[Viscosity and density fluctuations of natural respiratory gases and of mixtures of helium, oxygen and nitrogen due to temperature and composition of the gas mixture (author's transl)].

For the estimation and correction of errors in the measurement of the respiratory flow with viscosity-affected respiratory flow receptors the viscosity of natural respiratory gases (N2, O2, CO2, H2O) and of the ternary system helium-oxygen-nitrogen, which is of importance in pulmonary function diagnosis, was determined. Corresponding density values were calculated. Allowance was made for such special features of spirometry as exchange of O2 for CO2 and water vapour saturation at 37 degrees C. The viscosity of the ternary system is shown in a graph. The formulae indicated have been simplified as far as this was compatible with the demands of accuracy. The fluctuations in density and viscosity of natural respiratory gases can be read directly from a table.