Cold Related Tissue Injuries

Cold Related Tissue Injuries

  1. Cold-related tissue injuries are caused by exposure to cold temperatures and include nonfreezing and freezing injuries
  2. Almost always preventable; alcohol intoxication and drug use are major risk factors
  3. Most common areas of involvement are exposed areas of the ears, face, hands, and feet 
  4. Frostnip and pernio are nonfreezing cold-related injuries with no expectation of permanent tissue injury; typical treatment is passive rewarming 
  5. Frostbite requires urgent rewarming in circulating warm water (37 °C-39 °C) as soon as possible, with administration of warmed IV fluids 
  6. Rewarmed tissues require splinting and protection with soft bulky dressings
  7. Drug therapy aims to reduce inflammation and pain and to reestablish blood flow 
    • NSAIDs for antiprostaglandin, antiinflammatory, and analgesic purposes
    • If available, the prostacyclin analog iloprost may be considered for grades 2 through 4 of frostbite within 48 hours of thawing 
    • IV tissue plasminogen activator and IV heparin should be considered for grade 3 or greater frostbite within 24 hours of thawing 
  8. Surgical consultation is required for wound management; nonviable tissue may not be clearly demarcated for weeks after injury

Pitfalls

  • Do not begin rewarming if the potential for refreezing exists 
  • When freezing environmental conditions resolve, most frostbite will thaw spontaneously and should be allowed to do so even if rapid rewarming cannot be readily achieved. Do not intentionally keep tissue below freezing temperatures in this situation 
  • Walking on cold-damaged feet should be minimized (ie, done only to the extent that it prevents worse injury by helping to escape cold and reach treatment) 
  • Vigorous rubbing of frozen tissue will increase tissue damage and should be avoided 
  • Initial physical findings are not predictive of final tissue viability; definitive demarcation of viable tissue may take weeks 
  • Severity of frostbite may vary within a single extremity 
  • Cold-related tissue injuries are caused by exposure to cold temperatures and include nonfreezing and freezing injuries; degree of injury is proportional to severity of cold and duration of exposure
    • Nonfreezing injuries are frostnip and pernio (chilblains); freezing injury is frostbite
  • No tissue loss is anticipated with nonfreezing cold injury or with superficial frostbite, whereas deeper frostbite results in tissue necrosis

Classification

  • Nonfreezing cold injury
    • Nonfreezing injuries (ie, frostnip, pernio) occur at temperatures at or around freezing (0 °C)
      • Frostnip is a superficial cold injury characterized by vasoconstriction that resolves completely after rewarming 
      • Pernio (ie, chilblain) is an inflammatory skin injury caused by exposure to cold (often repeatedly) above the freezing point 
        • May be idiopathic or secondary to connective tissue disease or cryoglobulinemia
  • Freezing injury (ie, frostbite)
    • Occurs at temperatures below freezing (typically less than −4 °C) 
    • Several terminologies are used to classify frostbite
      • Older classification (used in most published literature) is based on both early skin appearance (after rewarming) and on delayed (3-6 weeks) visual demarcation of tissue viability; not useful for predicting need for eventual amputation at time of presentation 
        • First degree: minimal erythema and edema in early phase; some skin desquamation may occur later
        • Second degree: erythema, significant edema, and vesicles with clear fluid in early phase; desquamation and black eschar in later phase
        • Third degree: deep hemorrhagic blisters in early phase; skin necrosis and blue/gray discoloration in later phase
        • Fourth degree: mottled appearance (deep red or blue/gray) with minimal edema in early phase; becomes dry, black, and mummified in later phase
      • Newer, simpler classification by depth of tissue injury
        • Superficial (corresponds roughly to first- and second-degree frostbite): expected to heal without substantial tissue loss
          • Injury confined to skin above the dermal vascular plexus
        • Deep (corresponds roughly to third- and fourth-degree frostbite): as tissue heals, clear demarcation between viable and nonviable tissue emerges
          • Injury to skin extending into dermal vascular plexus and subcutaneous tissues; may extend to muscle, tendons, and bone
      • Classification for frostbite of extremities is based on frostbite topography (proximal extent of initial lesion on day 0 immediately after rewarming); useful for giving patients an early amputation risk estimate 
        • Grade 0: mildest form; no initial visible lesion; full recovery expected
        • Grade 1: lesion on the distal phalanx
        • Grade 2: lesion on the middle phalanx or proximal phalanx of the thumb/big toe
        • Grade 3: lesion on the proximal phalanx except for the thumb/big toe
        • Grade 4: lesion on the metacarpal/metatarsal
        • Grade 5: most severe form; initial lesion extends to carpal/tarsal area; usually leads to amputation of limb

