Preventing Frostbite

You may start to feel the bone chilling weather that hit parts of the country... and you may have heard the warnings to stay indoors if possible. Just opening a window a crack seemed to prove that was good advice. But as you trundle down the street in your many layers this winter, you may wonder if all this bundling up is always necessary. Cold weather experts say it is: You can run the risk of hypothermia and frostbite even in mild temperatures if you're not fully prepared to face the elements.

Failure to take the appropriate precautions can go far beyond a little Jack Frost nipping at your nose. Untreated frostbite can lead to amputation, and hypothermia can cause death in just 30 minutes. About 700 people in the United States die from hypothermia each year, according to the Centers for Disease Control and Prevention.

But Jay Biem, MD, a general internist and an associate professor of medicine at the University of Saskatchewan in Canada, explains that most cold weather conditions are preventable. "You just need to keep the precautions in mind, especially for our frail, susceptible people," he says.

Below, Dr. Biem discusses the early symptoms and treatment of cold weather conditions and offers tips to outdoor enthusiasts, the elderly and others on how to combat the cold, from avoiding alcohol to donning a waterproof outer layer.

What temperatures are usually considered harmful?
I can't give absolute temperatures because there are several factors that affect the risk of hypothermia and frostbite, such as the external environment, especially wind speed and humidity, the person's clothing and the person's individual susceptibility to the cold.

For hypothermia, exposure to nonfreezing temperatures, especially if prolonged, can overwhelm the body's ability to maintain its normal temperature.

There is a risk of frostbite with a temperature of 14 degrees Fahrenheit, especially if there's wind. With a temperature or a windchill equivalent temperature of minus 13, there's a major risk, and with a temperature or windchill equivalent temperature of minus 50, exposed skin freezes in just a few minutes.

What is the windchill factor?
It's a calculation that takes into account not only the temperature but also wind speed, which affects how quickly tissues freeze. The way we do it now is to actually quote an equivalent of what the temperature would be if there were no wind. It may be minus 10 outside, but because of the wind, it may be the equivalent of minus 40.

Are some people at higher risk for cold-related conditions than others?
Yes, a variety of factors affect the ability to maintain body temperature and avoid cold injury. People at the extremes of age are particularly sensitive to cold. Infants have a high body surface area to weight ratio and lose heat very quickly. Older people tend to have less muscle mass and therefore generate heat less well. People who are exhausted, either because of physical activity or fatigue, and people who are malnourished will not be able to generate sufficient heat as well. People with a variety of medical conditions like diabetes, thyroid disease, spinal and nerve disorders are also more susceptible to the cold. Certainly, the homeless population is at major risk; every winter in our large cities we see increased rates of death among the homeless.

How does the body react to a low temperature?
The body tries to maintain a normal temperature, and it does that by shifting blood flow to the circulation to the central body. The body turns on what's called the sympathetic nervous system. This constricts blood flow to the limbs, speeds the heart rate and increases the blood pressure. The muscles generate heat through shivering, and the bowel and bladder function also gets sluggish.

How does what you eat and drink affect body temperature?
Certainly being malnourished decreases the amount of energy available for body heat generation. Being dehydrated may decrease the peripheral blood flow, which decreases the delivery of heat to the limbs.

People really shouldn't mix alcohol with cold weather. Drinking alcohol and being out in the cold greatly increases the risk of hypothermia and frostbite. Alcohol increases the risks of falls and motor vehicle accidents, which can lead to being out is the cold for too long. It can impair the judgment that would lead a person to seek shelter. And alcohol decreases shivering that is needed for heat generation and can cause flushing, which increases body heat loss.

What is frostbite?
Frostbite is simply the freezing of body tissues, and it can be as simple as frostnip, which is freezing of the very superficial layer of the skin. Superficial freezing just affects the skin and fatty tissues and then deep frostbite is freezing way down to bone and muscle.

What are the symptoms of frostbite?
Early on in frostbite, the extremities, especially the hands, feet and face, have pain and tingling. They appear cold and pale. If the frostbite is more severe, the area will be numb. However, based on symptoms, it can be hard to determine how bad the frostbite is.

On re-warming, the frostbitten tissue may develop large blisters and swell. Damage to the blood vessels can lead to gangrene, and over the next several days to weeks, the extremities may turn black and infection may set in; amputation may be required.

What should people do before medical treatment is available?
The important things are to get that person into a warm environment. Frozen clothing that's not stuck to the frostbitten area could be removed. But if the clothing is adherent, it should be left in place until the area is re-warmed. A common misconception is that rubbing helps, but rubbing actually increases tissue damage.

Cold, numb hands or feet should be warmed immediately as long as there is not going to be refreezing on the way in to the hospital. Areas can be warmed with warm but not hot water (we want to avoid burns).

How is frostbite treated?
At the hospital, a frostbitten area is warmed. Then the treatment is supportive with watchful waiting. If there are signs of infection, we give antibiotics. If, as time goes on, big blisters form that rupture, we may need to apply a wound dressing. We tend to delay decisions about amputation until there is clear demarcation of dead or living tissue.

