Symptoms

The main respiratory symptoms experienced by workers affected by bronchiolitis obliterans include cough (usually without phlegm) and shortness of breath on exertion. The severity of the lung symptoms can range from only a mild cough to severe cough and shortness of breath on exertion. These symptoms typically do not improve when the worker goes home at the end of the workday or on weekends or vacations. Usually these symptoms are gradual in onset and progressive, but severe symptoms can occur suddenly. Some workers may experience fever, night sweats, and weight loss. Before arriving at a final diagnosis, doctors of affected workers initially thought that the symptoms might be due to asthma, chronic bronchitis, emphysema, pneumonia, or smoking.

Medical testing may reveal several of the following findings:

• Spirometry, a type of breathing test
• often shows fixed airways obstruction (i.e., difficulty blowing air out fast and no improvement with asthma medications)
• sometimes shows restriction (i.e., decreased ability to fully expand the lungs)
• Lung volumes may show hyperinflation (i.e., too much air in the lungs due to air trapping beyond obstructed airways)
• Diffusing capacity of the lung (DLCO) is generally normal, especially early in the disease
• Chest X-rays are usually normal but may show hyperinflation
• High-resolution computerized tomography scans of the chest at full inspiration and expiration may reveal heterogeneous air trapping on the expiratory view as well as haziness and thickened airway walls
• Lung biopsies may reveal evidence of constrictive bronchiolitis obliterans (i.e., severe narrowing or complete obstruction of the small airways). An open lung biopsy, such as by thoracoscopy, is more likely to be diagnostic than a transbronchial biopsy. Special processing, staining, and review of multiple tissue sections may be necessary for a diagnosis