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  • Writer's pictureWilliam W. Forgey, MD

Environmental Injuries part 2 of 3 - Cold Stress Injuries

Updated: Nov 12, 2020

Excerpt from The Prepper's Medical Handbook. Page reference numbers point to more in-depth treatment and self-reliant care available within the book.


Frostnip, or very light frostbite, can be readily treated in the field, if recognized early enough. This term is usually reserved for a form of superficial frostbite, but I am convinced there really is a separate entity that should be considered frostnip: The skin turns pure white in a small patch, generally the tip of the nose or ear edges. When frostnip is detected, cup your hands and blow on the affected parts to effect total rewarming.

Under identical exposure conditions, some people are more prone to this than others. On one of my trips into subarctic Canada, a companion almost constantly frostnipped his nose at rather mild temperatures (20°F, or 7°C). We frequently had to warn him, as he seemed oblivious to the fact that the tip of his nose would repeatedly frost.


Frostbite is the freezing of skin tissue. The temperature of the skin must be 24°F (4°C) before it will freeze. Risk for frostbite increases if the victim is hypothermic, dehydrated, injured, wearing tight-fitting clothing or boots, or is not removing boots and changing socks or checking his feet for frozen tissue at least nightly.

Traditionally, several degrees of frostbite are recognized, but the treatment for all is the same. The actual degree of severity will not be known until after the patient has been treated. In the field, most cases of frostbite are not identified until the area has already thawed and the blue, discolored skin is found when finally changing socks or actually looking at the area in question.

When superficial frostbite is suspected, thaw immediately so that it does not become a more serious, deep frostbite. Warm hands by withdrawing them into the parka through the sleeves—avoid opening the front of the parka to minimize heat loss. Feet should be thawed against a companion or cupped in your hands in a roomy sleeping bag or other insulated environment.

The specific therapy for a deeply frozen extremity is rapid thawing in warm water (approximately 110°F or 43°C). This thawing may take 20 to 30 minutes, but it should be continued until all paleness of the tops of the fingers or toes has turned to pink or burgundy red, but no longer. This will be very painful and will require pain medication (Rx: Norco 10/325, 1 tablet; nasal Stadol; or injectable Nubain will probably be required).

Avoid opening the blisters that form. Do not cut skin away but allow the digits to autoamputate over the next 3 months. Blisters will usually last 2 to 3 weeks and must be treated with care to prevent infections (best done in a hospital by gloved attendants; lacking that, this is handled quite adequately using clean dressings to soak up the fluids).

A black carapace will form in severe frostbite. This is a form of dry gangrene. The carapace will gradually fall off with amazingly good healing beneath. Efforts to hasten the carapace removal generally results in infection, delay in healing, and increased tissue loss. Leave these blackened areas alone. The black carapace separation can take over 6 months, but it is worth the wait. Without surgical interference, most frostbite wounds heal in 6 months to a year. All persons prior to leaving the grid already should have had their tetanus booster (within the previous 10 years is ideal, but see the discussion under immunizations, page 215). Treat for shock, with elevation of the feet and lowering of the head, as shock will frequently occur when these people enter a warm environment.

Once the victim has been thawed, very careful management of the thawed part is required. Refreezing will result in substantial tissue loss, and this must be avoided. The patient sometimes becomes a stretcher case if the foot is involved, but not always. For that reason, it may be necessary to leave the foot or leg(s) frozen and allow the victim to walk back to the evacuation point or the facility where the thawing will take place, realizing that the amount of damage is increasing the longer the area remains frozen. Early, rapid thawing is essential to minimize tissue loss. Do not allow the extremity to remain frozen unless it is essential to preserve life. Peter Freuchen, the great Greenland explorer, once walked days and miles keeping one leg frozen, knowing that when the leg thawed, he would be helpless. He lost his leg but saved his life. And that’s what can also happen to you: If you leave it frozen, you will lose the frozen part.

If a frozen foot has thawed and the patient must be transported, use cotton between toes (or fluff sterile gauze from the emergency kit and place it between toes) and cover other areas with a loose bandage to protect the skin during sleeping bag stretcher evacuation. The use of Spenco 2nd Skin for blister care would be ideal; see page 274.

Cold-Induced Bronchospasm

Cold-induced bronchospasm, a form of asthma sometimes called “frozen lung” or pulmonary chilling, occurs when breathing rapidly at very low temperatures, generally below 20°F (29°C). There is burning pain, sometimes coughing of blood, frequently asthmatic wheezing, and, with irritation of the diaphragm, pain in the shoulder(s) and upper stomach that may last for 1 to 2 weeks. The treatment is bed rest, steam inhalations, drinking extra water, humidification of the living area, and no smoking. Avoid this condition by using parka hoods, face masks, or breathing through mufflers, which result in rebreathing warm, humidified, expired air. The differential diagnosis must include the possibility of pneumonia. Pneumonia patients will also have high fevers (see page 63 for treatment).

Immersion Foot

Immersion foot results from wet, cool conditions with temperature exposures from 68°F (20°C) down to freezing. This is an extremely serious injury that can be worse than frostbite. There are two stages to this problem. In the first stage the foot is cold, swollen, waxy, and mottled with dark burgundy to blue splotches. This foot is resilient to palpation, whereas the frozen foot is very hard. The skin is sodden and friable. Loss of feeling makes walking difficult. The second stage lasts from days to weeks. The feet are swollen, red, and hot; blisters form; infection and gangrene are common.

To prevent this problem, avoid nonbreathing (rubber) footwear when possible, dry the feet and change wool socks when they get wet or sweaty (certainly every night), and periodically elevate, air, dry, and massage the feet to promote circulation. Avoid tight, constricting clothing. At a minimum remove boots and socks nightly, drying the feet and warming them before sleeping.

Treatment differs from frostbite and hypothermia in the following ways: (1) Give the patient 10 grains (650 mg) of aspirin every 6 hours to help decrease platelet adhesion and the clotting ability of the blood; (2) give additional Norco 10/325 every 4 hours for pain, but discontinue as soon as possible; (3) provide 1 ounce (30 ml) of hard liquor every hour while awake and 2 ounces (60 ml) every 2 hours during sleeping hours to vasodilate, or increase the flow of blood to the feet. There is no data concerning the value of using Plavix as an antiplatelet agent in treating immersion foot, but if you have it in your cardiac kit, use it. If you are unsure whether you are dealing with immersion foot or frostbite, or if the victim may have suffered both, treat for frostbite.


Chilblains result from the exposure of dry skin to temperatures from 60°F (16°C) to freezing. The skin is red, swollen, frequently tender, and itching. This is the mildest form of cold injury and no tissue loss results. Treatment is the prevention of further exposure with protective clothing over bare skin and, if available, the use of ointments such as A+D ointment or Vaseline (white petrolatum). The hydrocortisone 1% cream from the Topical Bandaging Module will help when applied 4 times daily.

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