Frostnip or Frostbite Overview

Prolonged exposure to cold temperatures can lead to tissue damage of affected areas. Prolonged exposure is often categorized by the level of freezing and damage that occurs.

Frostnip

Frostnip is a nonfreezing injury of the skin tissues, usually of the fingers, toes, ears, cheeks, and chin. Numbness and tingling are present, but no tissue injury occurs. Symptoms develop when blood vessels supplying the affected tissues narrow because of the cold temperature. Frostnip occurs at temperatures of about 15°C (59°F).

Chilblains

A more significant nonfreezing injury from exposure to cold temperatures is chilblains. As tissue temperature drops below 15°C (59°F), tissue injury progresses. The walls of small blood vessels break, and the tissues swell.

Frostbite

Frostbite is the destruction of body tissues due to freezing (at 0°C or 32°F). Ice crystal formation in the tissues breaks apart cells, thereby destroying the tissues.

Contributory Factors

Factors that may contribute to frostnip, chilblains, or frostbite include dehydration; poor conditioning; wearing wet or tight clothing; malnutrition; altitude; or medical conditions associated with poor circulation, such as diabetes, heart disease, anemia, or sickle cell disease.

Frostnip or Frostbite Symptoms

• Usually, the skin tissues affected with frostnip do not feel painful. Tissues affected with frostnip are soft and resilient (if a person presses against the tissue, the skin indentation springs back). Tissues may appear red, yellow, or gray. Full recovery is expected.
• The skin tissues affected with frostbite may lose sensation and may feel cold, solid, and woodlike. They may also appear pale, blue-tinged, and waxy. Tissues affected with frostbite are not resilient, and small blisters containing clear or bloody fluid may form.  
• Hypothermia (low body temperature) may occur, causing weakness, uncontrolled shivering, and confusion. Hypothermia occur in moderate temperatures under certain conditions, such as in a person who is wearing wet clothing or who has fallen into cold water. Frostbite does not necessarily occur with hypothermia.

Frostnip or Frostbite Treatment

• Frostnip is treated by rewarming the injured area. The affected extremity can often be rewarmed by placing against another person’s underarm or abdomen. The injured area should not be rubbed because doing so can injure cold tissues..
• Frostbite should be treated with rapid thawing in a warm (not hot) bath. Rubbing or manipulating the frostbitten area should be avoided. The affected extremity should not be thawed until the person is in a warm environment. Thawing and refreezing result in significantly more damage to the tissue.
• Frozen feet may be walked on if necessary. Once feet begin to thaw, walking on them should be avoided. Thawing and refreezing should also be avoided.
• All people with frostbite should be treated as if they are hypothermic until a temperature can be taken to prove otherwise.

Hypothermia Symptoms

• Mild symptoms include shivering, blue extremities, numbness, tingling, and blotchy skin.
• Severe symptoms include decreased coordination (core temperatures below 33.5°C/92°F), muscle rigidity, slow breathing, and slow or irregular pulse (the heart can be irregular at temperatures below 32°C/90°F, and the heart rate decreases by 50% at temperatures below 28°C/82°F). This can progress to dilated and fixed pupils, absent reflexes, and cardiac arrest and death below 25°C/77°F.

Hypothermia Treatment

• Dry the hypothermic person and cover him or her with blankets.
• Shelter the person from wind and water.
• Provide heat to the neck, underarms, and groin. Initially, heat only the trunk to avoid core temperature afterdrop. Afterdrop occurs when the extremities cool faster than the trunk. If the extremities are rewarmed, the colder blood within them will reenter the circulation and temporarily worsen the hypothermia.
• Keep the person lying down.
• Administer warm fluids only after the victim stops shivering (loss of the shivering reflex signifies significant hypothermia).
• Avoid suddenly moving/jarring the person because this may trigger an abnormal heart rhythm.
• CPR may be necessary. Resuscitation efforts should be continued until the person's body temperature rises to at least 95°F/35°C (never give up: one reported victim recovered in a morgue). All temperatures indicated are rectal measures, which give a closer indication of core temperature. If the person with hypothermia is cooperative, the temperature may be taken by mouth or other