Frostbite

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Frostbite is a change in the skin and subcutaneous tissue due to localized cold injury when exposed to temperatures < 2 degrees C.  It usually affects the most exposed appendages — that is, fingers, toes, nose, and ears. Some predisposing factors include:

  1. Wet skin or clothing
  2. Extreme wind chill
  3. Constricting garments
  4. Contact with cold metal or water
  5. Individuals with altered mental status (i.e. exhaustion, dehydration, malnutrition) who are unable to get out of the cold
  6. Altered response to cold stress due to comorbidities such as peripheral vascular disease, diabetes mellitus, Raynaud’s phenomenon, smoking or alcohol abuse.
  7. African-Americans and women may be at increased risk of frostbite1
  8. Can be due to application of ice packs to reduce swelling from musculoskeletal injuries so advise patients to interpose a cloth between ice packs and skin and limit treatment intervals to 20 minutes with a minute or two between applications.
  9. Case reports of severe facial, upper airway, and esophageal frostbite from recreational inhalation of halogenated hydrocarbons.

 

The pathophysiology of frostbite:

  1. Immediate cold-induced cell injury and death
    1. ice crystallization both extracellularly and intracellularly à lysis of cell membranes à cell death
  2. Subsequent inflammatory process mediated by thromboxane A2, prostaglandin F2-alpha, bradykinins, and histamine
    1. This results in tissue ischemia due to poor circulation to the area and ultimately necrosis.
  3. During rewarming, blood vessels leak fluid into the interstitium causing edema. After reperfusion, edema increases and there is cellular swelling as well. Thawing and refreezing lead to subsequent inflammatory damage to the affected area.

 

Clinical manifestations

  1. Most often affects fingers, toes, noses, ears, cheeks, and chins.
    1. Reports of frostbite of the cornea in individuals who keep their eyes open against strong winds.
  2. Patients complain of cold, numbness, and clumsiness of affected areas.
  3. Skin may be insensate, white or grayish-yellow in color and hard or waxy to touch.
  4. Usually graded by degrees similar to burn injuries; based on depth of tissue involvement
    1. 1st degree- central area of pallor and anesthesia with surrounding edema
    2. 2nd degree- blisters containing clear/milky fluid surrounded by edema and erythema developing in 24 hours
    3. 3rd degree- injury is deeper and blisters are hemorrhagic, progressing to black eschar over several weeks
    4. 4th degree- subcuticular involvement that may include muscle and bone in children. Complete tissue necrosis. Gangrene possible

 

Diagnostics

  1. Used to determine the extent of tissue involvement, response to therapy and long-term tissue viability
  2. Plain radiographs: may show coincidental trauma or cold-induced soft tissue swelling.
    1. Late radiographs may show bony destruction and damage to growth plates in children.
  3. Technetium (Tc)-99 scintigraphy: used to predict long-term viability of affected tissue with goal of earlier debridement or amputation rather than several week delay for demarcation. Also used to monitor response to topical therapy
  4. MRI/MRA: assess tissue viability with visualization of occluded blood vessels. Still limited experience.

 

Treatment

  1. Preshospital Care:
    1. Get patient to warm environment as soon as possible. Avoid rubbing, pressure, and mechanical trauma by using pads/splints to affected area.
    2. Remove wet clothing.
    3. Avoid walking on frostbitten feet to avoid tissue damage.
    4. Do not rewarm if there is a possibility of refreezing before reaching definitive care as this may result in further tissue damage.
    5. Avoid placing affected area in hot water or using stoves/fires to rewarm as this may result in burns to insensate tissue.
  2. Definitive Care in the hospital:
    1. Rewarm with immersion in water between 40-42 degrees centigrade. (104-108F). Higher temperatures may result in burns. Dry heat is difficult to regulate and not recommended. Rewarm until the skin is warm, red/purple, soft, and pliable, usually 15-30 minutes.
      1. Rewarming is often associated with itching and pain, may need analgesics (i.e. opioids).
    2. Elevate to decrease edema
    3. Bulky, sterile dressings to affected area
      1. Apply nonadherent gauze as first dressing layer, avoid occlusive dressing
    4. Maintain aseptic technique during wound treatment
    5. Protect lower extremity wounds with a cradle and upper extremities with sterile sheets
    6. Daily hydrotherapy to improve range of motion
    7. Splinting may be required to prevent contracture formation
    8. Tetanus prophlyaxis
      1. Thrombolysis: frostbite is associated with vascular thrombosis. Patients at high risk for life-altering amputation (multiple digits, proximal amputation) without contraindications to use tPA who present within 24 hours of injury, intra-arterial tPA is recommended with repeat angiograms.
    9. Drain, debride and bandage large non-hemorrhagic bullae that interfere with movement. Drain hemorrhagic bullae by aspiration but no debridement necessary. Minor bullae may be left intact.
    10. Prophylactic antibiotics are controversial. Nevertheless, parenteral antibiotics should be given at the earliest signs of infection. Cover for staph, strep, and pseudomonas species.
    11. Topical aloe and oral ibuprofen appear to limit inflammation although evidence is limited.
    12. Early surgical consultation to direct further management (i.e. hydrotherapy, tissue debridement, escharotomy, fasciotomy, and delayed amputation)

 

Sequelae of Frostbite Injury

  1. Infection/gangrene
  2. Autoamputation of affected area
  3. Cold hypersensitivity with subsequent increased risk of frostbite
  4. Atrophy of muscle, bone, nerves, and tendons
  5. Arthritis
  6. Vasospastic attacks
  7. Chronic paresthesias or decreased sensation (esp. of hands) to affected area

 

References

  1. Singer A.J. and Dagum A.B. Current Concepts: Current Managment of Acute Cutaneous Wounds. September 4, 2008. N Engl J Med 2008; 359:1037-1046
  2. DeGroot, DW, Castellani, JW, Williams, JO, Amoroso, PJ. Epidemiology of U.S. Army cold weather injuries, 1980-1999. Aviat Space Environ Med 2003; 74: 564.
  3. Mechem CC. Frostbite. Uptodate. February 11, 2008.
  4. Britt LD, Dascombe WH, Rodriguez A. New horizons in management of hypothermia and frostbite injury. Surgical Clinics of North America. April 1991

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