Diffusion coefficients and solubility coefficients for gases in biological fluids and tissues: a review

Abstract

Based on a review of 166 references for diffusion and solubility coefficients in biological fluids and tissues, we have tabulated experimental values for the gases Ar, CO2, H2, He, N2, Ne, N2O, O2, and SF6. Two major conclusions can be drawn: a) for tissues, there is a scarcity of available data; and b) in general, there are significant differences between values determined by different investigators, the discrepancies being most prominent for diffusion coefficients. For water, we give numeric values of the temperature coefficients and preferred diffusion and solubility coefficients at 25 degrees and 37 degrees C. Further, we describe several methods for estimation of coefficients where experimental data are lacking. For tissues, none of the formulas described give precise predictions for all gases, but rough estimates sufficient for most qualitative work can almost always be found. In particular, the data material indicates that for all tissues other than fatty tissues consisting of mainly triacylglycerols, the solubility coefficients for water may be used as a good approximation. Except for SF6, the error in this approximation probably does not exceed 20%. In contrast, diffusion coefficients for most tissues are from 25 to 50% lower than the respective coefficients in water, generally increasing with the water content of the tissue.