INJURIES AND ILLNESSES DUE TO COLD

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INJURIES AND ILLNESSES DUE TO COLD

HYPOTHERMIA (LOWERED BODY TEMPERATURE)

The body generates heat through metabolic processes that can be maximized with involuntary shivering to roughly 5 times the basal level (up to 10 times with maximum exercise). However, shivering is abolished after a few hours of exposure, because of exhaustion and depletion of muscle energy supplies. When a victim loses the ability to shiver, the cooling process becomes quite rapid. Skin, surface fat, and superficial muscle layers then act as an insulating “shell” for the core of vital organs (heart, lungs, liver, kidneys, and so on). People are tropical beings—that is, when they are naked and at rest, the environmental temperature at which body heat is neither gained nor lost is 82°F (28°C). Normal skin temperature in cool weather is 90°F to 93°F (32.2°C to 33.9°C); this can drop to 70°F to 73°F (21.1°C to 22.8°C) before core cooling begins. Accidental hypothermia occurs when there is an unintentional decrease of 3.6°F (2°C) from the normal core (measured rectally) body temperature of 98.6°F to 99.9°F (37°C to 37.7°C). Normal oral temperature is 98.6°F (37°C). Mild hypothermia is considered to occur when the core temperature is between normal and 91.4°F (33°C); moderate hypothermia is core body temperature below 91.4°F (33°C) down to 85.2°F (29°C); severe hypothermia is core body temperature below 85.2°F (29°C) down to 71.6°F (22°C); and profound hypothermia is below 71.6°F (22°C).

Heat is lost from the body to the environment by direct contact (conduction), air movement (convection), infrared energy emission (radiation), the conversion of liquid (sweat) to a gas (evaporation), and the exhalation of heated air from the lungs (respiration). It is important to note that the rate of heat loss via conduction is increased 5-fold in wet clothes and at least 25-fold in cold-water immersion. Windchill (Figure 176) refers to the increase in the rate of heat loss (convection) that would occur when a victim is exposed to moving air. This chill can be compounded further if the victim is wet (conduction, convection, and evaporation).

Figure 176 Windchill determination. To determine windchill, find the ambient air temperature on the top line, and then read down the column to the line that corresponds with the current wind speed. Example: When the air temperature is 10°F and the wind speed is 20 mph, the rate of heat loss is equivalent to −9°F under calm conditions. To convert to metric or Celsius, use the following: 1 mile = 1.61 kilometers; C = 5/9 (F − 32).

At a core body temperature of 96.8°F (36°C), metabolic rate, blood pressure and preshivering muscle tone increase. At 95°F (35°C), the body cannot be any more effective at generating heat by shivering.

Immersion hypothermia refers to the particular case in which a victim has become hypothermic because of sudden immersion into cold water. Again, water has a thermal conductivity approximately 25 times greater than air, and a person immersed in cold water rapidly transfers heat from his skin into the water. The actual rate of core temperature drop in a human is determined in part by these phenomena and in part by how quickly heat is transferred from the core to the skin, skin thickness, the presence or absence of clothing, the initial core temperature, gender, fitness, water temperature, drug effects, nutritional status, and behavior in the water.

A sudden plunge into cold water causes the victim to hyperventilate (see page 300), which may lead to confusion, muscle spasm, and loss of consciousness. The cold water rapidly cools muscles and the victim loses the ability to swim or tread water. Muscles and nerves may become ineffective within 10 minutes. Over the ensuing hour, shivering occurs and then ceases. Anyone pulled from cold water should be presumed to be hypothermic. In terms of survival, the aphorism is that when a person is plunged into very cold water (32°F or 0°C), he or she has 1 minute to control breathing (e.g., to stop hyperventilating from the “gasp reflex”), 10 minutes of purposeful movement before the muscles are numb and not responsive, 1 hour before hypothermia leads to unconsciousness, and 2 hours until profound hypothermia causes death.

The progression of hypothermia leads to predictable physiological responses, which roughly correspond to different body temperatures. Although not invariable, the signs and symptoms are as follows:

91.4°F to 98.6°F (33°C to 37°C). Sensation of cold; shivering; increased heart rate; urge to urinate; slight incoordination in hand movements; increased respiratory rate; increased reflexes (leg jerk when the knee is tapped); red face; muscular incoordination, stumbling gait, maladaptive behavior, rapid heart rate converting to slow heart rate, apathy.

