The exposure to cold in a survival situation ranks as one of the most difficult medical problems facing the survival paramedic. Cold injuries management and treatment should be part of your training if you spend a lot of time outdoors or if you happen to live in a cold climate.
A disaster that forces people to abandon their homes during winter is likely to generate large numbers of survivors suffering from various degrees of cold injury. The effects of cold on the body are multiple, and all of them require special considerations in survival planning. Unfortunately, few people have the basic knowledge of what cold injuries management and treatment require.
The effects of cold on the human body
Before we look at cold injuries management and treatment, we should first understand how our body is affected by cold weather. The first effect of cold on the body is the increase of caloric energy needed to maintain a positive heat balance. Lack of proper nutrition will result in a loss of body core temperature, and possibly hypothermia.
It is also very important to maintain adequate hydration in cold weather. Because of the low temperatures, the sensation of thirst is not often demanding even with heavy exertion.
In spite of the reduced sensation of thirst, the body still requires a minimum daily intake of two quarts per day. The kidneys are placed under increased demand for elimination of wastes by the cold, necessitating an increased fluid intake for their proper functioning.
The most immediate problem of cold is the radiation and convection loss of body heat. Body heat is most rapidly lost from the head, hands, and feet. Under extremely cold conditions, it is necessary to warm the breath on inspiration. An air warming mask, available in most drugstores, is useful for reducing the painful effect of breathing excessively frigid air.
Cold, by itself, is not the real enemy of winter. As long as the body is producing heat, adequate layered clothing will maintain a warm layer of air around the body. As soon as most clothing gets wet (extern-ally or from sweat), it loses all of its insulating capacity.
Wool and Hollofil synthetic fiber can maintain its insulating capacity when wet. For this reason, good wool socks should be worn on the feet in cold weather. Winter gloves, coats, and pants are also good insurance against loss of warmth from wetness.
The clothes you wear during the day should be carefully dried by a fire at night. An extra heavy loose woolen night suit with woolen bed socks should be part of the sleeping bag equipment. Sleeping in perspiration and snow soaked underclothing is ill-advised because of the loss of body temperature that will result.
A mummy-style sleeping bag filled with proper insulating fibers is preferred for winter use. It is best to sleep naked within the bag to allow for sufficient evaporation of body perspiration. To avoid dealing with cold injuries management the prepared camper or hiker must have the proper gear when exploring the great outdoors.
Falling in water during the cold season
An unfortunately too common accident of winter is a total immersion into cold water by a fall through thin ice over a lake or stream. This accident can result in severe hypothermia in a matter of minutes.
Crossing ice-covered bodies of water should be avoided if at all possible.
If it is essential to cross-ice, the following rules should be observed:
- If wearing snowshoes, loosen the harness so that they may be quickly removed.
- Always carry a long pole, both to test the footing ahead, and to aid in extrication if a fall through the ice does happen. While walking over the ice, hold the pole horizontally. If you plunge through the ice, the pole can serve as a bridge, both checking the fall and by affording a means to climb back out.
- Travel with your knife in front and on the outside of your clothing. A container of waterproof matches should always be kept pinned to your clothing.
- Stay away from rocks that protrude through the surface of the ice. Walk only on the inside curves of rivers and streams. The outside curves are likely to be thin ice because the current has eroded away the underside of the ice. Avoid walking on candle ice, which is ice several feet thick that has decomposed into long, vertical needles.
Falling through the ice
If the worst happens, and you do plunge through the ice, immediately drive the point of our knife into solid ice and use it to roll yourself out and away. It may be necessary to break away thin ice by hand to reach a surface strong enough to hold your weight.
Get as much of your arms as possible over the edge of the ice and bring your body as nearly horizontal to the ice as you can. Perhaps with a swimming motion of the feet, throw a leg over and roll to safety.
If only your feet have gotten wet, change your socks or squeeze them as dry as possible and wipe out the inside of the shoes or boots. Warm your feet against some other portion of the body, dress, and continue on with your trek.
