Differential diagnostic significance of complex values of gas exchange during submaximal physical effort in patients with emphysema and pulmonary fibrosis]

The aim of this study was to clarify a) whether the behaviour of functional dead space ratio (VD/VE), alveolo-arterial difference of oxygen tensions (AaDO2) and the venous admixture ratio (QVA/Qt) differed at rest and during submaximal exercise, between patients with pulmonary emphysema and interstitial pulmonary fibrosis as well as from the respective findings in healthy controls, and b) whether a differentiation between these two diseases could be achieved by investigations of complex pulmonary gas exchange. Eleven patients with pulmonary fibrosis (F), which had been diagnosed by pulmonary biopsies, 11 patients with pulmonary emphysema (E) and 11 healthy controls (C) were subjected to conventional pulmonary function tests (PFTs: spirometry, bodyplethysmography, DCO) immediately followed by examinations of pulmonary gas exchange conducted at rest and during an incremental submaximal cycle spiroergometry (ERGO). With normal PFTs for C, vital capacity was diminished in F and the 1" timed vital capacity (FEV1) as well as Tiffeneau's index were reduced in E, while air way resistance and functional residual capacity were augmented in the latter group. In all patients the CO-diffusing capacity was lower compared to C, however, without differences between F and E. In both E and F, the arterial O2 tension were lower at rest as well as during ERGO when compared to C, whereas VD/VE, QVA/Qt and AaDO2 as well as the specific ventilation for O2 were higher, respectively. Alveolar ventilation was similar in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)