As many parts of the United States are experiencing the coldest months of the year, health care providers are beginning to see an increased number of cases of hypothermia and frostbite.  Hypothermia occurs when the core body temperature drops below 35°C (95°F).  Those at extremes of age are at high risk for hypothermia.  Infants have ineffective shivering responses, increased surface-to-mass ratio, and an inability to provide personal protection against heat loss. Elderly individuals often have significant comorbid conditions such as dementia, psychiatric illness, immobility, malnutrition, and poor socioeconomic factors that contribute to an increased risk for hypothermia.  There are many other risk factors for hypothermia.  These risk factors can include toxic ingestions, environmental exposures due to hobbies or occupations, as well as comorbid conditions. 

In extreme cold situations, peripheral injury to tissues can occur.  Frostbite occurs when tissue temperature drops below 0°C (32°F), much below the level of hypothermia.  When frostbite occurs, ice-crystals form, leading to destruction of the cellular architecture.  This leads to stasis of blood flow, causing microvascular thrombosis.  Subsequent, progressive dermal ischemia ensues as the microvasculature begins to collapse and the tissue becomes edematous due to shunting of arteriovenous flow.  This leads to the late clinical findings of distal necrosis.

Clinically, frostbite always presents with a sensory deficiency related to cold temperatures. This sensory deficiency is related to light touch, ability to detect temperature, or ability to feel pain. Patient’s often describe the affected area as “numb” and “heavy”.  The appearance is often described as “waxy”. Frostbite is classified as superficial or deep.

Superficial frostbite is typically accompanied by numbness and erythema.  The acral areas and extremities are the most commonly affected areas.  The presence of  edema and vesiculation indicates deep frostbite.  Other signs of deep frostbite include tissue that appears waxy, yellow, mottled, or violaceous-white.

Treatments for frostbite are largely dependent on severity and are individualized.  Rewarming is paramount, and should occur in a medically supervised setting.  Antithrombotic and vasodilatory therapies may also be options for some patients.  Amputation is considered in extreme cases.

Read more about Frostbite:

Harrison’s Principles of Internal Medicine, 20e: Chapter 454: Hypothermia and Peripheral Cold Injuries

Current Medical Diagnosis and Treatment 2019: Chapter 37: Disorders Related to Environmental Emergencies