Local Cold Injuries: Frostnip, Frostbite, Trench Foot, and Chilblains Practice Questions

25 multiple-choice questions on Local cold injuries: frostnip, frostbite, trench foot, and chilblains for paramedic and EMT students, from Chapter 39 (Environmental Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. Frostnip differs from frostbite in that frostnip:

   1. A. Involves ice crystals deep in the muscle tissue
   2. B. Causes hemorrhagic blisters within an hour
   3. C. Freezes only the skin surface and is reversible
   4. D. Requires surgery to remove the dead tissue
   Show answer

   Answer: C. Freezes only the skin surface and is reversible

   Frostnip is superficial freezing of the skin that blanches and numbs but recovers fully with warming. Frostbite involves actual tissue freezing with ice crystal formation and possible tissue loss.

2. A skier has a white, numb patch on her cheek that is still soft to the touch. The best care is to:

   1. A. Rub the patch briskly with some clean snow
   2. B. Apply a chemical heat pack directly
   3. C. Leave it alone until she is indoors
   4. D. Warm it with a hand or a warm body area
   Show answer

   Answer: D. Warm it with a hand or a warm body area

   Frostnip responds to warming with skin-to-skin contact, such as a warm hand on the cheek or fingers in the armpit. Rubbing with snow adds mechanical injury and more cold.

3. Frostbite injures tissue mainly through:

   1. A. Ice crystals and impaired blood flow
   2. B. Direct burns from touching freezing metals
   3. C. Bacterial infection of the skin
   4. D. Loss of sodium in cold sweat
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   Answer: A. Ice crystals and impaired blood flow

   Ice crystals form in tissue and draw water out of cells, while vasoconstriction, sludging, and microthrombi cut off blood flow. Damage worsens during thaw and refreezing.

4. Deep frostbite of the fingers before thawing typically appears:

   1. A. Red, warm, swollen, and very painful
   2. B. Purple, soft, and swollen
   3. C. Pink and normal in texture
   4. D. White or gray, hard, and numb
   Show answer

   Answer: D. White or gray, hard, and numb

   Frozen tissue is waxy, white or gray-yellow, hard, and insensate. Swelling, blisters, and color changes appear after rewarming.

5. The most important factor in deciding whether to thaw frostbite in the field is whether:

   1. A. The patient can still feel the area
   2. B. The part can be kept from refreezing
   3. C. The skin has already formed blisters
   4. D. Pain medication has been given first
   Show answer

   Answer: B. The part can be kept from refreezing

   Thawing and refreezing causes far more tissue loss than leaving the part frozen, so field rewarming is done only if the part can stay thawed until definitive care. Sensation and blisters do not decide the timing.

6. A hiker with frozen feet must walk 3 km out to a trailhead. You should:

   1. A. Thaw the feet in warm water first
   2. B. Rub the feet with snow, then walk
   3. C. Leave the feet frozen until he is out
   4. D. Massage the feet to restore blood flow
   Show answer

   Answer: C. Leave the feet frozen until he is out

   Walking on frozen feet causes less damage than thawing them and then walking on the fragile, swollen tissue, which also risks refreezing. Thaw after evacuation.

7. When rapid rewarming of frostbite is appropriate, the part should be immersed in water at about:

   1. A. 20 to 25°C (68 to 77°F)
   2. B. 45 to 50°C (113 to 122°F)
   3. C. Ice-cold water at 0 to 4°C (32 to 39°F)
   4. D. 37 to 39°C (98.6 to 102.2°F)
   Show answer

   Answer: D. 37 to 39°C (98.6 to 102.2°F)

   Warm water near 37 to 39°C (98.6 to 102.2°F) thaws tissue quickly without burning numb skin. Hotter water can cause burns because the patient cannot feel the heat.

8. Rewarming frostbite in a warm-water bath generally takes about:

   1. A. 15 to 30 minutes
   2. B. 2 to 3 minutes
   3. C. 3 to 4 hours
   4. D. About 24 hours
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   Answer: A. 15 to 30 minutes

   Thawing is complete when the tissue is soft and red or purple, usually in 15 to 30 minutes. Stopping too early leaves frozen tissue behind.

