Prehospital Academy Lesson 37.1
Trauma: Thermal Emergencies Overview
This lesson provides an overview of thermal emergencies for EMTs, focusing on conditions related to exposure to extreme heat and cold. The human body maintains a core temperature within a narrow range, and deviations from this range can lead to life-threatening conditions. Understanding the factors affecting thermoregulation and implementing appropriate prehospital care is vital for positive patient outcomes.
Thermoregulation and Heat Exchange
Thermoregulation is the body's ability to maintain its core temperature. Heat is continuously gained and lost through several mechanisms:
Conduction: Direct transfer of heat from warmer to colder objects (e.g., touching a cold surface).
Convection: Transfer of heat by currents of air or water (e.g., wind chill).
Evaporation: Conversion of liquid (sweat) to gas, carrying heat away from the body.
Radiation: Transfer of heat as electromagnetic waves (e.g., body radiating heat to a cooler environment).
Factors Affecting Response to Thermal Exposure:
Age: Infants, young children, and the elderly have less efficient thermoregulation.
Physical Condition/Health: Chronic illnesses, medications, and overall health status.
Nutrition and Hydration: Poor nutrition or dehydration impairs the body's ability to cope.
Environmental Factors: Temperature, humidity, wind. Extreme temperatures are not always necessary for thermal emergencies to occur.
Heat-Related Emergencies
Caused by excessive heat exposure and/or impaired heat dissipation.
Heat Cramps:
Description: Painful muscle spasms, typically in the legs and abdomen, caused by electrolyte loss through sweating.
Signs/Symptoms: Muscle cramps, weakness.
Management: Move to a cool environment, oral hydration with electrolyte solutions, gentle stretching/massage.
Heat Exhaustion:
Description: A more severe form of heat illness characterized by profuse sweating and a normal or slightly elevated body temperature.
Signs/Symptoms: Weakness, dizziness, nausea, headache, muscle cramps, pale/cool/moist skin, tachycardia.
Management: Move to a cool environment, loosen clothing, lie patient down, oral hydration (if conscious and not nauseated), passive cooling. Monitor for worsening condition.
Heat Stroke:
Description: A life-threatening emergency where the body's thermoregulation fails, leading to a dangerously high core body temperature.
Signs/Symptoms: Altered mental status (confusion, delirium, seizures, coma), hot/dry or moist skin (sweating may cease), tachycardia, hypotension, rapid/shallow breathing.
Management: IMMEDIATE and aggressive cooling (cold water immersion, wet cloths, fanning), high-flow oxygen, IV fluids (advanced providers), rapid transport.
Cold-Related Emergencies
Caused by excessive cold exposure and/or impaired heat production.
Frostnip:
Description: Mildest form of cold injury, affects superficial skin layers.
Signs/Symptoms: Numbness, tingling, pale/reddened skin that remains soft.
Management: Remove from cold, cover affected area, rewarm gently.
Frostbite:
Description: Tissues freeze, leading to cellular damage. Can be superficial or deep.
Signs/Symptoms: Affected area is cold, hard, numb, waxy, and pale or mottled. Blisters may form later.
Management: Remove from cold, protect from further injury, gentle rewarming (do not rub), rapid transport. Avoid rewarming if there is a chance of refreezing.
Hypothermia:
Description: Core body temperature falls below 95°F (35°C). Can be mild, moderate, or severe.
Signs/Symptoms:
Mild: Shivering, "goosebumps," rapid breathing/pulse, clear mental status.
Moderate: Shivering stops, altered mental status, slow/irregular pulse and breathing, impaired coordination.
Severe: Unresponsive, no detectable pulse or breathing (appears dead), rigid muscles, pupils dilated.
Management:
Remove from cold environment, remove wet clothing.
Passive rewarming (warm blankets, insulate from ground) for mild cases.
Active external rewarming (warm packs to axillae, groin, neck) for moderate cases.
Handle gently (especially severe hypothermia) to avoid ventricular fibrillation.
High-flow oxygen, monitor cardiac rhythm.
"Not dead until warm and dead" principle.
Rapid transport to definitive care.
Critical Thinking Questions
You are treating a patient with suspected heat stroke. What is the most critical intervention you can perform, and why?
Explain why infants and the elderly are more susceptible to both heat and cold emergencies.
A patient with severe hypothermia appears unresponsive with no detectable pulse or breathing. What is the general principle guiding resuscitation efforts in such cases?
Differentiate between heat exhaustion and heat stroke based on key signs and symptoms.
You are responding to a patient with frostbite on their hands. What are the key considerations for rewarming, and what should you absolutely avoid doing?