The effect of temperature on the oxygen equilibrium curve of human blood

Abstract

The oxygen affinity of human blood was measured with the micro blood film technique over six-degree temperature intervals from 13 to 43°C. Results are expressed both as standard curves at pH 7.4 and for conditions of constant carbon dioxide content. P 50 (7.4) values found were 5.8, 8.3, 13.2, 19.7, 26.9 and 33.7 Torr at 13, 19, 25, 31, 37 and 43°C, respectively. The shape of the blood oxygen equilibrium curve was invariant with temperature. The measured CO 2-Bohr coefficient (Δlog P 50/ΔpH) ranged from −0.46 to −0.51 and was not temperature dependent. P 50 data for 7.4 followed a van't Hoff isochore with a slope, Δlog P 50/Δ(1/T K), of −2350 degrees and an enthalpy per mol of oxygen bound of −8.2 kcal/mol. Temperature dependence of blood oxygen affinity expressed for conditions of constant carbon dioxide content exceeds that of the standard curve. New data are used to calculate the temperature dependence of blood oxygen tension at constant total gas content as a functional of initial P O 2 and saturation.