85.2°F to 91.4°F (29°C to 33°C). Stupor; decreased or absent shivering; weakness; apathy, drowsiness, and/or confusion; poor judgment; slurred speech; inability to walk or follow commands; paradoxical undressing (inappropriate behavior); complaints of loss of vision; amnesia; rapid heart rate converting to slow heart rate; rapid breathing rate converting to shallow breathing; loss of shivering; possible nonreactive or dilated pupils, abnormal heart rhythms, diminished breathing.

71.6°F to 85.2°F (22°C to 29°C). Minimal breathing; coma; decreased respiratory rate; decreased neurologic reflexes progressing to no reflexes; no voluntary motion or response to pain; very slow heart rate, low blood pressure; maximum risk for ventricular fibrillation. The victim no longer can control his body temperature and rapidly cools to the surrounding environmental temperature.

Below 71.6°F (22°C). Rigid muscles; barely detectable or absent blood pressure, heart rate, and respirations; dilated pupils; risk for ventricular fibrillation; appearance of death.

The first principle of therapy is to suspect hypothermia. Any person who is found in a cold environment should be suspected of suffering from hypothermia. The definition of “cold environment” is variable. Someone who is wet, improperly dressed, and intoxicated with alcohol can become hypothermic in 70°F weather. Do not use yourself as an indicator of warmth—you may be perfectly comfortable while your companion is lapsing into hypothermia.

Unless the victim is found frozen in a block of ice or has been recently pulled from frigid waters, the most likely clue to a hypothermic state is altered mental status. The winter hiker who gradually loses interest and lags behind the group (“Just leave me behind—I’ll catch up”), who dresses inappropriately for the weather or begins to undress, or who begins to stumble and make inappropriate remarks should be immediately evaluated for low body temperature. A hypothermic individual may become anxious, repeat himself, or even become delusional. Never leave a victim of even mild hypothermia to fend for himself.

The second principle of therapy is to measure the victim’s temperature. This should be done, if possible, with a thermometer calibrated to read below 94°F (34.4°C), which is the cutoff for most standard oral thermometers. Hypothermia thermometers with a range of 75°F to 105°F (23.9°C to 40.5°C) are available. Temperature ideally should be measured rectally, although this is often impractical. Oral and axillary (armpit) temperatures are unreliable in this situation, and should be used only to screen for low body temperature. That is, if they are normal, the victim will have at least a normal body temperature, but could be hotter. However, if they are low, they may grossly understate how cold the victim really is, and should be followed with a rectal measurement. Digital electronic eardrum scanners used to measure temperature may also yield a false (compared to the core) reading.

Unless the victim has suffered a full cardiopulmonary arrest, the hypothermia itself may not be harmful. Unless tissue is actually frozen, cold is in many ways protective to the brain and heart. However, if a hypothermic victim is improperly transported or rewarmed, the process may precipitate ventricular fibrillation, in which the heart does not contract, but quivers in such a fashion as to be unable to pump blood. The burden of rescue is to transport and rewarm the victim in a way that does not precipitate ventricular fibrillation.

The following general rules of therapy apply to all cases:

1. Handle all victims gently. Rough handling can cause the heart to fibrillate (cause a cardiac arrest). Secure the scene and avoid creating additional victims via unstable snow, ice, or rock fall.

2. If necessary, protect the airway (see page 22) and cervical spine (see page 37). Stabilize all other major injuries, such as broken bones.

3. Prevent the victim from becoming any colder. Provide a shelter. Remove all his wet clothing and replace it with dry clothing. Don’t give away all of your clothing, however, or you may become hypothermic. Replace wet clothing with sleeping bags, insulated pads, bubble wrap, blankets, or even newspaper. The “blizzard pack” from Blizzard Protection Systems, Ltd. (www.blizzardpack.com) can be used to provide protection from the elements. The Pro-Tech Extreme bag or vest, SPACE brand emergency bag, SPACE brand all-weather blanket, and SPACE brand emergency blanket, all from MPI Outdoors (www.mpioutdoors.com), are other options for this purpose.

