Heat Exhaustion and Heatstroke: Pathophysiology, Autopsy Findings, and Complications

What is heat exhaustion?

A condition resulting from hypovolemia due to increased dehydration, leading to cardiovascular system failure.

What causes hyperthermia?

Prolonged exposure to elevated ambient temperatures and high humidity.

What is heat stroke?

The most severe type of heat exhaustion, associated with high temperatures, high humidity, and physical exertion.

What are common autopsy findings in heat-related deaths?

Visceral petechial hemorrhages on the heart, thorax, lungs, and thymus.

What are the cardiac autopsy findings associated with heat stress?

Subendocardial hemorrhages, myofiber degeneration, and transmural infarction.

What liver conditions are associated with heat-related illnesses?

Centrolobular congestion and necrosis.

What brain conditions can result from heat stress?

Congestion, edema, petechial hemorrhages, and degeneration of Purkinje cells.

What complications can arise after surviving heat-related illness?

Pneumonia, adult respiratory distress syndrome (ARDS), and acute tubular necrosis.

What is adrenal necrosis?

A condition that can occur as a complication of severe heat exhaustion.

What physiological effect does heat stress have on blood volume?

Marked vasodilation resulting in decreased circulating blood volume.

What electrolyte imbalance can occur due to heat stress?

Hyperkalemia.

What heart conditions can be caused by heat stress?

Tachycardia and arrhythmias.

What contributes to hyperthermia during heat stress?

Sustained contraction of skeletal muscle, which can lead to rhabdomyolysis.

What is the role of ryanodine receptor 1 (RYR 1) in heat stress?

RYR 1 regulates calcium release in muscle cells; its dysfunction leads to calcium leakage and increased muscle contraction.

What happens to thermal regulatory mechanisms during heat stroke?

They fail, leading to cessation of sweating and a rise in core temperature above 40°C.

Who is particularly at risk for heat-related illnesses?

The elderly, individuals with underlying conditions, and those undergoing physical activity.