AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Background

Frostbite is a cold-related injury characterized by freezing of tissue. Most cases are encountered in soldiers, in those who work outdoors in the cold, in homeless people, and among winter outdoor enthusiasts. Mountain frostbite is a variation observed among mountain climbers and others exposed to extremely cold temperatures at high altitude. It combines tissue freezing with hypoxia and general body dehydration.

Pathophysiology

Cold exposure leads to ice crystal formation, cellular dehydration, protein denaturation, inhibition of DNA synthesis, abnormal cell wall permeability with resultant osmotic changes, damage to capillaries, and pH changes. Rewarming causes cell swelling, erythrocyte and platelet aggregation, endothelial cell damage, thrombosis, tissue edema, increased compartment space pressure, bleb formation, localized ischemia, and tissue death.

Underlying responses to these injuries include generation of oxygen free radicals, production of prostaglandins and thromboxane A2, release of proteolytic enzymes, and generalized inflammation. Tissue injury is greatest when cooling is slow, cold exposure is prolonged, rate of rewarming is slow, and, especially, when tissue is partially thawed and refreezes.

Frequency

United States

No standardized reporting system exists; thus, true frequency of frostbite in the United States and abroad is unknown. Frostbite is uncommon in most of North America, except for northern states, Alaska, and Canada.

International

In Finland, a nation-wide study of hospital admissions for frostbite from 1986-1995 yielded an incidence of 2.5 cases per 100,000 inhabitants.¹

Mortality/Morbidity

• Frostbite is a disease of morbidity, not mortality. However, when combined with hypothermia or wound-related sepsis, death is possible.
• Long-term sequelae include paresthesias and sensory deficits, hyperhidrosis or anhidrosis, cracking skin and loss of nails, abnormal color changes indicative of vasospasm, cold sensitivity, joint stiffness, tremor, premature closure of epiphyses in children, osteoporosis, intrinsic muscle atrophy, and phantom pain of amputated extremities.

Race

During the Korean War, frostbite was more common among black soldiers than white soldiers. A US Army study of all cases of cold weather injuries, including frostbite, from 1980-1999 similarly demonstrated that African American men and women were 4 times and 2.2 times, respectively, as likely to sustain cold weather injuries as their white counterparts.²

Arabs appear to be similarly predisposed, as are individuals from warmer climates.

Sex

Most frostbite victims are male. This disparity may result from increased outdoor activity among males as opposed to genetic predisposition.

Age

In one case study, the mean patient age was 41 years.³

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

History

• Symptoms affecting frostbitten body parts include the following:
• • Coldness and firmness
  • Stinging, burning, numbness
  • Clumsiness
  • Pain, throbbing, burning, or electric current-like sensations on rewarming

Physical

• Location
• • While hands and feet are affected most frequently, shins, cheeks, nose, ears, and corneas may be involved.
  • As in thermal burns, frostbite injuries may be classified by degree.
  • First-degree injuries involve the epidermis, while fourth-degree injuries involve the epidermis, dermis, subcutaneous tissue, and deeper structures.
• Degree of injury
• • First-degree injury - Erythema, edema, waxy appearance, hard white plaques, and sensory deficit
  • Second-degree injury - Erythema, edema, and formation of blisters filled with clear or milky fluid and which are high in thromboxane (These blisters form within 24 hours of injury.)
  • Third-degree injury - Presence of blood-filled blisters, which progress to a black eschar over a matter of weeks
  • Fourth-degree injury - Full-thickness damage affecting muscles, tendons, and bone, with resultant tissue loss
• Other signs
• • Excessive sweating
  • Joint pain
  • Pallor or blue discoloration
  • Hyperemia
  • Skin necrosis
  • Gangrene

Causes

• Predisposing factors and populations at greatest risk include the following:
• • Individuals stranded in cold weather
  • Soldiers, cold weather rescuers, and laborers working in a cold environment
  • Winter and high-altitude athletes
  • Extremes of age
  • Homelessness
  • Altered mental status (eg, head trauma, ethanol or illicit drug abuse, psychiatric illness)
  • Exposure to water or dampness
  • Immobilization
  • Use of nicotine or other vasoconstrictive drugs
  • Previous cold injury
  • Use of inadequate or constrictive clothing
  • Persons exposed to chronic hand or arm vibration
• Underlying illness
• • Malnutrition
  • Infection
  • Peripheral vascular disease
  • Atherosclerosis
  • Arthritis
  • Diabetes
  • Thyroid disease

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Other Problems to be Considered

Pernio (chilblains)
Trench foot
Frostnip

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Lab Studies

• Lab studies are not important in the initial diagnosis and management of frostbite. However, they may be helpful in identifying delayed systemic complications, such as wound infection with sepsis or underlying hypothermia.
• Commonly encountered lab findings include evidence of hemoconcentration and depressed liver function.

