Medical Emergency
Cold Injuries : The Chill Within

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Introduction

Cold injuries have had profound effects upon the fighting force and military operations throughout history[1] including our own military experiences from the highest battlefield in the world, Siachen. Cold injuries are as preventable as heat injuries and require the medical services to work closely with the tactical commanders to implement effective prevention strategies[2]. The initial treatment offered by the Regimental Medical Officer (RMO) is crucial to the final outcome. This article attempts to review the various types of cold injuries and identify prevention and treatment strategies. Cold injuries are divided into freezing and nonfreezing injuries (occur with ambient temperature above freezing). They include hypothermia, frostnip, chilblains, immersion foot and frostbite. Exposure to cold can induce Raynaud's disease, Raynaud's phenomenon and allergic reactions to cold. Other conditions encountered during cold weather operations are acute mountain sickness, psychiatric and psychosocial disorders, snow blindness, and constipation (due to decreased fluid intake).

Section snippets

Thermodynamics [3]

Skin and subcutaneous tissues are maintained at a constant temperature (about 98.6°F) by the circulating blood. Blood gets its heat mainly from the energy given off by cellular metabolism. The optimum temperature for most enzymatic reactions is 98.6°F. In hypothermia, most organs, especially the heart and brain, become sluggish and eventually stop working. The hypothalamus is sensitive to blood temperature changes of as little as 0.5°C and also reacts to nerve impulses received from nerve

Hypothermia

Hypothermia is “a decrease in the core body temperature to a level at which normal muscular and cerebral functions are impaired”. Any temperature less than 98.6°F can be linked to hypothermia. The core temperature falls due to decreased basal metabolic rate (BMR) and body functions slow down.

Etiology

  • Acute exposure to cold wind at high altitude e.g. shelterless situation during blizzard

  • Immersion in cold water after ship wreck

  • Less acute, prolonged exposure to cold e.g. in a cold bunker

Aggravating factors

  • Improper clothing and equipment

  • Wetness

  • Fatigue, exhaustion

  • Dehydration and poor food intake

  • Lack of knowledge of hypothermia

  • Alcohol intake - causes vasodilation leading to increased heat loss

Clinical features

Watch for the “-umbles” - stumbles, mumbles, fumbles, and grumbles which show changes in motor coordination and levels of consciousness.

Mild hypothermia - core temperature 98.6°-96°F

  • Shivering - not under voluntary control

  • Can't do complex motor functions (ice climbing or skiing), can still walk & talk

  • Vasoconstriction of peripheral vessels manifesting as pallor

Moderate hypothermia-core temperature 95°-93°F

  • Dazed consciousness and/or irrational behaviour e.g. paradoxical undressing -

Treating hypothermia [4]

The basic principles of rewarming a hypothermic victim are to conserve the heat they have and replace the body fuel they are burning up to generate that heat. If a person is shivering, he has the ability to rewarm himself at a rate of 2°C per hour.

Mild-moderate hypothermia

Reduce heat loss with additional layers of dry clothing. Increase physical activity slowly in a sheltered environment.

Add fuel & fluids : It is essential to keep a hypothermic person adequately hydrated and fuelled. Carbohydrates (5 cal/g) are quickly released into blood stream for sudden brief heat surge and are best for quick energy intake especially for mild cases of hypothermia. Proteins (5 cal/g) are slowly released and heat given off over a longer period. Fats (9 cal/g) also release heat

Severe Hypothermia

Reduce heat loss: The idea is to provide a shell of total insulation for the patient. No matter how cold, patients can still internally rewarm themselves much more efficiently than any external rewarming. Make sure the patient is dry, and has a polypropylene layer to minimize sweating on the skin. The person must be protected from any moisture in the environment. Use multiple sleeping bags, wool blankets, wool clothing to create a minimum of 4” of insulation all the way around the patient,

Cardiopulmonary resuscitation(CPR) & Hypothermia

Patients in severe hypothermia may demonstrate all the accepted clinical signs of death like cold blue skin, fixed and dilated pupils, no discernible pulse or respiration, muscle rigidity, coma & unresponsive to any stimuli.

But they may still be alive in a “metabolic icebox” and can be revived. The old adage ‘a hypothermic patient is never cold and dead, only warm and dead’ still holds true. During severe hypothermia the heart is hyperexcitable and mechanical stimulation (such as CPR, moving

Frostnip

Frostnip is the freezing of top layers of skin tissue. It is generally reversible and manifests with numbness, white, waxy skin-top layer feels hard, rubbery but deeper tissue is still soft. It occurs typically on cheek, earlobes, fingers and toes. Frostnip is managed by gentle rewarming e.g. by blowing warm air on it or placing the area against a warm body part (partner's stomach or armpit). Avoid rubbing as this can damage the tissue by having ice crystals tear the cells.

Rewarm by immersing

Frostbite

Frostbite is more severe and includes all layers of skin. The skin appears white and has a “wooden” feel all the way through with numbness and possibly anaesthesia. Deep frostbite can include freezing of muscle and/or bone, it is very difficult to rewarm the appendage without some damage occurring.

  • First degree frostbite is similar to mild chilblain with hyperemia, mild itching, and edema. No blistering or peeling of skin occurs. (Fig. 2).