Cover the victim’s head and neck. Insulate the victim from above and below with blankets. Do not change blankets unless necessary to keep the victim dry. If possible, put him in a sleeping bag sandwiched between two warm rescuers. But remember that in this situation, no heat is really contributed by the bag itself. Do not count on a sleeping bag to be adequately prewarmed by a normothermic rescuer’s body heat. Another technique is to blow warm air from an electric hair dryer into the bag with the victim. Hot water in bottles, well insulated with clothing to prevent skin burns, may be placed next to the victim in areas of high heat transfer, such as the neck, chest wall, and groin. A great deal of warmth may be conserved by using a thin liner bag inside a normal sleeping bag.

4. Do not attempt to warm the victim by vigorous exercise, rubbing the arms and legs, or immersing in warm water. This is “rough handling” and can cause the heart to fibrillate if the victim is severely hypothermic.

5. Seek assistance as soon as possible.

Mild Hypothermia

The victim of mild hypothermia is awake, can answer questions intelligently, and complains of feeling cold. He may or may not be shivering.

Prevent the victim from becoming any colder. Get him out of the wind and into a shelter. If necessary, build a fire or ignite a stove for added warmth. Gently remove wet items of clothing and replace them with dry garments. This is very important, even if the victim will be very briefly exposed out in the open. If no dry replacements are available, the clothed victim should be covered with a waterproof tarp or poncho to prevent evaporative heat loss. Cover the head, neck, hands, and feet. Insulate the victim above and below with blankets. If the victim is coherent and can swallow without difficulty, encourage the ingestion of warm sweetened fluids. Good choices include warm gelatin (Jell-O), juice, or cocoa, because carbohydrates fuel shivering. If only cool or cold liquids are available for drinking, this is fine. Avoid heavily caffeinated beverages. If a dry sleeping bag is available, one or more rescuers should climb in with the victim and share body heat. However, this technique may not be very effective, and great care must be taken not to cause the victim to become wet (e.g., from the rescuer’s sweat). Do not apply commercial heat packs, hot-water-filled canteens, or hot rocks directly to the skin; they must be wrapped in blankets or towels to avoid serious burns. Try to keep the victim in a horizontal position until he is well hydrated. Do not vigorously massage the arms and legs, because skin rubbing suppresses shivering, dilates the skin, and does not contribute to rewarming.

Moderate Hypothermia

The victim of moderate hypothermia has become apathetic and mildly confused, wishes to be left behind, and is uncooperative. Speech is often slurred, and logic is on the wane. The victim rapidly becomes uncoordinated and clumsy, often stumbling. He has ceased to shiver, and shows signs of muscle stiffness. Unless you have a thermometer to measure this victim’s temperature, you must assume that he is severely hypothermic or will soon become so. Follow the directions for mild hypothermia, with the added caution that it is best not to allow this victim to walk about until he is fully alert; in addition, do not give him fluids to drink until he becomes wide awake and understands what is going on.

Severe Hypothermia

Depending on the body temperature, a victim who appears to be asleep may be in a complete coma. Below 86°F (30°C), humans become poikilothermic, like a snake, and take on the temperature of the environment.

Examine the victim carefully and gently for signs of life. Listen closely near the nose and mouth and examine chest movement for spontaneous breathing. Feel at the groin (femoral artery) and neck (carotid artery) for a weak and/or slow pulse (see page 33).

If the victim shows any signs of life (movement, pulse, respirations), do not initiate the chest compressions of cardiopulmonary resuscitation (CPR). If the victim is breathing regularly, even at a subnormal rate, his heart is beating. Because hypothermia is protective, the victim does not require a “normal” heart rate, respiratory rate, and blood pressure. Pumping on the chest unnecessarily is “rough handling,” and may induce ventricular fibrillation. Administer supplemental oxygen (see page 431) by facemask if it is available.

If the victim is breathing at a rate of less than 6 to 7 breaths per minute, you should begin mouth-to-mouth breathing (see page 29) to achieve an overall rate of 12 to 13 breaths per minute.

