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When the Weather Outside is Frightful: What Frostbite is and What it Does

Our last blog entry was concerned with hypothermia (see “Watch out for the Umbles: Preventing and Treating Hypothermia”) and to continue that thread, we’ll be looking at frostbite.

Frostbite occurs when skin and underlying tissues freeze. This is quite likely to happen when the environment is below freezing, especially to exposed skin or to tissues with inadequate blood circulation—often in the toes, nose, fingers, cheeks, ears and chin. The most common cause of frostbite is exposure to cold-weather conditions. The body restricts circulation by constricting blood vessels in the exposed areas and the extremities; this protects the core temperature and counteracts hypothermia. Frostbite can also be caused by direct contact with ice, freezing metals or very cold liquids.

The following factors increase the risk of frostbite:

  • Medical conditions that affect your ability to feel or respond to cold, such as exhaustion, dehydration, the effects of a stroke, diabetes and poor circulation to the limbs
  • Alcohol or drug use (alcohol speeds heat loss, and intoxicants increase the danger of falling asleep in the cold)
  • Smoking (decreases circulation by constricting blood vessels)
  • Mental illness, fear and panic, especially if judgment and or response to cold is impaired
  • Previously suffering  frostbite or cold injury
  • Victim is an infant or older adult (these age groups have a harder time producing and holding body heat)
  • Exposure at high altitude (the oxygen supply to the skin is reduced)

Cold exposure, like heat exposure, occurs in stages. Recognizing the onset of frostbite can reduce permanent damage. Victims of frostbite should seek medical attention after experiencing any severe cold exposure, whether or not frostbite occurred.

Stages of frostbite (and accompanying symptoms) include:

  • 1st degree - “Frostnip” is the first stage and does not cause permanent damage. Skin turns pale or red and feels very cold. May lead to prickling, itching and numbness. Warming the tissue may lead to pain and tingling (frostnip can lead to long-term sensitivity to heat and cold).
  • 2nd degree - Superficial frostbite causes reddened skin that later becomes pale or grayish-yellow, waxy in appearance. Skin is still soft but some ice crystals may be forming in the outer tissues. Skin may begin to feel warm. Rewarming at this stage may cause the skin to become bluish-purple or mottled. Swelling occurs and the victim may experience stinging or burning sensations. Fluid-filled blisters may form a day or two after rewarming. Injuries may take a month to heal.
  • 3rd/4th degree- Severe frostbite: affects all layers of the skin (muscles, tendons, blood vessels, and nerves); numbness or total loss of sensation.  Joints/muscles do not work. Large blisters form after 24-48 hours. Tissue turns black and hard after it dies. It may take months to determine how much damage has been caused by the freezing of tissue, so surgery to remove dead tissue (including amputation) is often delayed.

The advisability of thawing out frostbitten tissue depends on proximity to a stable, warm environment. When thawed tissue refreezes, the damage will increase. Movement of the victim should be kept to a minimum, as ice crystals in frozen tissues will cause further damage. Immobilizing frostbitten extremities (by bandaging and/or splinting) is advised. Trying to rewarm frostbitten tissue by massaging or rubbing it can be harmful, as the frozen tissue is susceptible to damage. If the victim’s tissues are in danger of re-freezing, thawing is not recommended. When tissues refreeze, the damage becomes worse.

Two methods are used for thawing frozen tissue; passive rewarming and active rewarming. Passive rewarming employs body heat or the environment (i.e. a warm room) to help the victim’s body to rewarm itself. Victims may be wrapped in blankets or other insulators to speed the process. Active rewarming occurs when heat is directly applied to a person, most often as an addition to passive rewarming. This may be difficult to accomplish without specific tools, so may be restricted to a hospital. The intent is to quickly warm the tissue in a manner that does not cause burning, so that damage is reduced. Tissues may be immersed in water that is at temperatures between 104-108°F (40-42°C). This process needs to be closely monitored by a medical professional as the warming of the peripheral tissues can increase the flow of blood back into the core of the body, dropping core temperature again and causing irregular heartbeat.

Victims of frostbite will likely experience substantial pain during the rewarming process. Pain medications such as ibuprofen, acetaminophen, and aspirin may be administered (as long as there are no allergies).

Remember, the best way to avoid frostbite is to avoid the conditions that cause it. Those who experience signs of early hypothermia should be moved into warm, dry environments as quickly as possible.  Should you suspect frostbite, see a medical professional as soon as possible.


Published on January 26, 2015