Frostbite

 

Alternative Names:- Cold exposure – arms or legs,congelatio in medical terminology

Definition:
Frostbite is damage to the skin and underlying tissues caused by extreme cold.It causes fluid in skin cells and the tissues beneath the skin to freeze and damages blood vessels. This leads to the formation of blood clots which block the flow of blood and prevent oxygen from getting to the tissues. All cells need oxygen to function properly, as without it they die.

Frostbite  is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas. The initial stages of frostbite are sometimes called “frostnip”.

Classification:-
There are several classifications for tissue damage caused by extreme cold including:

*Frostnip is a superficial cooling of tissues without cellular destruction.
*Chilblains are superficial ulcers of the skin that occur when a predisposed individual is repeatedly exposed to cold
*Frostbite involves tissue destruction.

Stages:-
At or below 0 °C (32 °F), blood vessels close to the skin start to constrict, and blood is shunted away from the extremities via the action of glomus bodies. The same response may also be a result of exposure to high winds. This constriction helps to preserve core body temperature. In extreme cold, or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of the body to dangerously low levels. This lack of blood leads to the eventual freezing and death of skin tissue in the affected areas. There are four degrees of frostbite. Each of these degrees has varying degrees of pain.

*First degree……..
This is called frostnip and this only affects the surface skin, which is frozen. On onset there is itching and pain, and then the skin develops white, red, and yellow patches and becomes numb. The area affected by frostnip usually does not become permanently damaged as only the skin’s top layers are affected. Long-term sensitivity to both heat and cold can sometimes happen after suffering from frostnip.

*Second degree……
If freezing continues, the skin may freeze and harden, but the deep tissues are not affected and remain soft and normal. Second degree injury usually blisters 1–2 days after becoming frozen. The blisters may become hard and blackened, but usually appear worse than they are. Most of the injuries heal in one month but the area may become permanently insensitive to both heat and cold.

*Third and Fourth degrees
If the area freezes further, deep frostbite occurs. The muscles, tendons, blood vessels, and nerves all freeze. The skin is hard, feels waxy, and use of the area is lost temporarily, and in severe cases, permanently. The deep frostbite results in areas of purplish blisters which turn black and which are generally blood-filled. Nerve damage in the area can result in a loss of feeling. This extreme frostbite may result in fingers and toes being amputated if the area becomes infected with gangrene. If the frostbite has gone on untreated they may fall off. The extent of the damage done to the area by the freezing process of the frostbite may take several months to assess, and this often delays surgery to remove the dead tissue

Symptoms:
The first symptoms are a “pins and needles” sensation followed by numbness. There may be an early throbbing or aching, but later on the affected part becomes insensate (feels like a “block of wood”).

Frostbitten skin is hard, pale, cold, and has no feeling. When skin has thawed out, it becomes red and painful (early frostbite). With more severe frostbite, the skin may appear white and numb (tissue has started to freeze).

Very severe frostbite(Third and Fourth degrees) may cause blisters, gangrene (blackened, dead tissue), and damage to deep structures such as tendons, muscles, nerves, and bone.

Causes:
Factors that contribute to frostbite include extreme cold, inadequate clothing, wet clothes, wind chill, and poor blood circulation. Poor circulation can be caused by tight clothing or boots, cramped positions, fatigue, certain medications, smoking, alcohol use, or diseases that affect the blood vessels, such as diabetes.

Exposure to liquid nitrogen, oxygen and other cryogenic liquids can cause frostbite.

Risk factors:
Risk factors for frostbite include using beta-blockers and having conditions such as diabetes and peripheral neuropathy.

Those with blood vessel damage caused by medical conditions, such as diabetes, or because of poor lifestyle habits such as smoking and high-fat diets, may also suffer frostbite more easily than others.

Drinking alcohol and taking certain medicines, such as beta blockers, also increases the likelihood of developing the condition.

Treatment:
When frostbite is suspected, the affected areas need to be warmed. However this should only be done when there’s no risk of them freezing again, which could cause further and possibly irreversible damage.

Ideally, warming should be performed under medical supervision, but this isn’t always possible.

It should be done slowly by immersing the areas in warm – not hot – water. As normal colour returns, they may appear red and swollen. Once this happens they can be removed from the water.

