Related Subjects: Acute Kidney Injury
|Acute Rhabdomyolysis
|Hyperkalaemia
About
- Heat stroke is defined by cerebral dysfunction in the context of body core temperature >40°C.
Different types
- Non-exertional: Elderly and very young are at highest risk often chronic illnesses and medications. Hot weather and high heat and humidity over time. Bedridden or living in poorly ventilated or no conditioned conditions. May be on Antiparkinsonian treatment, diuretics, or anticholinergic therapy or obese (harder to loose heat).
- Exertional heat stroke: young fit well people exercising in a
hot, humid environment, with clothing or equipment that restricts cooling. Athletes, labourers, Military. Causes altered mental state, ataxia, coma, and nuchal rigidity or posturing may also occur. Profuse sweating is a typical finding on examination. Drugs may play a role - cocaine, alcohol withdrawal, LSD, amphetamines.
Clinical
- High body temperature (above 40°C or 104°F)
- Altered mental state or delirium
- Anxiety, confusion, bizarre behaviour, loss of coordination
- Hallucinations, agitation, seizures
- Sweating may or may not be present
- Hypotension, tachycardia and coma in severe cases
Investigations
- FBC : raised WCC if infection
- U&E: AKI, hypokalaemia and low phosphate is seen
- Raised CK (usually in exertional heat stroke)
- Raised AST is poor prognostic indicator
- VBG: Respiratory alkalosis +/- lactic acidosis (exertional)
Complications
- Encephalopathy
- Renal failure or rhabdomyolysis (most commonly in exertional heat stroke)
- Acute respiratory distress syndrome
- Myocardial injury and circulatory collapse
- Hepatocellular injury
- Intestinal ischaemia and infarction
- Pancreatic injury
- Disseminated intravascular coagulation
Differentials
- Malignant hyperthermia
- Neuroleptic malignant syndrome
- Drug-induced hyperthermia
- Infections: Especially meningitis, encephalitis, and sepsis
- Endocrinopathies: thyroid storm and phaeochromocytoma
- CNS lesions: Hypothalamic bleeding, acute hydrocephalus
Prevention
- Stay hydrated and drink plenty of fluids.
- Avoid strenuous activity in hot and humid weather.
- Take frequent breaks in a cool or shaded area.
- Wear lightweight, loose-fitting clothing.
- Acclimate to hot conditions gradually.
- Monitor for early signs of heat-related illness and take action promptly.
Management
- ABC, IV fluids. Assessment of core body temperature.
- Rapid cooling is the main therapeutic goal for the treatment of heatstroke
- Immersion in ice water is effective but poorly tolerated for prolonged periods
- Tepid water spray (40°C) and a forced air stream from a fan.
- Ice packs. Target < 39°C or less is considered safe
- Dantrolene is not indicated for the treatment of heatstroke.
- Detect and manage any rhabdomyolysis