Facts You Should Know About Frostbite
Picture of the stages of frostbite
Frostbite occurs when tissues freeze. This condition happens when you are exposed to temperatures below the freezing point of skin. Hypothermia is the condition of developing an abnormally low body temperature. Frostbite and hypothermia are both cold-related medical emergencies.
The condition has long been recognized. A 5000-year-old pre-Columbian mummy discovered in the Chilean mountains offers the earliest documented evidence of frostbite. Napoleon's Surgeon General, Baron Dominique Larrey, provided the first description of the mechanisms of frostbite in 1812, during his army's retreat from Moscow. He also noted the harmful effects of the freeze-thaw-freeze cycle endured by soldiers who would warm their frozen hands and feet over the campfire at night only to refreeze those same parts by the next morning.
Although frostbite used to be a military problem, it is now a civilian one as well. The nose, cheeks, ears, fingers, and toes are most commonly affected. Everyone is susceptible, even people who have been living in cold climates for most of their lives. Some groups of people at greatest risk for frostbite and hypothermia include those:
- who spend a lot of time outside, such as the homeless, hikers, hunters, etc.;
- under the influence of alcohol;
- who are elderly without adequate heating, food, and shelter;
- who are exhausted or excessively dehydrated;
- who are mentally ill.
What Causes Frostbite?
Your body works to stay alive first and to stay functioning second.
- In conditions of prolonged cold exposure, the body sends signals to the blood vessels in the arms and legs telling them to constrict (narrow). By slowing blood flow to the skin, the body is able to send more blood to the vital organs, supplying them with critical nutrients, while also preventing a further decrease in internal body temperature by exposing less blood to the outside cold.
- As this process continues and the extremities (the parts farthest from the heart) become colder and colder, a condition called the hunter's response is initiated. The body's blood vessels are dilated (widened) for a period and then constricted again. Periods of dilatation are cycled with times of constriction in order to preserve as much function in the extremities as possible. However, when the brain senses that the person is in danger of hypothermia (when the body temperature drops significantly below 98.6 F [37 C]), it permanently constricts these blood vessels in order to prevent them from returning cold blood to the internal organs. When this happens, frostbite has begun.
- Frostbite is caused by two different means: cell death at the time of exposure and further cell deterioration and death because of a lack of oxygen.
- In the first, ice crystals form in the space outside of the cells. Water is lost from the cell's interior, and dehydration promotes the destruction of the cell.
- In the second, the damaged lining of the blood vessels is the main culprit. As blood flow returns to the extremities upon rewarming, it finds that the blood vessels themselves are injured, also by the cold. The vessel walls become permeable and blood leaks out into the tissues. Blood flow is impeded and turbulent and small clots form in the smallest vessels of the extremities. Because of these blood flow problems, complicated interactions occur, leading to inflammation that causes further tissue damage. This injury is the primary determinant of the amount of tissue damage that occurs in the end.
- It is rare for the inside of the cells themselves to be frozen. This phenomenon is only seen in very rapid freezing injuries, such as those produced by frozen metals.
What Are the Stages of Frostbite?
Three frostbite stages are:
- The first degree - irritates the skin
- The second degree - blisters but has no major damage
- The third degree - involves all layers of the skin and causes permanent tissue damage
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What Are the Symptoms and Signs of Frostbite?
Varieties of frostbite classification systems have been proposed. The easiest to understand, and perhaps the one that gives the best clues to the outcome, divides frostbite into two main categories: 1) superficial and 2) deep.
- In superficial frostbite, you may experience burning, numbness, tingling, itching, or cold sensations in the affected areas. The regions appear white and frozen, but if you press on them, they retain some resistance.
- In deep frostbite, there is an initial decrease in sensation that is eventually completely lost. Swelling and blood-filled blisters are noted over white or yellowish skin that looks waxy and turns a purplish blue as it rewards. The area is hard, has no resistance when pressed on, and may even appear blackened and dead.
- The affected person will experience significant pain as the areas are rewarmed and blood flow reestablished. A dull continuous ache transforms into a throbbing sensation in 2 to 3 days. This may last weeks to months until final tissue separation is complete.
- At first, the areas may appear deceptively healthy. Most people do not arrive at the doctor with frozen, dead tissue. Only time can reveal the final amount of tissue damage.
