Frostbite

Frostbite is caused by destruction of the tissues secondary to freezing. It usually occurs at temperatures less than 2 degrees Celcius.
It can be divided into two phases.

• Cooling Injury: Initial response of dilation and constriction of blood vessels in the tissues, followed by formation of tissue ice crystals. The tissue temperature continues to fall, forming ice crystals within the cells and leading to cell death.
• Rewarming Injury: Thawing of the limb leads to small blood vessel damage and formation of clots.

The tissue injury is effectively like a burn, ranging from first to fourth degree in severity. Fourth degree injuries involve muscle and bone and later become black and mummified. Commonly affected areas include fingers, toes, nose, ears and cheek.

Management of frostbite commences with removing affected areas from cold environment if possible. Splint the extremity to minimise motion. Provide adequate analgesia and give anti-inflammatories. Commence rapid rethawing in water at 40 - 42 degrees (dry heat rewarming leads to increased tissue loss) over approximately 15 minutes. Do not rub the affected part. Avoid refreezing as this can worsen tissue damage. Release large, non-haemorrhagic blisters. NO SMOKING. After rapid thaw, bed rest with dry air warming.