Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter IV: Cold Injury

Clinical Manifestations

United States Department of Defense

Patients generally describe initial feelings of cold discomfort in their extremities, followed by varying periods of pain and mild discomfort along with a cyclic, dull ache. These symptoms subside into a period of anesthesia. From there, cold injury progresses in a painless fashion. Patients often describe a sensation of walking on a wooden limb. Because of the anesthetic nature of cold injury, patients often say they were unaware that they were developing an injury. The hypothermia victim retreats inward psychologically; has dulled senses, a stumbling gait, muscle incoordination, and slurred speech; and is universally unaware of the insidious decrement in his capability.

In a cold, wet environment, trenchfoot often appears. Anesthesia of the limb in trenchfoot injury comes on rapidly. Pain which does not respond to analgesia limits the deployment of soldiers with normal appearing extremities. Most patients are unaware of or do not care about the potential severity of their injury. The first physical manifestation of frostbite injury is reddening of the skin, which later becomes pale, waxy white, and hard. Lack of mobility of skin over joints is a common finding. In hypothermia, shivering is a clear indication of loss of body temperature. Shivering varies with age, physical condition, degree of hypothermia, and amount of ingested drugs. Shivering can significantly limit an individual's performance of specific military tasks, including sighting targets, reading maps, and manipulating small dials and radios. It is a form of involuntary exercise that produces heat. When shivering stops, the patient is at the mercy of the environment. CNS involvement appears to be the most common outward manifestation of hypothermia. Decreased dexterity and coordination, speech and memory impairment, and the eventual loss of consciousness indicate progressive loss of neurologic function. Dysarthria is a specific early indication of hypothermia and is often one of the first recognizable signs of the loss of deep body temperature.

Judgment of the degree of frostbite has historically involved a retrospective grading system involving four categories. It is more useful and realistic, however, to determine two major categories: superficial and deep. Because frostbite is a continuum of events, the differentiation between first, second, third, and fourth degrees is often clouded and may take some days or weeks to become completely obvious.

In first-degree injuries, erythema and edema, along with transient tingling or burning, are early manifestations. The skin becomes mottled blue/grey and red, hot, and dry. Swelling begins within two or three hours and persists for ten days or more, depending upon the seriousness of the injury. Desquamation of the superficial epithelium begins in 5-10 days and may continue for as long as a month, but no deep tissue is lost. Parathesias, aching, and necrosis of the pressure points of the foot are common sequelae. Increased sensitivity to cold and hyperhydrosis may appear, especially with repeated first-degree injuries. It should be noted that it is difficult to differentiate first-degree frostbite from abrasion produced by the insulated vapor barrier boot. Medical personnel must be cognizant of the difference as both injuries occur in the same clinical setting.

Second-degree cold injury starts as does first-degree, but progresses to blister formation, anesthesia, and deep color change. Edema may form, but it disappears within days. Vesicles appear within 12-24 hours. They generally appear on the dorsum of the extremities, and when these vesicles dry they form an eschar. Blisters are a good clinical sign as long as they are filled with clear fluid. If the fluid is hemorrhagic, they are not a good sign. As these vesicles dry, they sluff cleanly with pink granulation tissue beneath or they form black eschars. Throbbing and aching pain occurs 3-10 days after this injury. Hyperhydrosis is apparent at the second or third weeks. Early rupture of the blisters with subsequent infection often occurs in second-degree cold injury. This infection significantly increases the severity of the frostbite injury.

Third-degree injury involves full skin thickness and extends into the subcutaneous tissue. Vesicles are smaller and may be hemorrhagic. Generalized edema of the extremity may occur, but it usually abates within 5-6 days. Subfacial pressure increases and compartment syndromes are common in third- and fourth-degree cold injuries. If pressure rises significantly with loss of distal blood flow, faciotomy along until vasodilators is indicated for therapy. The skin forms a black, hard, dry eschar, usually thicker and more intense shall that of the second-degree injury. When it finally demarcates, sloughing with some ulceration occurs if there is no complicating infection. The average healing time is 68 days. Patients often complain of burning, aching, throbbing, or shooting pains beginning on the fifth day and usually lasting through four or five weeks. Hyperhydrosis and cyanosis appear later and extreme cold sensitivity is a common post injury sequela.

In fourth-degree injury, there is destruction of the entire thickness of the part, including bone, resulting in extensive loss of tissue. After rewarming, tissue is cyanotic and insensitive, and blister formation, if present, is hemorrhagic. Severe pain on rewarming, along with a deep cyanotic appearance, regularly occurs. In rapidly-frozen extremities or the freeze-thaw-refreeze injury, dry gangrene progresses quickly with mummification. With slower freeze, there is some early swelling and deep pain, and demarcation takes much longer to occur. The line of demarcation becomes obvious at 20-36 days and extends into the bone in 60 or more days.

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Operational Medicine 2001

Health Care in Military Settings

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