Nonfreezing Injuries

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Immersion or "trench" foot is a significant cause of morbidity, particularly during military operations. Its name was first coined during World War I, after troops who stood in water-filled trenches for days developed this injury. It occurs in ambient temperatures of 0o to 10oC (32o to 50oF) and is caused by a prolonged exposure to cold water.29,32 The exact pathophysiology remains somewhat controversial, but it is widely believed that the prolonged vasoconstriction causes an ischemic injury leading to demyelination of nerve fibers, muscle atrophy, skin atrophy, and decreased compliance of the small vessels.24,25,32 On presentation, the affected limb appears mottled, pale, and cool to the touch. Sensation is impaired, and the victim will often describe the feeling as "walking on cotton wool." After rewarm-ing, the involved area becomes warm, dry, erythematous, and excruciatingly painful. This may last several weeks. Long-term sequelae include cold sensitivity, hyperhidrosis, paresthesias, and chronic neuropathic pain.32 Treatment of choice is removing the victim from the environment, elevating the affected extremity, and allowing passive rewarming.24,32

Although less severe, chilblains and pernio are also caused by prolonged exposure to a cold and wet environment. The ambient temperature is usually between 0o and 15oC (32o and 60oF) for these injuries to occur.25,32 Chilblains are subcutaneous vesicles that appear after 3 to 6 hours of exposure. They are usually painless and resolve with no long-term sequelae. As length of exposure reaches 12 hours or more, partial thickness eschars and deep pain can develop. The eschars slough without scarring; however, the pain may persist and is termed pernio.32 The major

Table 6-2 Protocol for Rapid Rewarming

1.

Admit frostbite patients to a specialized unit if possible.

2.

Do not discharge or transfer to another facility victims of acute frostbite requiring hospitalization unless it is necessary for specialized care. Transfer arrangements must protect the victim from cold exposure.

3.

On admission, rapidly rewarm the affected areas in warm water at 40° to 42°C (104° to 108°F), usually for 15 to 30 minutes or until thawing is complete.

4. On completion of rewarming, treat the affected parts as follows:

4. On completion of rewarming, treat the affected parts as follows:

a. Débride white blisters and institute topical treatment with aloe vera (Dermaide aloe) every 6 hours.

b. Leave hemorrhagic blisters intact and administer topical aloe vera (Dermaide aloe) every 6 hours.

c. Elevate the affected part(s) with splinting as indicated.

d. Administer antitetanus prophylaxis.

e. For analgesia, administer morphine or meperidine (Demerol) intravenously or intramuscularly as indicated.

f. Administer ibuprofen 400 mg orally every 12 hours.

g. Administer penicillin G 500,000U intravenously every 6 hours for 48 to 72 hours.

h. Perform hydrotherapy daily for 30 to 45 minutes at 40°C (104°F). The solution should meet the following specifications:

1. Large tank capacity: 425 gallons Fill level estimate: 285 gallons Sodium chloride: 9.7 kg

Calcium hypochlorite solution: 95 mL

2. Medium tank capacity: 270 gallons Fill level estimate: 108 gallons Sodium chloride: 3.7 kg

Calcium hypochlorite solution: 36mL

3. Small tank capacity: 95 gallons Fill level estimate: 72 gallons Sodium chloride: 2.5kg Potassium chloride: 71g

Calcium hypochlorite solution: 24mL

5. For documentation, obtain photographs on admission, at 24 hours, and serially every 2 to 3 days until discharge.

6. Discharge patients with specific instructions for protection of the injured areas to avoid reinjury and follow up weekly until wounds are stable. If the patient is being discharged with no open lesions, instruct him or her to use wool socks, wear a hat, and use mittens instead of gloves to decrease the loss of heat between the fingers. Explain to patients that they are more susceptible to refreezing, so they should avoid exposure to cold and should wear warm clothing and shoes or boots if going outside is necessary. Give similar instructions to patients who are discharged with open lesions. Also instruct these patients to keep the affected extremity elevated and to take ibuprofen 400mg orally every 12 hours. Aloe vera should be applied to the involved areas or scarlet red ointment used if the open areas are small.

From McCauley RL, Smith DJ, Robson MC, Heggers JP: Frostbite. In Auerbach PS (ed): Wilderness Medicine, 4th ed. St. Louis, Mosby, 2001, p. 188.

long-term complication associated with pernio is increased cold sensitivity. The pathology of these conditions is thought to be just like that of trench foot. The treatment is supportive, allow-

29 33

ing passive rewarming.

In addition to directly causing injury, the cold environment can stimulate other conditions in susceptible individuals. Cold urticaria with or without angioedema is produced by the degranulation of mast cells that are stimulated by the cold. Symptoms are generally mild and self-limited and may be relieved with the use of antihistamines.25,29 Bronchospasm may also be induced, particularly with hyperventilation of cold air. Cold-induced asthma is considered a variant of exercise-induced asthma. The cold air causes a drying of the mucosa due to evaporative loss and local irritation of the mucosa leading to a cascade of immune response and ultimately to smooth muscle contraction in the bronchial tree. Preactivity use of inhaled p2-agonist is the mainstay of treatment.25,29,34 Raynaud's disease is a condition caused by intermittent vasospasm of the digital vessels and is often exacerbated by cold. It may be associated with an underlying medical condition but is mainly idiopathic. With exposure, the digits become pale and numb. After rewarming, redness, swelling, and throbbing pain are seen. The primary treatment is avoidance of cold exposure.25,29 Cold air exposure of the nasal mucosa can stimulate an increase in mucous production resulting in rhinitis or "skier's nose." It causes no long-term problems and can be treated with nasal atropine sulfate.29

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