first aid

1. Chapter 20
Cold-Related Emergencies

2. Cold-Related Emergencies
• When surrounded by air or water cooler
than body temperature, the body
experiences heat loss.
− Normal body temperature is 98.6F.
• If body temperature falls much below that,
cold injuries can result.

3. How Cold Affects the Body
• The body has two internal mechanisms to
maintain body temperature.
− Vasoconstriction
• Tightening of blood vessels
− Shivering
• Stops when core temperature falls between 86F
and 90F

4. How Cold Affects the Body
• Physical activity produces heat.
− Heat loss increases if clothes become wet
with sweat.
• Susceptibility can be minimized by:
− Proper hydration and nutrition
− Avoiding alcohol, caffeine, and nicotine
− Limiting periods of inactivity

5. How Cold Affects the Body
• The colder the temperature, the greater
the potential for body heat to escape.
− The brain signals blood vessels in skin to
tighten, and blood flow to skin decreases.
− Because of reduced blood flow to skin, skin
temperature falls.

6. How Cold Affects the Body
• When exposure lasts more than an hour:
− Sensation, touch, and pain will be blunted.
− Dexterity and agility will be lost.
− A person’s ability to perform manual tasks will
be impaired.

7. Heat Loss From the Body
• Normal body temperature is maintained by
a balance of heat production and heat loss.
• Shivering increases heat production.
− Rapidly consumes calories stored as glycogen.
− Lack of food limits ability to produce heat.
− When glycogen stores are depleted, heat
output decreases.

8. Heat Loss From the Body
• Four mechanisms of heat loss
− Conduction
− Convection
− Evaporation
− Radiation
© Jones & Bartlett Learning.

9. Susceptibility to Cold Injury
• Physically unfit
• Dehydration
• Very lean people
• Older people
• Alcohol, caffeine
• Nicotine
• Inadequate
nutrition, illness,
injury
• Previous cold
injury

10. Effects of Altitude
• Air temperature drops 3.6F every 1,000
feet.
• Winds are more severe.
• Frostbite is more common above 8,000
feet.

11. Effects of Water
• Water conducts heat away from the body.
• Plunging into cold water can cause:
− Irregular heartbeat
− Gasping, hyperventilation
− Inhalation of water
− Heart failure
− Drowning

12. Effects of Wind
• Wind increases heat loss from skin
exposed to cold air.
• Windchill is the combined effect of the
ambient temperature and wind speed.

13. Effects of Metal and Liquid Fuels
• Can conduct heat away from skin rapidly
• Contact can cause nearly instantaneous
freezing.

14. Minimizing Effects of Cold
on the Body
• First layer
− Removes perspiration
• Middle layer
− Insulates
• First layer
− Protects against wind
© Simon Price/Alamy.

15. Nonfreezing Cold Injuries
• Can occur when conditions are cold and
wet, and hands and feet cannot be kept
warm and dry

16. Chilblain
• Painful
• Causes little or no permanent damage
• Can develop in 3 to 6 hours

17. Chilblain: What to Look For
• Swollen skin
• Skin that is tender, hot to the touch, and
possibly itchy
• Blisters
• Aching, prickly sensation, numbness

18. Chilblain: What to Do
• Get person out of cold.

19. Trench Foot
• Develops when skin on feet is exposed to
moisture and cold for 12 hours or longer
• Caused by:
− Wearing wet boots and shoes
− Prolonged immersion of feet in cold water
• Cold and moisture soften skin, causing
tissue loss and infection.

20. Trench Foot: What to Look For
• Itching, numbness, tingling pain
• Swollen feet and pale skin cold to touch
• Red or blue blotches on the skin
− Sometimes open weeping or bleeding

21. Trench Foot: What to Do
• Dry the skin.
• Rewarm foot gradually.
• Care for open weeping areas.
− Use mild soap and water.
− Apply a breathable dressing.

22. Freezing Cold Injuries
• Occur whenever air temperature is below
freezing
− Frostnip
• Freezing is limited to skin surface.
− Frostbite
• Freezing extends into the flesh.

23. Frostnip
• Frostnip is caused when water on the skin
surface freezes.
Courtesy of Neil Malcom Winkelmann.

24. Frostnip: What to Look For
• Yellow to gray skin color
• Frost on the skin
• Initial tingling or numbness that may
become painful

25. Frostnip: What to Do
• Get the person out of the cold.
• Gently warm affected area.
• Do not rub the affected area.

26. Frostbite
• Two ways of damage
− Tissue freezing
− Obstruction of blood
supply to the tissue
• Affects feet, hands,
ears, and nose
© American Academy of Orthopaedic Surgeons.

