Frostbite Basics

Silent Symptoms

Have you ever held an ice cube in your hand? The cold, prickly sensation you felt in your fingers was an early sign of frostbite. Of course, the cube probably melted before any damage to your skin or tissue could occur. But what if you were surrounded by ice and snow, like on the peak of a mountain? The situation could be a lot more serious. Even if you were dressed for the weather, prolonged exposure to the cold would allow frostbite to set in. The symptoms would begin with tingling and burning, and progress to numbness and blistering of the skin and hardening of the tissue underneath. Because frostbite has to do with blood circulation, the areas of your body most at risk would be those farthest from your heart, such as the hands and feet [source: Bjerke]. In some cases, frostbite can occur on the lips, nose and ears.

But what if you're exposed to the cold in a more everyday environment? Even ordinary activities such as shoveling the driveway or helping the kids build a snow fort can take a surprising toll. That's because frostbite can set in before you even know you're in danger. In fact, it takes longer to watch your favorite sitcom than it does for your skin to freeze when the wind chill reaches negative 28 degrees Fahrenheit (negative 33 Celsius) [source: Environment Canada]. How does all this happen?

Frostbite is the result of an internal process designed to save your life in cold conditions by sacrificing your limbs. The hands and feet contain microscopic junctions between arteries and veins. They're called arteriovenous anastomoses and they act as valves to control blood flow. Just as you can regulate the flow of tap water from a kitchen spigot by adjusting the handle, these junctions adjust blood flow to the extremities. How is this related to frostbite? When your body gets too cold, the arteriovenous anastomoses shut down blood flow to your hands and feet to keep your core temperature steady [source: Cheng]. Without the warm blood to keep tissues toasty, your toes and fingers are apt to freeze -- fast.

Plus, when your skin is exposed to freezing temperatures, ice crystals form in the spaces between cells. The freezing process dehydrates the cells' interiors and damages the skin and underlying tissue [source: Stoppler]. Combine cold temperatures with prolonged exposure and other harsh conditions, such as an oxygen-depleted altitude, and the risk for limb-altering frostbite increases [source: Mechem].

In Gardner's case, his odds of survival were better than the average person's. Why? Muscle mass, for starters. By using his large muscles to move, Gardner could create internal heat to encourage blood flow. Plus, years of athletic training and competition had accustomed his veins to infuse tissues with blood at a moment's notice [source: Speik]. Even so, Gardner's frostbite caused burn-like damage and the loss of a toe. He could have faced worse side effects, though. Up next, which we'll explore other consequences of frostbite and how to treat them.