Cold and injured

Norton talks recognition, prevention and treatment of common cold-weather medical emergencies.

By Patrick Norton

Photo by Noelle Otto

Right around this time of year outdoorsmen of all types are heading out into the wilderness to partake in their favorite winter sports. Be it hunting, skiing, snowboarding, snowshoeing or snowmobiling, the risk of suffering an injury in the cold greatly increases in the late fall, summer and early spring months. Bear in mind that snow and freezing temperatures are not required for one to experience a cold-related emergency. Even in warmer climates, especially in places such as the desert or at sea, where drastic temperature drops are common at night or during and after a submersion incident, hypothermia, frostbite or a non-freezing cold injury can occur. This piece will serve to familiarize the reader with the signs, symptoms and treatments of these common, and sometimes deadly, winter ailments. It will also show the importance of preparedness and proper training in recognizing and treating them early.

First, it is crucial to have a baseline understanding of the physiology of heat production and heat loss in the human body. There are three ways the body can produce heat on its own: resting metabolism, exercise and shivering. When the body is given energy as food, chemical reactions take place to convert energy to power the mechanisms that keep it alive and allow it to work. One of these energy conversions is turning the potential energy in food to heat energy. This resting metabolic rate will increase a bit in cold conditions, but it does not provide enough heat to sustain life in winter weather. The second form of heat production is physical exercise. Exercise is a great heat producer, whether through short bursts of intense exercise or constant, moderate movement. Exercise does have some constraints and concerns, however, that need to be considered. Athletic ability, conditioning, stamina and endurance as well as availability of energy in the form of food and water are limitations for exercise. Sweat production is another concern associated with an injury in a cold environment. These concerns highlight the importance of physical fitness, acclimatization, proper nutrition and hydration, effective winter clothing, layering and activity regulation. All will be addressed later.

The last physiological method of heat production is shivering. Yes, shivering is a mechanism for the body to create heat, not just a symptom of hypothermia. Essentially, shivering is a response to a drop in core body temperature. This response creates heat at a rate of approximately five times that of a resting metabolism. Again, this form of heat production is fed by food, water and oxygen. Shivering also decreases fine motor function, hindering the victim’s ability to perform essential tasks required to keep warm in the first place. This will bring us to the importance of preparedness and prevention of heat loss, but first a crash course on the forms of heat loss is in order.

There are four types of heat loss that occur in cold environments: conduction, convection, radiation and evaporation. Conduction is heat transfer through direct contact. For example, body heat transferring to the rock one may be sitting on. Convection can be thought of as heat loss due to air passing over the patient. Radiation is the indirect transfer of heat from a hot to a cold object. Heat is also lost through evaporation, either by sweating or by breathing. To maintain an adequate body temperature, it is imperative that the backwoodsman mitigate heat loss from all three forms of heat transfer and evaporation. When this is combined with proper nutrition, hydration and activity regulation, the chances of suffering a cold-related injury will greatly decrease.

The most important thing to do to fight hypothermia, and other cold-related injuries, is to establish preventative measures to ensure it does not happen in the first place. In order to be prepared, one must carry the proper gear and supplies, research the area’s conditions, acclimate to the environment and make a concrete plan for the trip and for possible emergencies. Also, before the wilderness enthusiast even leaves the house, he must train! This training includes learning effective and efficient wilderness living, survival and medical skills such as: camping, sheltering, fire building, camp cooking skills, proper wilderness layering, smart activity regulation and wilderness first aid (WFA). All too often, many people go out thinking they know exactly what to do because they have either been hunting or snowmobiling for so long that they automatically have gained survival or medical skills through osmosis, or they have watched enough hours of YouTube to know it all. This is not the case! Assume you will not rise to the occasion when an emergency happens. In general, these are the people that get into critical situations or die whether due to cold injuries or something else. Take the time to learn the proper skills. Teaching all of these skills are beyond the scope of this piece but learning to make an effective shelter and fire quickly, efficiently, and safely is a good place to start. Also learn to properly layer and regulate exercise.

The most effective and easy way to layer is the modular, three-layer system. This includes a form-fitting, moisture-wicking base layer of wool or synthetic material. Wool is preferred in the author’s opinion because it does not become stinky due to sweating. The second piece of this system is an insulating layer, also of wool or synthetic material. Down material is acceptable only in dry environments. This layer should not be too tight; the idea is to hold heat in the negative airspace of the fabric. The final layer is a breathable, waterproof shell. Gore-Tex is preferred, but there are other materials that do the trick as well. The purpose of this layer is to protect the wearer from wind and water, while allowing the other layers to breathe and expel any moisture that has built up. Do not forget to also wear warm headwear, footwear and handwear.

