What is the protocol for cooling in hyperthermia (elevated body temperature)?

From the Guidelines

Hyperthermia cooling protocols should be initiated immediately for patients with core body temperatures above 40°C (104°F), with the goal of reducing core temperature by at least 0.1-0.2°C per minute during the first 30 minutes of treatment, as recommended by the most recent guidelines 1.

Key Recommendations

• Begin by removing the patient from the heat source and all clothing, then apply rapid cooling methods including ice packs to the groin, axillae, neck, and head while covering the body with cold, wet sheets.
• Mist the patient with room temperature water while directing fans over the body to enhance evaporative cooling.
• Administer cold IV fluids (4°C normal saline) at 30 ml/kg over 30 minutes if available, as suggested by previous guidelines 1.
• Continue cooling until the core temperature reaches 38-39°C (100.4-102.2°F), monitoring temperature every 5-10 minutes to avoid overcooling.
• For severe cases, consider cold water immersion if feasible, as recommended by the American Heart Association and American Red Cross guidelines 1.

Rationale

The aggressive approach to cooling is necessary because hyperthermia can rapidly cause multi-organ failure through direct thermal injury to tissues, with mortality rates increasing significantly when treatment is delayed.

• The choice of cooling method should be based on the availability of resources and the patient's condition, with the goal of reaching the target temperature within 30 minutes from recognition of heat stroke symptoms 1.
• The use of benzodiazepines such as diazepam 5-10 mg IV may be considered for shivering, which can counteract cooling efforts.

Important Considerations

• The target core temperature to cool until is 39°C (102.2°F), as recommended by the American Heart Association and American Red Cross guidelines 1.
• The degree and duration of hyperthermia are known to adversely affect normal physiologic processes, making prompt treatment essential 1.
• The panel decided a time to target temperature within 30 minutes is an appropriate goal, despite the limited direct evidence, due to the ethical challenges with performing a randomized controlled trial in this setting 1.

From the FDA Drug Label

The use of Dantrolene Sodium for Injection in the management of malignant hyperthermia crisis is not a substitute for previously known supportive measures These measures must be individualized, but it will usually be necessary to ... institute cooling when necessary

• Institute cooling when necessary is part of the management of malignant hyperthermia crisis.
• The specific hyperthermia cooling protocol is not detailed in the label, but cooling is mentioned as a necessary measure when required. 2

From the Research

Hyperthermia Cooling Protocol

• Hyperthermia is an uncontrolled elevation of body temperature exceeding the body's ability to dissipate heat, and can result in dangerously high core temperatures and can rapidly become fatal 3
• Rapid diagnosis and prompt cooling are pivotal, since the condition triggers a cascade of metabolic events which may progress to irreversible injury or death 3
• Ice-water immersion and evaporative cooling are the methods of choice for cooling hyperthermic patients 3

Cooling Techniques

• Water immersion of adults with exertional hyperthermia resulted in faster cooling rates when compared to passive cooling 4
• No single water temperature range was found to be associated with a quicker core temperature reduction than another (cold, colder or ice) 4
• Water immersion techniques (using 1-17°C water) more effectively lowered core body temperatures when compared with passive cooling, in hyperthermic adults 4
• Cold-water immersion is recommended for the immediate field treatment of exertional heat stroke, with a rectal temperature cooling limit of 38.6°C to attenuate overcooling 5

Intensive Care Cooling

• Accurate nursing assessment determines the appropriate cooling intervention for hyperthermic and hyperpyrexic patients in intensive care 6
• Hyperthermia involves a dysfunction of thermoregulatory responses and responds best to physical cooling methods, while hyperpyrexia involves normal thermoregulatory responses responding at a higher level and responds best to central cooling interventions such as antipyretic therapy 6
• Tepid sponging and ice cool packs are not recommended as they induce shivering and vasoconstriction 6