How to Prevent Frostbite + Treat Hypothermia
Let's Chat About Being *Too* Cold...
Winter adventures present the opportunity to see the Earth after a costume change. Whether the land is snow covered or simply cold but bare, plants and animals wear their winter clothes, and even familiar places offer new discoveries. But cold-weather adventuring also presents the opportunity to develop hypothermia and frostbite, two potentially serious medical conditions. It’s important to note that while these conditions are risks in cold weather, “cold” can mean a summer rainstorm, not only a snowy midwinter day.
Like many medical concerns related to environmental factors, both hypothermia and frostbite are preventable with attention to detail during wilderness travel. Adventuring safely in cold conditions requires adding a few gauges to monitor on the mental instrument panel. Below, we’ll define hypothermia and frostbite and cover prevention and treatment of each in detail.
Hypothermia vs. Frostbite
What is Hypothermia?
Hypothermia is the condition in which the body loses heat faster than it can produce heat, causing the body’s core temperature to drop to a dangerously low level. Hypothermia happens on a continuum from mild to severe. Severe hypothermia is a life-threatening condition.
Signs and Symptoms of Hypothermia:
Mild Hypothermia // relatively controllable shivering, the “umbles” (patient fumbles, stumbles, mumbles, grumbles), patient seems confused and shows poor judgment (“mild stupidity”), increased heart rate and respiratory rate as body works to warm itself, pale and cool skin
Moderate Hypothermia // signs and symptoms of mild hypothermia worsen: shivering becomes uncontrollable, the “umbles” worsen, confusion increases, heart rate and respiratory rate increase further, skin becomes pale and cold
Severe Hypothermia // shivering ceases, heart rate and respiratory rate slows and may become undetectable, patient progresses to unconsciousness, skin becomes cyanotic (blue), muscle rigidity
What is Frostbite?
Frostbite is damage to tissue due to freezing. It happens most often on the extremities: fingers, toes, the nose, and ears. Signs and symptoms of frostbite differ according to the severity of the damage; like hypothermia, it occurs on a continuum.
Signs and Symptoms of Frostbite:
Superficial Frostbite // skin in the affected area is white, perhaps waxy, numb, cold to the touch, and still relatively soft and pliable. On warming, skin may turn reddish and peel, like a sunburn.
Partial-Thickness Frostbite // as in superficial frostbite, skin is white, waxy, numb, and cold to the touch. But skin in the affected area typically feels harder than in superficial frostbite and may remain dented after touching it. Also, unlike with superficial frostbite, blisters form on the damaged tissue after thawing.
Full-Thickness Frostbite // skin is pale white and frozen solid. The affected area is completely numb to the patient and feels ice cold and wooden to the rescuer.
How to Prevent Hypothermia & Frostbite
Like many other risks we face while adventuring outdoors (heat-related illnesses, snakebites), smart decision making goes a long way toward preventing cold-related emergencies, and it is much easier to prevent these emergencies than treat them in a wilderness setting. The human body is more susceptible to hypothermia and frostbite when dehydrated, under-fueled, and tired, so simply eating, drinking, and resting diligently are critical steps in avoiding hypothermia and dehydration.
Moisture is a major factor in the development of cold-related emergencies. Buck Tilton, Wilderness EMT and author of Wilderness First Responder, explains, “Although you may think cold is the dominant environmental factor in hypothermia, it is the combination of cold and wet that poses the greatest threat.” To avoid this dangerous combination of wet and cold, proper layering for winter activities is essential. On a winter adventure, it’s important to wear enough layers to stay comfortably warm while avoiding overdressing that leads to sweating. Achieving this delicate balance can require adjusting layers frequently. Remove a layer as you warm up, and immediately add a layer when you stop for a break. Even though we can be comfortable while moving with damp, sweaty base layers, as soon as we stop, these damp layers put us at risk for hypothermia.
Another important moisture management tool is wearing the right fabric. Cotton dangerously retains moisture and keeps you cold when wet, contributing to heat loss through conduction. Avoid cotton! Choose synthetic or wool layers instead.
Constricting footwear adds to the risk of both hypothermia and frostbite. Often our efforts to keep feet warm by wearing thick or multiple pairs of socks contribute to foot sweat, and excess sweat means dangerous moisture around a vulnerable extremity. Be sure your boots have ample room in the toe box for toes to wiggle, and avoid thick socks that keep toes sweaty. Instead, choose a more insulated boot. Cramped toes suffer from reduced circulation and are more susceptible to frostbite.
When recreating in winter, carry the gear needed to respond to a cold-related emergency. Consider items like extra layers of clothing, a sleeping bag, a stove and fuel, extra food, sources of simple carbohydrates like sugary drink mixes, something to insulate a patient from the cold ground, hand warmers, and something windproof and waterproof like a small emergency bivvy. Think about everything you would need to avoid hypothermia and frostbite during an unplanned overnight in the backcountry or to treat a hypothermic or frostbitten patient.
On an overnight winter trip, be sure to go to bed warm and dry. Let feet dry completely, then put on a dry pair of socks.
When traveling in winter, always bring a windproof and waterproof outer layer, even on sunny days. Be sure you have a way to protect even your extremities from wind and water; remember the details like a shell jacket with hood, wind and waterproof gloves, and gaiters to keep snow out of your boots.
How to Treat Hypothermia
The guiding principle for treating patients in any stage of hypothermia is to remove them from a cold, wet environment and move them to a warm, dry one. While following this guiding principle, there are specific treatment considerations for each stage of hypothermia.
