Frostbite

Introduction
Signs and symptoms
Causes
Risk factors
Complications
Treatment
Prevention

Unlike other warmblooded animals that have a layer of hair or blubber to keep them warm, you need an extra layer of clothing to keep you warm when it's cold outside. Without that extra layer of clothing, more heat escapes from your body than your body can produce. If too much heat escapes, the result is hypothermia. Exposure to cold water and certain medical conditions also can cause frostbite or hypothermia.

Frostbite occurs when your body's control mechanisms fail to maintain a normal body temperature. Signs and symptoms that may develop include gradual loss of mental and physical abilities. Severe frostbite can lead to death.

For most Americans, hypothermia isn't a serious risk. Still, each year nearly 700 people in the United States die of hypothermia. In addition to prolonged exposure to cold temperatures, factors that commonly increase your risk of hypothermia include advanced or very young age, substance abuse, impaired mental status and immersion in cold water.

When you're outdoors enjoying such activities as camping, hunting, fishing, boating and skiing, be aware of weather conditions and whether you or others with you are wet and cold. The best approach to being cold and wet is to move indoors and get warm and dry early - before you develop hypothermia.

Hypothermia usually comes on gradually. Often, people aren't aware that they need medical attention. Common signs to look for are shivering, which is your body's attempt to generate heat through muscle activity, and the "-umbles" - stumbles, mumbles, fumbles and grumbles. These behaviors may be a result of changes in consciousness and motor coordination caused by hypothermia.

Other signs and symptoms may include:

• Slurred speech
• Abnormally slow rate of breathing
• Cold, pale skin
• Fatigue, lethargy or apathy

The severity of hypothermia can vary, depending on how low your core body temperature goes. Severe hypothermia will eventually lead to cardiac and respiratory failure, then death.

Your normal core body temperature is usually right around 98.6 F. In hypothermia, your body fails to maintain a normal temperature. An internal body temperature of 95 F or lower signals hypothermia.

The cause of hypothermia usually is extended exposure to cold temperatures or a cool, damp environment. Other contributing causes include inadequate clothing and neglecting to adequately cover your extremities, particularly your head - a disproportionate amount of heat is lost through your head.

Hypothermia can happen not just in cold winter weather, when there are low temperatures or low wind chill factors, but under more mild conditions as well. A rain shower that soaks you to the skin on a cool day can lead to hypothermia if you don't move inside to warm up and dry off. If you stay outside, evaporation of the water from your skin further cools your body, dropping your internal temperature. A wind blowing over the wet parts of your body greatly increases evaporation and cooling.

An accidental fall into cold water also may lead to hypothermia. Hypothermia may develop within minutes of being exposed to cold water or it may take several hours, depending on the water temperature. Water doesn't have to be icy cold to cause hypothermia. Your body loses heat more quickly in water than in air. Any water temperature lower than body temperature causes your body to lose some heat.

Being in extreme cold, wearing wet clothes - especially in the presence of wind - and being in cold water can all play a part in increasing your chances of hypothermia. People who are elderly, very young, mentally impaired, intoxicated or who have certain health issues are especially vulnerable.

• Advanced age. People age 65 and older are especially vulnerable because they may have other illnesses or take medications that can interfere with the body's ability to regulate temperature.
• Very young age. Children usually lose heat faster than adults do. Children have a larger head-to-body ratio than adults do, making them more prone to heat loss through the head. Children may also ignore the cold because they're having too much fun to think about it. And they may not have the judgment to dress properly in cold weather or to get out of the cold when they feel cold. Infants may have a special problem with the cold because they have less efficient mechanisms for generating heat.
• Mental impairment. Individuals who have Alzheimer's disease or another illness that causes mental impairment may not be aware of the risks of being out in the cold. Wandering away from home is not uncommon among people with Alzheimer's, and many are unable to find their way back on their own, leaving them stranded and vulnerable to the weather.
• Alcohol and drug use. Alcohol may make your body feel warm inside, but it lowers your body's ability to retain heat. Both alcohol and drugs such as marijuana can keep your blood vessels dilated, restrict your shivering response, impair your judgment and alter your awareness of weather conditions.
• Certain medical conditions. Some health disorders affect the body's ability to respond to cold or to produce heat. Examples include untreated underactive thyroid (hypothyroidism), stroke, severe arthritis, Parkinson's disease, trauma, spinal cord injuries, burns, blood vessel or nerve disorders that affect sensation in your extremities (for example, peripheral neuropathy in people with diabetes), dehydration and any condition that limits activity or restrains the normal flow of blood. Older adults are more likely to have one or more of these risk factors.
• Water conditions. Factors contributing to your risk of hypothermia in cold water include the temperature of the water and the length of time you spend in it. Rescue time is crucial when a person accidentally falls into cold water. Chances of survival are affected by how cold the water is: The colder the water, the less the chance of survival.

Complications depend on how low your body temperature falls. If you're in water, you may lose consciousness and drown before your temperature drops low enough to cause death by hypothermia. Other complications may include:

• Frostbite
• Loss of limbs
• Coma

The lower your core body temperature, the greater your chance of complications and permanent damage.