If help is on the way (within 2 hours) and there are no signs of life whatsoever, or if you are in doubt (about whether the victim is hypothermic, for instance), you should begin standard CPR (see page 32). If possible, continue CPR until the victim reaches the hospital. Rescue breathing should take priority over chest compressions, particularly in the victim of cold-water immersion. There have been documented cases of “miraculous” recoveries from complete cardiopulmonary arrest associated with environmental hypothermia after prolonged resuscitation, presumably because of the protective effect of the cold. Remember, “no one is dead until he is warm and dead.” However, all of these victims were ultimately resurrected in the hospital, after they had been fully rewarmed.

A victim of severe hypothermia cannot be rewarmed in the field. If a hypothermic victim suffers what you determine to be a cardiac arrest in the wilderness, transport should be the first priority. If enough rescuers are present to allow CPR and simultaneous transport, do both. If you are the only person present, do not bother with CPR, because you will not be able to resuscitate the victim until he is rewarmed. Your only hope is that the victim is in a cold-protected state (“metabolic icebox”) and that you can extricate him (as gently as possible!) to sophisticated medical attention.

In any case of severe hypothermia, transport should be undertaken as soon as possible. Take care to cover the victim with dry blankets and to handle him as gently as possible. Rapid rewarming or restoration of circulation will release cold, acid-laden blood from the limbs back to the core organs, which may cause a profound deterioration of the victim.

Preparing a Hypothermic Victim for Transport

1. Keep the victim dry. Replace all wet clothing. If there is no replacement clothing available, wring out the wet clothing, including gloves and mittens, and then put it back on the victim. Lay the victim on a sleeping bag and then cover him with a layer of blankets. If necessary, use bubble wrap or some other insulating material. If the hands are extremely cold, pull them out of the sleeves of clothing in order to put the hands in the victim’s armpits for warming. See above for emergency waterproof blankets and bags. Cover everything with a plastic sheet.

2. Keep the victim horizontal. Do not allow massage of the extremities. Do not allow the victim to exert himself.

3. Splint and bandage all injuries as appropriate. Cover all open wounds.

4. Limit rewarming to methods that prevent further heat loss. Place insulated (e.g., with clothing) hot-water bottles in the victim’s armpits and groin. Keep his head and neck covered.

A Special Note about the Victim of Cold-Water Drowning

If a victim is pulled from icy waters and appears to be clinically dead (fixed dilated pupils, no respirations, no detectable pulse), perform CPR until a qualified medical person is available to intervene or you become exhausted. Because of the physiology of cold-water immersion, the victim may be sufficiently protected to survive the event.

Prevention of Hypothermia

1. Carry adequate food and thermal wear, such as Thermax, Capilene, and/or polypropylene (“polypro”) or wool undergarments. Anticipate the worst possible weather conditions. Dress in layers so that you can adjust clothing for overcooling, overheating, perspiration, and external moisture. Use a foundation layer to wick moisture from the body to outer layers. The first layer (such as CoolMax) should keep the skin cool and dry (to avoid perspiration). Add an insulation layer to provide incremental warmth. For shirts, use wool, fleece, Capilene, or polypropylene. Consider a turtleneck or neck gaiter. For pants, wear wool or pile, with a fly. Carry windproof and waterproof outer garments, mittens or gloves (with glove liners), socks, and a hat. In very cold weather, up to 70% of generated heat may be lost by radiation from the uncovered head. Boots should be large enough to accommodate a pair of polypropylene socks (“liner socks”) plus at least one pair of heavy wool socks without cramping the toes.

2. Stay dry. Avoid sweating.

3. Keep hands and feet dry. This is important to avoid frostbite as well. Hand Sense is a cream that can be applied to the hands to keep them dry by reducing perspiration. It was designed as a topical protectant, and is not a moisturizer. For the feet, aluminum chlorohydrate–containing antiperspirant sprayed onto the skin can help control sweating. Do this three times a week for the first week of winter, then once a week after that. Avoid leather boots that become soaked with moisture and do not dry out easily.

4. Do not exhaust yourself in cold weather. Do not sit down in the snow or on the ice without insulation beneath you.

5. Seek shelter in times of extreme cold and high winds. Don’t sit on cold rocks or metal. Insulate yourself from the ground with a pad, backpack, log, or tree limb. Carry a properly rated (for the cold) sleeping bag stuffed with Hollofil II, Quallofil, or down. Insulate hands and feet well, even when you are in your sleeping bag, which should be fluffed up before entry. Do not enter a sleeping bag if you are wet without drying off first if possible.

