Diffuse fibrotic lung disease: a correlative study
Diffuse fibrotic lung disease is a complex, clinically protean disorder. The authors have undertaken a large scale, multidisciplinary study of the etiology, pathogenesis, pathophysiology, and therapy of this disorder. This paper presents correlative clinical, physiologic, and pathologic data in a selected group of patients with diffuse fibrotic lung disease. The data suggest the following: obstructive disease of airways with increased resistance to air flow is present in a significant percentage of patients with diffuse fibrotic lung disease; although the peak transpulmonary pressure correlated with the degree of fibrosis, the lack of correlation of other parameters of the volume pressure curve with the histopathology casts doubt on the usefulness of the volume pressure relationships as a longterm monitor of diffuse fibrotic disease; exercise physiologic testing with quantitation of the rate of change in PaO2 with oxygen consumption appears to be the most sensitive correlate to clinical severity of disease; the dead space to tidal volume ratio during exercise correlates poorly with evidence of pulmonary vascular disease, but appears to correlate well with evidence of obstruction of airways. The value of this test in the diagnosis of pulmonary vascular disease must be interpreted in light of co existing abnormalities of distribution of ventilation.