Frostbite and Chilblains

What is Chilblains?

Chilblains occurs on the extremities (toes and fingers) and is evidenced by exposure to cold. Symptoms are swelling and redness of the skin. An important distinction between chilblains and Frostnip: Chilblains mostly occurs with moisture and the temperature does not have to be below freezing. Many of us may have had chilblains and it often resolves with rewarming without long term side effects.

What is Frostnip?

Frostnip involves the superficial layer of the skin and includes tissue death. Frostnip always involves temperatures below freezing or close to freezing. Frostnip skin will be seen as whiteish and pale. The skin is often firm and not pliable. This can be very painful. Frostnip involves vasoconstriction and can often lead to frostbite if not treated rapidly. One can feel numbness and the “pins and needles” sensation.

What is Frostbite?

Frostbite is the body’s inability to compensate for cold exposure which will then produce injury. Time of exposure, humidity, wind, clothing, a past history of frostbite and having vascular conditions all contribute to frostbite. Being a smoker as well as ethnic and cultural factors do play a role in frostbite. Those who have acclimated to the cold as the Inuit have less of a risk to frostbite than those from warm climates.

Frostbite Pathophysiology

There are three phases of frostbite:

1. Skin temperature drops, blood flow to the surface of the skin decreases. The body initiates “The Hunting Response.” This is a 5-10 minute cycle where blood vessels dilate and then contract which is the body’s response to rewarming. This first phase is the pre-freeze phase.
2. The freeze-thaw phase is where intracellular fluid shifts across membranes. In theory, this is when ice crystals form.
3. The last phase is the most severe and is the late stage or ischemic phase. The skin becomes necrotic and dies. There can actually be bone involvement at this phase. I have only had one case of this severity in a homeless man. It should be noted that these phases can overlap.

Frostbite Symptoms

Frostbite symptoms are classified in stages much like burns.

• First degree frostbite: Skin becomes red, no blisters. Throbbing and pain is common. Stinging with pins and needles sensation.
• Second degree frostbite: Redness and blisters are common. The blisters can have a blackened base as decreased oxygen leads to cell death.
• Third degree frostbite: Burns are deeper involving the second layer of skin dermis and involves blistering also.
• Fourth degree frostbite: This is the most severe. Muscle involvement and even bone involvement can occur in severe cases. Minimal swelling. Pain can be absent. This frequently leads to amputation.

What is Frostbite Treatment?

Outdoor treatment for frostbite is not complicated but can be cumbersome.

1. Remove all wet clothing and replace with dry clothing if possible.
2. If available, wrap effected areas with sterile gauze.
3. Elevate the effected area.
4. Rewarming – The controversy.  Should you rewarm in the field or wait till you are at a facility? If you are 4-5 days from being able to get back to civilization, advise to wait as rewarming then refreezing would clearly have a worse outcome. In researching the data, I have found zero good outcome studies of delayed rewarming vs rewarming and the effects of refreezing.
5. Place cotton or gauze between the toes and between the fingers.

Rewarming

Do not use snow and do not rub effected areas with your hands.

1. Water should be warmed to about 104 degrees – the average temperature of a hot tub. You do not need a thermometer to get close. Place your hand in the water. If you have to remove quickly, it is clearly above 104º F. At 104º F, you should be able to hold your hand in the water without getting burned ..close enough for the outdoors. Many waterproof watches like Casio will have a thermometer. You can submerge your watch for a temperature check.
2. Treat with non steroidal anti inflammatory like ibuprofen. It has an anti-prostaglandin property. It will help decrease inflammation.
3. Warm the frostbitten area for approximately 15-30 minutes. Repeat in about twenty minutes. In the clinic, blisters should be debrided. I would never debride the blisters in the field as they work as a nice barrier for infection. In the clinic, I apply Silvadene and bandage.
4. Tetanus must be updated.
5. Many advise hydrotherapy for 30-40 minutes daily until blood flow and pain  improve.

Misinformation

There is so much misinformation on the Internet and Youtube it is astonishing. Some misinformation is from prominent institutions. On the Mayo Clinic website, they advise coffee and hot chocolate for rewarming the system. Both are vasoconstrictors. Remember we are trying to increase blood flow to the extremities so NO caffeine, NO chocolate and NO smoking.

Frostbite Prevention

1. Be aware of the weather on your trip. Anticipate the long term forecast.
2. A waterproof bag is ideal with an extra set of clothes.
3. Remember the importance of layering. Layer nylon socks with wool socks as the top layer. Cotton will absorb water and sweat. NO COTTON SOCKS.
4. Warm your noggin. The majority of heat escapes through your head
5. If you smoke, it’s very helpful to decrease or stop before a cold weather expedition. Even 48 hours before will help with circulation.
6. Proper hydration is imperative. Fluids, fluids, fluids.
7. Pocket and foot warmers are very helpful.
8. Windmilling has proven to be effective in getting blood flow to your fingers. Taking your arm and rapidly swinging it in a circular motion helps.
9. Do not blow on fingers or toes due to saliva settling on the extremities you are blowing on.
10. There is some evidence that this is not the time to wash your hands. Frostbite has been shown to be more susceptible to those who have clean skin. Refer to study with Nordic fisherman who did not wash their hands for three to four days and had less evidence of frostbite than those with clean hands. Of course they were also acclimated better than others also.