Basics
Description
- Localized injury of epidermis and underlying tissue resulting from exposure to extreme cold or contact with extremely cold objects
- Distal extremities and unprotected areas (i.e., fingers, toes, ears, nose, and chin) most commonly affected
- Feet and hands account for 90% of frostbite injuries.
- Classified according to severity:
- Superficial, 1st degree: partial skin freezing
- Superficial, 2nd degree: full-thickness skin freezing
- Deep, 3rd degree: full-thickness skin and subcutaneous tissue freezing
- Deep, 4th degree: full-thickness skin, subcutaneous tissue, muscle, tendon, and bone freezing
- New classification of severity at day 0 has been proposed based on findings that correlate extent of frostbite with outcome of involved body part along with results of bone scans:
- 1st degree: leads to recovery
- 2nd degree: leads to soft tissue amputation
- 3rd degree: leads to bone amputation
- 4th degree: leads to large amputation with systemic effects
Risk Factors
- Alcohol use
- Arthritis
- Atherosclerosis
- Constricting clothing
- Diabetes mellitus
- High altitude
- Hypothermia
- Immobilization
- Improper use of aerosol sprays
- Previous cold injury
- Smoking tobacco
- Trauma
- Vasoconstrictive drugs
- Body parts most affected:
- Fingers
- Toes
- Nose
- Cheeks
- Ears
- Male genitalia
- Groups at risk:
- Mentally ill patients
- Patients with impaired circulation
- Winter sports enthusiasts and fans
- Homeless persons
- Very thin individuals
- Malnourished people
- Outdoor laborers
- Military personnel, especially those of African American and Afro-Caribbean descent, exposed to cold, wet climates
- Elderly people
- Very young people
General Prevention
- Avoid prolonged cold exposure whenever possible.
- Maintain adequate nutrition and hydration when spending time in cold weather.
- Dress appropriately for cold weather:
- Dress in layers: Clothing should be made of material that absorbs perspiration and prevents heat loss, and outerwear should be windproof and water repellent.
- Cover head, ears, and neck.
- Mittens help to conserve heat better than gloves do.
- Footwear should be water-repellent and insulated.
Pathophysiology
- Tissue damage and cell death result from initial freeze injury and inflammatory response that occurs with rewarming.
- Direct cellular damage can occur from frostbite. As temperature of freezing tissue approaches -2 ░C, extracellular ice crystals form and cause increased osmotic pressure in the interstitium, leading to cellular dehydration. As freezing continues, these shrinking, hyperosmolar cells die due to abnormal intracellular electrolyte concentrations. With rapid freezing, intracellular ice crystal formation occurs, resulting in immediate cell death.
- Indirect cellular damage results from progressive microvascular insult. Initial tissue response to extreme cold exposure is vasoconstriction. Blood flow to extremities is reduced as freezing continues. Ice crystals form in plasma, blood viscosity increases, and decreased circulation and formation of microthrombi occur in distal extremities, resulting in hypoxia, tissue damage, and ischemia.
- Oxygen free radicals and inflammatory mediators, especially prostaglandin F2 and thromboxane A2, contribute to tissue injury following rewarming and reperfusion of damaged tissue.
- Most severe injuries are seen in tissues that freeze, thaw, and freeze again.
Diagnosis
- Depends on severity
- Superficial, 1st degree: transient tingling, stinging, and burning followed by throbbing and aching with possible hyperhidrosis (excess sweating)
- Superficial, 2nd degree: numbness, with vasomotor disturbances in more severe cases
- Deep, 3rd degree: no sensation initially, followed by shooting pains, burning, throbbing, and aching
- Deep, 4th degree: absence of sensation, presence of muscle function, pain, and joint discomfort
History
- Was there prolonged exposure to cold environment? In frostbite, history of prolonged cold exposure is typical.
- Was there contact with a cold object, especially metal? Metal will drain heat from skin through conduction and increase the risk of frostbite.
- What was the timing and duration of exposure?
