Frostbite (Frostnip)

Frostbite is severe damage to tissues from temperatures below 95 F and 35 C rectally due to the formation of ice crystals within cells, rupturing the cells and leading to cell death. There are three stages of frostbite: frostnip (first-degree injury), second, and third, which is the most severe form of frostbite.

The differences between frostnip and frostbite are the severity of the injury.

• Frostnip is an injury that occurs on the surface skin and doesn't affect the deeper layers of the skin.
• Frostbite occurs when the body part is frozen and then develops ice crystals within the cells, which ruptures them and causes cell death.

Both frostnip and frostbite occur on the skin's surface like the cheek lips, ears, eyebrows, arms, hands, fingers, legs, and toes.

Frostbite is a severe injury and requires emergency treatment. Call 911 or go to your nearest urgent care or emergency department if you have frostbite.

Winter cold and snow provide several opportunities to get outside and participate in activities such as skiing, sledding, and snowmobiling. However, without proper protection, cold weather-related injuries can occur even when temperatures are above freezing (32 F, 0 C). This is especially true if there are high winds or wet clothing. In general, however, the temperature and the duration of exposure play a role in determining the extent and severity of cold weather-related injuries. This information describes the different types of cold weather-related injuries, as well as what to do to prevent and treat them before reaching a healthcare professional.

Cold weather-related injuries can be divided into two general categories:

1. Conditions that occur without the freezing of body tissue, for example:
   • chilblains,
   • trench foot, and
   • frostnip.
2. Injuries that occur with the freezing of body tissue, such as frostbite.

Hypothermia is a medical condition characterized by a core body temperature that is abnormally low.

Anybody can develop a cold weather-related injury.

• The young and the elderly are more prone to these injuries due to vascular compromise or inability to effectively redistribute body heat. In addition, individuals who work outdoors, the homeless, and those who engage in outdoor activities are more likely to develop cold weather-related injuries due to their increased chance and time of exposure to cold conditions.
• Alcohol and illicit drug use also make it more likely that individuals will develop a cold weather-related injury because they have impaired judgment and may not sense that they are in danger.
• Patients with certain medical conditions including psychiatric illness, circulatory problems, diabetes, dehydration, and smoking can develop a cold weather-related injury more quickly than others.

The signs and symptoms of frostbite depend on the extent and depth of tissue injury. People with superficial frostbite may experience the following signs and symptoms in the affected area:

• Pain
• Burning
• Tingling
• Numbness
• Pale-colored skin
• Clear-colored skin blisters may develop
• Firm-feeling skin with underlying soft tissue which can move over bony ridges

As the degree of injury progresses, it goes deeper into the skin layers and the body temperature is between 95 F and 35 C through the rectum. Frostbite signs and symptoms of deep frostbite can develop, which may include:

• complete loss of sensation,
• pale, yellowish, bluish, gray, or mottled skin color,
• formation of blood-filled skin blisters, and
• firm-feeling skin and underlying tissue, with the affected area feeling hard and solid.

With advanced frostbite injuries, the affected area can appear blackened and gangrene can develop, placing the affected individual at high risk for infection.

Frostnip is a mild cold weather-related injury that typically affects the face, cheeks, lips, ears, toes, and fingers. Symptoms of frostnip usually occur after exposure to cold weather. The area(s) may appear pale, accompanied by burning, itching or pain, tingling, and numbness. Simple rewarming restores standard color and sensation, with no subsequent permanent tissue damage.

Frostnip can be managed at home, and this condition does not typically require further evaluation.

Individuals with frostbite or suspected frostbite should immediately go to an emergency room. Furthermore, these individuals may also be suffering from hypothermia, which requires additional treatment and evaluation and may constitute a life-threatening condition. These are serious cold weather-related injuries that may require admission to a hospital.

Generally, frostbite is a self-diagnosable condition so no imaging or lab tests need to be ordered. Frostbite usually goes away within a few days to weeks unless there are complications, like amputation of the body part affected.

The appearance of frostbite may gradually change over time; the extent of the change depends on how severely the tissue is damaged. Figure 1 shows a hand with severe frostbite changes at the tips of the fingers and thumb (dark to black-appearing tissue) that gradually decreases in severity on the digits.