Diagnosis

Clinical Presentation

History

  • Individuals with a history of exposure to extremely cold air, water, or refrigerant chemicals are at risk for developing cold-related tissue injury
    • Degree of injury is directly proportional to the severity of cold and the duration of exposure
      • Relatively mild decreases in environmental temperatures require longer bouts of exposure to cause tissue injury
      • Exposure to extremely cold temperatures, including exposure to chemicals that are efficient thermal conductors (eg, solid carbon dioxide/dry ice), will cause tissue injury in a very short time
  • Frostnip: history of transient numbness and tingling after significant cold exposure
  • Pernio: history of itchy, painful, erythematous lesions on skin that has been exposed to the cold
    • Resolves over 2 weeks
    • Tends to recur or become chronic with repeated reexposure to cold, damp conditions
  • Frostbite: symptoms and signs of frostbite depend on severity of injury
    • In almost all cases, patient will report altered skin sensation
      • Numbness is a common symptom at presentation (75%) 
      • Complete lack of sensation at presentation is uncommon, and implies deep frostbite injury 
      • Sensation of clumsiness or heaviness of affected extremity (“block-of-wood” sensation) is common 
      • At least partial return of sensation during/after rewarming is expected in most cases 
      • Pain varies depending on depth of frostbite injury
        • Superficial frostbite
          • Patient may experience some pain during rewarming
          • Persistent burning sensation (days to weeks) is common
        • Deep frostbite
          • Significant pain during rewarming
          • Pain becomes throbbing after rewarming; lasts days to months
          • Electric-current–like shock sensation may begin a few days after thawing and last for up to 6 weeks
          • Long-term numbness and tingling is possible
    • Depending on depth of injury and duration of freezing, most patients will report some alteration in skin appearance (eg, blanching, mottling, violaceous color)
    • Severity of frostbite may vary within a single extremity 

Physical examination

  • Exposed or poorly protected areas of skin are most likely to be affected (eg, face, ears, fingers, toes, penis) 
  • It is often difficult to initially estimate severity based on physical examination, even after rewarming
    • Initial impression is usually much worse than actual damage to the deeper tissue
    • Varying depth of injury can coexist in the same limb
  • Frostnip
    • Affected area is pale
    • Mild hypoesthesia to touch may be present because of intense vasoconstriction; appearance and sensory testing normalize after warming
  • Pernio
    • 1 or more painful or pruritic erythematous macules or plaques appear within 24 hours of exposure 
    • Usually seen on face, hands, and feet (dorsum), and pretibial areas
    • Lesions may ulcerate or become bluish in color
    • Lesions can last up to 2 weeks 
  • Frostbite
    • If presenting soon after injury, frostbite of all degrees can look similar, with blanched, mottled, or waxy appearance
    • First-degree frostbite
      • Erythema after rewarming
      • Mild edema appears within hours of rewarming
      • Skin is soft and pliable when gently rolled over bony prominence
      • Decreased sensation is transient; sensory examination normalizes after rewarming
      • Later, white-to-yellow, firm, slightly raised plaque develops; slight desquamation may be noted
    • Second-degree frostbite
      • Erythema appears after rewarming
      • Significant edema appears within hours of rewarming
      • Superficial skin vesiculation with blisters filled with clear or milky fluid appear within first 24 hours 
      • Skin is soft and pliable when gently rolling over bony prominence
      • Decrease in sensation to touch may persist after rewarming
      • Healing (within weeks) leaves an atrophic area
    • Third-degree frostbite
      • Skin may appear mottled, with minimal hyperemia after rewarming
      • Significant edema after rewarming
      • Decreased sensation persists after rewarming
      • Deep, hemorrhagic blisters form
      • Necrosis and blue/gray discoloration in later phase
    • Fourth-degree frostbite
      • Deep red or blue-gray mottled appearance, which does not resolve after rewarming
      • Minimal edema after rewarming
      • Skin is hard or woody and cannot be rolled by examiner
      • Sensory examination reveals insensate tissue
      • Black, dry eschar forms (over days to weeks) followed by a line of demarcation and mummification (over weeks to months) 

