Reduced pulmonary diffusion capacity is a hallmark of COPD, although the relative contribution of the subcomponents of pulmonary diffusion--membranous component (Dm) and capillary volume (Vc)--is unknown. These components can be measured with the method of NO single-breath diffusion (DLNO). In a prospective study, pulmonary function tests including spirometry, body plethysmography and single-breath measurements of diffusion capacity with CO and NO were performed in 183 patients with COPD of varying severity. There was a severity-dependent decrease in DLCO. Furthermore, Dm as well as Vc was positively correlated with the severity of COPD measured by FEV1. In all stages of COPD, reduction of Vc was more pronounced than constriction of Dm. In patients with most severe COPD, the preponderance of the reduction of Vc was significantly more marked than in milder stages.We conclude that Dm as well as Vc contributes to the reduction of DLCO in COPD, with a predominance of Vc at all stages of COPD. This confirms the idea that the loss of pulmonary capillaries in COPD is functionally relevant.
Interferon alpha (IFN α)-based treatment of chronic hepatitis C viral (HCV) infection may induce pulmonary and extrapulmonary sarcoidosis. We report a case of a 50-year-old male patient who suffered from hepatitis C-induced liver cirrhosis with respiratory insufficiency due to severe hepatopulmonary syndrome. After 9 months of treatment with IFNα and ribavirin, he developed an asymptomatic, clinically occult pulmonary granulomatosis, which was not detectable in CT. The diagnosis was made by bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy. The condition did not progress to clinically apparent disease despite continuation of IFN alpha treatment.
A 45-year-old man referred with progressive shortness of breath. Chest X-ray revealed a diffuse parenchymal process in the lungs, which was characterized as a "crazy paving" pattern in the thoracic CT. Pulmonary function test showed severe impairment of diffusion capacity and apparent respiratory insufficiency. Bronchoalveolar lavage and histological examinations of transbronchial lung biopsies revealed alveolar proteinosis. Because of the presence of anti-granulocyte macrophage colony-stimulating factor (GM-CSF) autoantibodies, a primary form of this disorder was diagnosed. Therapeutic whole-lung lavage was performed twice and resulted in a continuing remission.
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