What is the pathophysiology of frostbite?

Updated: Oct 13, 2020
  • Author: Bobak Zonnoor , MD; Chief Editor: Dirk M Elston, MD  more...
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The cutaneous circulation plays a major role in maintaining thermal homeostasis. The skin loses heat more easily than it gains heat. Thus, humans acclimatize better to heat than to cold. Cutaneous vasodilation is controlled by direct local effects and decrease of sympathetic vascular tone. Maximum reflex vasodilation occurs when the sympathetic system is blocked.

The fingers, toes, ears, and nose—the skin structures most at risk for frostbite—contain multiple arteriovenous anastomoses that allow shunting of blood in order to preserve core temperature at the expense of peripheral tissue circulation.

The effect of skin temperature on cutaneous blood flow involves the following:

  • Normal cutaneous flow is 200-250 mL/min

  • At 15°C, maximal vasoconstriction is reached, with blood flow measured at 20-50 mL/min

  • Below 15°C, vasoconstriction is interrupted by rhythmic bursts of vasodilation occurring 3-5 times per hour and lasting 5-10 minutes; these bursts are more frequent and longer in individuals acclimated to the cold, making them less prone to frostbite injury

  • At 10°C, neurapraxia occurs, resulting in loss of cutaneous sensation

  • Below 0°C, negligible cutaneous blood flow allows the skin to freeze; without circulation, skin temperature drops at a rate exceeding 0.5°C per minute; smaller blood vessels (ie, microvasculature) freeze before larger blood vessels, and the venous system freezes before the arterial system because of lower flow rates

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