Causes

  • Exposure to cold temperatures from the environment, submersion in cold water, or contact with refrigerant chemicals
  • Localized inflammation seen with pernio may be idiopathic, presumed to be caused by abnormal neurovascular responses to skin temperature change
    • Pernio may also be secondary to an underlying inflammatory or rheumatologic process

Risk factors and/or associations

Age
  • May affect any age
Sex
  • Occurs in both sexes; in military populations, women reported to be at greater risk 
Other risk factors/associations
  • Cognitive impairment due to substance use or psychiatric disease (people with these conditions may not regulate their own exposure to the elements well) 
  • Motor transport in winter (risk of being injured or stranded by crashes or breakdowns)
  • Extreme winter sports
  • Mountain climbing
  • Construction or other outdoor work (especially with inadequate clothing) 
  • Military occupation with exposure to the elements 
  • Direct exposure to freezing materials like cold packs or solid carbon dioxide (dry ice) 
  • Recreational inhalation of halogenated hydrocarbons such as refrigerants 

Diagnostic Procedures

Primary diagnostic tools

  • Diagnosis is based on clinical impression with a history of cold exposure 
  • With frostbite
    • After rewarming, obtain imaging studies in some cases
      • Plain radiographs of affected area if history or examination suggest possibility of occult fracture or foreign body (pain may not be reported owing to frostbite-related anesthesia) 
      • For suspected deep frostbite, digital subtraction angiography, magnetic resonance angiography, or Technetium 99m scintigraphy for patients who present within 24 hours of rewarming to determine if thrombolytic therapy is needed 
      • In patients with delayed presentation (4-24 hours from the time of the frostbite thawing), noninvasive imaging with technetium pyrophosphate or magnetic resonance angiography can be used at an early stage to predict the likely levels of tissue viability for amputation 

Laboratory

  • When pernio is suspected, perform laboratory testing to investigate for secondary causes (ie, lupus, other inflammatory conditions) 
    • CBC
    • Serum protein electrophoresis with immunofixation
    • Antinuclear antibodies
    • Cryoglobulins

Imaging

  • Plain radiographs
    • Indicated on admission to evaluate for occult fracture or foreign body if trauma to the area cannot be excluded 
    • Adds minimal actionable information for evaluating degree of frostbite injury, but evolving changes are sometimes seen between acute and later phases; these changes are nonspecific 
      • Acute-stage radiographic findings
        • Superficial frostbite: may be normal or may show mild soft tissue swelling
        • Deep frostbite: marked soft tissue swelling
      • Delayed radiographic findings (weeks to months after injury) 
        • Osteitis and osteopenia are indirect signs of viable bone
        • Osteolysis (particularly at acral locations), sclerotic foci at the ends of involved bone, and/or periarticular erosions
  • Digital subtraction angiography
    • Indicated after rewarming for patients with deep frostbite presenting within the first 24 hours
    • Evaluates vessel patency in injured area and identifies potential targets for intra-arterial thrombolysis; may be repeated after thrombolysis to document patency
    • Findings include:
      • Impaired perfusion (lack of distal blush in affected digits)
      • Abrupt cutoffs in thrombosed vessels
  • Magnetic resonance angiography
    • In patients with delayed presentation (4-24 hours from the time of the frostbite thawing), noninvasive imaging with magnetic resonance angiography can be used at an early stage to predict the likely levels of tissue viability for amputation 
    • Alternative to digital subtraction angiography
  • Technetium 99m scintigraphy
    • As an alternative to angiography within the first 24 hours of thawing; used for determining need for thrombolytic therapy 
    • In patients with delayed presentation (4-24 hours from the time of the frostbite thawing), noninvasive imaging with technetium pyrophosphate can be used at an early stage to predict the likely levels of tissue viability for amputation 
    • Level of future amputation can be predicted in up to 84% of cases, weeks before the demarcation of viable and nonviable tissue on physical examination 
    • Viable tissue will have normal uptake and distribution of tracer can be seen on blood flow, soft tissue, and delayed-phase images 
    • Necrosis of deep tissue and bone (requiring surgical intervention) will have absence of tracer uptake in all phases 
    • Superficial tissue ischemia without infarction will have increased activity on blood flow and soft-tissue–phase images and normal to mildly increased uptake of tracer on delayed-phase images 
    • Soft tissue ischemia, which may be reversible, will have absent or diminished tracer on blood flow and soft-tissue–phase images and visible, but possibly diminished, uptake in underlying bone on delayed-phase images 