Figure 1. Frostbite on digits and thumb

Picture of the stages of frostbite

Frostbite occurs when body tissue is frozen, and it is the most serious of cold weather-related injuries. Frostbite usually affects the hands, feet, nose, ears, and cheeks, though other body areas may also be affected. This type of injury results from decreased blood flow and heat delivery to body tissues resulting in damaging ice crystal formation, which ultimately leads to cell death. Vascular damage and complex cellular metabolic abnormalities lead to tissue death upon rewarming of the affected tissue.

Tissue damage is most pronounced when there is prolonged cold weather exposure, the affected area slowly freezes, and the subsequent rewarming process is slow. Repeated thawing and refreezing of the affected tissue is particularly damaging and should always be avoided.

Frostbite injuries can be classified as either superficial or deep, depending on the tissue depth of the injury.

Superficial frostbite injuries involve the skin and subcutaneous tissues and deep frostbite injuries extend beyond the subcutaneous tissues and involve the tendons, muscles, nerves, and even bone. Superficial frostbite injuries have a better prognosis than deep frostbite injuries.

The initial treatment for any cold weather-related injury involves removing yourself or others from the precipitating cold environment, if possible, to prevent further heat loss.

• Move indoors, remove all wet clothing and constricting clothing (such as socks, boots, and gloves), and replace them with dry clothing.
• Avoid massaging or rubbing the affected area, as this only aggravates the injury.

It is important to note that some of these individuals may also suffer from hypothermia, a potentially life-threatening condition.

Frostnip treatment

• Frostnip will generally improve with conservative rewarming measures at home.
• Frostnip to the hands, for example, can be treated by breathing into cupped hands or placing the hands in the armpit area.
• Alternatively, the affected area can be submerged in warm water until the normal sensation is restored.

Frostbite treatment

• Frostbite requires immediate medical attention. Ideally, treatment should be instituted in a healthcare facility, when possible.
• Before transport to a health care facility, if possible, loosely wrap the affected area in a dry sterile bandage or a clean blanket to prevent further trauma. Cotton may be placed between the toes or fingers, if affected, to prevent any potentially damaging effects of rubbing against one another.
• The most effective treatment measure for frostbite is rapid rewarming. This is accomplished by immersing the affected area into a circulating tub of warm water that is between 40 to 42 C (104 to 108 F) for 20 to 40 minutes or until thawing is complete. Warm wet packs at the same temperature may be used if a tub is unavailable.
  • It is important NOT to rapidly rewarm and thaw the affected area if there is a risk that it may refreeze. This leads to more severe tissue damage and must be avoided.
  • During the rewarming process, the pain may be extreme, and oral or intravenous analgesics may be required.
• After rapid rewarming is complete, the affected area should be dressed and splinted. Further treatment will focus on wound care, pain control, and providing a tetanus vaccine booster shot if needed.
• Surgical consultation may be obtained for managing wound care, as well as for the longer-term sequelae of serious frostbite injuries that may require amputation of gangrenous tissue.

The recovery time for a frostbite injury depends on the extent of tissue injury and whether or not there are any subsequent complications, such as infection. It may take 1-3 months before it is possible to determine the extent of tissue damage and to delineate which tissue is still viable. Some individuals will require debridement, skin grafting, or amputation of the affected area. Some patients will experience long-term sequelae from frostbite injuries, such as sensitivity to the cold with associated pain or burning, arthritis, increased sweating, and tingling of the affected area. Rarely, death occurs from infection-related complications.

The prevention of cold weather-related injuries is best achieved through careful pre-planning and preparation for the cold, when possible.

• Travel with another person in case an emergency occurs. Take along an emergency kit and blankets in your car in case of a breakdown or accident.
• Dress warmly using multiple layers and adequately covering body areas prone to injury.
• Try to have an extra change of dry clothing so you can remove any wet clothing if necessary.
• Always keep your hands and feet dry and avoid wearing tight-fitting clothing on these areas as it may decrease circulation. Use waterproof shoes.
• Drink plenty of water and avoid alcohol, caffeinated drinks, and smoking. Carry high-calorie snacks to provide adequate nutrition.
• Most importantly, however, move indoors to a warmer environment when you begin to feel cold.