OBLITERATIVE BRONCHIOLITIS

Bronchiolitis Obliterans; Constrictive Bronchiolitis

Obliterative Bronchiolitis (OB) is a rare, irreversible, life-threatening form of 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 diseases, especially rheumatoid arthritis, organ transplant rejection, viral infections, drug reactions, prematurity complications, , 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 and fatigue,

OB is not the same disorder as bronchiolitis obliterans organizing pneumonia (BOOP), now known as cryptogenic organizing pneumonia (COP), 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: Although a definitive diagnosis of OB requires can only made by a lung biopsy, other diagnostic tests which aid in the diagnosis include:

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  Lung volume measurements showing an elevated residual volume and chest x-ray with evidence of hyperinflation;

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  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; and

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  Spirometry which typically shows airway obstruction that is generally unresponsive to bronchodilators. A restrictive pattern may be seen in some cases.

Physical findings:

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  Dry cough;

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  Shortness of breath; and

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  Fatigue and wheezing in the absence of a cold or asthma.

ICD-9: 491.8

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 may require a lung transplant. Post-lung transplantation, OB continues to be a major life-threatening complication, affecting up to 50% 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 PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and examination that describes diagnostic features and physical findings;

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  Biopsy reports;

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  CT scans;

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  Pulmonary function tests ( PFTs) including diffusing capacity of the lungs for carbon monoxide (DLCO) tests, spirometry, and arterial blood gas (ABG) tests; and

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  Response, if any, to a regimen of treatment.

Suggested Listings for Evaluation:

REMARKS

A description of findings establishing the diagnosis and response to treatment is needed when evaluating this condition.