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While many in the Northern Hemisphere cannot avoid winter exposure, others actively seek outdoor activities on skis, snowmobiles, or ice fishing. Paramount to your comfort and safety is prevention and treatment of cold-related injuries. Frostbite is the one that most consider but non-freezing cold injuries also occur. Respiratory problems are caused from cold air by increasing secretions and decreasing pulmonary function.
Frostbite occurs when tissue freezes, forming ice crystals. Skin freezes at 210 F but will occur more rapidly and at higher temperatures with wind and moisture. Cells can survive freezing and thawing but small blood vessel damage causes clots to obstruct circulation leading to tissue death. Among risk factors that increase frostbite risk are diabetes, cardiac problems, peripheral vascular spasm (Raynaud’s phenomenon), and heavy alcohol consumption which contributes to heat loss and hypothermia.
We have all noted that our ears, nose, fingers, and toes seem to become cold quickly. The body conserves heat by first constricting vessels to organs non-essential to life and these high surface area structures farthest from the heart are the most susceptible. Feet are particularly susceptible due to mechanical trauma and moisture condensation. Moisture in footwear is the most important variable that affects thermal insulation and comfort according to Swedish research, so foot protection is essential. Moisture in combination with motion may reduce insulation and thus protection against cold by 45%. Proper attention to food, exercise, insulation with nonconstrictive clothing, and protection from moisture is needed to maintain heat production.
If frostbite develops, the best treatment is rapid and continued submersion in warm water (104-1070 F) for at least 30 minutes. The best action is to get to facilities where this is controlled. Treatment is quite difficult in the field because it requires sufficient fuel and water for a complete thaw and the temperature must be tightly controlled. Too much heat or the dry heat from a fire can dessicate tissue and extend the damage. It is much better to not thaw the body part if there is a chance of a refreeze which will result in greater damage. Do not massage the body part to minimize further trauma to the damaged tissue. As the body part thaws, it will turn red as blood flow returns but nerve reactivation will cause pain requiring medication. Blister formation after thawing suggests more severe injury, especially if filled with blood. Wrap the body part with sterile bandages with pads between digits and elevate it. Photos uploaded to the internet can allow immediate access to hospital-based specialists who can assess cold injuries and advise on early field care.
Non-freezing cold injury can also affect tissue. Chilblain and pernio are conditions characterized by itchy, painful, swollen skin after a few hours of exposure. Pain medication and the avoidance of secondary exposure are important. Both of these conditions resolve after drying and rewarming with no prolonged damage. Trenchfoot is a much more serious condition following several days of cold, wet feet. The white, cold feet become red, hot, and painful after warming and these symptoms intensify over the next few weeks and may persist. All of these conditions emphasize the need to keep feet warm and dry.
Resolution of frostbite may take weeks to delineate the area of damage. Frostnip is the condition where tissue recovers within a few days without permanent damage. With actual frostbite, the salvaged tissue may be cold sensitive for years. This was impressed upon me by a patient who as a young Marine decades ago fought his way out of the Choisin Reservoir in the Korean War in deep winter. He complained more about the continued effects of his frostbite than the surgical problem which required my services.
So, bundle up, keep your feet dry and warm, come inside for the spirits!
Michael J. Manyak, MD
VP National Eagle Scout Association
Author, Lizard Bites and Street Riots, Travel Emergencies and Your Health, Safety, and Security
Twitter: @LizardBites
1 George R. R. Martin
March 4, 2016
