Frostbite Workup

Author: C Crawford Mechem, MD, MS, FACEP; Chief Editor: Dirk M Elston, MD more...

Updated: Dec 16, 2011

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Approach Considerations
Laboratory Studies
Radiography and Angiography
Scintigraphy and Bone Scans
Other Tests
Histologic Findings
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Approach Considerations

Laboratory studies of tissue samples, blister fluid, or blood ordinarily do not provide any useful, clinically relevant information in isolated frostbite. Concurrent hypothermia, prolonged exposure with systemic physiologic changes, and previous medical illnesses may exist, however, and laboratory studies in these cases may be helpful.

Routine imaging studies early in the diagnosis and treatment of frostbite are rarely helpful in determining the extent and amount of tissue damage. Because transitory vascular instability lasts 2-3 weeks after the frostbite injury, no imaging technique (eg, thermography, angiography, plethysmography, radioisotope bone scanning) reliably predicts tissue demarcation during the initial frostbite presentation.

Laboratory Studies

Frostbite is a clinical diagnosis. Although laboratory studies are not important in the initial diagnosis and management of frostbite, they may be helpful in identifying delayed systemic complications, such as wound infection with sepsis or complications of underlying hypothermia.

Baseline laboratory studies to consider include complete blood count (CBC), electrolytes, blood urea nitrogen (BUN), creatine, glucose level, and liver function tests. Urinalysis may be used to detect evidence of myoglobinuria. Obtain Gram stains and cultures from suspected frostbite wound infections.

Radiography and Angiography

Radiography often demonstrates soft-tissue edema but does not distinguish viable from nonviable tissue. 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.

Angiography often shows slowing of blood flow to the distal vasculature, but this too does not correlate well with eventual tissue loss. When a vasodilator is added, this technique can more accurately predict the final pattern of ischemia that will be observed after 2-3 weeks of observation. Arteriography is of limited value because it only images large vessels, not microvasculature. It cannot be used to estimate bone cell perfusion or viability.

Scintigraphy and Bone Scans

Technetium-99m (^99m Tc) scintigraphy is sensitive and specific for tissue injury. Some authors recommend using it early in the management of frostbite (48 hours after injury) to aid in directing earlier debridement of nonviable soft tissue. This allows nonviable tissue to be visualized earlier than by clinical examination and thus presumably shortens patient hospitalization. However, no adequate randomized, prospective trials have confirmed this recommendation.

An increased use of scintigraphy in the early and late stages of management has been reported in the medical literature, but the largest series examined only 20 patients.^{[28, 29]}In addition, scintigraphy is useful in assessing the response of damaged tissue to therapy.

Similarly, bone scans may help to delineate nonviable bone but should be reserved until microscopic tissue damage has had time to present itself clinically.

Other Tests

Magnetic resonance imaging (MRI) has been suggested as a more accurate assessment tool for predicting the limits of nonviable tissue and for guiding early surgical debridement. Clinically, however, neither MRI nor any of the other imaging techniques discussed here has proved consistently superior to 3-4 weeks of watchful waiting for demarcation.

Laser Doppler flowmetry may someday provide a means of predicting the extent of tissue viability in patients with frostbite.

Histologic Findings

The presence of a greater number of intracellular ice crystals compared to extracellular ice crystals suggests a rapid cooling of the skin.

The time frame of frostbite injury is as follows:

First hour - Endothelial leakage
First 6 hours - Erythrocyte extravasation
Within 6-24 hours - Leukocyte migration and vasculitis
Within 1-2 weeks - Medial degeneration, loss of intracellular attachments, and vacuolization of keratinocytes

Proceed to Treatment & Management

Contributor Information and Disclosures

Author

C Crawford Mechem, MD, MS, FACEP Associate Professor, Department of Emergency Medicine, University of Pennsylvania School of Medicine; Emergency Medical Services Medical Director, Philadelphia Fire Department

C Crawford Mechem, MD, MS, FACEP is a member of the following medical societies: American College of Emergency Physicians, National Association of EMS Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

David Cheng, MD Associate Professor of Emergency Medicine, Education Director, Associate Emergency Medicine Residency Director, Case Medical Center

David Cheng, MD is a member of the following medical societies: American College of Emergency Physicians, American Heart Association, Council of Emergency Medicine Residency Directors, International Society for Mountain Medicine, National Association of EMS Physicians, Society for Academic Emergency Medicine, Society of Critical Care Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Tonya M Thompson, MD, MA Assistant Professor, Departments of Pediatrics and Emergency Medicine, Associate Fellowship Director, Pediatric Emergency Medicine Fellowship, Associate Medical Director, The PULSE Simulation Center, Arkansas Children's Hospital, University of Arkansas for Medical Sciences College of Medicine

Tonya M Thompson, MD, MA is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, American College of Emergency Physicians, American Medical Women's Association, Phi Beta Kappa, and Southern Society for Pediatric Research

Disclosure: Nothing to disclose.

Ramy Yakobi, MD, MBA Medical Director, Department of Emergency Medicine, Beth Israel Medical Center

Ramy Yakobi, MD, MBA is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD Director, Ackerman Academy of Dermatopathology, New York

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

H Scott Bjerke, MD, FACS Clinical Associate Professor, Department of Surgery, University of Missouri-Kansas City School of Medicine; Medical Director of Trauma Services, Research Medical Center; Clinical Associate Professor, Department of Surgery, Indiana University School of Medicine

H Scott Bjerke, MD, FACS is a member of the following medical societies: American Association for the History of Medicine, American Association for the Surgery of Trauma, American College of Surgeons, Association for Academic Surgery, Eastern Association for the Surgery of Trauma, Midwest Surgical Association, National Association of EMS Physicians, Pan-Pacific Surgical Association, Royal Society of Medicine, Southwestern Surgical Congress, andWilderness Medical Society