Heat stroke medical therapy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2]

Overview

The heat stroke is primarily managed by removing the patient from the environment to minimize heat exposure and to ionitiate rapid cooling protocols.

Medical Therapy

The heat stroke is primarily managed by:

• Removing the patient from the environment to minimize heat exposure
• Initiating cooling protocols as soon as possible
• Providing support to the effected organs

The Management of Heat Stroke*
Condition	Intervention	Goal
Out of Hospital
Heat stress (due to heat wave, summer heat, or strenuous exercise), with changes in mental status (anxiety, delirium, seizures, or coma)	Measure the patient’s core temperature (with a rectal probe) If the core temperature is >40°C, move the patient to a cooler place, remove his or her clothing, and initiate external cooling: Cold packs on the neck, axillae, and groin; Continuous fanning (or opening of the ambulance windows) Spraying of the skin with water at 25°C to 30°C Position an unconscious patient on his or her side and clear the airway Administer oxygen at 4 liters/min Give isotonic crystalloid (normal saline) Rapidly transfer the patient to an emergency department	Diagnose heat stroke† Lower the core temperature to <39.4°C, promote cooling by conduction, and promote cooling by evaporation Minimize the risk of aspiration Increase arterial oxygen saturation to >90% Provide volume expansion
In Hospital
Cooling period	Confirm diagnosis with thermometer calibrated to measure high temperatures (40°C to 47°C).
Hyperthermia	Monitor the rectal and skin temperatures; continue cooling	Keep rectal temperature <39.4°C§ and skin temperature 30°C–33°C
Seizures	Give benzodiazepines	Control seizures
Respiratory failure	Consider elective intubation (for impaired gag and cough reflexes or deterioration of respiratory function)	Protect airway and augment oxygenation (arterial oxygen saturation >90%)
Hypotension	Administer fluids for volume expansion, consider vasopressors, and consider monitoring central venous pressure	Increase mean arterial pressure to >60 mm Hg and restore organ perfusion and tissue oxygenation
Rhabdomyolysis	Expand volume with normal saline and administer intravenous furosemide, mannitol, and sodium bicarbonate	Prevent myoglobin-induced renal injury: promote renal blood flow, diuresis, and alkalization of urine
	Monitor serum potassium and calcium levels and treat hyperkalemia	Prevent life-threatening cardiac arrhythmia
After cooling
Multiorgan dysfunction	Supportive therapy	Recovery of organ function

*Adopted from Heat Stroke.

Cooling

The cooling is done on the following principles:

• The heat is transferred from the body core to the skin and then dissipated into the air.
• Vasodilatation of the vessels in the skin occurs as a compensatory mechanism to help dissipate the heat
• Cooling therapies focus on increasing and facilitating the transfer of heat from the body to the surroundings while keeping the vasodilatory cooling mechanism intact. They can utilize:
  • Increasing the gradient of temperature between the body and the surroundings (cooling by the help of conduction)
  • Increasing the water vapor pressure gradient between the body and the surroundings (cooling by the help of evaporation)
  • Accelerating the flow of air closer to the skin (cooling by the help of convection)
• These can be achieved by:
  • Application of water
  • Application of ice
  • Fanning

Methods of Cooling

Methods of Cooling*
Techniques based on Conductive cooling
External	Cold-water immersion
	Application of cold packs or ice slush over part of the body or the whole body
	Use of cooling blankets
Internal	Iced gastric lavage
	Iced peritoneal lavage
Techniques based on Evaporative or Convective cooling
	Fanning the undressed patient at room temperature (20°C to 22°C)
	Wetting of the body surface during continuous fanning
	Use of a body-cooling unit

*Adopted from Heat Stroke.

Avoidance of Excessive cooling

Most of the techniques used for cooling can decrease the temperature of the skin excessively. Temperature can fall up to 30°C or lower resulting in compensatory mechanisms like:

• Vasoconstriction and
• Shivering

These responses are not desired and can result in inappropriate management of hyperthermia. This can be avoided by an alternate or combined application of the following along with the cooling techniques:

• Massaging of the body
• Spraying lukewarm water of 40°C
• Exposing to moving air which is hot i.e around 45°C

Cooling Rates

• A decrease in temperature at the rate of 0.15°C or 0.27°F per minute has been successfully tested.

Use of Pharmacological Agents

Pharmocological agents have not proven to be of benefit in case of hyprethermia or heat stroke. The agents that have been considered include:

• Dantrolene sodium
  • It is used for malignant hyperthermia
  • Its use is no more recommended for heat stroke
• Antipyretics
  • Acetaminophen
  • NSAIDs like Ibuprofen

Recovery

The revival of the functioning of the central nervous system is a positive prognostic sign. It is usually seen following aggressive therapy. 20% patients face residual damage of the brain and a higher mortality is associated with this.