Development of an FEA-Based Whole-Body Human Thermal Model for Evaluating Blood Cooling/Warming Techniques

Whole- body thermal models can be useful to predict physiological and thermal responses to clinical treatments and environmental changes. Existing models extensively simplify body geometry and incompletely or inaccurately represent the thermal interaction between blood and tissue, producing results of minimal value. Additionally, existing models often require custom- written computer code and extensive computational resources, which limit their use. The present work develops a new whole- body thermal model using a commercially available FEA software to accurately assess thermal interaction between vasculature, body tissue, environment, and thermal treatment. This model proposes a more accurate body geometry, including an internal region representing vital organs. Body blood is represented as a lumped system, for which an energy balance equation is developed. This energy balance is coupled with the energy flow in body tissue, which is modeled by the Pennes bioheat equation. The developed model is tested in a case study which evaluates the effectiveness of inducing hypothermia via intravenous infusion of a mixture of 50% ice/ 50% saline at a rate of 450 ml/ hr. The blood energy balance is temporally discretized, and simulation is performed in a time- step fashion. Body temperature distribution and blood temperature are reported at each time step. Results indicate that body temperature reduction of 0.58° C is obtained in the first hour of the treatment, and approximately 2.3 hrs are required to achieve a 1.0° C body temperature decrease. Results can be extrapolated for lengthy treatments. Agreement with clinical studies suggests potential for the model to be used in simulating other dynamic thermal processes