Abstract

The values determining the pulmonary gas exchange, alveolar ventilation (VA), lung perfusion (Q), and O2 diffusing capacity (DL), were ascertained in numerous experiments for various forms and intensities of physical work. However, a theoretical analysis of the gas exchange conditions on the basis of this data has not yet been carried out. An analysis of this is possible now since alignment nomograms exist, from which the alveolar and endcapillary O2 and CO2 partial pressures can be determined as functions of VA/Q and DL/Q. The aim of this theoretical investigation was to calculate the alveolar-arterial partial pressure differences (AaD) as functions of the work intensity and to analyze the factors influencing AaD. The alveolar-arterial O2 partial pressure difference (AaDO2) can be attributed to three factors, namely the inhomogeneities of VA/Q, the limitation of the O2 diffusion by the value of DL/Q, and the admixture of venous shunt blood. The pertinent AaDO2 portions can be quantitatively determined by means of those nomograms. One thus obtains evidence for the degree to which the above-mentioned factors, for various loads, contribute to the overall AaDO2. Verf.-Referat (gekuerzt)