Mild // assist the patient in removing all wet (even mildly damp) clothing and changing into dry clothing. Assist the patient in moving to a warm environment, for example, a sleeping bag on an insulted pad on a waterproof surface, like a tarp. Give the patient warm liquids and snacks, starting with the simplest carbohydrates. A warm, sugary drink is a great starting point. Do not give the patient caffeine or alcohol. Providing the patient with a tightly closed hot water bottle to hold or put near their feet can help. Additionally, if the patient is able, encourage light exercise, like sit-ups inside a sleeping bag.
Moderate // remove all damp clothing. Respectfully and carefully check for even slightly damp base layers. A hypothermic patient should be handled gently, an important thing to keep in mind if cutting off damp clothing is necessary. Set up a hypothermia wrap, a.k.a. a “hypo wrap,” a heat-retaining human burrito of sorts. Spread out a large, waterproof, windproof material, like a tarp or rainfly, on the ground to serve at the “tortilla.” Place an insulating layer in the center of the “tortilla.” This layer could be a sleeping pad or an improvised solution, like the patient’s pack. Place a sleeping bag on top of the insulation, and unzip it so the patient can be carried onto the sleeping bag and placed inside. Very gently transport the patient onto the sleeping bag, and zip it up all the way. Add any other available insulating materials on top of the sleeping bag, then wrap the tarp or similar around the patient, bringing one corner at a time into the center, starting with the bottom corner. A patient recovering from moderate hypothermia may need a rest day to refuel and recharge before resuming wilderness travel. Mild and moderately hypothermic patients who recover completely can remain in the wilderness; no evacuation is required.
Severe // severe hypothermia is life threatening, and successful wilderness treatment can be difficult. But critically, you can prevent severe hypothermia if you monitor yourself and your adventure partners for signs and symptoms of mild and moderate hypothermia and treat immediately. Severe hypothermia is one end of a continuum; hypothermia does not become severe instantly. If you do find yourself treating severe hypothermia, however, it is crucial to treat the patient exceptionally gently and not to rush. A severely hypothermic patient’s heart rate and respiratory rate has slowed so dramatically that their brain is not receiving enough oxygen. Even before removing wet clothing, give the patient supplemental oxygen (unlikely in the backcountry) or rescue breaths. Wilderness EMT Buck Tilton recommends administering five to fifteen minutes of rescue breathing before moving the patient. Regular rescue breathing may be necessary for the duration of the rescue. After the initial period of rescue breathing, treat the patient by removing all wet clothing and placing in a hypo wrap, as in moderate hypothermia. The patient should be evacuated by the gentlest method possible.
How to Treat Frostbite
Treatment for frostbite involves gently rewarming the affected area and, if necessary, evacuating the patient. There are specific treatment considerations for each stage of frostbite, but while treating any stage, avoid two common mistakes. DO NOT massage cold tissue to rewarm it, and DO NOT place the damaged tissue near a source of radiant heat, like a fire. Both of these practices can worsen tissue damage. No matter the stage, it is critical to prevent the affected area from refreezing.
Superficial Frostbite // the ideal way to rewarm superficially frostbitten skin is in circulating 99 to 102 degree water. Simple submersion is acceptable given the unlikelihood of circulating the water, but water must be changed and reheated frequently to maintain adequate temperature (in the likely absence of a thermometer, test the temperature by dipping an elbow in the water; it should feel comfortably warm but not too hot to keep an elbow in for a prolonged period of time). Even this method is difficult to implement in the backcountry, however, and rewarming with skin-to-skin contact is the next best option. Tilton advises, for example, warming cold fingers in a warm armpit or cold toes against a warm belly. Administer aspirin or ibuprofen according to directions on the label to help with pain during rewarming. Topical application of aloe can also help with healing.
Partial-Thickness Frostbite // follow the same treatment guidelines as for superficial frostbite. Blisters that form on partial-thickness frostbite should be protected with dry dressings to prevent rupture. In case of ruptured blisters, cover the open wounds with antibiotic ointment and sterile dressings. Keeping the affected area above the patient’s heart may ease pain. It’s important to keep the patient well hydrated. Evacuate any patient that experiences blister formation due to frostbite.
Full-Thickness Frostbite // full-thickness frostbite should be thawed according to the same procedures outlined above. But keep an important consideration in mind: the priority of rewarming the damaged tissue must be balanced against the need to evacuate the patient. A patient can hike out on a numb and frozen foot, but once the tissue has been thawed, the foot is typically in far too much pain to use for hiking. The damaged tissue should be thawed as soon as it can be accomplished without risk of refreezing and as soon as it is clear the patient can be evacuated without needing to use the damaged area.
But Also…Non-Freezing Cold Injuries
Even when not exposed to sub-freezing temperatures, tissue can suffer damage due to prolonged exposure to cold and usually wet conditions. This type of injury is known as nonfreezing cold injury (NFCI), immersion foot, and trench foot. Like hypothermia and frostbite, this injury occurs on a continuum from mild to severe and typically begins with skin that is cold to the touch, numbness, swelling, and white or bluish skin. Upon rewarming, the damaged tissue often looks red and swells. The patient may feel painful tingling, and blisters may form. Treat NFCI according to the same principles as frostbite, rewarming and administering aspirin or ibuprofen for pain. Wash and dry the foot thoroughly.
The Best Treatment = Avoidance!
Avoiding hypothermia and frostbite is much easier than treating it. Simple yet easy to neglect practices protect against both conditions: hydrating well (keeping urine very light in color), snacking often, and minimizing fatigue. At the first sign of hypothermia or frostbite, stop and mitigate. Shivering? Remove damp layers and put on dry, warm clothing. Make a warm drink and eat a snack. Losing feeling in your toes? Loosen your snowshoe binding or micro spikes strap and rewarm those toes. Stopping and mitigating signs and symptoms of hypothermia or frostbite is time consuming, but letting mild hypothermia or superficial frostbite progress to a more severe stage is far more time consuming and life threatening.
