Keep it Cool with Frostbite

This week – the return of the King.  Sakib himself shares some information on appropriate care for frostbite injuries

Play it cool with frostbite

Quickhit:

–       Risk of cold injuries such as frostbite correlated with temperature, windchill, moisture

  • Risk is <5% when ambient temp (including wind chill) is >5 F (-15C)
  • Most often occur at ambient temp < -4 F (-20C)

–       Pathophys = freezing alone not sufficient to cause tissue death, Thawing contributing to endothelial damage is cause of majority of damage (see continue reading below)

–       Zone of injury = Zone of Coagulation, Zone of Hyperemia, Zone of Stasis

–       Treatment = Rapid re-warming with warm water. Do not debride any tissue initially.

–       Complications

  • 65% pt. experience sequeulae from their injuries
  • Hypersensitivity to cold, pain, ongoing numbness
  • Asthritis, bone deformities, dystrophia

Read below to get more thorough treatment maneuvers and further info on Frostbite Injury!

Environment: chance of frostbite 95% at temp of -7.8 C. Windchill and moisture contribute and cause freezing at higher temps. Prolonged moisture and supra-freezing temps leads to similar entity: trench foot. Listen to Lieutenant Dan, keep those feet dry. Among civilians, predisposing factors are homelessness, alcoholism or drug abuse, outdoor work, and outdoor sports.Clinical picture: Numbness, tingling, burning sensation of extremity after cold exposure. Area is discolored (ranging from white, blue, to black/eschar if advanced).  Most commonly affected are hands, feets, and head (ears, nose, cheeks).Mechanism:-       Ice crystals extracellulary causes intracellular dehydration and hyperosmolarity. Proteins denature, cell membrane loses integrity.-       Upon thawing: endothelial damage! Arachidonic acid cascade -> venule and arterial thrombosis -> ischemia and necrosis -> dry gangrene.Degrees:1st/frostnip- red, swollen, no blisters. Sensation of stinging and burning, followed by throbbing. Skin sloughs days later

2nd– full thickness of skin. Edema and clear blisters. Blisters slough in days and may turn black (eschar) – reference image below:

Frostbite1

3rd– into subQ blood vessels. Hemorrhagic blisters, skin necrosis, “block of wood” feeling

4th– all layers of tissue. Little edema, nonblanching cyanosis, mottled. Turns into mummified eschar.  Reference image below:

Frostbite2

In the beginning, difficult to differentiate. Classify as just superficial or deep.

Zones of Injury

–       Zone of Coagulation = Most severe and usually most distal, damage irreversible

–       Zone of Hyperemia = Least severe and usually most proximal, damage resolves on own without treatment in <10 days

–       Zone of Stasis = Middle zone characterized by severe by possibley reversible damage, **treatment has benefit**

In the field: Cover and immobilize to prevent further injury. Do not heat until risk of refreeze eliminated! Refreezing = bad news bears. Also, do not apply dry heat (from heater, warm surface). Stabilize other injuries.

At the hospital:

1. Place in gently circulating warm water at 40-42 C for 20-30 min of until pliable and erythematous.

2. Manage pain! Thawing process extremely painful. Opiates and elevation.

3. Pen G 500,000 units IV bid x3 days, tetanus vaccine

4. t-PA and heparin after thawing has been shown to reduce digit amputations in severe cases.

5. Severity of ischemia can be assessed by absent doppler pulses, no improvement with rewarming, and no perfusion on bone scan.

6. Aspirin and prostacyclin may be of benefit.

7. Apply aloe vera q6 hours. Clear blisters can be debrided, hemorrhagic cannot.

8. Surgery: demarcation occurs after 3-4 weeks, and autoamputation may follow. Amputation should be done sooner if wet gangrene or infection occurs.

9. Wet vs. Dry Gangrene: dry is simply coagulative necrosis. It is dry and mummified. Add in bacteria and or a moist body part (mouth, vagina, etc) and you get wet gangrene, which has progressed from coagulative to liquefactive necrosis. When its wet, you can tell/smell.

Twomey, JA. “An open-label study to evaluate safety and efficacy of t-pa in treatment of severe frostbite.” J trauma. 2005.

Ikäheimo TM. Frostbite and Other Localized Cold Injuries. In: Tintinalli JE, Stapczynski JS, Cline DM, Ma OJ, Cydulka RK, Meckler GD, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill; 2011.

Cauchy, E. “A controlled trial of a prostacyclin and rt-PA in the treatment of severe frostbite.” NEJM. 2011; 364: 189-190.

Tintinalli

Contributor: Sakib Motalib

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