Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Frostbite Update

Dr. Claire Turchi and I recently provided information that was published in an article about frostbite, with the reference citation of Turchi C, Auerbach PS: Frostbite.

The following is some highlighted information from that publication:

Frostbite is an injury produced by tissue freezing following exposure to cold. The degree of severity is determined by the depth of the freezing and subsequent injury. There may be areas of different degrees of frostbite present on the same limb.

There are multiple classification systems for frostbite, but one commonly in use designates the injury in categories as:

First degree: redness and numbness, sometimes with a white or yellowish, firm area.

Second degree: superficial skin blistering with clear or milky fluid in blisters, surrounded by redness and swelling.

Third degree: deep blisters characterized by purple (blood-containing) fluid.

Fourth degree: injury deeper than the skin, sometimes leading to severe blackening and hardening of tissues, indicative of dead tissue ("mummification").

The body parts of humans most likely to become frozen are the hands, feet, nose, and ears. Perhaps the most important anatomical-physiological site of any cold injury is the lining of microscopic (in size) blood vessels. These supply precious blood flow to tissues, so if they are irreparably harmed, then the tissues are injured and cannot recover.

Patients suffering frostbite have a history of exposure to freezing weather. They usually describe a sensation of cold in affected limbs, followed by reports of loss of sensation or numbness. Once rewarming has begun, they may complain of extreme pain during or after rewarming, as sensation returns to the tissues.

Some clinicians believe that the pattern of blister formation is useful to determine the severity of the injury. Victims may suffer fractures or joint dislocation due to bearing weight on frostbitten feet.

The mainstay of treatment is rapid rewarming, but protection from refreezing must be assured before rewarming is started.
Supportive care includes adequate pain medication, keeping the victim well hydrated, and excellent wound care. Precautions that can be taken to protect injured tissue in the field include replacing wet clothing with dry, soft clothing, and wrapping affected body parts in a blanket for protection during transport.

Affected areas should be rapidly rewarmed in gently circulated warm water at 40° to 42° Centigrade to (104° to 108° Fahrenheit) until rewarming is complete (usually 15 to 30 minutes). If a thermometer is not available, nonscalding water can be used, or water at a temperature that a non-frostbitten extremity can be comfortably submerged in for 45 minutes. Antibacterial soap can be added to protect against infection. Warm wet packs can be used if a tub is not available. Temperatures above 40°C to 42°C (104°F to 108°F) or dry heat can cause burn injuries. Thawing is complete when the furthest tip of the affected limb is soft and flushes. All blisters may be treated topically with aloe vera gel or lotion every 6 hours. Padding with cotton or soft gauze should be used between digits. The rewarmed tissues should be very gently dressed. Affected parts should be kept elevated and splinted if necessary to avoid further injury.

In the field, a non-steroidal antiinflammatory drug such as ibuprofen is recommended for pain relief and to reduce inflammation. Stronger pain medication may be needed. Keep the victim well hydrated.

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.