3. Definitions
A continuum of increasingly severe exertional heat illnesses caused by
dehydration, electrolyte losses, and failure of body’s thermoregulatory
mechanisms.
Exercise Associated Muscle Cramps (Heat Cramps)
Heat Exhaustion
Heat Injury
Heat Stroke
4. Epidemiology
Predominantly in children and elderly
Male >Female
EHS- 4.5/100,000 person’s affected per FB season
~600 deaths/year in the USA
5. Exercise Associated Muscle Cramps (Heat
Cramps)
• painful involuntary muscle contractions/spasms
occurring in the setting of strenuous exercise and hot
temperatures
6. Heat Exhaustion
• Athlete has obvious difficulty continuing with exercise
• Core body temperature is usually 101 to 104ºF at the time
of collapse
• No significant dysfunction of the central nervous system
(seizure, altered consciousness, persistent delirium) is
present
8. Heat Injury
• Exertional heat illness with evidence of both hyperthermia
and end organ damage, but without any significant
neurologic manifestations.
• Collapse during strenuous activity, a core temperature
above 104 to 105°F, and the absence of neurologic
findings.
9. Exertional Heat Stroke
• Multisystem illness characterized by central nervous
system (CNS) dysfunction (encephalopathy) and
additional organ and tissue damage (eg, acute kidney
injury, liver injury, rhabdomyolysis).
• Core temp > 104F
11. Severe Non-Exertional Hyperthermia
(Classic Heat Stoke)
• Most often patients over 70, with underlying chronic
medical conditions that impair thermoregulation, prevent
removal from a hot environment, or interfere with access
to hydration or attempts at cooling
12. Thermoregulation
Evaporation-occurs when water vaporizes from the skin
and respiratory tract. Most effective mechanism.
Conduction-direct heat transfer to an adjacent, cooler
object.
Convection-transfer of heat to a gas or liquid moving over
the body. Heat transfer occurs when the gas or liquid is
colder than the body.
Radiation-is the emission of electromagnetic heat waves
13. Risk Factors
Poor physical conditioning
Salt or water depletion
Obesity
Acute febrile or GI illnesses
Chronic disease (HTN, DM, CAD)
ETOH
Clothing
Medications
15. Differential Diagnosis
Febrile illnesses, sepsis
Drug induced fluid loss
Arrhythmia or MI
Acute cocaine intoxication
Neuroleptic malignant syndrome
Malignant hyperthermia – autosomal disorder where patients have
abnormal muscle metabolism on exposure to halothane or skeletal
muscle reactants
16. Treatment
General measures
• Gradual fluid and electrolyte replacement with normal saline
• Body immersion in ice water
• Evaporative cooling
• *any method to cool patient’s body*
17. Prevention
Proper hydration
Elderly at increased risk because of diminished thirst signaling
Patient education to emphasize importance of appropriate
conditioning and acclimatization
Adjusting activity according to Wet Bulb Globe Test (WBGT)
WBGT = 0.1 x Dry Bulb Temperature (DBT) + 0.7 x Wet Bulb
Temperature (WBT) + 0.2 x Globe Temperature (GT)
21. Conclusion
While these ailments are not that common, they can produce
devastating consequences if not addressed
Incidence will likely increase with growing elderly population
Patient education important
