Hyperthermia

Hyperthermia refers to a body's core temperature that is abnormally high due to external heat or impaired heat dissipation, without a change in the hypothalamic set point. It is distinct from fever, where the body's thermostat is raised in response to infection or inflammation.

Common causes include heat exposure in hot environments, strenuous exercise in heat, or conditions that impair sweating or circulation. In addition, malignant hyperthermia is a rare genetic reaction to certain anesthetics or muscle relaxants, causing rapid temperature rise. Severe hyperthermia can progress to heat stroke, with impaired mental status and organ dysfunction.

Excess heat overwhelms thermoregulation, leading to accelerated metabolism, protein and enzyme denaturation, and cellular injury. High temperatures disrupt membranes, trigger inflammatory responses, and may cause multiorgan failure if not promptly treated.

Diagnosis is based on core body temperature and clinical signs such as altered mental status, tachycardia, and dehydration. Treatment focuses on rapid cooling (ice water immersion or evaporative cooling), removal of heat sources, hydration, and electrolyte management. Malignant hyperthermia requires dantrolene administration and cessation of triggering agents.

Hyperthermia therapy refers to deliberate elevation of tumor temperature to 40-45°C to enhance radiotherapy or chemotherapy. It can be locally or regionally applied using various devices; mechanisms include increased tumor perfusion, oxygenation, and sensitization of cancer cells to radiation.

Prognosis depends on cause and speed of treatment; with prompt cooling, outcomes are favorable for heat-related illnesses. Prevention includes acclimatization, hydration, cooling strategies, and avoiding high-risk activities during heat waves.