Property value estimation for inhaled therapeutic binary gas mixtures: He, Xe, N2O, and N2 with O2

In this paper estimates based on kinetic theory are provided of density, viscosity, mean free path, thermal conductivity, specific heat at constant pressure, and diffusivity over a range of concentrations of He-O2, Xe-O2, N2O-O2 and N2-O2 mixtures at room (or normal) and body temperature, 20 and 37°C, respectively and at atmospheric pressure.Property value estimations have been provided for therapeutic gas mixtures and compared to experimental values obtained from the literature where possible.Inhaled therapeutic gases in use today include helium (He) for respiratory treatments, and xenon (Xe) and nitrous oxide (N2O) for anesthesia. For clinical applications these gases are used in the form of mixtures with oxygen in a range of concentrations (typically starting from 20% oxygen (O2) concentration by volume, which is equivalent to a mole fraction of 0.20) so as to maintain adequate oxygenation. Other gases, such as nitric oxide (NO) for pulmonary vascular dilation, are used only in trace amounts.The property values of therapeutic gas mixtures are important in designing devices, defining delivery parameters, and in understanding the therapeutic effects. Properties of interest include density, viscosity, mean free path, thermal conductivity, specific heat, and diffusivity. In the medical literature the vast majority of articles related to gas mixtures report property values only for the pure substances or estimates based on (volume or molar) concentration weighted averages [1-7]. However, if the molecular size or structures of the component gases are very different a more accurate estimate could be considered [8-10]. For this reason property values of helium and xenon mixtures should be considered for more accurate estimation.Starting with kinetic theory for molecules treated as hard spheres as a basis, a rich literature has developed regarding the modeling of property values based on first principles and increasing complexity of the molecular interactions; in particul