Do not overtighten footwear as this can inhibit circulation to the feet and toes. The following is a simple example of how to employ this modular system along with proper exercise management. Imagine the wearer of this three-layer system is at the bottom of a fairly steep slope. The next step in the expedition is to get to the top. The wearer is fairly certain that he will create heat through the exercise required to get there, so he sheds his middle, insulating layer. He begins to climb but maintains a moderate level of exertion using a steady pace, following a switchback pattern up the hill. Doing this, rather than forging straight up the hill as fast as he can. Option one will mitigate sweat production, which could freeze or increase his chances of hypothermia or another cold-related injury. If the hill climb is quite long, he can take frequent rests as he begins to feel himself start to sweat or overexert. Certainly, by the time he gets to the top, he will want to take a good rest, eventually donning the insulating layer again before cooling off too much. This is an easy-to-follow example, but it is important to be strategic and diligent, no matter how complex the scenario.

Finishing the topic of prevention, adequately fueling the body is required to perform exercise, simple tasks and to power the metabolic heat production mechanisms addressed earlier in this article. Make sure food is consumed regularly, in proper amounts and according to the intensity of activity. Remember, food intake should be increased in colder environments, whether intense exercise is involved or not. Carbohydrates are converted into kinetic and heat energy very quickly, which is likened to tinder in fire-building. Fats and proteins will provide more sustained energy. Lastly, proper hydration is of the utmost importance to prevent not only a heat-related injury, but a cold one as well. It allows for adequate perfusion to supply oxygen and nutrients to the cells and to circulate warm blood to the vital organs and extremities. Pre-hydrate before an activity and hydrate often during the activity. Make sure to have electrolytes available so the body can absorb the water it is supplied. Under normal circumstances, food provides the body with enough electrolytes, but under strenuous activity, the rule of thumb is one liter of electrolyte replacement for every two liters of regular water.

If these measures fail, cold injuries may ensue. There are different types of cold-related injuries, and each has different levels of severity. A cold injury may also occur in conjunction with other injuries. Therefore, in a wilderness setting, the primary patient assessment not only includes airway, breathing and circulation assessment and intervention, but spinal disability and environmental measures as well. It is recommended to take a WFA course, at minimum, to learn to properly carry out a patient assessment, which every patient deserves. The first type of cold injury is hypothermia.

The key to treating hypothermia is to recognize the signs and symptoms early and treat it immediately. The signs and symptoms of hypothermia vary depending on the severity of the condition. These include shivering, goosebumps, loss of fine motor functions, stiff extremities, clumsiness, poor decision making and confusion. When these symptoms increase and the patient will begin to become more uncoordinated, beginning to include an altered gait and falling. They will often show signs of obvious mental status changes, at this stage, the patient should be considered to have moderate hypothermia. These symptoms are often called “the umbles” or stumbles, fumbles, and mumbles. To treat mild and moderate hypothermia, dry the patient, dress him/her in warm clothing, move him/her to a warmer location protected from wind and encourage movement if possible. In moderate cases, the patient may need to be put in a sleeping bag with an insulating pad between them and the ground. The patient should be given warm drinks with plenty of sugar if swallowing is possible. The caregiver should also put hot, but not scalding, water bottles or chemical heat packs on critical places such as the torso, back, armpits and groin with a layer of clothing in between. Once the patient is warmed, he may begin to have solid food such as candy or energy bars, progressing to full meals with fats and proteins. Fires with a reflector wall or space blanket will also help rewarm the patient. Most times, rewarming a mildly hypothermic patient can be done in the field and the patient may continue the trip once ready. In moderate cases, this becomes more difficult but can still be possible. Keep in mind, the rewarming process may take a long time and may not always succeed in the field. Be persistent and do not allow for any more heat loss.

If hypothermia progresses, the patient may stop shivering due to energy depletion and show a profound decrease in mental status, muscle rigidity and a lowered heart and respiratory rate. This is severe hypothermia, a life-threatening condition. The patient likely will not be able to swallow, so giving warm drinks and food will not be possible. In cases of moderate or severe hypothermia, the patient should be put in a hypothermia wrap (hypo-wrap) or “hypo-burrito”. Many useful modifications can be made to improve the hypo-wrap and can be viewed online or learned in a wilderness medicine course. However, the basic principles of the hypo-wrap remain the same in all variations. Begin by heating water bottles or activating chemical heat packs. Lay the patient down on a large, waterproof sheet, such as a plastic tarp or drop cloth. Put the patient in at least one sleeping bag or wrap in blankets with an insulating pad underneath. Place the bottles or heat packs in the critical areas mentioned above, including by the feet. Finally, wrap the patient in the waterproof sheeting by tucking the edges under the patient to keep warmth inside the wrap. A cloth or scarf may be placed over the patient’s mouth to prevent evaporative heat loss.