What is hypothermia?
Hypothermia occurs when the central body temperature is less than 95 degrees Fahrenheit. Standard thermometers may not measure low temperatures. Early on in hypothermia, the body tries to maintain heat through shivering. The heart rate and blood pressure are increased and bowel and bladder function are sluggish. The extremities are cold. As the hypothermia becomes severe, shivering may stop. Patients become confused and even comatose. The heart may have irregularities and may stop.

How is hypothermia treated?
For a patient who is suspected to have hypothermia, bystanders should call 911. The patient needs to be taken out of the cold environment and monitored carefully and treated gently because they're predisposed to heart rhythm problems.

For young people, who have just mildly low temperature and who can generate heat through shivering, warm blankets may be enough. But for moderate and severe cases, re-warming needs to more active. In the hospital, we can use warmed intravenous fluids and warmed oxygen. For severe cases, we can get warm water into the body cavities to warm the body centrally.

For patients who are cold and pulseless, cardiac bypass may be lifesaving. This is a procedure where blood is taken from the patient, warmed and then given back. We've seen some miraculous recoveries of some patients here in Western Canada, especially children. Although they appeared dead, they were brought back to life with re-warming.

How can hypothermia and frostbite be prevented?
I think a lot of prevention is common sense. Obviously, avoiding exposure to extreme cold, taking precautions, thinking about susceptibility, and dressing properly can prevent hypothermia and frostbite. Weather reports and the reporting of temperatures as well as the wind-chill equivalent helps people assess the risk.

Obviously, dressing in proper clothing is important. In cold weather, people should wear loose fitting clothing that covers the head. Clothing should include insulating layers and the outer layer should be windproof. So when people are too warm, they are able to remove those layers to avoid sweating, because body moisture increases susceptibility to cold. When people are cold, they should add more layers.

For frail, older people, a fall outdoors in the winter can be fatal because they may be unable to get back inside. People need to avoid falls by wearing proper footwear, having canes with traction and using handrails. Also, workers shouldn't ignore the warning symptoms of frostbite or hypothermia. When people experience cold, pain, and tingling in the extremities or face, they need to seek shelter.

Do you have any special advice for people who engage in winter sports?
I think people with chronic medical problems considering participating in winter sports activities should seek medical advice. Outdoor winter sports tend to take more energy and require more exertion than other sports.

People should avoid going out on really cold and/or windy days. When they do go out, they need to dress appropriately with layers and clothing that is not too constrictive. If a sport involves speed through cold air, such as skiing, that is going to increase the risk of frostbite. Good headgear including a facemask and windproof clothing layer are important. If winter athletes get wet, they can get cold quickly. For example, downhill skiers, snowboarders, cross-country skiers can be incredibly susceptible to the cold if they get wet.

People shouldn't mix alcohol with their outdoor sporting activity because it definitely increases the risk of accidents and susceptibility to cold.

Do you have any special advice for children?
I think a lot of the same advice applies. Children need to be educated about the risks of cold exposure. They need to know about the symptoms of frostbite and hypothermia. They need to be told how important it is to dress appropriately and to seek shelter. They need to tell their parents where they're going. Around the home, parents need to take measures to prevent small children from wandering outdoors.

How are cardiac conditions affected by cold weather?
There have been a number of studies worldwide that have shown associations between cold weather and adverse health outcomes such as cardiovascular disease. The body's response to cold is to increase heart rate and blood pressure and that increases the oxygen demands of the heart. When there is an increased workload, sometimes that vigorous activity can lead to a plaque rupture if there's hardening of the arteries. A classic example is associated with the first heavy snowfall. People who have to shovel may be unaccustomed to this exertion. Some collapse with a heart attack because of this exertion, combined with increased heart rate and blood pressure from the cold.

Are there any other conditions associated with the cold?
Cold exposure can make a number of heart, lung and blood conditions worse. Asthma may be precipitated by cold. On exposure to cold, some people—especially women—will get cold, pale, numb hands due to a clamping down of the blood vessels. This disorder is called Raynaud's phenomenon. Local cold exposure can damage a nerve and cause persistent numbness and tingling. Some people get itching patches on cold exposure.

What preparations need to be made in the homes?
People need to think about what they would do in case of a heating failure. The preparation depends on the living situation and the environment. In a rural or remote area, the danger is much greater. People need to prepare the home with adequate backup heating source, as well as food supplies and prescription medication. Supplies need to be appropriate for how long the heating failure could last.

How can people protect themselves if they're stuck out in the cold?
Every situation is different. If people are stuck in a car, it's often better to stay in the vehicle, out of the wind. People can huddle together while a waiting for rescue. They should use whatever they have to keep dry and warm and out of the wind.

For winter car travel, people should have a cell phone. Some people keep sleeping bags and candles in the trunk. Prevention and preparedness for the cold are crucial.

You know, the winter is a beautiful but dangerous time of year that gives us an exquisite appreciation of summer.