Introduction
Cold injuries have had profound effects upon the fighting force and military
operations throughout history including our own military experiences from Valley Forge
through World War II and Korea. Cold injuries are as preventable as heat injuries and
require the medical department to work closely with the line commander to recommend
effective prevention strategies for such injuries.
Risk factors for cold injury
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Age
The very young and the elderly are more susceptible.
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Rate
Lower enlisted rates more at risk of immersion foot and frostbite due to a greater degree
of exposure than higher grades or rates.
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Previous Cold Injury
This increases the risk of subsequent cold injury.
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Fatigue
Mental and physical fatigue increases carelessness and the neglect of activities necessary
to survive in the cold.
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Trauma and tissue injuries
Other injuries with blood or volume loss, or tissue injury will inhibit peripheral
circulation and increase the risk of cold injury.
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Discipline, training, and experience
Poorly motivated, negative individuals tend to be less active, pay less attention to
personal hygiene needs, and are more at risk of cold injury.
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Race and Area of Origin
Dark skinned individuals and persons from warmer climates tend to be more susceptible to
cold injuries.
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Activity
Too much or too little activity increases risk of cold injury.
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Nutrition / hydration.
Increased exercise requirements due to heavy clothing, equipment, and snow can increase
fluid and caloric requirements up to 7,000 calories/day.
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Drugs and other medications.
Tobacco use leads to vasoconstriction and is prohibited during the treatment of frostbite.
Alcohol leads to mental impairment and peripheral vasodilatation increases core heat loss.
Basic principles for the prevention of cold injury
Training
The education of all personnel on how to practice personal prevention measures should
include the following subjects:
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proper foot care
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frequent changing of clothing
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the exercise of extremities in pinned-down positions
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proper dress and work in a cold environment
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recognition of symptoms of cold injury
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buddy aid treatment
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maintaining adequate hydration and nutritional status
Proper cold weather clothing
Proper cold weather clothing based on area of operation. Reference (c) provides use and
ordering information for cold weather clothing.
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 environments should be performed whenever possible.
This usually takes 1-4 weeks.
Don't touch cold metal with bare skin or spill gasoline on skin or clothes.
Cold injuries are divided into freezing and nonfreezing injuries. Other conditions
commonly occurring during cold weather operations are acute mountain sickness, carbon
monoxide poisoning, snowblindness, and constipation (due to decreased fluid intake).
Nonfreezing Injuries (occur with ambient
temperatures above freezing)
Chilblains 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. Treatment includes gradually rewarming of the exposed area at
room temperature. After rewarming, there may be erythema, edema, and itching of the limb
and skin. Superficial blisters or ulcers may appear with repeated episodes. Usually the
duty time lost from this injury is insignificant.
Immersion Injuries
Immersion injuries result from prolonged exposure to cold water, usually 12 hours or
longer at temperatures of 50-70 F or for shorter periods at or near 32 F. Trenchfoot is an
immersion injury seen in trench warfare where mobility is limited and dry boots and socks
are unobtainable. Initially the injured limb will be cold, swollen, and appear waxy-white
with cyanotic burgundy-to-blue splotches. The skin is anesthetic and deep musculoskeletal
sensation is lost. Walking will be difficult.
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. Initially,
painful hyperemia and swelling with superficial blistering can be seen. Bed rest,
cleanliness, and pain relief 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 return to full duty. However, moderate to severe cases can take
months to heal and most of these patients do not return to full duty. Expect to MEDEVAC
these patients to the rear for convalescence.
Freezing injuries
Freezing injuries and frostbite result from exposure to temperature below freezing. The
speed of onset, depth, and severity of injury depend on the temperature, wind-chill, and
the duration of exposure. Cellular injury and death occur from cellular trauma due to ice
crystal formation and from complex vascular reactions occurring in cold exposure. If the
tissue has been frozen, it appears dead white and is hard or even brittle. Differentiation
of the types and severity of injury may be difficult even after rewarming has occurred.
There are four degrees of frostbite and definitive classification of severity is possible
only in retrospect, after the case is complete.
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First degree frostbite is similar to mild chilblain with hyperemia, mild itching,
and edema. No blistering or peeling of skin occurs.
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Blistering and desquamation characterize second degree frostbite.
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Third degree frostbite is associated with necrosis of skin and subcutaneous
tissue with ulceration.
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Fourth degree frostbite includes destruction of connective tissues and bone, with
gangrene. Secondary infections and nonfreezing injuries are not uncommon, particularly if
there is a history of a freeze-thaw-refreeze cycle with the tissue.
Treatment of frostbite
Treatment for 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 made a litter patient.
If they cannot be made a litter patient and must walk to further treatment, wait until
evacuation to begin rewarming the injured area. The freeze-thaw-refreeze cycle causes more
damage than waiting for definitive treatment.
Battalion Aid Station care
At the battalion aid station, rapid rewarming of the injured area should occur in a
carefully controlled water bath, using a thermometer, at 104 F, not to exceed 108 F.
Rewarming may be quite painful and require analgesics and sedatives. 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 litter patients. A tetanus
toxoid booster should be given. Do not give prophylactic antibiotics. Patients with more
than first degree frostbite should be evacuated as soon as possible to a definitive
treatment facility since the extent of injury may not be readily apparent and
convalescence is usually prolonged.
Active debridement or minor surgery
Active debridement or minor surgery on frostbitten tissue should never be
done in the field. It may take days to weeks for the demarcation line between viable and
nonviable tissue to form.
Signs noted in early rewarming that affect prognosis
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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 color that blanches.
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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 tissue necrosis: fever, tachycardia, and prostration; superimposed
trauma; cyanotic or dark red skin that does not blanch on pressure. Note: All cold
injuries must be reported on NEHC-5100/3.
References
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NAVMED P-5052-29: Technical Information Manual for Medical Corps Offcers, Chapter 29,
Cold Injury (1976). S/N 0510-LP-074-1091