11.04 Frostbite and Frostnip
Frostnip occurs when skin surfaces such as the tip of the nose and ears are exposed to an environment cold enouth to freeze the epidermis. These prominent exposed surfaces become blanched and develop paresthesias and numbness. As they are rewarmed, they become erythematous and at times painful.
Superficial frostbite can be either a partial or a full thickness freezing of the dermis. The frozen surfaces appear white and feel soft and doughy. With rewarming these areas will become erythematous and edematous with severe pain. Blistering will occur within 24-48 hours with deeper partial thickness frostbite.
What to do:
- When there is no longer any danger of re-exposure and re-freezing, rapidly warm the affected part with heated blankets (warm hands in the case of frostnip) or in a warm bath (38-40 degrees C).
- A strong anesthetic such as meperidine (Demerol) or morphine may be required to control pain.
- When blistering occurs, bullae should ot be ruptured. If the blisters are open, though, they should be debrided and gently cleansed with povidone-iodine and normal saline. Silvadene cream may be applied, followed by a sterile absorbent dressing.
- Patients should be provided with follow up care and warned that healing of the deeper injuries may be slow and produce skin that remains sensistive for weeks. In addition, there may be permanent damage to fingernails, long term paresthesia, and permanent cold sensitivity.
What not to do:
- Do not warm the injured skin surface while in the field if there is a change that re-freezing will occur. Re-exposing even mildly frostbitten tissue to the cold without complete re-warming can result in additional damage.
- Do not rub the injured skin surface in an attempt to warm it by friction: this can also create further tissue destruction.
- Do not allow the patient to smoke. Smoking causes vasoconstriction and may further decrease blood flow to the frostbitten extremity.
- Do not confuse frostnip and superfician frostbite with deep frostbite. Severe frostbite, when the deep tissue or extremity is frozen with a woody feeling and lifeless appearence, requires inpatient management and could be associated with life-threatening hypothermia.
Frostbite is more common in persons exposed to cold at high altitudes. The areas of the body most likely to suffer are those farthest from the trunk or large muscles: ear lobes, nose, cheeks, hands and feet. Touching cold metal with bare hands can cause immediate frostbite, as can the spilling of gasoline or other volatile liquids on the skin at very low temperatures. Of course, prevention is the best "treatment" for frostbits. Heavily insulated, waterproof clothing gives the best frostbite prevention.
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