Basics
Description
- Tissue damage caused by cold temperature exposure
- Mechanism:
- Tissue damage results from:
- Direct cell damage: Intracellular ice crystal formation
- Indirect cell damage: Extracellular ice crystal formation leads to intracellular dehydration and enzymatic disruption.
- Reperfusion injury: Occurs upon rewarming. Fluid rich in inflammatory mediators (prostaglandin and thromboxane) extravasates through damaged endothelium promoting vasoconstriction and platelet aggregation.
- Clear blisters form from extracellular exudation of fluid.
- Hemorrhagic blisters occur when deeper subdermal vessels are disrupted, indicating more severe tissue injury.
- The end result is arterial thrombosis, ischemia, and ultimately, necrosis.
- Devitalized tissue demarcates as the injury evolves over weeks to months, hence the phrase "frostbite in January, amputate in July."�
Etiology
- Cold exposure: Duration of exposure, wind chill, humidity, and wet skin and clothing all increase the likelihood of frostbite.
- Predisposing factors:
- Extremes of age
- Altered mental status (intoxication or psychiatric illness)
- Poor circulatory status
Diagnosis
Signs and Symptoms
- 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.
Essential Workup
- 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
Diagnosis Tests & Interpretation
Lab
- 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
Imaging
Technetium-99 scintigraphy or MRA: �
- May be helpful in early identification of salvageable vs. unsalvageable tissue
- Permits earlier decision about amputation
Diagnostic Procedures/Surgery
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.
Differential Diagnosis
- 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
Pre-Hospital
- 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.
- Hypothermia:
- Common in frostbite victims
- In the severely hypothermic patient, avoid rough handling to minimize risk of cardiac dysrhythmias.
Initial Stabilization/Therapy
- 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.
Ed Treatment/Procedures
- 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 d �bridement 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
Medication
- 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
Disposition
Admission Criteria
- 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.
Discharge Criteria
Minimal superficial injury, all others should be admitted. �
Issues for Referral
General, burn, plastic, or hand surgeon should be consulted in all but the most superficial of cases. �
Followup Recommendations
All discharged patients should be referred to a general, burn, plastic, or hand surgeon. �
Pearls and Pitfalls
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
Additional Reading
- 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.
See Also (Topic, Algorithm, Electronic Media Element)
Hypothermia �
Codes
ICD9
- 991.0 Frostbite of face
- 991.1 Frostbite of hand
- 991.3 Frostbite of other and unspecified sites
- 991.2 Frostbite of foot
ICD10
- T33.09XA Superficial frostbite of other part of head, init encntr
- T33.90XA Superficial frostbite of unspecified sites, init encntr
- T33.539A Superficial frostbite of unspecified finger(s), init encntr
- T33.839A Superficial frostbite of unspecified toe(s), init encntr
- T33.019A Superficial frostbite of unspecified ear, initial encounter
- T33.02XA Superficial frostbite of nose, initial encounter
- T33.521A Superficial frostbite of right hand, initial encounter
- T33.522A Superficial frostbite of left hand, initial encounter
- T33.529A Superficial frostbite of unspecified hand, initial encounter
- T33.531A Superficial frostbite of right finger(s), initial encounter
- T33.532A Superficial frostbite of left finger(s), initial encounter
- T33.821A Superficial frostbite of right foot, initial encounter
- T33.822A Superficial frostbite of left foot, initial encounter
- T33.829A Superficial frostbite of unspecified foot, initial encounter
- T33.831A Superficial frostbite of right toe(s), initial encounter
- T33.832A Superficial frostbite of left toe(s), initial encounter
- T34.019A Frostbite with tissue necrosis of unsp ear, init encntr
- T34.02XA Frostbite with tissue necrosis of nose, initial encounter
- T34.09XA Frostbite w tissue necrosis of oth part of head, init encntr
- T34.539A Frostbite w tissue necrosis of unsp finger(s), init encntr
- T34.839A Frostbite with tissue necrosis of unsp toe(s), init encntr
- T34.90XA Frostbite with tissue necrosis of unsp sites, init encntr
SNOMED
- 370977006 frostbite (disorder)
- 4763005 frostbite of hand (disorder)
- 86018005 frostbite of face (disorder)
- 35195001 frostbite of foot (disorder)
- 212924009 Frostbite with tissue necrosis (disorder)
- 410703004 superficial frostbite (disorder)