Pathophysiology of Heat Transfer

Heat transfer to and from the body occurs via the following four mechanisms: conduction, convection, radiation, and evaporation. Elderly persons are at an increased risk for heat-related illness because of underlying illness, medication use, declining adaptive thermoregulatory mechanisms and a limited social support network. Underlying causes of decreased thermoregulatory mechanisms include heart disease, skin diseases, extensive burns, dehydration, endocrine disorders such as diabetes and thyroid disorders, neurologic diseases and fever.

Heat Transfer Examples

A paramedic who is standing in their underwear in a desert will result in vasoconstriction of the core vasculature, and the vasodilation of the peripheries. This leads to a shunt of the bulk of the person’s blood from the core to the peripheries, where they can cool more rapidly.

Contrastingly, if the same paramedic ended up in the snow still their underwear, their peripheries would vasoconstrict, shunting blood from the peripheries to the core, in order to maintain as much body temperature as possible.