Differential Diagnosis

Most common

  • Raynaud phenomenon
    • Episodic excessive vasoconstriction in response to cold, resulting in sharply demarcated skin pallor on digits
    • Occurs at temperatures above freezing and resolves quickly with removal of cold stimuli
  • Cryoglobulinemia and cryofibrinogenemia
    • Abnormal proteins in the blood precipitate and thicken when exposed to cool temperatures
    • Leads to purpura and skin necrosis in exposed areas; no purpura present with frostbite
    • Blood testing can confirm the presence of cryoprecipitates
  • Vasculitis
    • Lesions thought to be caused by pernio that persist beyond 2 to 3 weeks may instead be caused by vasculitis
    • Constitutional symptoms more likely to be present
    • A variety of blood test results may be abnormal with vasculitis, depending on the underlying cause (eg, nonspecific markers of inflammation, antineutrophil cytoplasmic antibodies)
    • Biopsy will definitively differentiate 

Treatment Goals

  • Prevent ongoing tissue injury
  • Reestablish adequate perfusion to ischemic and frozen tissue
  • Surgically remove nonviable tissue

Disposition

Admission criteria

Hospital admission and discharge are determined on an individual basis, considering severity of injury, coexisting injuries, comorbidities, and need for hospital-based intervention 

All patients with deep frostbite require hospital admission 

Patients with superficial frostbite can usually be managed as outpatients or with brief inpatient stays followed by wound care instructions 

Criteria for ICU admission
  • Because of the intensive care required in early therapeutic intervention, every patient with evidence of deep frostbite requires ICU admission
  • All patients with cold-related tissue injury and concomitant hypothermia require ICU admission

Recommendations for specialist referral

  • Consult specialist for all patients with any degree of frostbite
    • Surgeon is typically involved in decisions regarding use of thrombolytic therapy after initial perfusion imaging studies
    • If thrombolytic therapy is contraindicated, consult surgeon or other clinician with experience in frostbite about alternative therapies, including administration of vasodilators
    • Consult surgeon for wound management and possible debridement of nonviable tissue or amputation
      • Vascular surgeon should be considered for deep frostbite of lower extremities
      • Hand surgeon or plastic surgeon may be most appropriate consultant for deep frostbite of upper extremity

Treatment Options

Frostnip and pernio are nonfreezing cold-related injuries with no expectation of permanent tissue injury 

  • Treatment consists of removing individual from the cold exposure and passive rewarming
  • Nifedipine is sometimes used for its vasodilatory effect, but data are limited 
  • Topical nitroglycerin has been used successfully (case reports and case series) to treat the vasospasm associated with pernio 

Frostbite treatment should begin before admission and continue through hospitalization with active rewarming and management directed at reestablishing perfusion to ischemic and frozen tissue 