- Was there any treatment prior to presentation?
- Does the patient have any underlying conditions or behaviors that put him or her at risk?
- Peripheral vascular disease, medications, smoking, etc.
Physical Exam
- Superficial, 1st degree: waxy appearance, erythema, and edema of involved area without blister formation
- Superficial, 2nd degree
- Erythema, significant edema, blisters with clear fluid within 6-24 hours
- Desquamation may occur with eschar formation 7-14 days after initial injury.
- Deep, 3rd degree: hemorrhagic blisters, necrosis of skin and subcutaneous tissues, skin discoloration in 5-10 days
- Deep, 4th degree: initially, little edema with cyanosis or mottling; eventually, complete necrosis, then becomes black, dry, and mummifies; occasionally results in self-amputation
Diagnostic Tests & Interpretation
Lab
Usually not necessary but may be indicated when infection is suspected á
Imaging
- No diagnostic studies done immediately after rewarming can accurately predict amount of nonviable tissue.
- Radionucleotide angiography with 99m-Tc-pertechnetate or triple-phase bone scanning with 99m-Tc-methylene diphosphonate 1-2 weeks after initial injury is advocated by some to assess tissue viability in cases of 3rd- and 4th-degree frostbite.
- MRI and MRA are being advocated by some as superior techniques for severe frostbite. They allow for direct visualization of occluded vessels and tissue, giving a more clear-cut demarcation of ischemic tissue injury, which may allow for earlier surgical intervention.
Differential Diagnosis
- Frostnip: mild form of cold injury with pallor and painful, tingling sensation. Warming of cold tissue results in no tissue damage.
- Hypothermia
- Thermal injury: easily excluded based on history but can result from warming techniques
Treatment
Medication
- Tetanus prophylaxis: dT, dTap, or DT/DTaP, depending on age, and tetanus immunoglobulin if patient not fully immunized
- Anti-thromboxane agents (NSAIDs, prostaglandin E1 [PGE1]) to prevent intravascular thrombosis
- Pentoxifylline (a phosphodiesterase inhibitor) should be considered with severe frostbite. It has been shown to enhance tissue viability by increasing blood flow and reducing platelet activity.
- Analgesics: as indicated
- Antibiotics: given prophylactically by some; others recommend waiting for signs of infection or necrotic tissue.
- Tissue plasminogen activator (tPA) is being used by frostbite specialists within 24 hours of acute, severe frostbite. It is useful when microvascular thrombosis has already developed. Studies show it can significantly reduce digital amputation rates
Additional Treatment
General Measures
- Check core temperature to rule out hypothermia, which would need to be addressed first.
- Remove constrictive clothing and jewelry.
- Rapid rewarming in warm water (40-42 ░C) for 15-45 minutes
- Do not rewarm slowly.
- Rewarming is complete when skin is soft and sensation returns.
- Usually all that is needed for superficial, 1st-degree frostbite
- Apply dry, sterile dressings to affected areas and between frostbitten toes and fingers.
- Intact nontense clear blisters should be left in place and wrapped with loosely applied dry gauze dressings. Rupturing may increase the risk of infection.
- Tense or hemorrhagic blister may be carefully aspirated, but this increases the risk for infection.
- Ruptured blisters should be debrided and covered with antibiotic ointment and nonadhesive dressings.
- Elevate affected parts to minimize edema.
- Daily hydrotherapy with hexachlorophene or povidone-iodine added to water
- Topical application of aloe vera (for its antiprostaglandin effect) to debrided blisters and intact hemorrhagic blisters to minimize further thromboxane synthesis
Alert
- Prohibit nicotine use because of its vasoconstrictive properties.
- Full extent of injury may not be apparent at presentation. Close observation is important.
Surgery/Other Procedures
- Conservative surgical intervention: recommended because it usually takes 6-8 weeks for injured tissue to declare viability
- Escharotomy: performed on digits with impaired circulation or movement
- Fasciotomy: performed if significant edema causes compartment syndrome
- Early amputation and debridement with closure of wound site: necessary for uncontrolled infection
- Debridement of mummified tissue: performed after 1-3 months
Inpatient Considerations
Admission Criteria
- Do not rub the area; it may cause mechanical injury.