If you become thoroughly drenched, roll quickly in the most absorbent snow available. Immediately build a tire to dry out completely. It may also be necessary to build a windbreak to prevent heat loss by convection with resultant hypothermia.
After a cold plunge, drink a hot beverage to maintain body core temperature. DO NOT drink alcohol for warmth. It opens skin blood vessels and causes a more rapid loss of body heat than normal.
This article will show you what beverages are recommended and which one should be avoided when dealing with hypothermia.
Peripheral Or Focal Cold Injuries management
Sustained exposure of the cold-sensitive areas of the body results in various degrees of injury, similar to the degrees of damage of burns. These are:
First Degree (chilblains)
A first-degree injury results from exposure, several hours at a time, to a temperature between 32 degrees F. to 60 degrees F. It is usually associated with high humidity. These are the most common situations you will encounter in cold injuries management.
Redness and swelling of the affected areas, burning dermatitis, tingling, and later a deep-seated ache is present.
Second Degree (immersion/trench-foot)
This occurs in cases of immersion foot, with exposure to cold water (50 degrees and below) for twelve hours or more, or to water at approximately 70 degrees F. for several days. Immobilization and dependency of the limbs are contributing factors.
Symptoms of immersion foot:
Swelling of the legs and feet, bluish discoloration of the skin, numbness, itching, blisters, pain, and neuromuscular changes.
Trench foot occurs with exposure to damp cold (32 degrees F. to 50 degrees F.) for several hours. As with immersion foot, trench foot is aggravated by the dependency of the limbs, prolonged immobility, and tight constrictive clothing.
Symptoms of trench-foot:
First is the blanching of the affected part, tingling, followed by numbness. The legs and feet swell, and the skin develops a dusky red, or bluish discoloration, and blisters develop with intense, burning pain. Neuromuscular changes may occur if the injury is severe enough.
This injury occurs with exposure to dry cold at temperatures of 20 degrees F. or colder for a brief period, or exposure to approximately 0 degrees F. for several hours.
Burning pain, stinging, and then numbness. Ice crystals in the skin may cause grey or white waxy coloration of the skin. The skin will move over bony prominences. Swelling and blisters may occur with aching pain requiring analgesics for relief.
There may be a noticeable limitation of motion in the affected part. Death of tissues, resulting in gangrene may occur, resulting in a sloughing (casting away) of the destroyed tissues.
Fourth Degree (freezing)
This results from exposure to 20 degrees F. to 60 degrees F. and below. It may occur immediately to exposed fingers and toes, with extension to the limbs as exposure is prolonged. Although this may not be a common occurrence in cold injuries management, chances are you may one day have to deal with a freezing person.
Ice crystals appear in the entire thickness of the skin down to the bone, indicated by a pallid, yellow, waxy color. The skin will not move over bony prominences. Swelling and large blisters, intense pain and loss of motion occurs. Gangrene of the part is almost unavoidable.
Cold Injuries Management – Understanding how damage occurs
The exact mechanism of focal cold injuries is unknown. It appears to be a combination of actual cell damage caused by the cold and from changes in the blood vessels supplying the part. Modern research has shown that there are two possible mechanisms of cell injury caused by cold.
Slow cooling of cells seems to cause them to shrink in size, and then take up excess salts which cause them to swell and die. Rapid cooling results in the formation of ice crystals inside the cell. In itself, this may allow for the survival of the cell if thawing is accomplished rapidly instead of slowly. Slow thawing of frozen tissue seems to cause the formation of large ice crystals inside the cell, which kill it.
The vascular changes include dilation of the blood vessels with a sludging of blood in the microvasculature, which arrests circulation to the cells. There also are marked differences in individual response to cold.
The chances of injury by exposure to low temperatures seem to be increased in those with darkly pigmented skin, advanced in age or in poor general condition. Anoxia (lack of oxygen) caused by high altitude climbing or flying causes cold injuries at higher temperatures and with less exposure than at ground level.
Accurate determination of the actual extent of tissue damage at the time the injury occurs is impossible. The affected tissues are usually white, very cold to the touch, have lost their pliability, and become hard and anesthetic with further cooling.
