Analysis of Tissue Temperature Variation Considering Blood Oxygen Dissociation Curves

Abstract

When blood flow is partially blocked by external pressure, heat transport by blood flow is reduced proportionally to the blood flow rate. However, heat generated by metabolism is not reduced as that of the heat transport by blood flow because hemoglobin releases more oxygen to tissues due to the shift of the oxygen dissociation curve which is induced by changes in the tissue oxygen content, pH and temperature. The temperature variation of tissues subject to such reduction of blood flow rate is analyzed numerically using the Pennes' bio-heat equation. In the equation, the heat transport by blood flow and the metabolic heat generation are assumed to be proportional to the blood flow rate, and the metabolic heat generation is estimated from the existing oxygen dissociation curve. As the result, the difference between the decrease of heat transport by blood flow and that of oxygen release by hemoglobin has been found to result in the shift of the equilibrium tissue temperature to a higher temperature when the tissues are thermally insulated from outside.