A combined macro and microvascular model for whole limb heat transfer

Area of Science:

• Physiology
• Biomedical Engineering
• Thermodynamics

Background:

• Accurate modeling of heat transfer in limbs is crucial for understanding thermoregulation.
• Existing models often simplify complex microvascular and macrovascular interactions.
• Limb heat exchange is influenced by environmental conditions, activity levels, and tissue perfusion.

Purpose of the Study:

• To develop a new prototype model for whole limb heat transfer.
• To couple countercurrent heat exchange in central vessels with microvascular models of muscle and cutaneous tissues.
• To analyze limb temperature distribution and venous return under diverse conditions.

Main Methods:

• A coupled model integrating macrovascular countercurrent heat exchange with microvascular bioheat equations (Weinbaum and Jiji).
• Incorporation of arbitrary axial variations in tissue cross-sectional area and blood distribution.
• Inclusion of hand heat exchange and treatment of venous return and surface temperatures as unknowns.

Main Results:

• The model successfully simulates local microvascular temperature fields within muscle tissue.
• It accounts for blood flow and heat loss from the hand.
• Representative solutions are provided for resting and exercising limbs across a range of environmental conditions.

Conclusions:

• The proposed model offers a more comprehensive approach to whole limb thermoregulation.
• It allows for detailed analysis of temperature dynamics in different tissue layers.
• The model is valuable for studying physiological responses to thermal stress and exercise.