Acute Care During Extreme Heat: Recommendations and Information for Health Care Workers
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ISBN: 978-0-660-73102-5
Cat.No.: H144-133/2024E-PDF
HC Pub.: 240466
Recognize Heat Illnesses and Heat Sensitive Diseases
- Heat exposure can result in direct illnesses including: Heat Edema, Heat Rash, Heat Cramps, Heat Syncope (fainting) and Heat Exhaustion. These can be self-limiting, but should always be addressed with treatment.
- Exertional Heat Stroke and Classic Heat Stroke are medical emergencies and require immediate action from a health care worker and hospitalization.
- Exposure to heat may also present as exacerbation of Cardiovascular, Renal, Pulmonary or Psychiatric illnesses.
Key Actions
- Recognize and identify heat as a factor in illness or death.
- Recognize Heat Stroke, and activate emergency medical services.
- Record heat as a contributing factor to illness for improved recognition and monitoring.
Heat Exhaustion | Heat Stroke | |
---|---|---|
Temperature | Core temperature elevated but <40°C (104°F) | Core temperature ≥ 40°C (104°F) |
Neurological |
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Mental status changes:
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Cardiac |
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Skin |
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Other |
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Outcome | Untreated and with ongoing heat exposure, heat exhaustion can worsen and become heat stroke. |
In later stages, pulmonary edema, hepatic failure, renal failure, rhabdomyolysis (muscle fibre breakdown), death |
Key Risk Factors Associated with Heat-Related Illnesses and Death in Extreme Heat
- Older adults
- Living circumstances (confined to bed, social isolation, reduced income, malnutrition, reduced access to cooling options)
- Those having chronic diseases including:
- Cardiovascular disease (hypertension, coronary artery disease, heart conduction disorders)
- Mental and behavioural disorders (due to psychoactive substance use, alcoholism)
- Mental illness (dementia, depression, schizophrenia, Alzheimer's)
- Neurological disease (Parkinson's disease)
- Respiratory illness (chronic obstructive pulmonary disease (COPD), asthma)
- Renal disease (renal failure)
- Metabolic conditions (diabetes, obesity)
Medication | Mechanism |
---|---|
Antiadrenergics and β-Blockers (e.g. Atenolol, Metoprolol) |
Can decrease cardiac output, and therefore shunting of warm blood from body core to periphery, limiting cooling. |
Anticholinergics (e.g. Scopolamine) |
Can prevent sweat glands from functioning properly (i.e. inhibit rate of sweating and therefore rate of cooling). |
Antidepressants (e.g. Prozac, Zoloft, other SSRIs) |
Many have anticholinergic properties (see above) and some can raise the brain's thermal set-point decreasing centrally induced thermoregulation. SSRIs can increase the risk of hyponatremia. |
Antihistamines (e.g. Brompheniramine) |
Can inhibit the sweating mechanism. |
Anti-Parkinson's agents (e.g. Benztropine, Levodopa, Trihexyphenidyl) |
Can inhibit the sweating mechanism. |
Antipsychotics (e.g. Olanzapine) |
Can inhibit the sweating mechanism. Can induce a hyperthermic syndrome (neuroleptic malignant syndrome) on their own, which would be compounded by the effects of heat. |
Sympathomimetics (e.g. Pseudoephedrine) |
Can prevent dilation of the blood vessels in the skin of the periphery (hands, feet, face) reducing the ability to dissipate heat by convection. |
Diuretics (e.g. Lasix) |
Can lead to dehydration and hyponatremia is a common side effect. |
Several drug classes (e.g. cholinesterase inhibitors, antiarrhythmics, calcium blockers) |
Can provoke diarrhea and/or vomiting, leading to dehydration. |
Key Actions to Address Risk Factors
- Educate and increase awareness of the risk factors, signs and symptoms and treatment for heat illnesses, both for patients, care givers and health care workers.
- Help patient assess their risk and discuss preventive actions they could take to reduce risks before and during extreme heat events. (Refer to the Health Canada's Heat-Health Fact Sheet Series)
Treatment Priorities
Cool and Hydrate
- Heat stroke is a medical emergency and requires hospitalization.
- Cool the body early, monitor vital signs. This can prevent later stage damage and death.
- Exertional heat stroke - cool quickly with ice-water baths.
- Classic heat stroke - more often occurs in people with other chronic conditions.
- Treat dehydration.
- Check for over-hydration, hyponatremia, especially in athletes; assess patient's recent physical activity.
For additional information refer to Health Canada's Extreme Heat Events Guidelines: Technical Guide for Health Care Workers
For further information email: Climatinfo@hc-sc.gc.ca
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