First Aid:

1. Shelter the person from the cold and move him or her to a warmer place. Remove any constricting jewelry and wet clothing. Look for signs of hypothermia (lowered body temperature) and treat accordingly.

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2. If immediate medical help is available, it is usually best to wrap the affected areas in sterile dressings (remember to separate affected fingers and toes) and transport the person to an emergency department for further care.

3. If immediate care is not available, rewarming first aid may be given. Soak the affected areas in warm (never hot) water — or repeatedly apply warm cloths to affected ears, nose, or cheeks — for 20 to 30 minutes. The recommended water temperature is 104 to 108 degrees Fahrenheit. Keep circulating the water to aid the warming process. Severe burning pain, swelling, and color changes may occur during warming. Warming is complete when the skin is soft and sensation returns.

4. Apply dry, sterile dressings to the frostbitten areas. Put dressings between frostbitten fingers or toes to keep them separated.

5. Move thawed areas as little as possible.

6. Refreezing of thawed extremities can cause more severe damage. Prevent refreezing by wrapping the thawed areas and keeping the person warm. If protection from refreezing cannot be guaranteed, it may be better to delay the initial rewarming process until a warm, safe location is reached.

7. If the frostbite is extensive, give warm drinks to the person in order to replace lost fluids.

DO NOT

•Do NOT thaw out a frostbitten area if it cannot be kept thawed. Refreezing may make tissue damage even worse.
•Do NOT use direct dry heat (such as a radiator, campfire, heating pad, or hair dryer) to thaw the frostbitten areas. Direct heat can burn the tissues that are already damaged.
•Do NOT rub or massage the affected area.
•Do NOT disturb blisters on frostbitten skin.

Contact your health care professional if:-

•There has been severe frostbite, or if normal feeling and color do not return promptly after home treatment for mild frostbite
•Frostbite has occurred recently and new symptoms develop, such as fever, malaise, discoloration, or drainage from the affected body part
•Do NOT smoke or drink alcoholic beverages during recovery as both can interfere with blood circulation.

Surgery:
Debridement and or amputation of necrotic tissue is usually delayed. This has led to the adage “Frozen in January, amputate in July” with exceptions only being made for signs of infections or gas gangrene
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Prognosis:
A number of long term sequelae can occur after frost bite. These include: transient or permanent changes in sensation, electric shocks, increased sweating, cancers, and bone destruction/arthritis in the area affected

Research:
Evidence is insufficient to determine whether or not hyperbaric oxygen therapy as an adjunctive treatment can assist in tissue salvage. There have been case reports but few actual research studies to show the effectiveness.

Medical sympathectomy using intravenous reserpine has also been attempted with limited success.

While extreme weather conditions (cold and wind) increase the risk of frostbite it appears that certain individuals and population groups appear more resistant to milder forms of frostbite, perhaps due to longer term exposure and adaptation to cold weather environments. The “Hunter’s Response” or Axon reflex are examples of this type of adaptation.

Prevention:
Be aware of factors that can contribute to frostbite, such as extreme cold, wet clothes, high winds, and poor circulation. Poor circulation can be caused by tight clothing or boots, cramped positions, fatigue, certain medications, smoking, alcohol use, or diseases that affect the blood vessels, such as diabetes.

Wear suitable clothing in cold temperatures and protect exposed areas. In cold weather, wear mittens (not gloves); wind-proof, water-resistant, layered clothing; two pairs of socks; and a hat or scarf that covers the ears (to avoid substantial heat loss through the scalp).

If you expect to be exposed to the cold for a long period of time, don’t drink alcohol or smoke, and get adequate food and rest.

If caught in a severe snowstorm, find shelter early or increase physical activity to maintain body warmth.

Exposure to liquid nitrogen, oxygen and other cryogenic liquids should be avoided or to be handeled with care.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.bbc.co.uk/health/physical_health/conditions/frostbite.shtml
http://www.nlm.nih.gov/medlineplus/ency/article/000057.htm
http://en.wikipedia.org/wiki/Frostbite

http://healthwise-everythinghealth.blogspot.com/2010/01/frostbite.html

http://www.empowher.com/media/reference/frostbite

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