Obliterative Bronchiolitis (OB) is a rare, irreversible, life-threatening form of interstitial lung disease that occurs when the small airway branches of the lungs (bronchioles) are compressed and narrowed by scar tissue (fibrosis) and inflammation. Extensive scarring results in decreased lung function. Causes of OB include collagen vascular disease, organ transplant rejection, viral infections, drug reactions, prematurity complications, rheumatoid arthritis, oral emergency medicines (for example, activated charcoal), exposure to toxic fumes (for example, diacetyl, sulfur dioxide, ammonia, chlorine, mustard gas, ozone), and idiopathic (no known cause). Symptoms of OB include coughing (usually without phlegm), shortness of breath on exertion, wheezing, fever, night sweats, weight loss, frequent or persistent eye, nose, and throat or skin irritation.
OB is not the same disorder as bronchiolitis obliterans organizing pneumonia (BOOP), which is a treatable disorder with a favorable prognosis. OB is also a distinctly different disorder than pediatric bronchiolitis, which is a very common childhood respiratory illness with a good prognosis.
DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Diagnostic testing: OB can only be definitely diagnosed by a lung biopsy. Other diagnostic testing for OB includes lung volume assessments and chest x-ray with evidence of hyperinflation; and high resolution computerized tomography (CT) of the chest at full inspiration and expiration showing evidence of heterogeneous air trapping, mosaic attenuation, bronchial wall thickening, cylindrical bronchiectasis, or scattered ground glass opacities. Spirometry may show airway obstruction or restriction that is generally unresponsive to bronchodilators. OB can only be definitely diagnosed by a lung biopsy.
ONSET AND PROGRESSION
The progression of OB varies from person to person with symptoms starting either gradually or suddenly. Two to eight weeks after a respiratory illness or exposure to toxic fumes, dry cough, shortness of breath (especially on exertion), fatigue, and wheezing may occur. Severe cases often require a lung transplant. Post-lung transplantation, OB continues to be a major life-threatening complication, affecting up to 50-60% of people who survive five years after transplantation.
There is currently no cure for OB. Bronchodilators, inhaled corticosteroids, oxygen supplementation, and, in the case of lung transplantation, immunosuppressants, are prescribed to control symptoms. Response to treatment is generally poor.
Suggested MER for evaluation:
Clinical history and examination that describes diagnostic features and physical findings
CT scans, pulmonary function tests ( PFTs, spirometry, DLCO, or ABG)
Response, if any, to a regimen of treatment