27. Frostbite: What to Look For
(Before Thawing)
• Superficial frostbite
− White, waxy, or grayish yellow skin
− Part feels cold and numb.
− Tingling, stinging, aching
− Stiff or crusty skin
− Underlying tissue is soft.

28. Frostbite: What to Look For
(Before Thawing)
• Deep frostbite
− Part feels cold, hard, and solid and cannot be
depressed.
− Pale, waxy skin
− Painfully cold part stops hurting.

29. Frostbite: What to Do
(Before Thawing)
• Get person to warm area.
• Remove wet clothing and constricting items.
• Do not attempt to thaw the part if:
− Medical care is less than 2 hours away.
− The affected area has thawed.
− Shelter, warm water, and a container are not
available.
− Risk of refreezing exists.

30. Frostbite: What to Do
(Before Thawing)
• Use the wet, rapid rewarming method if:
− Medical care is more than 2 hours away.
− No possibility of refreezing
− Shelter, warm water, and a container are
available.
• If the wet, rapid rewarming method is not
possible, slow rewarming can be done.

31. Wet, Rapid, Rewarming Method
• Place part in warm water.
• Maintain water temperature.
• Usually takes 20 to 40 minutes
• Air dry the area; do not rub.
• Give pain medication.
• Apply warm cloths to ear or facial injuries.

32. Frostbite: What to Look For
(After Thawing)
• First-degree
− Warm, swollen,
and tender
• Second-degree
− Blisters form.
• Enlarge over
several days
• Third-degree
− Small blisters with
red-blue or purple
fluid
− Red or blue skin
− Might not blanch

33. Frostbite: What to Do
(After Thawing)
• For feet, do not allow person to walk.
• Protect area from contact.
• Place dry gauze between toes and fingers.
• Slightly elevate affected part.
• Apply aloe vera gel.
• Provide pain medication and give fluids.
• Seek medical care.

34. Hypothermia
• A life-threatening condition in which the
body’s core temperature falls below 95°F
• Heartbeat/breathing may be undetected.
• Consider whenever person’s behavior and
history and the weather conditions indicate
abnormal heat loss

35. Types of Cold Exposure
• Acute
− Usually in water
− 6 hours or less
• Subacute
− 6 to 24 hours
− Land or water
• Chronic
− Occurs on land
− Exceeds 24 hours

36. Hypothermia Symptoms
• Change in mental status
• Shivering
• Cool abdomen
• Low core body temperature

37. Difference Between Mild and
Severe Hypothermia
• Based on core body temperature
• In severe cases, shivering stops.
− Do not start CPR if:
• Core body temperature is below 60°F.
• Chest is frozen.
• Submerged in water for more than 60 minutes
• A lethal injury exists.
• Transport will be delayed.
• Rescuers are endangered.

38. CPR and Severe Hypothermia
• Do not start until after you have checked
person’s circulation for 1 minute.
• f no detectible pulse after 1 minute, start
CPR.
• CPR can be delayed, given intermittently,
or given for several hours.

39. Mild Hypothermia:
What to Look For
• Vigorous, uncontrolled shivering
• The “umbles”
• Cool or cold skin on abdomen, chest, or
back
• Core body temperature above 90°F

40. Mild Hypothermia: What to Do
• Stop further heat loss.
• Apply heat to the chest, armpits, and back.
• Warm lower arms and legs in 107°F to
113°F water.
• Give warm, sugary drinks.

41. Severe Hypothermia:
What to Look For
• Rigid and stiff muscles
• No shivering
• Skin feels ice cold and appears blue.
• Altered mental status—not alert
• Slow heart rate and breathing rate
• The person may appear to be dead.

42. Severe Hypothermia: What to Do
• Follow steps for treating hypothermia.
• Cut off the person’s wet clothing.
• Monitor breathing; give CPR if necessary.
• Call 9-1-1.
• Check heart rate for 1 minute before
starting CPR.
• Provide rewarming.

43. Adding Heat
• Problems with rewarming:
− Warm water immersion requires a lot of warm
water and a bathtub.
− Body-to-body contact in insulated sleeping
bag is not better than shivering.
− No evidence that chemical heating pads are
capable of rewarming a hypothermic person.

44. Dehydration
• Occurs because of unperceived fluid loss
combined with inadequate fluid intake
• Cold weather: fluid lost through breath
− Drink even if not thirsty.
− Monitor color and volume of urine.
− Do not consume unmelted snow and ice.