Imaging Studies

• Tc-99m (Technetium 99) pertechnetate scintigraphy is sensitive and specific for tissue injury. Some studies have shown good correlation between scintigraphy findings at 48 hours after injury and ultimate extent of deep-tissue injury. In addition, scintigraphy is useful in assessing the response of damaged tissue to therapy.
• Radiographs identify clinically suspected fractures or dislocations but are otherwise rarely useful in initial evaluation. They may assist in the diagnosis of long-term complications, such as osteomyelitis.
• Arteriography is of limited value because it only images large vessels, not microvasculature. It cannot be used to estimate bone cell perfusion or viability.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Prehospital Care

• Address life-threatening conditions first.
• Replace wet clothing with dry, soft clothing to minimize further heat loss.
• Initiate rewarming of affected area as soon as possible. Do not attempt rewarming if a danger of refreezing is present. Avoid rubbing the affected area with warm hands or snow, as this can cause further injury. If the affected body part is an extremity, wrap it in a blanket for mechanical protection during transport. Avoid alcohol or sedatives, which can enhance heat loss and impair shivering.
• It is better to walk with frozen feet to shelter than to attempt rewarming at the scene; however, walking on frostbitten feet may cause tissue chipping or fracture.

Emergency Department Care

• Address life-threatening conditions first. Fluid resuscitation, especially in persons with mountain frostbite, enhances blood flow and tissue perfusion.
• Rapidly rewarm the affected body part, avoiding further trauma.
• • An appropriate warming technique is the use of a whirlpool bath or tub of water at 40-42°C. Mild antibacterial soap may be added. Avoid warmer temperatures or dry heat because of the risk of thermal injury.
  • If a tub is not available, use warm wet packs at the same temperature.
  • Avoid massaging the affected area, as this can cause further injury.
  • Administer analgesics, such as morphine sulfate, as needed for pain.
• Thawing usually takes 20-40 minutes and is complete when the distal tip of the affected area flushes. Once thawed, keep the body part on sterile sheets, elevated, and splinted when possible. A cradle may be used over an injured lower extremity to avoid pressure or trauma.
• Debride clear blisters to prevent thromboxane-mediated tissue injury. Leave hemorrhagic blisters intact to reduce risk of infection.
• In patients with an associated dislocation, perform reduction as soon as thawing is complete. Manage fractures conservatively until postthaw edema has resolved.

Consultations

• The only indication for early surgical intervention is debridement of blisters or necrotic tissue and fasciotomy in the case of compartment syndrome. Early surgical consultation for amputation is rarely needed.
• It often takes 1-3 months for frostbitten tissue to be declared viable. The affected area generally heals or mummifies without surgery. Therefore, unless guided by scintigraphy, delay amputation as long as possible.
• Lower extremity involvement, infection, and delay in seeking medical attention are associated with an increased risk of operative therapy.
• Surgical consultation is appropriate for guiding long-term management, including debridement for infections not responding to conservative management or for skin grafting.
• Hyperbaric oxygen therapy may play a role in the long-term management of frostbite injury. However, the current medical literature on this topic is limited to case reports.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

The goals of medical management of frostbite are pain control and prevention of complications, such as further tissue damage or infection.

In addition to the interventions described elsewhere, several medication regimens may be beneficial but have not been prospectively validated and doses standardized. These include the daily infusion of low molecular weight dextran, which may prevent erythrocyte clumping in cold-injured blood vessels. Low-dose infusions of heparin may prevent microthrombosis. Recent research suggests that intravenous heparin combined with intravenous tissue plasminogen activator (tPA) may improve outcome in patients with frostbite of the digits. Finally, bupivacaine has been used for either cervical or lumbar sympathetic blockade to decrease sympathetic tone and relieve pain, but its efficacy is unclear.

Drug Category: Nonsteroidal anti-inflammatory drugs (NSAIDs)

These drugs have analgesic and antipyretic activities. Their mechanism of action is not known, but these agents may inhibit cyclooxygenase activity and prostaglandin synthesis.

Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil and platelet aggregation, and various cell-membrane functions.

Drug Category: Antibiotics

These agents are used for wound infection prophylaxis. Their use is controversial and not recommended by some experts unless signs of infection develop.

Drug Category: Topical agents

These agents are applied to debrided clear blisters and intact hemorrhagic blisters. They minimize further thromboxane synthesis.

Drug Category: Toxoids

These agents are used for tetanus immunization in patients at risk of frostbite-associated tetanus. Booster injection in previously immunized individuals is recommended to prevent this potentially lethal syndrome. These should be supplemented with tetanus Ig, 250 U IM, if patient was never fully immunized.

Drug Category: Immune globulins

Patients who may not have been immunized against C tetani products should receive tetanus Ig (Hyper-Tet).

Drug Category: Analgesics

These agents are used for pain control during rewarming.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Further Inpatient Care

• Place the patient on a high-protein, high-calorie diet to promote healing.
• Place cotton pledgets between frostbitten digits to decrease tissue maceration.
• Encourage active motion of the affected part as soon as possible.
• Continue whirlpool baths twice a day, adding surgical soap to the water.
• Discourage the patient from smoking.

Further Outpatient Care

• Strongly counsel patients with frostbite regarding their increased susceptibility to frostbite injury and appropriate techniques to avoid cold.
• Advise patients that the frostbitten area may be more sensitive to cold, with associated burning and tingling.

In/Out Patient Meds

• The patient's hospital course dictates choice of outpatient medications and may include antibiotics, analgesics, and ibuprofen.

Transfer

• Transfer the patient to another facility if treating personnel are unfamiliar with management of frostbite and its sequelae. In some settings, burn units have particular expertise in managing severe frostbite injuries. In one report, 29% of homeless patients admitted to a burn unit were admitted for frostbite.⁴ Therefore, transfer to a facility with a burn unit may be considered.

Complications

• Wound infection (observed in 30% of patients in one case series; may be the result of Staphylococcus aureus, beta-hemolytic streptococci, gram-negative rods, or anaerobes⁵)
• Tetanus (Frostbite is considered a high-risk wound.)
• Hyperglycemia
• Acidosis
• Refractory dysrhythmias
• Tissue loss
• Gangrene
• Death

Prognosis

• Favorable prognostic signs
• • Early sensation to pinprick
  • Healthy-appearing skin color
  • Clear rather than hemorrhagic blebs
• Poor prognostic signs
• • Cyanosis
  • Hemorrhagic blebs that do not extend to tips of digits
  • Frozen appearance of tissue

Patient Education

• Cold weather
• • The primary defense against frostbite is to get out of the cold. If this is not possible, preplanning and use of appropriate clothing are mandatory. Follow weather forecasts, with special attention to both predicted temperature as well as wind-chill temperature index.
  • Cover head, neck, and face in windy conditions. Avoid tight-fitting clothing, particularly on hands and feet. Keep hands and feet dry. Wear mittens instead of gloves. Wear clothing in multiple layers. Avoid perspiration by using adequately ventilated clothing.
  • Increase fluid and caloric intake in cold weather.
  • Do not wash hands, face, or feet frequently under extreme cold conditions, as weather-beaten skin is more resistant to frostbite.
  • Avoid alcohol and tobacco.
  • Keep toenails and fingernails trimmed.
  • Keep tetanus immunization status current.
  • In remote areas, use a buddy system to help prevent cold injury. Have a system for rapid evacuation, if needed.
  • At high altitudes, individuals should moderate their activity to minimize the work of breathing and associated heat loss through the respiratory tree. Use of supplemental oxygen has been found to reduce the incidence of frostbite among mountain climbers.
• For excellent patient education resources, visit eMedicine's Environmental Exposures and Injuries Center and Infections Center. Also, see eMedicine's patient education articles Frostbite and Tetanus.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Media file 1:  Frostbite of the foot. Photo courtesy of Kevin P. Kilgore, MD, Department of Emergency Medicine, Regions Hospital.
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Media file 2:  Frostbite of the ear. Photo courtesy of Kevin P. Kilgore, MD, Department of Emergency Medicine, Regions Hospital.
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Media file 3:  Frostbite of the hand.
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REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

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Article Last Updated: Jul 18, 2007