6. Do not become dehydrated. In the cold, dehydration is caused by evaporation from the respiratory tree, increased urination, and inadequate fluid intake. Drink at least 3 to 4 quarts (liters) of fluid daily. During extreme exercise, drink at least 5 to 6 quarts per day. Ingesting snow is an inefficient way to replace water, because it worsens hypothermia. Drink cold water from a stream in preference to eating snow. Do not skip meals. Do not consume alcoholic beverages in cold weather. They cause an initial sensation of warmth because of dilation of superficial skin blood vessels, but this same effect contributes markedly to heat loss. At night, fill a canteen or Nalgene water container with at least 1 quart (liter) of water, and sleep with it to keep it from freezing.

7. Consume adequate calories.

WHAT TO DO IF YOU FALL THROUGH THE ICE

If you fall through the ice into very cold water, the “1-10-1 Principle” states that a person has 1 minute to get breathing under control, 10 minutes of meaningful movement, and 1 hour before one goes unconscious due to hypothermia:

1. When a person falls into extremely cold water, he begins to gasp and hyperventilate. Control your breathing. Calm down and slow your breathing rate, so that you are not hyperventilating. This generally takes 30 seconds to 2 minutes.

2. Keep your hands and arms on top of the ice and kick your feet vigorously, to bring your body to a horizontal position and propel you up onto the ice. Otherwise, keep swimming at a minimum. Keep clothing on in the water—it contributes to insulation and helps with flotation. If you are able to slide your body out of the water onto the ice, do not stand up. Roll or slide your body away from the opening onto thicker ice, where you may now stand. Try to leave in the direction from which you first approached, as this ice has already proven that it can withstand your weight. If you cannot exit the water, try to hold your arms on top of the ice, so that they freeze to the ice, which will prevent you from submerging under the surface of the water. This may give you an extra hour of survival time.

HOW TO ASSIST SOMEONE WHO HAS FALLEN THROUGH THE ICE

If someone has fallen through the ice, it is an urgent and dangerous situation. Although it is important to rescue the victim, it is equally important to not create additional victims.

1. Recognize that ice conditions are unsafe. No one else should approach the area.

2. Resist the urge to rush up to help the victim, so that you don’t also fall through the ice. Encourage the victim to remain calm and not panic. Direct the victim to an area of strong ice and to attempt a self rescue, as described above.

3. If self rescue is not accomplished, you can throw a buoyant object to the victim to help him remain floating. Before it is thrown, tie a rope or cord to the object, so that if the victim can hold onto it, you might be able to pull the victim. If only a rope is available, tie a large loop at the end, which the victim can grab. Instruct the victim to put the loop over the body and under the arms, put one arm through the loop and bend his elbow around the rope, or just hold on.

4. The victim might be reached with a long tree branch, ladder, or other object that can be pushed along the surface of the ice. It is important for the rescuer to not get too close to the hole in the ice.

5. If the victim cannot be removed from the water using the techniques above, he should be instructed to hold the arms up on the ice for the purpose of letting them freeze to the ice while help is summoned.

6. To avoid falling through ice in the first place, you should look for signage that might indicate its safety or unsafety; check with local authorities if they have any information; travel across ice under observation of someone else; bring safety equipment; wear a lifejacket or other flotation device; avoid traveling on ice at night; select “blue ice” over white ice or gray ice; and avoid ice with cracks or slushy areas.

WINTER STORM PREPAREDNESS

Outdoor, and indeed urban, travelers should always plan for the unusual and unexpected. Tools include familiarity with weather forecasts, strategizing worst-case scenarios, carrying emergency items, avoiding solo travel, and leaving notice of the projected route and expected time of return. With good planning, deteriorating weather or a forced unexpected night outdoors might then become more of an inconvenience than a life-threatening ordeal. While we usually consider a life-or-death situation due to the elements to be associated with a remote expedition or natural disaster, it can happen during a routine drive along the highway on the way to a ski destination.