Cold Injuries Management and Treatment
Before field treatment of focal cold injuries can take place, it is necessary to remove the victim to the driest, warmest, most windproof location available.
Exchange wet clothing for dry, if possible. If transportation is to be delayed, build a fire or have the victim huddle against another person(s) within available blankets or sleeping bags.
Warm hands and feet beneath armpits and thighs. Facial frostbite can be prevented by making faces to maintain circulation and warmth.
Cold injuries management and procedures:
- Rapidly rewarm by moist heat as in warm water immersion or with compresses. This should only be undertaken after it is certain that the victim will not suffer further injury by refreezing of the thawed parts. It is better to postpone rapid rewarming for a few hours than to be forced to repeat the process. Tissue death is certain of refreezing occurs. Once a safe place has been reached, and rapid rewarming performed, no further rapid rewarming should be done even if a temporary drop in temperature occurs. The warming solution should be between 100 degrees F. and 110 degrees F., checked by a thermometer. Regulated dry heat is also effective.
- After rewarming, exposure to air at about 70 degrees F. is most satisfactory. The skin often becomes blotchy red and painful on rewarming.
- Administer analgesics for severe pain. Aspirin, in addition to having a pain-killing effect, also reduces platelet stickiness, which may aid in preventing the sludging of blood in the vessels.
- Give warm drinks as desired.
- If the skin is broken, it should be treated with topical antibiotics such as silver sulfadiazine of sulfamylon. Assure that tetanus immunity is current (given within the past 10 years).
- Evaluate and treat for any coexistent trauma or illness.
- Administer antibiotics systemically if a spreading infection is present.
- Maintain observation until the extent of the injury can be determined (in some cases for as long as a week).
- The use of topical dilute dimethyl sulfoxide (DMSO) has been found useful in limiting the tissue injury from excessive cold exposure. If DMSO is available, under survival conditions, nothing is lost by trying it. The above treatment regimen is based on the sound principles of re-establishing circulation and thawing frozen cells so that normal function may be resumed.
In the past, many falsely conceived and dangerous procedures have been used to treat focal cold injuries. Many people still believe in these remedies because of the long-standing nature of the false information.
Things to avoid in cold injuries management and treatment
These methods should never be used in cold injuries management. DO NOT:
- Rub or compress the affected part with ice, snow, or cold water. Massage or friction of any kind is harmful.
- Empty the contents of blisters or Webs.
- Allow the use of the injured part, especially weight hearing, unless absolutely necessary.
- Apply pressure dressings or ointment of any type.
- Allow the use of tobacco or coffee.
- Administer anticoagulants (such as heparin), corticosteroids, or vasodilators. They are of no value and may cause harm.
- Perform surgery early after the injury. Frequently, the loss of tissue is superficial.
The most serious effect of cold to suffer under survival conditions is a generalized loss of body temperature, known as Core Hypothermia, or Severe Cold Exposure.
Severe chilling of the whole body, resulting in a rectal temperature of 95 degrees F. or below from exposure to cold environmental conditions or immersion, leads to a progressive decrease of physiologic processes that eventually becomes irreversible.
The ability to survive hypothermia depends on the length of exposure and the rapidity of cooling. Inherent constitutional factors (some persons tolerate cold temperatures better than others), environmental factors (altitude, barometric pressure, humidity), and physical condition (age, nutritional status. pre-existent disease or injury) all play a role in the development of hypothermia.
Survival after rectal temperatures as low as 60 degrees F. has been reported. A favorable physical status seems more important than the method of rewarming.
Treatment of Core Hypothermia:
- Apply blankets, preferably reflective blankets.
- Insert a urinary catheter to monitor urine output. Intravenous fluids must be limited until kidney function is re-established; usually, 12 to 18 hours after treatment has begun.
- Conduct a careful search for any underlying disease processes. Hypothermia may completely mask infection and signs of other diseases. Do not administer any drugs until body temperatures approach normal.
