Environ

Frostbite

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Frostbite, Frostnip

  • Definitions
  1. Frostbite
    1. Skin (and deeper structures) freeze resulting in tissue injury
  2. Frostnip
    1. Superficial ice crystals deposit on the skin surface without tissue injury
  • Risk Factors
  1. Peripheral Vascular Disease
  2. Peripheral Neuropathy (e.g. Diabetic Neuropathy)
  3. Prolonged cold or moisture exposure
  4. High wind (high wind chill)
  5. High altitude
  6. Inadequate clothing
  7. Malnutrition
  8. Extremes of age
  9. Vasoconstrictive agents (e.g. nicotine)
  10. Altered Mental Status
  1. Room Temperature
    1. Normal skin perfusion >200 ml/min
  2. Skin Temperature 59 F (15 C)
    1. Skin perfusion 20-50 ml/min
    2. Vasoconstriction interrupted by periods of vasodilation lasting 5-10 minutes each, recurring every 15-20 minutes
  3. Skin Temperature 50 F (10 C)
    1. Skin sensation lost (Neuropraxia)
  4. Skin Temperature 32 F (0 C)
    1. Minimal skin perfusion
    2. Skin Temperature drops each minute by 0.9 F (0.5 C)
  5. Skin Temperature <31.1 F (-0.5 C)
    1. Intra and extracellular water crystals form, disrupting membranes and protein structures
    2. Osmotic gradient and electrolyte shifts occur and ultimately lead to cell death
    3. Vascular stasis and ultimately tissue ischemia and necrosis
  • Pathophysiology
  • Stages of Frostbite
  1. Pre-freeze
    1. Superficial tissues are cooled
  2. Freeze-thaw
    1. Intra and extracellular water crystals form, disrupting membranes and protein structures and cell death
    2. Thawing may lead to inflammatory response and reperfusion injury
  3. Vascular stasis
    1. Vasoconstriction alternates with vasodilation resulting in vessel leaks and intravascular coagulation
  4. Tissue ischemia and necrosis
    1. Intravascular thrombosis with secondary tissue ischemia and infarction
  • Signs
  • Classification - 4 category (similar to Burn Injury classification)
  1. Precautions
    1. Classification should only be applied after rewarming is complete
    2. Accurate classification may be delayed for first 1-3 months
  2. First-degree Frostbite (superficial skin)
    1. Numb, erythematous skin
    2. May develop yellow-white Plaques
    3. Tissue may slough
  3. Second-degree Frostbite (full skin thickness)
    1. Clear to milky fluid-filled bullae
    2. Surrounding edema and erythema forms in the first 24 hours after injury
  4. Third-degree Frostbite (full skin thickness AND subcutaneous tissue involvement)
    1. Hemorrhagic bullae
  5. Fourth-degree Frostbite (full skin thickness AND muscle/bone involvement)
    1. Mottled, deep red or cyanotic skin
    2. Bone and muscle freezing
    3. Dry , black mummified skin
  • Signs
  • Classification - 2 category (preferred in the acute setting)
  1. Distribution - high risk areas
    1. Extremities (hands, feet)
    2. Face (ears, nose)
    3. Genitalia (penis)
  2. Superficial Frostbite (includes first and second degree Frostbite as above)
    1. Erythema and edema
    2. Minimal to no tissue loss
    3. No hemorrhagic bullae (but clear or milky bullae may be present)
  3. Deep Frostbite (includes third and fourth degree Frostbite as above)
    1. Woody-feel to skin
    2. Hemorrhagic bullae
    3. Tissue loss (including bone and muscle injury)
    4. Mummification or amputation
  • Management
  • Acute
  1. Precautions
    1. Do not rewarm if chance of refreezing (risk of inflammation, thrombosis, cell death)
    2. Do not rub or massage skin
    3. Clear any evaporative liquids (e.g. gas, Alcohol)
    4. Avoid external dry heat (e.g. fire, radiator)
  2. Initial measures
    1. Remove all jewelry and wet clothing
    2. Rapid rewarming in warm (40-42 C, 104-107.6 F) water bath for 15-30 min
      1. Continue until skin is pliable, soft, red or purple
    3. Elevate involved area (decrease edema)
    4. Protect the injured limb with padding
    5. Opioid Analgesics and or NSAIDS (esp. for rewarming)
    6. Topical aloe vera applied to thawed tissue every 6 hours
    7. Tetanus prophylaxis
    8. Consider aspirating clear-milky bullae
      1. Do not aspirate or debride hemorrhagic tissue (may dessicate deeper tissue injury)
    9. Daily Hydrotherapy (30 to 45 minutes at 40 C, 104 F) improves range of motion and function
  3. Other measures (discuss with local consultants)
    1. Tissue plasminogen activator (tPA)
      1. Has been used for deep Frostbite within first 24 hours to reduce risk of amputation
      2. Ibrahim (2015) J Burn Care Res 36(2): e62-6 [PubMed]
    2. Hyperbaric oxygen
  • Management
  • Longterm
  1. Refer deeper Frostbite to wound care or burn specialist
  2. Indications for transfer or referral to higher level of care (e.g. burn center)
    1. Deep Frostbite
    2. Extensive limb involvement
    3. Concerns for Compartment Syndrome (if unable to manage locally)
  3. Surgical Management
    1. Delay surgical amputation or debridement for 1-3 months until demarcation of mummified areas
    2. Earlier debridement may be needed if refractory superinfection occurs
  • Complications
  1. Compartment Syndrome
  2. Excessive sweating
  3. Cool extremities
  4. Numbness
  5. Abnormal color
  6. Nail Disorder
  7. Skin Pigment Changes
  8. More susceptible to second injury
  9. Limb Amputations (4th degree, mummified tissue)
  • Prevention
  1. Never ignore numbness in a cold extremity
  • Images
  1. Presentation Graphic
    1. erEnvironFrostbite.jpg
  • References
  1. Civitarese and Sciano (2018) Crit Dec Emerg Med 32(2): 3-16