There are milder conditions related to frostbite, including frostnip, chilblains, and trench foot.
- Frostnip refers to the development of tingling sensations (paresthesias) that occur due to cold exposure. They disappear upon rewarming without any tissue damage.
- Chilblain (or pernio) refers to a localized area of tissue inflammation that appears as swollen and reddish or purple. These develop in response to repeated exposure to damp, cold conditions above the freezing point. Chilblains may itch or be painful.
- Trench foot was described in World War I as a result of repeated exposure to dampness and cold and exacerbated by tight boots. The affected feet are reddened, swollen, painful or numb, and may be covered with bleeding blisters. This condition is still observed in some homeless persons today.
When to Seek Medical Care for Frostbite
Seek medical care if you think you, or someone you know has frostbite. A health-care professional must be able to see and feel the affected area. A telephone call is not sufficient with the exception of the mildest cases of cold injury to the hands or feet. The person who has or may have frostbite needs to be evaluated by a medical professional for care.
At the time of initial evaluation, it is very difficult to categorize the injury as superficial or deep, and even more difficult to ascertain the amount of tissue damage. Therefore, if you or someone you are with has frostbite they should be seen by a healthcare professional who will supervise the rewarming process, attempt to classify the injury, and further guide the treatment process. Someone with frostbite will need evaluation and possible treatment for hypothermia and dehydration.
How Do Doctors Diagnose Frostbite?
The doctor will take a history in order to gather information on the events of the exposure and the medical condition prior to the cold injury.
- The doctor will take note of the vital signs, including temperature, pulse, blood pressure, and respiratory rate in order to exclude or treat any immediate life threats such as hypothermia or severe infection.
- X-rays or other imaging studies may be performed, but they probably will be deferred until weeks later when they are more useful to the treatment team.
- The doctor will collect data in order to classify the injury as superficial or deep and the prognosis as favorable or poor.
A good prognosis is heralded by intact sensation, normal skin color, blisters with clear fluid, the ability to deform the skin with pressure, and the skin becoming pink when thawed.
Blisters with dark fluid, skin turning dark blue when thawed, and an inability to indent the skin with pressure indicate a poor prognosis.
What Is First Aid Treatment for Frostbite?
The first step for a person who may have frostbite is to call for medical help. If you are in an area that has an emergency medical alert system such as 911 while attending to the injured person, have someone call 911 and best explain the condition of the patient. Remove all wet clothing from the affected area, and elevate the area higher than the heart if possible to avoid swelling. Keep the person dry and warm. If they are immobile and unable to walk try to keep the person busy with conversation. Keep the body warm and dry if possible.
Are There Home Remedies for Frostbite?
First steps in frostbite treatment.
- Call for help.
- Keep the affected body part elevated in order to reduce swelling
- Move to a warm area to prevent further heat loss.
- Note that many people with frostbite may be experiencing hypothermia. Saving their lives is more important than preserving a finger or foot.
- Do not walk on frostbitten toes or feet if possible.
- Remove all wet clothing and constrictive jewelry because they may further block blood flow.
- Give the person warm, non-alcoholic, non-caffeinated fluids to drink.
- Apply a dry, sterile bandage, place cotton between any involved fingers or toes (to prevent rubbing), and take the person to a medical facility as soon as possible.
- Never rewarm an affected area if there is any chance it may freeze again. This thaw-refreeze cycle is very harmful and leads to disastrous results. If medical care is not immediately available and there is no chance of refreezing, you can use body heat to warm an injured body part (for example placing frostbitten fingers beneath the armpit). Another option if medical care is not readily available, and there is no chance of refreezing, is to immerse the affected areas in warm (not hot) water.
- Do not rub the frozen area with snow (or anything else). The friction created by this technique will only cause further tissue damage.
- Above all, keep in mind that the final amount of tissue destruction is proportional to the time it remains frozen, not to the absolute temperature to which it was exposed. Therefore, rapid transport to a hospital is very important.
What Is the Medical Treatment for Frostbite?
After initial life-threatening problems are excluded or managed, rewarming is the highest priority in medical care.
- This is accomplished in the hospital rapidly in a circulating water bath heated to 40 C to 42 C (104 F to 107.6 F) and continued until the thaw is complete (usually 15 to 30 minutes).