- Rapid rewarming is necessary if the rectal temperature is close to the lethal limit (85 degrees F. and below). Apply heat under close supervision by any and all means available. This includes warm fluids by intravenous route and by rectum.
Warm liquids can be administered into the stomach via a nasogastric tube. The rate of body temperature increase is not related to the methods used and rarely exceeds 1.2 degrees F./hour.
The urinary output should be carefully monitored by catheter collection. Close observation for the signs and symptoms of the detrimental effects of rapid rewarming (cardiac instability and hypertension) must be maintained around the clock.
The institution of CPR (cardiopulmonary resuscitation) procedures may become necessary at any point during the rewarming of the hypothermia casualty. Severe hypothermia reduces the tissue demands for oxygen.
In a situation where a fall through the ice into freezing water has occurred, CPR may be effective after long-term immersion. If a rescuer finds someone who has been submerged in cold water, he should immediately commence CPR in the hope that life may be salvaged. Such resuscitation efforts carry the risk of reviving a person with severe brain damage from insufficient oxygen.
In cold injuries management, the major complication is the production of gangrene in the affected tissues. This is believed to occur from the sludging of red blood cells leading to a blockage of the capillaries. The gangrene produced is commonly superficial or limited to the extremities.
To prevent this sludging of red blood cells, it is recommended that low molecular weight dextran be administered intravenously along with full doses of aspirin. Treatment of evident gangrene will be necessary if preventive measures are too late to save the tissues.
In cold injuries management and treatment, it has been observed that the strangulating effect of the black necrotic eschar frequently results in gangrene of the entire finger or toe.
To prevent this, the eschar (dry slough) should be bivalved (split on two sides) as soon as possible. This operation is painless and can be accomplished in a few minutes. If the eschar is hard and thick, it can be softened by immersion in sterile lukewarm water containing liquid soap.
Some black eschars peel and leave healthy and sensitive skin underneath. Nails are often shed, but a satisfactory recovery can occur.
Gangrene of the hand should be treated with a conservative attitude. Apparently, mummified fingers may peel gradually, leaving healthy fingers. It cannot be determined until a period of three months have elapsed if amputation of the digits is necessary. Amputation for gangrene induced by extreme cold can be deferred until the tissues are obviously at serious risk for infection.
Amputations under field conditions should be undertaken as an extreme last resort to prevent serious systemic infection resulting from the retention of dead tissues. Under no circumstances should a paramedic perform amputation of the digits unless it is certain that life itself is threatened by overwhelming infection.
Gangrene of an entire limb is rare from environmental exposure to cold. However, there is a class of severe cold injury caused by being exposed to liquid propane used for fuel. This type of injury is common in rural areas where propane is used to fuel tractors and other farm equipment. The greatest amount of damage is done when liquid propane contacts the skin. One such case had to have an arm amputated because of deep damage to the tissues.
Though not a cold injuries management topic per se, snow blindness is still a common problem of winter. This is caused by actual ultraviolet burns of the cornea by reflected sunlight of snowfields. This condition is manifested by a painful inflammation of the eyes which become bloodshot, tear excessively and feel like there is grit in them.
Infection commonly occurs and is indicated by a purulent discharge that sticks the lids together. Treatment requires the application of an ophthalmic antibiotic ointment or drops (Neosporin or genoptic).
Prevention of snow blindness requires protection of the eyes from UV radiation. This may be obtained by using polarized sunglasses or goggles.
An expedient field pair of snow glasses can be made by cutting small slits in a piece of birch bark for the eyes, and by turning down a little tab at the bottom of the slits. This will prevent reflected sunlight from entering the eyes.
Applying lampblack along the bottom of the eyes will also aid in preventing UV eye burns.
Cold injuries management should be conducted only if the person knows what he or she is doing. There are many survival myths that cover the topic of saving a person from cold exposure, and it’s better to be able and identify fact from fiction. Cold management and treatment become mandatory for outdoor enthusiasts and people living in harsh climates.
This article has been written by James H. Redford MD for Prepper’s Will.
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