- Do not expose the area to direct heat; it may cause burn injury.
- Refreezing after thawing leads to increased injury.
- Remove wet clothing and constricting jewelry.
Ongoing Care
Prognosis
- Depends on degree of cold injury
- Superficial, 1st-degree frostbite heals in a few weeks.
- Favorable indicators: sensation in affected area, healthy-looking skin color, blisters filled with clear fluid
- Unfavorable indicators: cyanosis, blood-filled blisters, unhealthy-looking skin color
- Early rehabilitation often needed for functional recovery.
- Long-term follow-up for 6-12 months to monitor for sequelae
- Education to avoid reexposure and reinjury
Complications
- Arthritis
- Changes in skin color
- Chronic numbness
- Chronic pain
- Cold hypersensitivity
- Digital deformities
- Gangrene
- Growth plate abnormalities (only in children)
- Hyperesthesias
- Neuropathy
- Premature closure of the physis (in children)
- Reduced sensitivity to touch
- Rhabdomyolysis
- Squamous cell carcinoma (rare)
- Tetanus
- Tissue loss
- Wound infection
Additional Reading
- Biem áJ, Koehncke áN, Classen áD, et al. Out of the cold: management of hypothermia and frostbite. CMAJ. 2003;168(3):305-311. á[View Abstract]
- Hallam áMJ, Cubison áT, Dheansa áB, et al. Managing frostbite. BMJ. 2010;341:c5864. á[View Abstract]
- Murphy áJV, Banwell áPE, Roberts áAH, et al. Frostbite: pathogenesis and treatment. J Trauma. 2000;48(1):171-178. á[View Abstract]
- Noonan áB, Bancroft áRW, Dines áJS, et al. Heat-and cold-induced injuries in athletes: evaluation and management. J Am Acad Orthop Surg. 2012;20(12):744-754. á[View Abstract]
- Twomey áJA, Peltier áGL, Zera áRT. An open-label study to evaluate the safety and efficacy of tissue plasminogen activator in treatment of frostbite. J Trauma. 2005;59(6):1350-1354. á[View Abstract]
- Woo áEK, Lee áJW, Hur áGY, et al. Proposed treatment protocol for frostbite: a retrospective analysis of 17 case based on a 3-year single-institution experience. Arch Plast Surg. 2013:40(5):510-516. á[View Abstract]
Codes
ICD09
- 991.3 Frostbite of other and unspecified sites
- 991.2 Frostbite of foot
- 991.1 Frostbite of hand
- 991 Frostbite of face
ICD10
- T33.90XA Superficial frostbite of unspecified sites, init encntr
- T34.90XA Frostbite with tissue necrosis of unsp sites, init encntr
- T33.829A Superficial frostbite of unspecified foot, initial encounter
- T33.529A Superficial frostbite of unspecified hand, initial encounter
- T33.521A Superficial frostbite of right hand, initial encounter
- T33.822A Superficial frostbite of left foot, initial encounter
- T34.829A Frostbite with tissue necrosis of unsp foot, init encntr
- T33.522A Superficial frostbite of left hand, initial encounter
- T34.529A Frostbite with tissue necrosis of unsp hand, init encntr
- T34.821A Frostbite with tissue necrosis of right foot, init encntr
- T33.821A Superficial frostbite of right foot, initial encounter
- T34.521A Frostbite with tissue necrosis of right hand, init encntr
- T34.522A Frostbite with tissue necrosis of left hand, init encntr
- T34.09XA Frostbite w tissue necrosis of oth part of head, init encntr
- T34.822A Frostbite with tissue necrosis of left foot, init encntr
SNOMED
- 370977006 frostbite (disorder)
- 35195001 frostbite of foot (disorder)
- 4763005 frostbite of hand (disorder)
- 86018005 frostbite of face (disorder)
FAQ
- Q: Why did I need to get a tetanus shot when I had frostbite?
