterized by complete obliteration of the small airways following a severe insult

• Most common form in children is postinfectious, following a lower airway tract infection with adenovirus; influenza, rubeola, Bordetella, and Mycoplasma are also implicated

• Other causes include

  • Connective tissue diseases

  • Chronic aspiration

  • Stevens-Johnson syndrome

  • Posttransplantation (lung or bone marrow)

  • Inhalational injury

• Many cases of bronchiolitis obliterans are idiopathic

• Mechanical ventilation for severe adenoviral respiratory infection is a strong risk factor

Clinical Findings

Symptoms and Signs

• Dyspnea

• Cough

• Exercise intolerance

Differential Diagnosis

• Poorly treated asthma

• Cystic fibrosis

• Bronchopulmonary dysplasia

Diagnosis

• Chest radiograph abnormalities include evidence of heterogeneous air trapping and airway wall thickening

• Classic findings on high-resolution chest CT include

  • Mosaic perfusion pattern

  • Vascular attenuation

  • Central bronchiectasis

• Ventilation-perfusion scans

  • May show pattern of mismatch

  • Not typically required for diagnosis

• Pulmonary angiograms reveal decreased vasculature in involved lung

• Bronchograms show marked pruning of the bronchial tree

Treatment

• Supportive care

  • Supplemental oxygen for hypoxemia

  • Routine vaccination

  • Avoidance of environmental irritant exposure

  • Exercise

  • Nutritional support

• Inhaled bronchodilators (β-agonists and anticholinergic) may reverse airway obstruction if the disease has a reactive component

• Systemic corticosteroids

  • May help reverse the obstruction or prevent ongoing damage

  • Monthly pulse-dose corticosteroids will reduce the risk of adverse effects associated with long-term corticosteroids.

• Antibiotics should be used as indicated for pneumonia

• Azithromycin has been shown to have therapeutic benefit in bronchiolitis obliterans syndrome after lung transplantation

• Lung transplant may be an option for patients with severe, progressive disease

Outcome

Complications

• Persistent airway obstruction

• Recurrent wheezing

• Bronchiectasis

• Chronic atelectasis

• Recurrent pneumonia

• Unilateral hyperlucent lung syndrome

Prognosis

• Depends in part on the underlying cause as well as the age of onset

• Postinfectious bronchiolitis obliterans tends to be nonprogressive with low mortality and the possibility of slow improvement

• Bronchiolitis obliterans resulting from transplantation or Stevens-Johnson syndrome may have a rapidly progressive course leading to death or need for lung transplantation

References