Frostbite occurs when tissues freeze. This condition happens when you are
exposed to temperatures below the freezing point of skin.
The condition has long been recognized. A 5000-year-old pre-Columbian mummy
discovered in the Chilean mountains offers the earliest documented evidence of
frostbite. More recently, Napoleon’s surgeon general, Baron Dominique Larrey,
provided the first description of the mechanisms of frostbite in 1812, during
his army’s retreat from Moscow. He also noted the harmful effects of the
freeze-thaw-freeze cycle endured by soldiers who would warm their frozen hands
and feet over the campfire at night only to refreeze those same parts
by the next morning.
Although frostbite used to be a military problem, it is now a civilian one
as well. Most people who get frostbite are males aged 30-49 years. The nose,
cheeks, ears, fingers, and toes (your extremities) are most commonly affected.
Everyone is susceptible, even people who have been living in cold climates for
most of their lives.
Your body works to stay alive first and to stay functioning second.
In conditions of prolonged cold exposure, your body sends signals to the
blood vessels in your arms and legs telling them to constrict (narrow). By
slowing blood flow to the skin, your body is able to send more blood to the
vital organs, supplying them with critical nutrients, while also preventing a
further decrease in internal body temperature by exposing less blood to the
As this process continues and your extremities (the parts farthest from
your heart) become colder and colder, a condition called the hunter’s response
is initiated. Your blood vessels are dilated (widened) for a period of time and
then constricted again. Periods of dilatation are cycled with times of
constriction in order to preserve as much function in your extremities as
possible. However, when your brain senses that you are in danger of hypothermia
(when your body temperature drops significantly below 98.6°F), it permanently
constricts these blood vessels in order to prevent them from returning cold
blood to the internal organs. When this happens, frostbite has begun.
Frostbite is caused by 2 different means: cell death at the time of
exposure and further cell deterioration and death because of a lack of
In the first, ice crystals form in the space outside of the cells. Water is
lost from the cell’s interior, and dehydration promotes the destruction of the
In the second, the damaged lining of the blood vessels is the main culprit.
As blood flow returns to the extremities upon rewarming, it finds that the
blood vessels themselves are injured, also by the cold. Holes appear in vessel
walls and blood leaks out into the tissues. Flow is impeded and turbulent, and
small clots form in the smallest vessels of the extremities. Because of these
blood flow problems, complicated interactions occur, and inflammation causes
further tissue damage. This injury is the primary determinant of the amount of
tissue damage you will have in the end.
It is rare for the inside of the cells themselves to be frozen. This
phenomenon is only seen in very rapid freezing injuries, such as those produced
by frozen metals.