Unlike many in Hollywood and Washington DC who pretend to have PhD’s in environmental science, we admit that what we know to be a fact about global warming can be written on the head of a pin with a jackhammer. But we are darn sure it has been cold these past few weeks and that it will get colder before it gets warmer again. So we thought now was a good time to discuss a specific type of injury that can occur when exposed to freezing temperatures. Cold injury runs the gamut from inconvenient to life threatening. Prevention is obviously best and early intervention and treatment is essential to prevent these potentials from becoming reality.

There are three general types of cold injury: Chilblain, Immersion foot (trench foot) and frostbite. Only frostbite involves the actual freezing of tissues as part of actual injury. As you would expect certain co-existing conditions make someone more or less susceptible to cold injury. Also because these injuries pre-date modern medicine, there are myths about treatment that are quite harmful indeed.

Chilblain is cold injury that falls into the irritating rather than the threatening category. It is characterized by red, scattered areas of itching and burning skin, mostly on the back of the hands and feet. This injury is seen almost exclusively in those folks with vascular disorders such as Raynaud’s syndrome and other “collagen” diseases. These lesions tend to appear as the weather changes to cold and go away with the spring. There is no treatment per se, except maybe moving to warmer climates.

The very politics of the world we live in has been shaped to a greater or lesser extent by the cold injury known as trench-foot, or less colorfully as immersion foot. This condition has been following the footsteps of the military since before recorded history, but impacts the hunter and hiker as well. What happens with immersion foot is that the body reacts to cold feet in a manner devised to preserve the central warmth of the chest and central nervous system. It does so by shunting blood away from the heat draining feet.

Now this injury requires time to occur and is not a consequence of a few hours of cold feet in the tree stand or waterfowling. Wet or damp feet assist in the development of this injury by making it easier for your feet to lose their precious heat even when exposed to temperatures not far below 50 F (10 C). A period of 10 - 12 hours will usually be sufficient to induce immersion foot in the right conditions. If your toes are toasty, then regardless of outside temperatures, you can't suffer this illness. Layered socks, insulated, waterproof boots that allow for circulation and moisture wicking materials are safe guards here. Cigarettes, alcohol, and conditions that pre-dispose to reduced blood flow are risk factors for trench-foot.

Immersion injury goes through three phases: First as a natural response to hours of cold exposure the body begins to shut down blood flow to the feet. Clinically the feet become swollen, blue (sometimes white) and sensation is diminished. Actual pulses are difficult to detect in the affected lower extremity and naturally the foot feels cold. This lack of blood flow causes damage to nerves, small blood vessels and other tissues if prolonged. When re-warming does occur, the body over compensates the blood starved tissue and the extremity is very painful, hot, dry and red.