Recognition and Treatment of Frostnip
and Frostbite
The
following information is adapted from the Merck Manual (17th Edition
1999). Additional information is also available at merckmanual.com.
Frostnip
Reversible injury due to exposure to subfreezing conditions.
FROSTNIP manifests as firm, cold, white areas on the face, ears, or extremities. Peeling or blistering (as from sunburn) may occur in 24 to 72 hours. Occasionally, mild hypersensitivity to cold persists for life. Frostnip can be treated by warming the affected area with an unaffected hand or a warm object.
Frostbite
Injury due to freezing of tissue cells.
FROSTBITE of extremities occurs in extreme cold, especially at high altitude, and is aggravated if core temperature is subnormal, even though hypothermia may not be apparent.
Ice crystals form within or between tissue cells. Blood
vessels constrict to reduce heat loss from skin and surrounding tissues. Much of the damage occurs during
re-warming.
The affected area is cold, hard, white, and is usually not painful (freezing of the tissue temporarily anesthetizes it). When warmed, it becomes blotchy red, swollen, and painful. Blisters form within 4 to 6 hours. Blisters filled with clear fluid and located near ends of fingers, toes, earlobes, etc. usually indicate superficial damage. Blisters that are blood-filled and closer to the body usually indicate deeper damage and tissue loss. Superficial damage heals without residual tissue loss. Freezing of deeper tissue may cause gangrene which may present as hard and blackened or as a soft, gray, swollen covering over healthy tissue. The depth of tissue loss depends on the duration and depth of freezing. All degrees of frostbite may produce long-term symptoms--sensitivity to cold, excessive sweating, faulty nail growth, and numbness.
Treatment
Frostbitten extremities should be warmed rapidly in water that is warm to the hand of the treater (not warmer 105° F). The victim may not be able to adequately judge the water temperature. Ears/earlobes may be re-warmed using a warm, wet cloth. It is extremely important to avoid scalding the anesthetized tissues. If warm water is not immediately available, re-warming of the extremity against the body of the injured individual, placing hands under a shirt, inside pockets, wrapping in a blanket or towel, etc. can be used as alternatives until warm water is available. Rubbing of the extremity is not recommended because of the potential to further damage the tissue. Heating pads are also not recommended since the victim may not be able to feel the excessive heat due to impaired sensation, thus increasing the potential for burns. When the victim must walk some distance to receive care and a lower extremity is affected, thawing is NOT advised. Thawed tissue is further damaged by trauma (eg, walking) and, if refrozen, is certain to be severely damaged. If the frozen part cannot be safely thawed immediately, it should be gently cleaned, dried, and protected in sterile compresses until thawing in a warmer, more stable situation is possible. The victim should be given ibuprofen 400 mg, if available, and the whole body kept warm. The longer a part remains frozen, the greater the ultimate damage may be.
Emergency room assessment may be necessary in the case of extensive tissue involvement. Preventing infection is essential. Tetanus toxoid should be given if this immunization is not up to date.
After warming, extremities should be kept dry, open to warm air, and as sterile as possible. Many victims are dehydrated. Fluids should be given to restore proper hydration. Preferred medical therapies vary, but the goal is to restore capillary circulation and minimize cell damage. No treatment for the long-lasting symptoms of frostbite (eg, numbness, hypersensitivity to cold) is known.
(Mrs.) A. M. Davis, M.S., R.N., C.S., A.R.N.P.
Head Nurse,
(AMD