[Respiratory gas exchange during breathing of O2 in different inert gases (author's transl)].

In 15 patients with chronic bronchitis with or without emphysema breathing of room air was compared with breathing of 20.9% O2 in helium and in argon. Minute ventilation and alveolar ventilation showed no differences, whereas the alveolar and arterial pO2 and PCO2 showed an improvement of the CO2 gas exchange and a deterioration of the O2 gas exchange. This contradictory behaviour cannot be explained by shunts or inhomogeneities or influence of gaseous or alveolo-capillary diffusion. Perhaps the physicochemical properties of the alveolo-capillary membrane change by the depletion of nitrogen. The recommendation of helium-oxygen breathing, proposed by other authors for patients with obstructive airway diseases, cannot be supported, when the gas exchange for O2 is deteriorated.