  • Second degree frostbite is characterized by

Treatment of frostbite

Treatment of frostbite begins in the field with first aid or buddy aid. Protect the individual from further harm, keep warm, remove any restricting clothing, and begin rewarming. If the lower extremity is involved, the patient must be evacuated as soon as feasible. If he cannot be transported immediately, wait until evacuation to begin rewarming the injured area. The freeze-thaw-refreeze cycle causes more damage than waiting for definitive treatment.

Regimental Aid Post(RAP)

At the RAP, rewarm the injured area in a carefully controlled water bath at 104°F (not to exceed 108°F). Rewarming may be quite painful and requires analgesics and sedatives. Hydration must be maintained with intravenous fluids if required [9]. Once thawing is complete the injured part must be kept clean and dry and protected from further trauma. All patients with cold injuries of the lower extremity are best evacuated. A tetanus toxoid booster should be given. Prophylactic antibiotics are not

Active debridement or minor surgery

Active debridement or minor surgery on frostbitten tissue should never be done in the field [10]. It may take days to weeks for the demarcation line between viable and nonviable tissue to form. Bone scans have been used for early appreciation of bone involvement but are usually not available in our setting [11, 12]. Similarly, hyperbaric oxygen therapy is capable of improving nutritive skin blood flow in frostbitten areas more than 2 weeks after the injury [13].

Signs noted in early rewarming that affect prognosis

  • Good prognostic signs: Large, clear blebs developing early and extending to the tips of the digits; rapid return of sensation; return to normal temperature in the injured area; rapid capillary filling time after pressure blanching; pink or mildly erythematous skin colour that blanches.

  • Poor prognostic signs: Hard, white, cold, and insensitive tissue; cold and cyanotic tissue without blebs or blisters; complete absence of edema; dark hemorrhagic blebs, early mummification; constitutional signs of

Chilblains

Chilblains (erythema pernio) is a superficial tissue injury that occurs after prolonged or intermittent exposure to temperatures above freezing and high humidity with high winds. Initial pallor characterizes chilblains followed by erythema and pruritus of the affected area. Women and young children are the most susceptible and chilblains commonly involve cheek and ears, fingers and toes. The cold exposure causes damage to peripheral capillary beds, this damage is permanent and the redness and

Trench foot-immersion foot

Trench foot is a process similar to chilblains. It is caused by prolonged immersion of the feet in cool, wet conditions. This can occur at temperatures as high as 60°F if the feet are constantly wet e.g. sea sports.

Since wet feet lose heat 25 times faster than dry, the body uses vasoconstriction to shut down peripheral circulation in the foot to prevent heat loss. Skin tissue begins to die because of lack of oxygen and nutrients and due to buildup of toxic products. The skin is initially

Treatment and prevention of Trench foot

Treatment consists of gentle drying, elevation, and exposure of the extremity in an environmental temperature of 64°-72°F, while keeping the rest of the body warm. Since the tissue is not frozen as in severe frostbite, it is more susceptible to damage by walking on it. Bed rest, cleanliness, and pain relief with NSAIDs are essential. The prognosis depends upon the extent of the original tissue and nerve damage. Minimal and mild cases can resolve in hours to days or weeks and most eventually

Eye Injuries

Freezing of cornea: Caused by forcing the eyes open during strong winds without goggles. Treatment is very controlled, rapid rewarming e.g. placing a warm hand or compress over the closed eye. After rewarming the eyes must be completely covered with patches for 24-48 hours.

Eyelashes freezing together: Put hand over eye until ice melts, then open the eye.

Snowblindness (sunburn of the eyes): Prevention by wearing good sunglasses with side shields or goggles. Eye protection from sun is just as

Basic principles for the prevention of cold injury

Keeping warm in a cold environment requires several layers of clothing-preferably wool or synthetics such as polypropylene, because these materials insulate even when wet. Since the body loses a large amount of heat from the head, warm headgear is essential. Adequate food and fluid intake provides fuel to be burned, and warm fluids directly provide heat and prevent dehydration. Alcoholic beverages should be avoided, because alcohol causes cutaneous vasodilatation, which makes the body

Training

The education of all personnel on how to practise personal prevention measures should include the following subjects:

  • proper foot care

  • frequent changing of clothing

  • the exercise of extremities in pinned-down positions

  • proper dress and work in a cold environment

  • recognition of symptoms of cold injury

  • buddy aid treatment

  • maintaining adequate hydration and nutritional status

Proper cold weather clothing

Proper cold weather clothing based on area of operation.

Command support

Command support is very important in enforcing prevention guidelines whenever possible. These areas should include the distribution and enforced wearing of cold weather clothing, proper personal hygiene, especially foot care, proper rotation cycles into sheltered areas, and the distribution of sufficient rations and fluids for cold weather operations, particularly hot liquids.

Early diagnosis and treatment

Emphasis is placed on early diagnosis and treatment of cold injuries by medical personnel.

Acclimatization

Acclimatization to cold weather environment should be performed whenever possible. This usually takes 1-4 weeks.

Avoid accidents

Don't touch cold metal with bare skin or spill gasoline on skin or clothes

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References (13)

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