Figure 1. Image of the top of left foot taken on hospital admission.
Figure 2. The base of the foot shows signs of frostbite.
A 58-year-old man with diabetes was admitted to the hospital 2 days earlier with frostbite injuries to both feet. One week ago, the man reports he helped a neighbor shovel her driveway while he wore tennis shoes. When he came inside, he reports that his toes were cold, swollen, and red. A couple of days later, he notices that his toes start to turn black and purple. Over the next few days, he begins to get pain in the toes and trouble walking. He was admitted to the hospital and a vascular surgery consult determines he had good blood flow to both feet. The right foot looks nearly identical to the left (Figures 1-2).
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This patient has sustained frostbite injuries to both feet. As tissue begins to cool and freeze upon exposure to a cold environment, microvascular vasoconstriction develops that can cause local tissue ischemia and paresthesia. Prolonged exposure to the cold will result in capillary blood flow disruption, thrombosis, and irreversible tissue damage. Tissue injury also causes a release of inflammatory mediators, which peak during rewarming, leading to further hypoxia.1,2
Thrombolytics, rewarming techniques, anti-inflammatory medications, hyperbaric oxygen, and antibiotics are all used during the early phase of a frostbite injury. However, by 1 week after injury the soft tissue damage is likely irreversible and these treatments are no longer helpful.2
Severe frostbite injuries can form a hard, black, leathery eschar over a week from injury. After 3 weeks, a clear line of demarcation starts to form separating viable tissue with eschar. Dead tissue and eschar require amputation until viable tissue is reached. The line of demarcation may take up to 6 to 8 weeks to become clear; therefore, toe/foot amputation after frostbite injury is not performed urgently, but rather electively when the amount of tissue requiring amputation becomes clear.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Millet JD, Brown RK, Levi B, et al. Frostbite: spectrum of imaging findings and guidelines for management. Radiographics. 2016;36(7):2154-2169. doi:10.1148/rg.2016160045
2. Grieve AW, Davis P, Dhillon S, Richards P, Hillebrandt D, Imray C. A clinical review of the management of frostbite. BMJ Militar Health. 2011;157(1):73-78. doi:10.1136/jramc-157-01-13