Frostbite occurs when extreme cold causes localized damage to skin and other tissues. Essentially, the fluid in the cells of the skin and other tissues freeze, which can form clots in blood vessels, and reduce the supply of oxygen to tissues. Frostnip refers to the initial stages of frostbite. Cold injury refers to several conditions caused by extreme cold, such as frostnip, chilblains, frostbite, hypothermia, and trench foot. If temperatures drop to freezing, the blood vessels close to exposed skin start to narrow (constrict) in an attempt to keep the core of the body warm.
When it is very cold, or exposure to cold is prolonged, blood flow to some parts of the body, for example the fingers and hands, can drop to dangerously low levels - lack of oxygen-rich blood to the affected area(s) can lead to tissue cell death.
Signals of frostbite include a lack of feeling in the affected area; skin that appears waxy, is cold to the touch, or is discolored (flushed, white or gray, yellow or blue).
Hypothermia is another cold-related emergency. Hypothermia may quickly become life threatening. Hypothermia is caused by the cooling of the body due to failure of the body’s warming system. The goals of first aid are to restore normal body temperature and to care for any conditions while waiting for Emergency Medical Services personnel.
Signals of hypothermia include: shivering, numbness, glassy stare, apathy, weakness, impaired judgment and loss of consciousness.