- A: Injuries, such as frostbite, that cause dead skin are at risk for causing tetanus. The absence of oxygen in dead tissues allows tetanus spore to reproduce and produce the toxin that leads to tetanus.
- Q: I've heard that your eyes can get frostbite. Is that true?
- A: Frozen corneas (the surface layer of the eye) have been reported in persons partaking in high wind-chill activities such as snowmobiling and skiing. Prevention is possible with the use of protective goggles/sunglasses.
- Q: My children's doctor recommended that we use sunscreen when we go skiing. Will the sunscreen help prevent frostbite?
- A: Although sunscreen is necessary to prevent getting sunburn that can occur from the sunlight's reflection off the snow, it will not decrease the risk for frostbite from the cold exposure.
- Q: I live in Buffalo, New York, where the winters are very cold and the windchill factor is often below zero. My children like playing outside, especially in the snow. How can I prevent them from getting frostbite?
- A: Because there is a risk of frostbite with a wind-chill factor of -25 ░C, try to encourage indoor play when the temperature dips this low. It is important to have the children come inside frequently to warm up and for you to check for signs of cold injury.
- Q: My family members are avid skiers. While traveling in Europe last winter, I purchased a protective emollient that was sold there. Can protective emollients prevent frostbite if used on the face and exposed areas while skiing?
- A: No. Research has shown that the use of "protective"Ł emollients and creams leads to a false sense of safety and leads to an increased risk of frostbite. This is thought to be due mostly to the failure to use more efficient protective measures when the emollients and creams are used.
- Q: If my child has had frostbite in the past, can she get it again?
- A: Yes. Children who have had a previous frostbite injury are at increased risk for repeat injury, especially in the location of previous damage. Appropriate clothing and limitation of cold exposure should be strictly enforced.
- Q: To prevent frostbite, is there a temperature below which I should not let my child go out to play?
- A: Although body tissue freezes more quickly at lower temperatures, the degree of damage from frostbite is related to the length of time tissue remains frozen. Therefore, the amount of time spent outside during cold weather should never be prolonged.
- Q: How can I tell if my child has frostbite or just cold fingers?
- A: Cold fingers are red and may be painful but do not become numb or white. Frostbitten fingers are painful, white, and waxy prior to rewarming and turn red with rewarming. The sequential development of digital blanching, occasional cyanosis, and erythema of the fingers or toes following cold exposure and subsequent rewarming is known as Raynaud phenomenon.
- Q: If I suspect frostbite in my child and we are outdoors without access to warm water, are there any options for treatment?
- A: If there is a delay in reaching shelter, you can start to thaw your child's body part by using your body as a warmer by placing the exposed body part under your armpit and keeping it there until further care can be initiated. Before starting the rewarming process, you must be sure refreezing will not recur.
- Q: When should I call the doctor?
- A: The doctor should be called if, after rewarming, the skin is not soft and/or sensation does not return to normal. Call the doctor immediately if the skin is discolored and cold, blisters develop during rewarming, or there are signs of infection, such as the appearance of red streaks leading from the affected area, pus accumulation, or fever.
- Q: We are going on a winter vacation this year and expect to spend a lot of time outside skiing and sledding. What types of clothing should I pack for my 6-year-old son?
- A: It would be a good idea to pack a few pairs of waterproof mittens, a ski suit or ski pants, waterproof boots, thick cotton socks, and cotton thermal under garments. Try to make sure your son stays dry and warm. Take frequent breaks indoors to warm up and check your child for any early signs of cold injury.
- Q: Is frostnip the same thing as frostbite?
- A: No. Frostnip is the mildest form of cold injury, which commonly occurs on exposed parts of the body, such as the fingers, nose, and ears. The symptoms of frostnip are numbness and pallor of the involved body parts. Warming of these areas is the only treatment that is needed, and there is no associated tissue damage.