Rosen & Barkin's 5-Minute Emergency Medicine Consult (286 page)

DIAGNOSIS

• Extremities (fingers, toes) and head (ears, nose) most commonly affected.
  
• After rewarming frostbite can be classified; however, initial classification often fails to provide an accurate prognosis and does not alter initial management.
  
• Superficial frostbite:
  
  • Only skin structures involved. Usually no tissue loss.
    
  • 1st degree: Erythema and edema with stinging, burning, and throbbing. No blisters or necrosis.
    
  • 2nd degree: Significant edema, clear blister formation. Numbness common.
    
• Deep frostbite:
  
  • Tissue loss inevitable.
    
  • 3rd degree: Involves subcutaneous tissue. Hemorrhagic blister formation due to subdermal venous plexus injury:
    
    • Initially insensate, injuries develop severe pain/burning on rewarming.
      
  • 4th degree: Involves muscle, tendon, and bone. Initially mottled, deep red, or cyanotic.
    
  • Unfavorable prognostic indicators include: Hemorrhagic blisters, persistent cyanosis, mottling, anesthesia, and reduced mobility after rewarming.
    
  • Devitalized tissue demarcates as the injury evolves over weeks to months forming skin necrosis and dry black eschar.
    

• Diagnosis is based on the clinical presentation. Wound description should include skin color and temperature, blister formation and color, and soft tissue consistency.
  
• A neurologic and vascular exam should include pulses (by Doppler if necessary), cap refill, and 2-point discrimination.
  
• Look for underlying factors contributing to cold exposure and comorbid conditions requiring emergency management:
  
  • Hypothermia
    
  • Trauma
    
  • Hypoglycemia
    
  • Cardiac or neurologic problems
    
  • Intoxication/overdose
    
  • Compartment syndrome
    

• None indicated in mild cases
  
• For deep frostbite:
  
  • CBC
    
  • Electrolytes, BUN/creatinine, glucose
    
  • Urinalysis/CK for evidence for myoglobinuria
    
• Cultures and Gram stains from open areas when infection suspected
  

Technetium-99 scintigraphy or MRA:

• May be helpful in early identification of salvageable vs. unsalvageable tissue
  
• Permits earlier decision about amputation
  

Method to create a warm water bath in the ED:

• Whirlpool hydrotherapy ideal, however, most EDs do not have
  
• Mix hot and cold tap water from a standard hospital sink in a large basin
  
• Use a thermometer to keep temperature between 40°C and 42°C.
  
• The water will cool quickly: Intermittently add warm water or replace the water to keep the temperature in the proper range.
  
• Warmer temperatures can cause thermal injury while cooler temperatures delay thawing and decrease tissue survival.
  

• Frostnip:
  
  • Superficial, reversible ice crystal formation without tissue destruction
    
  • Transient numbness and paresthesia resolve after dry rewarming.
    
• Trench (immersion) foot:
  
  • Exposure to wet cold for prolonged periods
    
  • Neurovascular damage without ice crystal formation
    
  • Pallor, mottling, paresthesias, pulselessness, paralysis, and numbness
    
  • May be difficult to distinguish from post-thaw phase of frostbite
    
  • Hyperemia with dry rewarming may last up to 6 wk.
    
• Chilblains:
  
  • Chronic repeated exposure to dry cold
    
  • Localized erythema, cyanosis, plaques, and vesicles
    
  • Recurrent episodes common in patients with underlying vasculitis
    
  • Symptomatic treatment, dry rewarming
    

TREATMENT

• Protect and immobilize frostbitten area during transport
  
• Remove restrictive or wet garments
  
• Avoid dry rewarming of the frostbitten limb if there is a likelihood of refreezing injury during transport.
  
• If evacuation will be delayed and suitable facilities are available, field rewarming in warm (40°C–42°C) water can be attempted.
  
• Rubbing, manipulating the limb, or applying snow while it is still frozen is contraindicated.
  

• ABCs management
  
• Identify and correct hypothermia.
  
