What causes severe hyperthermia?

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From the Guidelines

Severe hyperthermia causes multiple organ dysfunction and can be life-threatening if not treated promptly, with major consequences including neurological dysfunction, cardiovascular collapse, and metabolic acidosis, as reported in a study published in 2021 1.

Causes and Consequences of Severe Hyperthermia

Severe hyperthermia occurs when body temperature rises above 40°C (104°F), overwhelming the body's temperature regulation mechanisms. The condition damages cellular structures, denatures proteins, and disrupts enzyme function throughout the body.

  • Major consequences include:
    • Neurological dysfunction (confusion, seizures, coma)
    • Cardiovascular collapse (hypotension, arrhythmias)
    • Respiratory distress
    • Acute kidney injury
    • Liver damage
    • Rhabdomyolysis (muscle breakdown)
    • Coagulopathy (blood clotting abnormalities)
    • Metabolic acidosis According to a study published in 2007, heatstroke is a leading cause of mortality and neurologic morbidity when there is an unaccustomed and sustained increase in climatic temperature 1.

Treatment and Prevention of Severe Hyperthermia

Treatment requires immediate cooling through methods like ice packs, cold water immersion, or evaporative cooling with misting and fans, as recommended in a guideline published in 2021 1.

  • Intravenous fluids are essential to restore volume and electrolyte balance.
  • Benzodiazepines may be needed for seizures, and organ-specific supportive care is often required.
  • Prevention involves avoiding excessive heat exposure, staying hydrated, and being cautious with medications or conditions that impair temperature regulation, as suggested in a study published in 2021 1.

Management of Malignant Hyperthermia

In cases of malignant hyperthermia, it is crucial to eliminate the trigger agent, give i.v. dantrolene, and start active body cooling, as recommended in a guideline published in 2021 1.

  • Activated charcoal filters can be used to adsorb inhalational anaesthetics.
  • Dantrolene sodium is an antidote to malignant hyperthermia, inhibiting the excessive release of calcium into the muscle cell.
  • The European Malignant Hyperthermia Group provides guidelines on the perioperative management of malignant hyperthermia-susceptible patients, including the use of activated charcoal filters and avoidance of prophylactic administration of dantrolene 1.

From the Research

Severe Hyperthermia Causes

  • Severe hyperthermia can be caused by various factors, including:
    • Heat stroke 2, 3, 4
    • Malignant hyperthermia 5, 2, 6
    • Serotonin syndrome 5, 2, 6
    • Neuroleptic malignant syndrome 5, 2, 6
    • Anticholinergic poisoning 5
    • Sympathomimetic poisoning 5
    • Certain drugs, such as amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), and tricyclic antidepressants (TCAs) 6
  • These conditions can lead to a hypermetabolic state, causing the body's temperature regulation mechanisms to fail, resulting in dangerously high core temperatures 5, 6
  • Severe hyperthermia can also be triggered by environmental factors, such as high ambient temperatures, heatwaves, and exertion 3, 4

Clinical Presentation

  • Symptoms of severe hyperthermia can include:
    • Elevated body temperature 5, 2, 6, 3, 4
    • Altered mental status 5, 2, 4
    • Muscle rigidity 5
    • Convulsions 5
    • Metabolic acidosis 5
    • Headache, weakness, dizziness, and an inability to continue activity 4
  • If left untreated, severe hyperthermia can lead to organ dysfunction, failure, and death 5, 2, 3, 4

Treatment

  • Prompt treatment is essential to prevent long-term damage and reduce mortality 5, 2, 3, 4
  • Treatment options include:
    • Immediate discontinuation of the suspected offending agent(s) 5
    • Supportive care, such as external cooling, volume resuscitation, and hydration 5, 2, 3, 4
    • Pharmacologic therapy, such as benzodiazepines, bromocriptine, and dantrolene 5
    • Ice-water immersion and evaporative cooling 2
    • Applying ice packs to the head, neck, axilla, and groin 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Treatment of hyperthermia].

Ugeskrift for laeger, 2017

Research

Critical illness aspects of heatstroke: A hot topic.

Journal of the Intensive Care Society, 2023

Research

Heat-related illness.

American family physician, 2011

Research

Diagnosis and treatment of drug-induced hyperthermia.

American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 2013

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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