Winter storm preparedness is essential for anyone who drives a motor vehicle in snow country. One must always be aware of the possibility of spending an unplanned night out in a vehicle. Causes include bad weather, breakdown, having an accident, running out of fuel, becoming lost, and getting stuck. Winter driving is especially hazardous because of the dangers of driving on snow or ice, losing visibility and orientation, fewer people on the road from whom to receive assistance, and the threats of frostbite and hypothermia. Accepting the possibility of trouble, carrying a vehicle survival kit (see below), and giving some thought to survival strategies will help prevent a night out in your car from deteriorating into a life-threatening experience.

Most travelers dress to arrive at a destination and not to survive a night out; in other words, they dress “to arrive, not to survive.” A vehicle survival kit (listed below) should include extra clothing, blankets or sleeping bags, food, water, signaling equipment, and communications equipment (cell phone, citizen’s band radio, etc.). It is also always better to stay with the vehicle, which provides significant protection and which is more visible to rescuers than a person on foot. Most laypersons are not experienced trail-blazing in wilderness environments, and particularly when landmarks are obscured by rain or snow, and darkness and cold weather conspire to alter orientation and judgment.

In cold weather, and especially for long-distance travel, drivers should keep their vehicles in the best possible mechanical condition. Drivers should use winter-grade oil, the proper amount of radiator antifreeze, deicer fluid for the fuel tank, and antifreezing solution in the windshield-cleaning fluid. Windshield wiper blades that are becoming worn should be replaced and special snow-and-ice–resistant blades used when available. A combination snow brush and ice scraper should be carried. A can of deicer is useful for frozen door locks and wiper blades. Snow tires, preferably studded (illegal in some states), are desirable, but even with special tires and/or four-wheel drive, chains should be carried. All-wheel drive or four-wheel drive is optimal, and front-wheel drive is superior to rear-wheel drive. The battery should be kept charged, the exhaust system free of leaks, and the gas tank full (“drive on the upper half of your tank”).

Despite best efforts, you may become stranded or lost. If that happens, tie a brightly colored piece of cloth (such as a length of surveyor’s tape) to the antenna. At night, leave the inside dome light illuminated so that it may be seen by snowplow drivers and rescuers. Headlights use too much current, so use the dome light. If necessary for heat, the standard recommendation has been that the motor and heater can be run for 2 minutes each hour (after checking to see if that exhaust pipe is free of snow). However, a more recent recommendation is that since it takes more gasoline to start a cold engine than a warm one, one should initially turn the heat up all the way and run the car engine until the inside is comfortable. Then, shut off the engine and wait until it becomes uncomfortably cold inside the car (which could be 10 to 30 minutes depending on outside temperature). The engine, however, will still be “warm.” Start the engine again and run the heater until the occupants feel warm. Keep repeating this process.

Keep the tailpipe free from snow pack. Carbon monoxide (CO) poisoning can be a threat, so do not go to sleep inside the car with the engine running; if the engine is running, keep a downwind window cracked 1 to 2 inches in case there is a CO leak into the interior of the vehicle. A reusable CO detector is a wise addition to the survival kit. One or two large candles (“fat Christmas candle” size) should be carried to provide heat and light if the gasoline supply runs out, since two lit candles can raise the interior temperature well above freezing. However, resources should be used sparingly because you are never sure how long you will be stranded.

Foresight enough to include heavy clothing and blankets or sleeping bags in the cold-weather vehicle survival kit is better than relying excessively on external heat generation. Do not smoke tobacco products or drink alcohol. If you have to exit the vehicle in a snowstorm, put on additional windproof clothing and snow goggles, and tie a lifeline to yourself and the door handle before moving away from the vehicle.

You must decide whether to wait for rescue or attempt to walk out under your own power. If rescue is possible, it is almost always better to remain in a snug shelter and conserve your strength. If you decide to leave, you must effectively mark your trail, to aid rescuers and enable you to return to the site if necessary. Travel should never be attempted in severe or extremely cold weather, or in deep snow without snowshoes or skis. If no chance of rescue exists, prepare as best as possible, wait for good weather, and then travel in the most logical direction.

