Pulmonary Diffusion of Carbon Dioxide

Changes of O2 and CO2 pressures and concentrations of blood passing through the lungs have been calculated for one specific case, assuming normal values for the physiological parameters involved, constant alveolar pressures of O2 and CO2, and validity of the diffusion hypothesis. It is concluded that CO2 does not diffuse as rapidly as is generally assumed, the rate being initially about 2·5 times the mean rate, then decreasing gradually to about half the mean rate and finally increasing to the mean rate.