- Narcotic pain medications may be given because this process is very painful.
- Because dehydration is very common, IV fluids may also be given.
After rewarming, post-thaw care is undertaken in order to prevent infection and a continuing lack of oxygen to the area.
- The clear blisters are debrided (dead tissue is removed) while the bloody ones are often left intact so as not to disturb the underlying blood vessels.
- When there is a great risk of damage enough to require amputation (for example, multiple digits, or proximal amputation), tPA (tissue plasminogen activator) may be given into an artery to reduce the incidence of blood clots. This can only be given to people who are not at risk for significant bleeding complications.
- A tetanus booster is given if needed.
People with frostbite are hospitalized for at least 1 to 2 days to determine the extent of the injury and to receive further treatment.
- Aloe vera cream is applied every 6 hours, and the area is elevated and splinted.
- Ibuprofen or a similar anti-inflammatory OTC medication may be given to decrease inflammation.
- For deep frostbite, daily water therapy in a 40 C (104 F) whirlpool bath will be performed in order to remove any dead tissue.
There are a number of experimental therapies for frostbite, many of which aim to further treat the inflammation or decreased blood flow seen in frostbite. As of yet, none of these treatments has proven beneficial.
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How Long Do Frostbite Symptoms Last? Is Frostbite Curable?
Symptoms follow a predictable pathway. Numbness initially is followed by a throbbing sensation that begins with rewarming and may last weeks to months. This is then typically replaced by a lingering feeling of tingling with occasional electric-shock sensations. Cold sensitivity, sensory loss, chronic pain, and a variety of other symptoms may last for years.
The treatment of frostbite is done over a period of weeks to months. Definitive therapy such as surgery may not be performed for up to 6 months after the initial injury. Therefore, it is important to establish a working relationship between you and your doctor that will continue throughout the healing process.
Is It Possible to Prevent Frostbite?
The first step in preventing frostbite is knowing whether you are at increased risk for the injury.
- Most cases of frostbite are seen in alcoholics, people with psychiatric illness, victims of car accidents or car breakdowns in bad weather, and cases of recreational drug misuse.
- All of these conditions share the problem of cold exposure and either the unwillingness or inability of a person to remove himself or herself from this threat.
- Tobacco smokers and people with diseases of the blood vessels (such as those with diabetes) also are at increased risk because they have an already decreased amount of blood flow to their arms and legs.
- Homelessness, fatigue, dehydration, improper clothing, and high altitude are additional risk factors.
Although people don't always know or acknowledge these dangers, many of the dangers can be reduced or prevented.
- Dress for the weather.
- Layers are best, and mittens are better than gloves (keeps your warm fingers together while warming each other).
- Wear two pairs of socks with the inner layer made of synthetic fiber, such as polypropylene, to wick water away from the skin and the outer layer made of wool for increased insulation.
- Shoes should be waterproof.
- Cover your head, face, nose, and ears at all times.
- Clothes should fit loosely to avoid a decrease in blood flow to the arms and legs.
- Always travel with a friend in case help is needed.
- Avoid smoking and alcohol.
- The very old, very young, those who are not in good physical condition, and people with diabetes and anyone with vessel disease should take extra precautions.
- Be especially wary of wet and windy conditions. The "feels like" temperature (windchill) is actually much lower than the stated air temperature.
What Is the Prognosis for Frostbite?
A common saying among surgeons who have treated people with frostbite is "frostbite in January, amputate in July." It often takes months before the final separation between healthy and dead tissue may be determined. If surgery is performed too early, the risks of removing tissue that may eventually recover or leaving behind tissue that may eventually die are great. Some radiographic techniques currently are being investigated that may be able to make this division much sooner, thus permitting earlier definitive treatment.
Beyond this waiting period, many people will suffer long-term symptoms because of their frostbite. Common symptoms include pain or abnormal sensations in the extremity, heat or cold sensitivity, excessive sweating, and arthritis.
Reviewed on 4/17/2020
United States. Centers for Disease Control and Prevention (CDC). "Prevent Hypothermia & Frostbite." Feb. 8, 2019. <https://www.cdc.gov/disasters/winter/staysafe/frostbite.html>
Zonnoor, B. "Frostbite Treatment and Management." Medscape. July 29, 2019. <https://emedicine.medscape.com/article/926249-treatment>