Dual Role of Diffusion in Tissue Gas Exchange: Blood-Tissue Equilibration and Diffusion Shunt

Abstract
In a previous study the washout kinetics of two inert gases of different diffusivity, methane (CH4) and sulfur hexafluoride (SF6), was found to be incompatible with the assumption of exclusive perfusion limitation (Piiper and Meyer, in press). Also models with additional tissue-blood diffusion limitation could not explain the experimental findings. Only a model incorporating veno-arterial back diffusion appeared to provide a satisfactory agreement between model predictions and experimental data.