Seek immediate medical attention for anyone who appears to have hypothermia. Until medical help is available, follow these guidelines for caring for someone with hypothermia.

What to do

• Move the person out of the cold. Preventing additional heat loss is crucial. If you're unable to move the person out of the cold, shield the person from the cold and wind as best you can.
• Remove wet clothing. If the person is wearing wet clothing, remove it and replace it with a dry covering. Cover the person's head. Try not to move the person too much. Cut away clothing if you need to.
• Insulate the person's body from the cold ground. Lay the person faceup on a blanket or other warm surface.
• Monitor breathing. A person with severe hypothermia may appear unconscious, with no apparent signs of a pulse or breathing. If the person's breathing has stopped or appears dangerously low or shallow, begin cardiopulmonary resuscitation (CPR) immediately if you're trained.
• Share body heat. To warm the person's body, remove your clothing and lie next to the person, making skin-to-skin contact. Then cover both bodies with a blanket.
• Provide warm beverages. If the affected person is alert and is able to swallow, have the person drink a warm, nonalcoholic beverage to help warm the body.

What not to do

• Don't apply direct heat. Don't use hot water, a heating pad or a heating lamp to warm the victim. Instead, apply warm compresses to the neck, chest wall and groin. Don't attempt to warm the arms and legs. Heat applied to the arms and legs forces cold blood back toward the heart, lungs and brain, causing the core body temperature to drop. This can be fatal.
• Don't massage or rub the person. Handle people with hypothermia gently because they're at risk of cardiac arrest.
• Don't provide alcoholic beverages. Alcohol lowers the body's ability to retain heat.

What a doctor may do
A doctor will be able to take steps to warm the body from the inside out, if necessary. One method may involve giving the person warm fluids intravenously. In severe cases of hypothermia, hemodialysis may restore normal body temperatures quickly. Hemodialysis is a medical procedure that removes extra fluid, chemicals and wastes from the blood by filtering the blood through an artificial kidney. It's often used in people with kidney failure. In a hypothermia situation, the blood is removed purely to warm it rapidly outside the body and then have it returned to the body.

For people most at risk of hypothermia - those who are older, have mental or physical impairments or who are homeless - community outreach programs and medical and social support services can be of great help. Identifying and checking in on vulnerable people and groups, preventing prolonged exposure to the cold and ensuring adequate heating are ways to help reduce the number of hypothermia deaths. Monitoring bracelets may provide assistance for people who have a tendency to wander from home. In addition, public health prevention strategies can help educate people about the dangers of prolonged exposure to cold.

Avoid excessive alcohol consumption and the use of illegal substances, because these may increase your risk of hypothermia. Also, don't drink alcohol and operate a boat or other watercraft. Alcohol can impair your ability to navigate the waters, increasing your risk of an accident and of falling into cold water.

Staying healthy in cold weather
Before you or your children step out into cold air, remember the advice that follows with the simple acronym COLD:

• C for cover. Wear a hat or other protective covering to prevent body heat from escaping from your head, face and neck. Cover your hands with mittens instead of gloves. Mittens are more effective than gloves are because mittens keep your fingers in closer contact with one another.
• O for overexertion. Avoid activities that would cause you to sweat a lot. The combination of wet clothing and cold weather can give you chills.
• L for layers. Wear loosefitting, layered, lightweight clothing. Outer clothing made of tightly woven, water-repellent material is best for wind protection. Wool, silk or polypropylene inner layers hold more body heat than cotton does.
• D for dry. Stay as dry as possible. In the winter, pay special attention to places where snow can enter, such as in loose mittens or snow boots.

During cold-weather months, keep emergency supplies in your car in case you get stranded. Supplies may include several blankets, matches, candles and some foodstuffs, such as granola bars or crackers. A cell phone also can come in handy. If your car is stuck in a snowbank, be careful about leaving the engine running, as infiltration of carbon monoxide inside the car may pose a silent danger.

Cold-water cautions
Water doesn't have to be extremely cold to cause hypothermia. Any water that's colder than body temperature causes heat loss. Water that's colder than 70 F can quickly begin to cause hypothermia. The following tips may increase your survival time in cold water, if you accidentally fall in:

• Wear a life jacket. If you plan to ride in a watercraft, wear a life jacket. A life jacket can help you stay alive longer in cold water by allowing you to float without using energy and providing some insulation.

• Don't panic. If you're unable to swim to safety, stay calm. Unnecessary movements require you to exert extra energy and lose body heat.

• Position your body to minimize heat loss. Use a body position known as the heat escape lessening position (HELP) to reduce heat loss while you wait for assistance. Hold your knees to your chest to protect the trunk of your body. If you're wearing a life jacket that turns your face down in this position, bring your legs tightly together, your arms to your sides and your head back.

• Huddle with others. If you've fallen into cold water with other people, keep warm by facing each other in a tight circle.

• Don't remove your clothing. Buckle, button and zip up your clothes. Cover your head if you have a hood. The layer of water between your clothing and your body will be warmed and help insulate you.

• Don't attempt to swim unless you're close to safety. Unless a boat, another person or a life jacket is close by, stay put. Swimming expends extra energy, lowers body temperature and can shorten survival time.