bite it frosty

frostbite, lets review (from here)

a. First-degree frostbite is an epidermal injury. The affected area is usually limited in extent, involving the skin that has had brief contact with very cold air or metal (e.g., touching an outside door handle). The frozen skin is initially a white or yellow plaque. It thaws quickly becoming wheal-like, red and painful. Since deep tissues are not frozen (though they may be cold) mobility is normal. The affected area may become edematous but does not blister. Desquamation of the frost-bitten skin with complete clinical healing follows in 7-10 days.

b. Second-degree frostbite involves the whole epidermis and may also affect superficial dermis. The initial frozen appearance is the same as in first-degree frostbite. Since the freezing involves deeper layers and usually occurs in tissue with prolonged cold exposure, some limitation of motion is present early. Thawing is rapid with return of mobility and appearance of pain in affected areas. A bulla, with clear fluid, forms in the injured area over several hours after thawing. The blister fluid is extravasated from the dermis. Usually, the upper layers of dermis are preserved which permits rapid re-epithelialization after injury. Second-degree injuries produce no permanent tissue loss. Healing is complete but takes three to four weeks. Some amount of first-degree injury is frequently present in the immediate vicinity of second-degree frostbite. Frostbite should be looked for on all other exposed areas. Following second-degree frostbite, cold sensitivity may persist in the injured area.

c. Third-degree frostbite involves the dermis to at least the reticular layer. Initially, the frozen tissue is stiff and restricts mobility. After thawing, mobility is restored briefly, but the affected skin swells rapidly and hemorrhagic bullae develop due to damage to the dermal vascular plexus. The swelling restricts mobility. Significant skin loss follows slowly through mummification and sloughing. Healing is also slow, progressing from adjacent and residual underlying dermis. There may be slight permanent tissue loss. Residual cold sensitivity is common.

d. Fourth-degree frostbite involves the full thickness of the skin and underlying tissue, even including bone. Initially the frozen tissue has no mobility. Thawing restores passive mobility, but intrinsic muscle function is lost. Skin reperfusion after thawing is poor. Bullae and edema do not develop. The affected area shows early necrotic change. The injury evolves slowly (weeks) to mummification, sloughing, and auto-amputation. Whatever dermal healing occurs is from adjacent skin. Significant permanent anatomic and functional loss is the rule.

e. Corneal frostbite is a rare, but profoundly disabling injury. The evolution is similar to any deep ocular keratitis. Permanent corneal opacification requiring corneal transplant is a common outcome.

now lets talk temps (link InteliHealth here)

Frostbite is the freezing of body tissues (skin, muscle, bone) in extreme cold. At or below 59° Fahrenheit, blood vessels close to the skin start to narrow (constrict). This helps to preserve your core body temperature. In extreme cold or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of your body to dangerously low levels. The combination of cold temperature and poor blood flow can cause tissue injury. Frostbite is most likely to happen in body parts farthest from the heart, and those with a lot of surface area exposed to cold. These areas include the toes, fingers, ears and nose.

Body tissue will not freeze until the outside temperature is at or below 28° Fahrenheit. If areas of tissue exposed to extreme cold begin to freeze, ice crystals form in some cells and fluid flows into these cells. This can cause the cells to burst. Additional damage can occur when the tissue is warmed again, because damaged blood vessels can leak fluid and proteins into tissue, causing swelling and blistering.

and some handy tables from WMRC, link here

(click on image to enlarge)

first aid, from MedlinePlus, link here:

1. Shelter the victim from the cold and move the victim to a warmer place. Remove any constricting jewelry and wet clothing. Look for signs of hypothermia (lowered body temperature) and treat accordingly.

2. If immediate medical help is available, it is usually best to wrap the affected areas in sterile dressings (remember to separate affected fingers and toes) and transport the victim to an emergency department for further care.

3. If immediate care is not available, re-warming first aid may be given. Immerse the affected areas in warm (never HOT) water -- or repeatedly apply warm cloths to affected ears, nose, or cheeks -- for 20 to 30 minutes. The recommended water temperature is 104 to 108 degrees Fahrenheit. Keep circulating the water to aid the warming process. Severe burning pain,swelling, and color changes may occur during warming. Warming is complete when the skin is soft and sensation returns.

4. Apply dry, sterile dressing to the frostbitten areas. Put dressings between frostbitten fingers or toes to keep them separated.

5. Move thawed areas as little as possible.

6. Re-freezing of thawed extremities can cause more severe damage. Prevent re-freezing by wrapping the thawed areas and keeping the victim warm. If re-freezing cannot be guaranteed, it may be better to delay the initial re-warming process until a warm, safe location is reached.

7. If the frostbite is extensive, give warm drinks to the victim in order to replace lost fluids.

Do Not

• DO NOT thaw out a frostbitten area if it cannot be kept thawed. Refreezing may make tissue damage even worse.
• DO NOT use direct dry heat (such as a radiator, campfire, heating pad, or hair dryer) to thaw the frostbitten areas. Direct heat can burn the tissues that are already damaged.
• DO NOT rub or massage the affected area.
• DO NOT disturb blisters on frostbitten skin.
• DO NOT smoke or drink alcoholic beverages during recovery as both can interfere with blood circulation.

Call immediately for emergency medical assistance if

• There has been severe frostbite, or if normal feeling and color do not return promptly after home treatment for mild frostbite.
• Frostbite has occurred recently and new symptoms develop, such as fever, malaise, discoloration, or drainage from the affected body part.