• IV fluid volume expansion with 0.9% NS for severe frostbite
  
• Protect frostbitten areas from excessive handling during resuscitation.
  

• If the injury is <24 hr old and has not yet been rewarmed:
  
  • Initiate rapid rewarming of the frostbitten extremity in a 40–42°C water bath for 15–30 min.
    
  • Stop treatment when the limb is warm, red, and pliable.
    
  • Monitor water temperature closely to prevent thermal injury.
    
• Analgesia: IV morphine
  
• NSAIDs (e.g., ibuprofen) to combat the effects of prostaglandins on skin necrosis.
  
• Aloe vera topical cream:
  
  • Recommended for all intact blisters
    
  • Combats the arachidonic acid cascade
    
  • Avoid preparations containing alcohol, scent, salicylates, all of which interfere with aloe effectiveness.
    
• Blister débridement or aspiration:
  
  • Indicated for clear blebs:
    
    • Removes thromboxane and prostaglandins
      
  • Contraindicated for hemorrhagic blebs:
    
    • Exposes deeper structures to dehydration and infection
      
• Tetanus prophylaxis
  
• Antibacterial prophylaxis:
  
  • Consider during the hyperemic recovery phase (at least 2–3 days) in severely frostbitten areas
    
  • Against
    Streptococci
    ,
    Staphylococci
    , and
    Pseudomonas
    species (cephalosporin, penicillinase-resistant penicillin, quinolone)
    
  • Topical antibacterial agents interfere with the use of aloe vera cream and should be considered a 2nd-line approach.
    
• Elevation and splinting of frostbitten area
  
• Change dressing 2–4 times daily.
  
• Avoid vasoconstrictive agents (including tobacco).
  
• Adjunctive treatments include:
  
  • Thrombolytic therapy (<24 hr of cold exposure):
    
    • Both intra-arterial and systemic tPA may improve tissue salvage rates.
      
    • Consult with plastic/burn surgeon before treatment.
      
  • Vasodilator therapy:
    
    • Pentoxifylline—limited data
      
    • Iloprost—limited data and availability
      

• Aloe vera: Topical cream (70% concentration) q6h
  
• Cephalexin (cephalosporin): 500 mg (peds: 25–50 mg/kg/24h q6h) PO QID
  
• Ciprofloxacin (quinolone): 500 mg PO BID
  
• Dicloxacillin (penicillinase-resistant penicillin): 500 mg (peds: 12.5–25 mg/kg/24h q6h) PO QID
  
• Ibuprofen (NSAID): 800 mg (peds: 40 mg/kg/24h q6–8h) PO TID
  
• Morphine sulfate: 0.1–0.2 mg/kg (peds: 0.1 mg/kg) IV or IM PRN (titrate to patient response)
  

FOLLOW-UP

• All but the most superficial cases should be admitted.
  
• Lower admission threshold where risk of refreezing exists.
  
• Immersion (trench) foot patients may be discharged only if an environment that allows for proper treatment can be provided.
  

Minimal superficial injury, all others should be admitted.

General, burn, plastic, or hand surgeon should be consulted in all but the most superficial of cases.

All discharged patients should be referred to a general, burn, plastic, or hand surgeon.

Pitfalls:

• Allowing freeze, thaw, refreeze cycle to occur
  
• Failure to keep warm water bath between 40°C and 42°C during rewarming
  
• Failure to address hypothermia or other systemic illness
  
• Failure to consider compartment syndrome in a pulseless frostbitten extremity
  

• Gross EA, Moore JC. Using thrombolytics in frostbite injury.
  J Emerg Trauma Shock.
  2012;5(3):267–271.
  
• McIntosh SE, Hamonko M, Freer L, et al. Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite.
  Wilderness Environ Med.
  2011;22(2):156–166.
  
• Murphy JV, Banwell PE, Roberts AH, et al. Frostbite: Pathogenesis and treatment.
  J Trauma
  . 2000;48(1):171–178.
  
• Wolfson AB, ed.
  Harwood-Nuss’ Emergency Medicine.
  5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:1599–1603.
  

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