9. Rapid rewarming of frostbite is typically:

   1. A. Painless because the nerves are dead
   2. B. Very painful and needs analgesia
   3. C. Itchy but not truly painful
   4. D. Painful mainly in older adults
   Show answer

   Answer: B. Very painful and needs analgesia

   Thawing frostbite causes intense pain as nerves recover, so plan for analgesia such as an opioid or NSAID per protocol. The numbness of frozen tissue disappears during rewarming.

10. A patient with frostbitten fingers asks why you will not dry them in front of the vehicle heater. You explain that dry heat:

    1. A. Thaws tissue much faster than a water bath
    2. B. Prevents blisters from forming later
    3. C. Rewarms unevenly and can burn numb skin
    4. D. Is preferred for the toes and feet
    Show answer

    Answer: C. Rewarms unevenly and can burn numb skin

    Radiant or dry heat from heaters, fires, and exhaust warms unevenly and can burn insensate tissue. Warm-water immersion is the preferred method when thawing is appropriate.

11. After thawing, a frostbitten hand develops large blisters filled with clear fluid. In the field you should:

    1. A. Drain the blisters with a sterile needle
    2. B. Leave the blisters intact and pad them
    3. C. Remove the blister roof to inspect it
    4. D. Rub the blisters until they are flat
    Show answer

    Answer: B. Leave the blisters intact and pad them

    Field care leaves blisters intact and covers the part in loose, dry, bulky dressings with gauze between the digits. Hospital care decides on draining clear blisters; hemorrhagic blisters signal deeper injury.

12. Blood-filled (hemorrhagic) blisters after thawing frostbite indicate:

    1. A. Superficial injury that will heal fast
    2. B. An infection that needs antibiotics
    3. C. Deeper injury to the dermal vessels
    4. D. Normal healing within the first hour
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    Answer: C. Deeper injury to the dermal vessels

    Hemorrhagic blisters mean damage reaching the deep dermis and its vascular plexus and predict a worse outcome. Clear blisters typically indicate more superficial injury.

13. After rewarming frostbitten toes, you should:

    1. A. Elevate and splint the foot loosely
    2. B. Wrap the toes tightly with an elastic bandage
    3. C. Keep the foot lowered to aid blood flow
    4. D. Massage the toes to restore warmth
    Show answer

    Answer: A. Elevate and splint the foot loosely

    Elevation reduces edema and loose, padded splinting with cotton between the digits protects fragile tissue. Tight wraps impair blood flow to already damaged tissue, letting the foot hang down increases swelling, and massage injures the fragile thawed tissue.

14. A patient has both moderate hypothermia and frostbitten feet. The priority is to:

    1. A. Thaw the feet in warm water
    2. B. Massage the feet to warm them
    3. C. Splint both legs for transport
    4. D. Treat the hypothermia first
    Show answer

    Answer: D. Treat the hypothermia first

    Core hypothermia threatens life, whereas frostbite threatens tissue, so warming the core and gentle handling come first. Thawing the extremities first can also worsen afterdrop.

15. A soldier's feet have been wet and cold, but not frozen, in his boots for several days. They are pale, swollen, numb, and now becoming red and painful. This is:

    1. A. Trench foot
    2. B. Frostbite
    3. C. Frostnip
    4. D. Cellulitis
    Show answer

    Answer: A. Trench foot

    Trench (immersion) foot is a nonfreezing injury from prolonged exposure to wet cold above freezing, causing vascular and nerve damage. Frostbite requires actual freezing of tissue.

16. Trench foot is best managed by:

    1. A. Rapid rewarming in 45°C (113°F) water for an hour
    2. B. Drying, gently warming, and elevating the feet
    3. C. Massaging the feet with warm oil
    4. D. Keeping the feet wet until arrival
    Show answer

    Answer: B. Drying, gently warming, and elevating the feet

    Remove wet footwear, dry and gently warm the feet, elevate them, and protect them from pressure. Massage and hot water can injure the damaged tissue.

17. Trench foot can be prevented by:

    1. A. Wearing tighter, waterproof boots
    2. B. Wearing two pairs of cotton socks
    3. C. Keeping boots on overnight to stay warm
    4. D. Changing to dry socks often
    Show answer

    Answer: D. Changing to dry socks often

    Keeping the feet dry, changing socks frequently, and allowing the feet to air out prevents immersion injury. Tight boots impair circulation and increase the risk, cotton holds moisture against the skin, and leaving boots on overnight keeps the feet wet instead of letting them dry.