When handling this patient, be very gentle so as not to cause cold blood to circulate to the heart. This may cause a life-threatening heart arrhythmia. Keep in mind that the patient’s pulse and respiratory rate may be difficult to detect, so go slow with the assessment. If they are absent, CPR may be performed. However, when in doubt, give only rescue breaths. Due to the preserving nature of cold, the patient may appear deceased, but given in-hospital warming and resuscitation care, many patients do survive. Remember, “the patient is not dead until he is warm and dead.” In most cases of mild or moderate hypothermia, evacuation is generally not necessary, and the patient can be rewarmed and continue activity as long as mental status returns to normal. With severe hypothermia and some cases of moderate hypothermia, the patient should be quickly and gently evacuated to a higher level of care.

Frostbite is a condition in which tissue, most commonly that of the fingers, toes, ears, nose and cheeks, freezes locally. The fluids between the cells of the tissues freeze, causing damage from the friction between the ice crystals and constriction of blood flow due to blood clots in the blood vessels of the affected area. Frostbite is categorized in much the same way that burns are. Superficial frostbite, also known as frostnip, affects the outer layer of skin, causing it to appear red at first, then grey or white and waxy. The patient may experience numbness, tingling or pain. Partial-thickness frostbite affects the tissues underneath the outer most layer. The signs and symptoms for partial-thickness frostbite are much the same as for superficial frostbite, but the outer tissues may feel hard and frozen, while the underlying tissues may be softer. Full-thickness frostbite, occurring deeper into the muscle tissue of the patient, will also have similar signs and symptoms to those of superficial and partial-thickness frostbite, but the outer and underlying tissues will feel hard and frozen. It is difficult to determine the severity of frostbite until after it is rewarmed, but the presence of blisters within 24 to 48 hours of rewarming may indicate partial-thickness, while the absence of blisters may indicate full-thickness frostbite. The treatment of frostbite is mostly the same across the board when it comes to severity.

The patient should be brought into a warmer place, and wet clothes and jewelry should be removed. The affected area may be rewarmed if there is no chance of refreezing. This can be done by skin-to-skin contact or sticking fingers in the armpits. However, rubbing is not a good idea as this can cause more damage. Do not expose the affected area to flame or rub snow on it. Ideally, the injured area should be rewarmed by submersion in 99°F - 102°F water. This is best done in a hospital setting since a constant warm water supply is required. Under-thawing can result in further damaged tissue. A flush of pink indicates that rewarming is taking place and blisters may form. This process will be very painful. Pain management measures, such as Ibuprofen are recommended here. After the area is rewarmed, use extreme care when handling the area, placing padding between fingers and toes and wrapping and protecting the affected part. Encourage the patient not to use the injured body part.

Quickly evacuate any person with frostbite, being careful with the injured area. It is imperative to avoid rewarming if the chance of refreezing is high during evacuation. Preventative measures for frostbite are similar to those of hypothermia, with the addition of being especially careful to cover at-risk body parts and not touching frozen, metal objects. Frostbite is generally not life-threatening but can lead to loss of function and even amputation. Remember, it is easier and safer to stay warm than to treat a cold injury.

The final injury that will be addressed is a non-freezing cold injury, commonly known as trench foot. Trench foot is caused by prolonged exposure, usually in the feet, to cold, wet conditions, resulting in lack of blood, oxygen and nutrients to the extremity. The symptoms of trench foot include swollen, cold, painful, white or gray, shiny or mottled feet. Pain, numbness, or tingling may occur. Capillary refill may be slowed. This can be tested by pressing fingers on the affected part and watching the color return to the area. This should take less than two seconds. In severe cases, blisters or gangrene and long-term disability may develop, as well as the need for amputation. If the patient experiences any numbness or tingling, be suspicious of developing trench foot. Treatment of trench foot involves rewarming the affected area at room temperature, elevating the affected body part and encouraging bed rest to avoid further trauma. Avoid trench foot by being very diligent in keeping feet dry and warm. It is important to dry and change socks frequently, avoid overtightening footwear, sleep with warm, dry feet and pay special attention to the needs of feet, examining and massaging them at regular intervals. Sometimes getting wet, cold feet is unavoidable, but care should be taken to keep them as dry as possible by using terrain to your advantage and the proper equipment, including plenty of thick wool socks and galoshes or waterproof boots with gaiters. In general, non-freezing cold injuries do not require evacuation.

Although not exhaustive, this article will give the reader an informative introduction to understanding, recognizing and treating some of the more common cold-related injuries that may occur during outings into the wilderness. The most important takeaway should be that preparedness and prevention are the preferred and safest methods for addressing these conditions. Proper research and training are encouraged before heading out into the wild. The author believes that it behooves everyone who works or plays outdoors to take a two-day wilderness first aid course to prepare for their next trip. Visit for more details on WFA and survival courses in Northwest Montana or find an instructor near you. Stay warm out there!