From the Guidelines
Obliterative bronchiolitis is a serious lung disease that requires prompt treatment with immunosuppressants and potentially azithromycin to slow disease progression and improve quality of life, as recommended by the British Thoracic Society guideline 1.
Definition and Causes
Obliterative bronchiolitis is characterized by inflammation and scarring of the small airways, leading to progressive airflow obstruction. It can occur after lung or bone marrow transplantation, exposure to toxic fumes, certain medications, connective tissue diseases, and severe respiratory infections 1.
Symptoms and Diagnosis
Symptoms typically include shortness of breath, dry cough, wheezing, and fatigue that worsen over time. Early diagnosis is crucial but challenging, often requiring high-resolution CT scans and pulmonary function tests showing fixed airflow obstruction 1.
Treatment and Management
Treatment focuses on slowing disease progression rather than cure, primarily using immunosuppressants like corticosteroids (prednisone 0.5-1 mg/kg/day, tapered based on response) and calcineurin inhibitors (tacrolimus, cyclosporine) 1. Azithromycin (250-500 mg three times weekly) may be used for its anti-inflammatory properties, especially in patients with neutrophilic bronchoalveolar lavage results 1. Bronchodilators like albuterol or tiotropium may help symptom management, and oxygen therapy is often needed as the disease progresses. In severe cases, lung transplantation may be considered.
Key Considerations
The disease mechanism involves an abnormal immune response causing inflammation that leads to irreversible fibrosis of the airways, making prevention through minimizing exposure to known triggers particularly important for high-risk individuals 1. The use of long-term macrolides, such as azithromycin, has been shown to be effective in preventing and treating bronchiolitis obliterans syndrome (BOS) in lung transplant patients, and should be considered as part of the treatment plan 1.
From the Research
Definition and Characteristics
- Obliterative bronchiolitis (OB) is a clinical syndrome marked by progressive dyspnea and cough with the absence of parenchymal lung disease on radiographic studies 2.
- Pulmonary function testing reveals an obstructive ventilatory defect that is typically not reversed by inhaled bronchodilator 2.
- The diagnosis of OB is often based on clinical, physiological, and radiological data, and transbronchial biopsies are insufficiently sensitive to achieve diagnosis 2.
Causes and Risk Factors
- OB has been documented in a variety of exposures, including fumes from flavoring plants, smoke from burn pits, and environmental sulfur gas 2.
- Among lung transplant recipients, "bronchiolitis obliterans syndrome," a disorder with clinical and histopathological similarity to OB, represents the leading cause of long-term allograft dysfunction and mortality 2, 3, 4.
- Severe acute rejection and recurrent acute rejection have been shown to confer the greatest risk for obliterative bronchiolitis, signifying the central importance of alloimmunity in the disease process 4.
Treatment and Management
- Augmentation of immunosuppression is occasionally effective in slowing or reversing the progression of disease, though a significant number of patients will be nonresponders 2.
- Long-term azithromycin treatment has been shown to improve FEV1 in about 42% of patients with established bronchiolitis obliterans syndrome (BOS) 3, 5.
- Azithromycin can down-regulate pulmonary inflammation, and its beneficial effects on gastroesophageal reflux disease may be a mechanism of action 5.
- A multidisciplinary approach and care in specialized centers are required for the management of bronchiolitis obliterans, particularly in children 6.
Diagnosis and Prognosis
- The diagnosis of OB is usually based on a combination of history, clinical and radiological findings, although lung biopsy and histopathology remain the gold standard approaches to confirm OB 6.
- The prognosis of OB is often poor, with significant progression of disease, and lung transplantation (or retransplantation) may be necessary 2.