  • Prehospital care
    • Walking on cold-damaged feet should be minimized (ie, done only to the extent that it prevents worse injury by helping to escape cold and reach treatment) 
    • Remove wet clothing and jewelry and move the patient to a warm environment
    • Avoid vigorous rubbing of frozen tissue as it causes further damage 
    • Elevate frostbitten areas above the level of the heart (if possible) to reduce edema
    • Provide oxygen via face mask or nasal cannula if patient is hypoxic or at an altitude of 4000 m or higher
    • Rewarming should not be started if refreezing is expected before definitive care; it is safer to keep the affected part frozen, as repeated freeze/thaw cycles worsen injury
      • Begin rewarming only if definitive care is more than 2 hours away 
      • Initially, use body heat to rewarm frozen tissue until alternative rewarming methods are available
      • Immerse frozen tissue in warm (37 °C-39 °C) water; avoidance of water that is too hot is critical 
        • If available, add small amounts of antibiotic solutions (eg, povidone-iodine, chlorhexidine) to rewarming solution to prevent cellulitis
      • Do not place frozen tissue near a flame or other heat source
        • Frozen tissue has decreased sensation and heat sources can cause thermal burns
    • Hydrate patient
      • Use oral fluids if patient is awake and alert with no nausea or vomiting
      • If available, infuse IV saline (warmed to 40 °C if possible) if patient is nauseated or has altered mental status 
        • Small boluses of IV saline are preferable to prevent solution from cooling
    • Give oral ibuprofen to decrease inflammation and treat pain (some experts use aspirin instead) 
      • If pain relief is insufficient, add an opioid analgesic 
    • Do not aspirate, lance, or otherwise disturb blisters in the field unless they pose an obstacle to movement and evacuation 
      • Blisters filled with clear or cloudy fluid can be aspirated with a needle and covered with a clean bandage
      • Hemorrhagic blisters should not be aspirated or disturbed
    • Splint and protect frozen tissue with bulky dressings
    • Wilderness Medical Society has proposed 2 additional treatments be considered for patients in austere conditions where evacuation to a hospital within 24 to 48 hours is unlikely, and when an experienced physician with appropriate medical supplies is present 
      • Iloprost (prostacyclin vasodilator) given intravenously for grade 2 through grade 4 frostbite within 48 hours of rewarming 
      • Recombinant tissue plasminogen activator (ie, alteplase) for grade 3 or greater frostbite where amputation is otherwise inevitable, and within 24 hours of rewarming 
  • Hospital care
    • Rewarming is best accomplished by immersion in gently circulating warm water (37 °C-39 °C) 
      • Rewarming is very painful and analgesia should be provided
      • Thawing usually takes about 30 minutes 
      • Rewarmed tissue will be soft and erythematous; reversal of vasoconstriction is indicated by redness over affected area
      • If tissue has already completely thawed before arrival, rewarming will not be beneficial 
    • Initiate hydration with warm IV fluid
    • Low-molecular-weight dextran is a volume expander that decreases blood viscosity; may be infused intravenously if available and if more aggressive treatments will not be used, but benefit is questionable 
    • Give oral ibuprofen to decrease inflammation and treat pain (aspirin is an alternative drug used in some experimental protocols) 
      • If pain relief is insufficient, add an opioid analgesic 
    • IV or intra-arterial thrombolytics with heparin anticoagulation may be indicated to treat thrombosis in frozen microvasculature up to 24 hours after rewarming when imaging studies fail to demonstrate adequate perfusion 
      • Consider ratio of risk (eg, systemic and catheter-site bleeding, compartment syndrome) versus benefit in each patient 
      • Wilderness Medical Society guidelines recommend it only for deep injuries (corresponding to grade 3 or 4 injury in proposed classification) with potential for significant morbidity (eg, frostbite extending to the proximal interphalangeal joints) 
        • Tissue plasminogen activator provided within 24 hours of thawing reduces tissue damage and digital amputation rates (reduction in digital amputation rate from 41% to 10 % in retrospective study) 
        • Time to thrombolysis appears to be very important, with best outcomes within 12 hours and ideally as soon as possible 
      • IV heparin is used as an adjunct to prevent recurrent local thrombosis
        • Use IV and subcutaneous unfractionated heparin or low-molecular-weight heparin only as an adjunct to tissue plasminogen activator, not as monotherapy for treatment of frostbite
    • Vasodilators may improve outcome for deep frostbite without the risk of thrombolytics; however, data are sparse 
      • IV or intra-arterial iloprost, a prostacyclin analog, is not available in the United States, but is recommended where available as a first line treatment (with appropriate monitoring, as it may result in hypotension)
        • Effective (based on randomized controlled trial with 47 subjects) in reducing amputations up to 48 hours after rewarming; better safety profile than thrombolytic therapy 
      • Pentoxifylline is a phosphodiesterase inhibitor and vasodilator with limited data to support its use for treatment of frostbite 
      • Intra-arterial nitroglycerin infusion is sometimes used before tissue plasminogen activator 
    • Debridement of blisters is controversial, but it is reasonable to aspirate clear or cloudy blister fluid, clean the area, and cover with a sterile dressing 
      • Hemorrhagic blisters should be left intact and covered with a clean, protective dressing 
      • Aloe vera ointment or gel (reduces prostaglandin and thromboxane formation) should be applied topically to thawed tissue and intact or aspirated blisters before dressing changes 
    • Tetanus prophylaxis should be administered if patient has not received immunization prophylaxis within 5 years
  • Post-thaw therapy
    • Daily hydrotherapy
    • Debridement of nonviable tissue should be delayed (usually 4-8 weeks or longer)
    • Amputation may be required if injury extends to deeper tissues

