Shape of the Expiratory Flow-volume Curve of Chronic Obstructive Pulmonary Disease and Interstitial Pneumonia Patients at Rest and during Exercise

[Purpose] We examined the shape of the expiratory flow-volume (FV) curve of chronic obstructive pulmonary disease (COPD) and interstitial pneumonia (IP) patients at rest and during exercise. [Subjects] The subjects were 9 COPD patients and 8 IP patients. [Method] We plotted the expiratory FV curve of subjects at rest and while subjects pedaled a bicycle ergometer, and compared the FV curves, lung capacity changes, and expiratory flow limitations between the two groups of patients. [Results] Expiratory flow limitation and dynamic hyperinflation were more apparent in COPD patients, and the shape of the expiratory FV curve was more likely to be concave during exercise. Expiratory flow limitation was not often seen in IP patients, and the expiration FV curve was convex, both at rest and at peak exercise. [Conclusion] The shape of the expiratory FV curve of COPD patients shows greater concavity during exercise than that of IP patients.