The failure or complete shutdown of the body's heating system creates two problems; localized cold injuries and generalized cold injuries. Localized cold injuries involve the most vulnerable body parts; the ears, nose, face, fingers and toes. Generalized cold conditions affect the whole body, especially the brain.

The severity of a cold injury depends upon the amount of exposure time, the exposure temperature and the wind velocity. In order to warm itself, the body uses two primary methods. First, blood is shunted to the core of the body where it is kept warmer and heat loss is reduced, and secondly, the body shivers in an attempt to generate heat. The shunting of blood to the core of the body will result in a pronounced sympathetic response in which you will see appearance changes with the skin.

Due to this shunting process the areas with reduced circulation will cool rapidly and begin to freeze. It primarily affects the skin, nose, ears, fingers and toes. This condition is called frostbite. In severe cases, ice crystals start forming inside the body and cause damage to blood vessels, nerves and other tissues.

The affected area will first become red and inflamed but may quickly turn pale. If this condition progresses, the tissue will become gray or waxy in appearance. The patient will likely lose sensation in the area and feel no pain. The lack of pain indicates the tissues are actually frozen and some permanent damage, including the possibility of tissue loss may result.

Management for frostbite is relatively simple and straightforward. Move the patient to a warm environment but don't let them walk or stand on an injured extremity. Remove any wet or restrictive clothing and warm the affected body part in warm water. The water temperature for rewarming is approximately 104-105 degrees Fahrenheit. Only begin rewarming if there is no chance of the injured part getting frostbitten again. Do not rub the frostbitten parts because it is very painful and the friction can result in more tissue damage.

If shunting and shivering fail to keep up with heat loss, we say the heating mechanism of the body has failed. When this happens, the core temperature of the body starts to drop. A drop in core temperature of more than several degrees result in hypothermal. Since the brain is very susceptible to temperature changes, it is affected quickly by the cold and will cause the patient to have an altered level of responsiveness. In many cases, these patients do not even realize they are in danger.

Although the traditional setting for hypothermia is outdoors, it doesn't just occur in the snow or in very cold climates. It is quite common for hypothermia to occur in urban settings and it often involves the elderly. Factors contributing to hypothermia are medical conditions, environment, age and if drugs, alcohol or poison are involved. Becoming hypothermic can be a sudden or gradual process. Sudden immersion into very cold water, such as falling through thin ice into a lake can bring about life-threatening hypothermia in just a matter of minutes. By comparison, the hunter who tracks a deer in the rain may slowly develop hypothermia over a period of four or five hours. Regardless of the onset time-span, as a patient's core temperature drops, so will their level of responsiveness. With this comes a change in decision-making capabilities and the ability to perform fine motor skills.

Once the body can no longer generate heat through shivering, movement will cease and your patient may appear dead. EMS should be summoned any time hypothermia is suspected. Your first goal when managing a hypothermic patient is to prevent further heat loss. Remove the patient from the cold environment and begin to rewarm them gradually. When handling a hypothermic patient be gentle, as abrupt movements can cause the heart to begin fibrillating. Removing wet clothes and placing the patient next to a heat source will aid in the warming process.

For the patient who can still generate heat, wrap them in blankets or pre-warmed towels. Using your body heat by lying close to them is also very helpful.

Heating from the outside in is a very slow process, possibly taking hours. If the patient is alert enough to protect their own airway, give them warm liquids by mouth. Warm water, juice or soup are excellent in this situation. Avoid alcoholic beverages or any caffeinated drinks as they can negatively impact the rewarming process. Do not allow the patient to smoke because nicotine can cause further constriction of blood vessels and worsen tissue damage.

When you encounter a hypothermic patient who appears dead, approach patient care like any other situation. You should assess responsiveness, evaluate ABC's, call 911 and apply an AED. Due to the low body core temperature, it is unlikely that defibrillation will be successful. Once body core temperatures fall below 83 degrees, electrical therapy (AED) is extremely ineffective.