18. Chilblains (pernio) are:

    1. A. Full-thickness frozen areas on the fingers
    2. B. Ice crystals within the cornea of the eye
    3. C. Itchy, red lesions from repeated cold, damp exposure
    4. D. Blisters that form after touching frozen metal surfaces
    Show answer

    Answer: C. Itchy, red lesions from repeated cold, damp exposure

    Pernio results from repeated exposure to cold, damp, nonfreezing conditions and causes red-purple, itchy, tender skin lesions. It is a nonfreezing injury, unlike frostbite.

19. A child's tongue is stuck to a frozen metal pole. The best approach is to:

    1. A. Pull the tongue off the pole quickly
    2. B. Cut the tissue free with a scalpel
    3. C. Breathe on it and wait for it to thaw
    4. D. Pour warm water over the contact area
    Show answer

    Answer: D. Pour warm water over the contact area

    Warm water releases the frozen bond without tearing the mucosa. Pulling the tongue free rips away tissue.

20. Which factor increases the risk of frostbite?

    1. A. Smoking and peripheral vascular disease
    2. B. Wearing loose, layered, dry clothing outdoors
    3. C. Adequate food and fluid intake
    4. D. Frequent movement of the fingers
    Show answer

    Answer: A. Smoking and peripheral vascular disease

    Nicotine causes vasoconstriction and vascular disease limits blood flow, both predisposing to frostbite, as do tight clothing, wet skin, alcohol, and wind. Loose, dry layers protect against it.

21. A homeless man has frostbite of his fingers. After rapid rewarming, ibuprofen may be given per protocol mainly because it:

    1. A. Reverses the ice crystal formation in tissue
    2. B. Raises his core body temperature
    3. C. Limits prostaglandin-driven tissue injury
    4. D. Prevents the need for analgesia
    Show answer

    Answer: C. Limits prostaglandin-driven tissue injury

    NSAIDs such as ibuprofen block thromboxane and prostaglandins that worsen vasoconstriction and tissue loss after thawing. They do not affect core temperature.

22. The areas most prone to frostbite are the:

    1. A. Chest, abdomen, flanks, and the upper back
    2. B. Fingers, toes, ears, nose, and cheeks
    3. C. Thighs, buttocks, and lower back
    4. D. Upper arms and the shoulders
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    Answer: B. Fingers, toes, ears, nose, and cheeks

    Distal parts with high surface area and less blood flow freeze first, especially when the body vasoconstricts to protect the core. The trunk stays warm longest.

23. Superficial frostbite can be distinguished from deep frostbite before thawing because superficial frostbite:

    1. A. Has firm skin with soft tissue beneath
    2. B. Feels hard throughout on deep palpation
    3. C. Looks darker than deep frostbite does
    4. D. Is painful while it is still frozen
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    Answer: A. Has firm skin with soft tissue beneath

    In superficial frostbite the skin is firm or waxy but the underlying tissue is still pliable. In deep frostbite the entire part feels hard, like wood, all the way through.

24. A climber's frostbitten hand was thawed at a hut and is now swollen and blistered. Before evacuation in subfreezing weather, the most important step is to:

    1. A. Drain the blisters to reduce swelling
    2. B. Protect the hand so it cannot refreeze
    3. C. Leave the hand uncovered and exposed to the air
    4. D. Apply topical alcohol to sterilize it
    Show answer

    Answer: B. Protect the hand so it cannot refreeze

    Refreezing of thawed tissue causes severe additional damage, so the hand must be wrapped in dry, bulky, insulating dressings. Blisters should be left intact in the field.

25. A hiker's feet are cold and numb but not frozen, inside tight, wet boots. Before transport you should:

    1. A. Leave the boots on until hospital arrival
    2. B. Pack snow around the boots to cool them
    3. C. Remove the wet boots and socks gently
    4. D. Rub the feet briskly to restore warmth
    Show answer

    Answer: C. Remove the wet boots and socks gently

    Wet, tight footwear keeps cooling the feet and impairs circulation, so remove it gently, dry the feet, and insulate them; boots frozen to the feet are left for the hospital. Rubbing injures cold, numb tissue.