Drug therapy

  • NSAID
    • Ibuprofen
      • Ibuprofen Oral tablet or Oral suspension; Infants, Children, Adolescents, and Adults: 12 mg/kg divided twice daily (to a maximum of 2,400 mg/day divided 4 times daily if the patient is experiencing pain) until frostbite is healed or surgical management occurs (typically 4 to 6 weeks). 
  • Volume expander
    • Low-molecular-weight dextran
      • No specific dosage recommendation for frostbite; dosage provided is for indication of surgical deep venous thrombosis prophylaxis
      • Dextran, Sodium Chloride Solution for injection (Dextran 40); Infants: 5 mL/kg administered on day 1. Continue treatment (5 mL/kg/dose) for an additional 2 to 3 days. Further treatment depends on the risk of thromboembolic complications.
      • Dextran, Sodium Chloride Solution for injection (Dextran 40); Children: 10 mL/kg administered on day 1. Continue treatment (10 mL/kg/dose) for an additional 2 to 3 days. Further treatment depends on the risk of thromboembolic complications.
      • Dextran, Sodium Chloride Solution for injection (Dextran 40); Adolescents and Adults: 500 to 1,000 mL (approximately 10 mL/kg) administered on day 1. Continue treatment at a dose of 500 mL/day for an additional 2 to 3 days. Further treatment depends on the risk of thromboembolic complications.
  • Vasodilators
    • Iloprost
      • Only vasodilator with reasonable data to support its use, but IV formulation not available in the United States 
      • No guideline-recommended dosage available; protocol used in controlled clinical trial 
        • Iloprost solution for injection; Adults: 0.5 to 2 ng/kg/minute for 6 hours per day (intervention: iloprost plus aspirin for 8 days; risk of amputation 0%, p < 0.01). 
        • Iloprost solution for injection; Adults: 2 ng/kg/minute for 6 hours per day (intervention: iloprost plus aspirin for 8 days plus thrombolytic agent on first day; risk of amputation 19%, p < 0.03). 
  • IV thrombolysis
    • Alteplase
      • Alteplase injection for pediatric or adult patients must be directed by a surgical specialist
      • No guideline-recommended dosage; various protocols have been published but not yet validated by randomized controlled trials
        • Alteplase Solution for injection; Adults: 3 mg IV or intra-arterial bolus (0.1 mg/mL solution), followed by an infusion of 10 mg/hr (1 mg/mL solution) until specialists recommend discontinuation. Administer concurrently with heparin 500 units/hr. 
        • Administer within 24 hours of injury; either IV or intra-arterial route may be used 
  • Heparin anticoagulation (used in conjunction with a thrombolytic)
    • Dosage should be determined by a surgical specialist
  • Wound care of blisters after thawing
    • Aloe vera ointment
      • Aloe Polysaccharide Topical ointment; Adults, Adolescents, and Children: Apply to affected area(s) 3 to 4 times daily or as directed.

