COLD INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 407

Cigarette smoking constricts the blood vessels in the skin and aggravates local cold in-
juries such as frostbite.
Diagnosis and Prognosis
The early signs of frostbite are cold, pain, and pallor of the affected tissues. Some in-
dividuals suffer little pain. Pain disappears as tissues begin to freeze, a highly significant
warning sign. As freezing progresses, tissues become even whiter, all sensation is lost, and
tissues become quite hard. With extensive frostbite, such as an entire hand or foot, tissues
often have a dull purple color. Frostbite of the face, tip of the nose, or ears can be recog-
nized by the pain and pallor of the affected tissues.
The extent and severity of frostbite are notoriously difficult to judge accurately while
tissues are still frozen or immediately after thawing. However, a few hours after thawing
prognosticsignsbegintoappear.Minorfrostbite(frostnip)thatinvolvesonlythetipsofthe
fingers or toes, the tip of the nose, or small areas of the face or ears produces redness and
swelling that lasts for a few days but leaves no permanent damage.
With more severe injuries, blisters develop after rewarming and may cover entire digits
( Figs. 26-3 and 26-4 ). If the blisters contain clear fluid and extend to the tips of the digits,
the underlying tissues can be expected to recover. If the blisters do not extend to the tips of
the digits, the unblistered tissues are usually lost. When the blisters are filled with bloody
fluid, much of the underlying tissues cannot recover. The most severe frostbite injuries are
not followed by blisters and retain a deep purple color.