Temperature control

What is the normal core body temperature for proper function?

Approximately 37°C (98.6°F).

How is body heat produced?

• Conversion of food to energy 

• Muscle contraction (exercise or shivering) 

How does the body respond when temperature increases?

• Vasodilation: Superficial blood vessels widen to release heat (via convection).

• Sweating: Evaporation cools the blood more effectively than convection.

How does the body conserve heat in cold environments?

• Vasoconstriction: Blood vessels narrow to retain core heat.

• Shivering: Generates heat when vasoconstriction alone isn't sufficient

What environmental factors affect body temperature?

Air temperature, humidity, and wind.

What causes frostbite and what areas are most affected?

Exposure to temperatures below 0°C

Common in ears, nose, cheeks, fingers, and toes.

What causes tissue damage in frostbite?

Ice crystals form between/within cells → cell damage or death

What are signs of superficial frostbite (frostnip)?

• White, waxy skin

• Hard outer layer, soft deeper tissue

• Pain followed by numbness

What are signs of deep frostbite?

• Grey-blue skin (was white/waxy)

• Skin is cold and hard

• Complete numbness in the area

What factors affect the severity of frostbite?

• Duration of exposure

• Movement or trauma

• Thawing method

How do you care for superficial frostbite?

• Move to warmth

• Use warm hands or breath

• Warm against body (e.g., armpits)

• Do NOT rub the area

How do you manage deep frostbite?

• Do NOT thaw if refreezing is possible

• Rewarm gently in 38–40°C water

• Handle the tissue carefully

• Do NOT rub

What defines hypothermia?

A drop in core body temperature below 35°C (95°F).

What are general signs of hypothermia?

• Shivering (may stop when severe)

• Slow/irregular pulse

• Numbness, glassy stare

• Apathy, confusion, ↓ LOC

Describe Stage 1 (Mild) hypothermia (35–36°C).

• HR/RR: Normal

• Shivering, slurred speech

• Conscious, withdrawn

Describe Stage 2 (Moderate) hypothermia (30–34°C).

• Slow, weak HR

• Shallow, slow RR

• Clumsy, confused, sleepy

• Shivering may stop

Describe Stage 3 (Severe) hypothermia (<30°C).

• Weak, irregular or absent pulse

• Slow or absent breathing

• No shivering

• Unconscious

What factors increase the risk of cold injuries?

• Wind-chill

• Inadequate clothing

• Age extremes (young/elderly)

• Poor health, fatigue, alcohol/drugs

How can hypothermia be prevented?

• Dress in layers

• Stay dry and sheltered

• Avoid overexertion in cold/wet conditions

How is hypothermia treated?

• Check – Call – Care

• Handle gently

• Remove from cold, change wet clothes

• Warm slowly (no hot water immersion)

• Monitor ABCs and vitals

What is hyperthermia?

Inability to regulate body temperature in hot environments.

What are types of hyperthermia-related conditions?

• Heat cramps

• Heat exhaustion

• Heat stroke (2nd leading cause of athlete deaths)

Signs & symptoms of heat exhaustion?

• Excessive sweating

• Pale, cold, clammy skin

• Weak, rapid pulse

• Vomiting, shallow breathing

• Headache, cramps, faintness

Treatment for heat exhaustion?

• Check – Call – Care

• Move to shade, loosen clothing

• Give O₂ (15 LPM via non-rebreather)

• Slowly give water if conscious

• Anti-shock position

What are the two types of heat stroke?

• Classic: Failure of thermoregulation

• Exertional: Due to intense activity in heat

Signs & symptoms of heat stroke?

• Body temp > 40°C

• Rapid, bounding pulse (may weaken later)

• Flushed, hot dry skin (classic)

• Flushed, sweaty skin (exertional)

Treatment of heat stroke?

• Check – Call – Care

• Cool area, loosen clothing

• O₂ at 15 LPM

• Responsive: give water slowly

• Use ice-soaked towels on neck, torso, groin

What causes heat cramps and where do they occur?

• Caused by fluid/electrolyte loss from sweat and exertion

• Affects legs, arms, and abdominal muscles

Why are heat cramps important?

They are an early warning sign of impending heat exhaustion or heat stroke and may require medical attention.