Nondrug and supportive care

After initial rewarming, continue daily or twice daily whirlpool therapy with warm water 

  • Water temperature should be 37 °C to 39 °C 
  • Decisions regarding how long to continue repeated whirlpool baths and local wound care are made by the surgical consultant; data are insufficient to recommend specific duration of therapy

Tetanus prophylaxis

  • Td is preferred over single-antigen tetanus toxoid to enhance diphtheria protection. A preferred alternative may be Boostrix, Tdap for patients 10 to 18 years of age or Adacel for patients at least 11 years of age
  • Tetanus toxoid fluid (tetanus toxoid plain) is no longer commercially available in the U.S.
  • Tetanus and Diphtheria Toxoids Adsorbed Suspension for Injection; Adults, Adolescents, and Children 7 years of age and older: 0.5 mL IM. A single dose of Tdap is preferred to Td in patients 10 years and older if the patient has not previously received Tdap. If immunization history is unknown or less than 3 doses of a tetanus toxoid vaccine have previously been given, give vaccine for clean, minor wounds or other severe or contaminated wounds. If 3 doses or more of a tetanus toxoid-containing vaccine have been given, give vaccine for clean, minor wounds if 10 years or more have elapsed since the last tetanus toxoid-containing vaccine, or for other severe or contaminated wounds if 5 years or more have elapsed since the last tetanus toxoid-containing vaccine. Wait at least 10 years before giving a tetanus toxoid-containing vaccine for emergency prophylaxis if a serious Arthus-type hypersensitivity reaction occurred after previous tetanus toxoid receipt.
Procedures
Splinting

General explanation

  • Once rewarmed, damaged tissue should be placed in the position of function and splinted with soft, bulky gauze
  • Elevate the bandaged and splinted tissue above the level of the heart to decrease swelling

Indication

  • Cold-injured tissue that has been rewarmed

Comorbidities

  • Hypothermia
    • Mild hypothermia may be treated concurrently with the frostbite injury 
    • Moderate and severe hypothermia should be treated effectively before treating the frostbite injury 
  • Traumatic injuries
  • Altered mental status caused by drugs or alcohol

Special populations

  • Patients with pernio require work-up for underlying inflammatory and rheumatologic conditions

Monitoring

  • For deep frostbite, examination of the involved cold-injured areas is necessary every 3 to 5 days for a duration of weeks to 3 months to identify viable tissue versus nonviable tissue that might require surgical debridement 
  • Additional Technetium 99m scintigraphy days to weeks after injury is typically performed to evaluate interval change in areas of questionable uptake identified at the prior scan 

Complications

  • Compartment syndrome
    • Consider in cases of extreme edema or constricting eschar with increasing pain
    • Requires urgent measurement of compartment pressure and surgical consultation for decompression
  • Dry gangrene
    • If autoamputation does not occur, damaged tissue requires surgical debridement
  • Chronic pain and cold sensitivity
    • Once tissue has been damaged by cold, it is vulnerable to recurrent vasospasm whenever it is again exposed to cold

Prognosis

  • Success at rewarming damaged tissue is unpredictable
  • When added to aspirin therapy, iloprost alone or in combination with thrombolytic therapy decreases risk for digital amputation in stages 3 to 4 of frostbite 
  • Definitive demarcation to determine viable versus nonviable tissue may take weeks
  • Once nonviable tissue is defined, prognosis for recovery of that tissue is hopeless

Prevention 

  • Avoid alcohol and drug use before exposure to cold environments
  • Prepare for exposure to cold
    • Wear warm clothing in layers that protect the face, hands, and feet
    • Wear water-resistant socks, shoes, and gloves
    • Remove wet clothing as soon as possible

References

McIntosh SE et al: Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite: 2019 update. Wilderness Environ Med. 30(45):S19-S32, 2019

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