The best way for a lost or stranded person to aid potential rescuers is to do everything possible to draw attention to his or her location. Most modern rescues utilize ground parties, helicopters, and fixed-wing aircraft. Besides radios, cell phones, and other electronic equipment, signaling devices are either auditory or visual. Three of anything is a universal distress signal: three whistle blasts, three horn blasts, three fires. The most effective auditory device is a whistle. Blowing a whistle is less tiring than shouting, and the distinctive sound can be heard farther than a human voice. An effective visual ground-to-air signal device is a glass signal mirror with a sighting device, which can be seen up to 10 miles away but requires sunlight. Special rescue beacons are available and can be carried as emergency equipment. These include strobe lights, laser signal lights, special beacons with both signaling and GPS capability, and personal locator beacons (PLBs).

Smoke is easily seen by day and a fire or flashlight by night. On a cloudy day, black smoke is more visible than white; the reverse is true on a sunny day. White smoke stands out well against a green forest background but not against snow. Black smoke can be produced by burning parts of a vehicle, such as rubber or oil, and white smoke by adding green vegetation to a fire. The lost person who anticipates an air search should keep a fire going with large supplies of dry, burnable material (wood and brush) and have a large pile of cut green vegetation close by. When an aircraft is heard, the dry materials are placed on the fire, allowed to flare, and then armloads of the green vegetation are piled on top. This produces lots of smoke and a hot thermal updraft to carry it aloft.

A vehicle cold weather survival kit should include the following items:

1. Sleeping bag or two blankets for each occupant

2. Extra winter clothing, including gloves, boots, and snow goggles, for each occupant

3. Emergency food

4. Metal cup

5. Waterproof matches

6. Long-burning candles, at least two

7. First-aid kit

8. Spare doses of personal medications

9. Swiss army knife or Leatherman-type multitool

10. Three 3 lb empty coffee cans with lids, for melting snow or sanitary purposes

11. Toilet paper

12. Cell phone and/or citizen’s band radio, with chargers

13. Portable radio receiver, with spare batteries

14. Flashlight with extra batteries and bulb

15. Battery booster cables and/or car battery recharging unit (plugs into cigarette lighter)

16. Extra quart of automobile oil (place some in hubcap and burn for emergency smoke signal)

17. Tire chains

18. Jack and spare tire

19. Road flares

20. Snow shovel

21. Windshield scraper and brush

22. Tow strap or chain

23. Small sack of sand or cat litter

24. Two plastic gallon drinking water jugs, full

25. Tool kit

26. Gas line deicer

27. Flagging, such as surveyor’s tape (tie to top of radio antenna for signal)

28. Duct tape

29. Notebook and pencil/marker

30. Long rope (e.g., clothesline) to act as safety rope if you leave car in blizzard

31. Carbon monoxide detector

32. Ax

33. Saw

34. Full tank of gas

FROSTBITE

Frostbite is an injury caused by the actual freezing of tissues. Factors that predispose a person to frostbite include poor circulation (caused by previous cold injuries, tobacco use, alcohol ingestion, diseases of the blood vessels, constricting garments, poorly fitting boots, old age), fatigue, and extremes of cold exposure. Windchill contributes markedly to frostbite risk. For instance, at an air temperature of 15°F (−9.4°C), a 55 mph (88 km per hour) wind causes the same rate of heat loss as a 5 mph (8 km per hour) breeze at an air temperature of 0°F (−17.8°C). Furthermore, since a human in motion creates his own wind (while riding a snowmobile, for example), the risk for frostbite for such a person increases. Humidity and wetness also increase the propensity for frostbite.

During exposure, once the temperature of a hand or foot drops to 59°F (15°C), the blood vessels maximally constrict and minimal blood flow occurs. As the limb temperature declines to 50°F (10°C), there may be brief periods of blood vessel dilation, alternated with constriction, as the body attempts to provide some protection from the cold. This is known as the “hunting response” and is seen more commonly in the Inuit (Eskimos) and those of Nordic descent. Below 50°F (10°C), the skin becomes numb and injury may go unnoticed until it is too late. Tissue at the body surface freezes at or below a temperature of 24.8°F (−4°C) because of the effect of underlying warm tissue. Once circulation is abolished, the skin temperature may drop at a rate in excess of 1°F (0.56°C) per minute. Once tissue freezes, it cools rapidly to attain the temperature of the environment.

