Thomas Falasca, DO FACA FACPM
December 29, 2022
The danger of peripheral cold-related injuries is upon us. Although it is usual to think only of frostbite, peripheral cold-related injuries also include frostnip, chilblain, and trench foot.1
Why Peripheral?
These cold-related injuries are peripheral because they localize to specific body parts as opposed to hypothermia which affects the entire body. Nevertheless, the regional effect does not diminish their importance because 1) they can result in amputation of the affected part, 2) their complications can result in a threat to life, and 3) the high visibility of the peripheral injury can detract attention from a co-existing life-threatening systemic hypothermia.
Frostnip
Frostnip is the mildest form of cold injury. It affects the ears, cheeks, fingers, toes, or nose and occurs when the small blood vessels of these areas contract to conserve heat in the body. The affected area may sting, burn, and feel cold. Burning may become more intense as the area rewarms. Tissues do not freeze and the skin remains soft and pliable. Frostnip may occur in skiers experiencing fast-moving, cold air.
Frostnip is reversible with no damage. It responds to gently rewarming the skin by holding the hands in the armpits or gently using warm water. Do not use hot water or heating pads as they may burn somewhat numb skin.
The main problem in frostnip is determining that it is not the much more serious frostbite. Signs of this are 1) the skin turning whiter or paler, 2) losing the sensation of cold, 3) skin becoming less soft and pliable, and 4) escalating pain. More on frostbite later. 2
Chilblains
Chilblains is more severe than frostnip. It typically occurs on the fingers, toes, and ears.
Chilblains consists of tender or itchy or burning bumps often with a red or purplish discoloration that turns white with fingertip pressure. It follows exposure to damp and cold, but non-freezing conditions; and, thus, it is more common in late winter and early spring. Chilblains lasts at least 24 hours but typically resolves spontaneously in 1-3 weeks.
While frostnip is caused by the contraction of blood vessels, chilblains is caused by an inflammation of blood vessels.
Chilblains is more common in young and middle-aged adults, especially females. Predisposing conditions are smoking, outdoor exposure, and disorders of the bone marrow and connective tissue. There seems to be a familial tendency toward chilblains.3, 4
Trench Foot
Trench foot consists of tingling pain and itching, progressing to complete numbness and leg cramps. The skin is initially red, progressing to grey and finally blue. The soles of the feet are quite tender to palpation.
Trench foot is associated with prolonged exposure to wetness and cold but non-freezing conditions especially with dependency and immobilization of lower extremities confined by tight footwear. As the name implies, it has been often seen in soldiers and shipwreck survivors. Trench foot is a disease of the nerves and blood vessels of the feet. Recovery can take months and may be complicated by bacterial or fungal infection along with moist gangrene.5
Frostbite
In distinction to all the above-mentioned diseases, which are associated with non-freezing cold, frostbite is associated with freezing cold.
Frostbite results from the freezing and crystalizing of fluids outside and sometimes inside the cells. The result is dehydration within the cells, cell membrane damage, and obstruction of the smallest blood vessels causing interruption of blood flow. Further damage can result from inflammation when blood flow is reestablished.
Areas most frequently involved are hands, feet, nose, and ears.
Frostbite occurs in both superficial and deep forms. Superficial frostbite involves the skin and tissues just under it. The area is numb, cold, white, and waxy. With thawing, the area becomes painful and red, then swelling ensues along with blisters fill with clear fluid.
Deep frostbite involves muscles, tendons, nerves, blood vessels, and even bone. The area is hard, wood-like and numb, with a grey color that may persist even after warming. Any blisters are filed with bloody fluid. It is often difficult to assess the depth of tissue involvement. If gangrene ensues, it is of the dry, mummified type rather than the moist gangrene of trench foot.
Frostbite risk factors are high altitude, severe wind chill, wet skin, previous cold injury, extremes of age, homelessness, and altered mental state from trauma, ethanol or drug use, or psychiatric illness.6
Prevention of Peripheral Cold-related Injury
Many events of peripheral cold-related injury can be prevented by following these simple steps.
Wear several layers of light, loose clothing to trap insulating air.
Use mittens instead of gloves because they reduce exposed surface area.
Wear at least two pair of socks.
Cover the face and head.
Avoid tight clothing.
Avoid getting clothing wet.
Avoid smoking and alcohol.
Avoid warming and then refreezing affected areas.
Conclusion
Cold-related injuries warrant serious attention and caution. They can result in permanent disability or even loss of a limb. Systemic hypothermia and complications such as infection may eventuate in death. Don’t become a victim. Be safe and comfortable in any cold situation.
Thomas Falasca, DO
Sources
1 Peters, B. (2021, October 16). Cold injuries. Practice Essentials, Overview, Systemic Hypothermia. Retrieved December 30, 2022, from https://emedicine.medscape.com/article/1278523-overview
2 Gotter, A. (2018, March 20). Frostnip: Definition, vs. Frostbite, pictures, and Recovery Time. Healthline. Retrieved December 30, 2022, from https://www.healthline.com/health/frostnip
3 Chilblains. DermNet. (n.d.). Retrieved December 30, 2022, from https://dermnetnz.org/topics/chilblains
4 Chilblains (Pernio): What is it, symptoms, causes & treatment. Cleveland Clinic. (n.d.). Retrieved December 30, 2022, from https://my.clevelandclinic.org/health/diseases/21817-chilblains-pernio
5 Bush, J., Lofgran, T., & Watson, S. (2022, August 8). National Center for Biotechnology Information. Retrieved December 30, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK482364/
6 Zonnoor, B. (2021, December 15). Frostbite. Background, Pathophysiology, Etiology. Retrieved December 30, 2022, from https://emedicine.medscape.com/article/926249
