Pulmonaler Gasaustausch nach Ersatz des Luftstickstoffs durch andere inerte Gase
Pulmonary gas exchange after replacement of air by other inert gases
The influence of physical properties of the breathing medium on alveolar gas exchange was studied measuring alveolar-arterial partial pressure differences (ΔP) for 02 and CO2 in artificially ventilated, anesthetized dogs replacing air nitrogen by helium, argon or sulphur hexafluoride. In both hypoxia and normoxia the ΔPO2 were found to decrease in the sequence He-O2 >N2-O2>Ar-O2>SF6-O2, while ΔPCO2 remained practically unchanged. Additional measurements of pulmonary diffusing capacity for CO (DCO) using the single breath technique revealed no significant differences between the four gas mixtures used. To interpret these results the possible roles played by diffusion limitation (stratification), Taylor dispersion and viscosity-dependent ventilation-perfusion inhomogeneities are discussed.
Key wordsAlveolar-arterial PO2 and PCO2 differences CO transfer Inert gases Stratification distribution
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