The major immediate symptom of a frostbite injury is numbness, occasionally preceded by itching and prickly pain. The frostbitten area will appear to be white, with a yellow or bluish (grayish) waxy (sometimes mottled) tint. If the injury is superficial, as commonly occurs on the face, the skin is firm and may indent with a touch, because the underlying tissue is still soft and pliable. If the injury is deep, the skin may feel hard and actually be frozen solid. A hand or foot may feel clumsy or absent. The areas most commonly affected are the fingertips and toes (particularly in cramped footwear), followed by the earlobes, nose tip, cheeks, and other exposed skin. These parts have little heat-generating capability and no significant insulation. Male joggers have had their genitals frostbitten.

Rapid rewarming is the standard therapy. However, do not thaw out a frostbitten body part if it cannot be kept thawed. In other words, if you come on a lost hiker 10 miles (16 km) back in the woods who has frostbitten toes, do not use your stove to heat water to thaw out his feet if he will then have to put his wet boots back on and hike out—refreezing his toes in the process. Frostbitten tissue is severely damaged and is prone to reinjury; refreezing causes an injury that will far exceed the initial frostbite wound. It is much better to walk out on frostbitten toes until safety is reached than to thaw and allow refreezing. Thus, if a victim needs to be transported to another site for rewarming, do not allow “slow” or partial rewarming, particularly if there is a chance that the tissue will be allowed to refreeze. Pad the affected body part, apply a protective splint, and hustle the victim to the site where the definitive thaw will take place. Do not allow tobacco or alcohol use.

Once the victim has reached a location (shelter) where refreezing will not occur, remove all constrictive jewelry and wet clothing. Replace wet clothes with dry garments. Immerse the frostbitten part in water heated to 104°F to 108°F (40°C to 42.2°C). Do not induce a burn injury by using hotter water. You can estimate 108°F (42.2°C) water by considering it to be water in which normal skin can be submerged for a prolonged period with minimal discomfort. Heated tap water may be too hot. Never use a numb frostbitten finger or toe to test water temperature. It is best to use your own hand or the victim’s uninjured hand to test the temperature. Circulate the water to allow thawing to proceed as rapidly as possible. When adding more hot water, take the body part out, add the water, test the temperature, and then reimmerse the part. It is best to use a container in which the body part can be immersed without touching the sides; for instance, a 20-quart (20-liter) pot will accommodate a foot. If the skin is frozen to mittens or metal, use heated water to remove them. Never rewarm the tissues by vigorous rubbing or by using the heat of a campfire, camp stove, or car exhaust, because you most certainly will damage the tissues.

If the victim is hypothermic, attend first to the hypothermia. Thawing should not be undertaken until the core body temperature has reached 95°F (35°C) (see page 305).

Thawing of the tissues usually requires 30 to 45 minutes. It is complete when the skin is soft and pliable, and color (usually quite red; rarely, bluish) and sensation have returned. Allowing the limb to move in the circulating water is fine, but massage may be harmful. Moderate to extreme burning pain may occur during the last 5 to 10 minutes of rewarming, particularly if the frostbitten tissue was numb before rewarming.

Thawed frostbite may be present in a number of stages, much like a burn injury. These are recognized as follows:

First degree. Numbness, redness, and swelling; no tissue loss.

Second degree. Superficial blistering, with clear (yellowish) or milky fluid in the blisters, surrounded by redness and swelling. There is little, if any, tissue loss.

Third degree. Deep blistering, with purple blood-containing fluid in the blisters. There is usually tissue loss.

Fourth degree. Extremely deep involvement (including bone); induces mummification. There is always tissue loss.

Sensation may remain until blisters appear at 6 to 24 hours after rapid rewarming. These often do not extend to the ends of fingers and toes (Figure 177). Leave these blisters intact. After thawing the skin, protect it with fluffy, sterile bandages (aloe vera lotion, gel, or cream should be applied, if available). Pad gently between the digits with sterile cotton or wool pads, held in place by a loose, rolled bandage. Transport the victim to a medical facility. Administer ibuprofen 400 mg or aspirin 325 mg twice a day. If frostbite involves the feet, try to minimize walking. Do not allow tobacco use or the drinking of alcohol. Keep the victim well hydrated with warm beverages. Administer pain medications as needed.