What are the diagnostic criteria and management strategies for heat stroke (Hyperthermia)?

From the Guidelines

Heat stroke is a life-threatening emergency that requires immediate cooling and supportive care, with the goal of reducing core body temperature to less than 39°C (102.2°F) as quickly as possible, as recommended by the 2020 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations 1. The diagnostic criteria for heat stroke include a core body temperature exceeding 40°C (104°F) with central nervous system dysfunction in the setting of heat exposure. Management begins with immediate cooling and supportive care.

• Move the patient to a cool environment and remove excess clothing.
• Initiate rapid cooling using whole-body (neck-down) water immersion (1°C–26°C, or 33.8°F–78.8°F) until the core body temperature is less than 39°C (102.2°F), as recommended by the 2020 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations 1.
• If water immersion is not possible, use any other active-cooling methods, such as cold water dousing, ice packs to neck/groin/axillae, or evaporative cooling with fans and water misting.
• Continuously monitor core temperature, aiming to reduce it to 38-39°C within 30 minutes to prevent overcooling.
• Provide IV fluid resuscitation with isotonic crystalloids like normal saline, typically starting with 1-2 liters while monitoring for volume overload, as the hemodynamic management of heatstroke should include fluid replacement sufficient to restore blood pressure and tissue perfusion 1.
• Manage seizures with benzodiazepines such as lorazepam 2-4mg IV or diazepam 5-10mg IV.
• Treat hypoglycemia with D50W 50mL IV if needed.
• Monitor for and address complications including rhabdomyolysis, acute kidney injury, electrolyte abnormalities, coagulopathy, and hepatic injury. The 2024 American Heart Association and American Red Cross guidelines for first aid also emphasize the importance of rapid cooling and intravenous fluids in the management of heatstroke, and highlight that survival from heatstroke is related to the speed at which temperature reduction is achieved; faster cooling is associated with better survival 1.
• Patients require hospital admission for continued monitoring and management of complications. Heat stroke causes multi-organ dysfunction through direct thermal injury to tissues, systemic inflammatory response, and endothelial damage, making rapid cooling crucial to prevent irreversible organ damage and death.

From the Research

Diagnostic Criteria for Heat Stroke

• Heat stroke is defined as a core body temperature >40.6 degrees C, with associated clinical manifestations such as extreme fatigue, hot dry skin or heavy perspiration, nausea, vomiting, diarrhea, disorientation, dizziness, uncoordinated movements, and reddened face 2
• The diagnosis of heat stroke can be based on Bouchama's definition or Japan Association of Acute Medicine (JAAM) criteria 3
• Heat stroke is classified into Non-Exertional Heatstroke (NEHS) and Exertional Heatstroke (EHS) 3, 4

Management of Heat Stroke

• The basic principle of heat stroke management is early resuscitation and immediate cooling 3
• Active cooling measures are recommended over passive cooling methods, with cold- or ice-water immersion achieving the fastest cooling rate 5
• Cooling techniques such as ice-water immersion or evaporation plus convection can be used to cool heat-stroke patients 6
• Evaporative plus convective cooling may be augmented by crushed ice or ice packs applied diffusely to the body, and chilled intravenous fluids may also supplement primary cooling 6
• Water immersion techniques (using 1-17 °C water) can rapidly reduce core body temperature in settings where it is feasible 4

Cooling Methods

• Ice-water immersion has been shown to be highly effective in exertional heat stroke, with a zero fatality rate in large case series of younger, fit patients 6
• Evaporative plus convective cooling may be more suitable for older patients with nonexertional heat stroke 6
• Cold water immersion or convection evaporation method can be implemented based on the specific patient characteristic 3
• There is no evidence to support pharmacological interventions that affect temperature control in heat stroke patients, and they should be avoided 5