[Changes in intrapulmonary compression gas volume during measurement of the flow-volume curve]

Changes in intrapulmonary compression gas volume during flow-volume curve measurement were studied in 77 patients with bronchial asthma, 20 patients with emphysema, and 14 patients with pulmonary fibrosis. The peak point of intrapulmonary compression gas volume was observed at FEF 75 in the bronchial asthma and emphysema patients, and of FEF 25 in the pulmonary fibrosis patients. In the bronchial asthma patients, intrapulmonary compression gas volume increased significantly compared to the healthy control groups; that increase was especially obvious in cases where airway obstruction was severe, e.g. when FEV 1.0% was below 69% (p < 0.05). By contrast, the emphysema patients did not exhibit any significant increase in intrapulmonary compression gas volume compared to healthy control groups despite the existence of obstructive impairments. This study demonstrated that the intrapulmonary compression gas volume-curve is a useful index for the diagnosis of pulmonary diseases when combined with measurements of FVC and FEV 1.0%.