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Interviewer: My name is Vivian Lee. I'm the senior vice president for health sciences at the Ï㽶ÊÓƵ of Utah, and today we're going to talk about the cold. This can mean dangerous medical problems for people that are exposed to the cold for long periods of time and even short periods of time. Joining me today is Dr. Amalia Cochran, assistant professor of medicine at the Ï㽶ÊÓƵ of Utah's department of surgery. She's also an attending surgeon in the university hospital's burn unit and a leading expert on frostbite. Welcome to the show.

Dr. Amalia Cochran: Thank you very much.

Interviewer: We had an experience that made me have to go online and look up frostbite and I realized there wasn't as much information as I would hope. My daughter came back. She was fine after a whole day of skiing, and then she got into the bathtub and she started screaming because she said her feet were really painful and then the tips of her toes were dark red, almost bluish. At that point in time you can imagine I just panicked and tried to look online. I thought, here you are, the expert, let me ask you, what was happening with her? How could I have prevented that?

Dr. Amalia Cochran: It honestly sounds to me like she probably had a case of frost nip. When you're out skiing you've got a prolonged exposure, as does anyone who's outdoors during this weather. The fact that prior to that exposure to the warm water bath she hadn't really had any significant complaints and you hadn't really noticed anything different . . .

Interviewer: No, and is that because you have numbness so you don't even realize what's happening?

Dr. Amalia Cochran: Precisely. There is numbness with frost nip and you see very few changes in the skin if someone has a case of frost nip.

Interviewer: Frost nip is different from frost bite?

Dr. Amalia Cochran: Frost nip is the extremely mild form of frost bite. The way that we tend to differentiate between them is that frost bite involves tissue changes where the skin will actually blister up versus frost nip where there is some of that damage to the skin and the soft tissue but not to the level where it blisters.

Interviewer: Is it blistering because the tissue is actually freezing? What's actually happening there in the skin?

Dr. Amalia Cochran: There are really two different things that occur in the skin with a frost bite or a frost nip injury. One of those is the direct cold injury from the temperature. That impacts the tissues. They do freeze. Little crystals form in them. The other phenomenon that occurs in association with that is ischemia where there is poor blood flow to the cold effected areas. Initially, when the outdoor temperature drops or when we're exposed to lower temperatures somewhere in the neighborhood of 50 degrees fahrenheit, there's a cold induced phase of dilation that occurs.

Interviewer: Blood vessels expand. All of a sudden this blood rushes back in, and then what happens?

Dr. Amalia Cochran: Right. But then after that they constrict. They narrow back down and so the blood flow diminishes.

Interviewer: One of the things about this that worries me is that because of the numbness the kids don't even seem to know that it's happening, so how do we know that that damage is occurring?

Dr. Amalia Cochran: Cold checks are what are recommended in the Alpine mountaineering literature. I think they apply to those of us that are recreational outdoor in the winter as well. The concept of cold checks is that you get yourself to a relatively sheltered location, and I phrase it that way since this is from the Alpine mountaineering literature because there would be a relative shelter if you're skiing, you can say, hey, let's take a hot chocolate break after an hour and a half, and go in and check fingers, check toes.

Interviewer: We do them every half hour sometimes.

Dr. Amalia Cochran: Some days that's really appropriate. You can check everyone's fingers, check everyone's toes. If you notice that the fingertips or the toes are looking particularly pale, if they start getting a little bit woody in terms of how they feel, if they're not as soft as they normally feel, any of those sort of characteristics, that would make you concerned that you may have the early phases of a cold injury occurring.

Interviewer: How can we prevent it?

Dr. Amalia Cochran: Preventing it is a little bit tough if you have a love for winter sports. One of the things is that if you are someone who knows that you have circulatory challenges finding ways to keep your fingers and toes warm.

Interviewer: So even when it's not that cold our fingers and toes get kind of cold. We're particularly sensitive to developing it.

Dr. Amalia Cochran: Absolutely. Be mindful. I tell people I have something known as Raynaud's phenomenon, which means that when I get cold my blood vessels in my fingers and my toes clamp down. So I not only very easily get cold fingers and toes but I'm at higher risk for cold injury. So when I ski I have heaters in my boots and my mittens.

Interviewer: Those hand warmer, toe warmer type things?

Dr. Amalia Cochran: They're actually battery packs.

Interviewer: Oh, I didn't know they made that.

Dr. Amalia Cochran: Yeah, they're a little spendy but they're worth it. I whine a lot less and I have to take fewer breaks.

Interviewer: But short of that, you recommend the hand warmers and toe warmers?

Dr. Amalia Cochran: They're definitely helpful.

Interviewer: Dr. Cochran, you're not only an expert in frostbite but you're also a leader in burn injuries. I noticed we recently had an avalanche victim who had frostbite and was cared for in our burn unit. Maybe you can explain to us this relationship. Why are the frostbite patients and the burn patients all cared for by the same people?

Dr. Amalia Cochran: That surprises people and I know our avalanche victim was a little confused when I showed up and introduced myself and said I was a burn surgeon. She gave me this puzzled look. I said, "Trust me. This is going to be okay." There are a couple of reasons that frost bite victims end up in the care of the burn unit, and one of those is because the mechanism of injury, the way that the body works to generate the frostbite injury or the cold injury is actually very similar to what ends up happening if people have a burn injury. The underlying pathophysiology, to use the big fancy word for it, of what causes the tissue damage is very similar. The other part of it is that with more major cases of frostbite when people have blisters or if they don't get treatment in a timely fashion they can even have gangrene where the tissues die, we are experts in managing soft tissue loss and getting areas of soft tissue loss closed or covered because of the fact that that's what we do with burns. So it ends up making our frostbite practice a very logical extension of what we're already doing.

Interviewer: One of the things I read online when I was reading about this was that you're not supposed to rub the tissues. Why not?

Dr. Amalia Cochran: That's an old wives tale. Historically, people were advised to remove their gloves and their boots and rub the area with snow even to help with cold injury if they thought they were getting cold injury. The problem with doing that is you extend the damage in the soft tissues with the friction. So it's actually not helpful to do that

Interviewer: So the tissue is already pretty fragile and if you're rubbing it you're just making the damage worse.

Dr. Amalia Cochran: Right. So the recommendation for rewarming now is a 40 degree centigrade, which is around 100 degree fahrenheit, warm water bath.

Interviewer: Is 100 degrees about a normal temperature bath?

Dr. Amalia Cochran: It would be a warm bath.

Interviewer: A warm bath.

Dr. Amalia Cochran: Yes.

Interviewer: I was always told that you need to keep your central body really, really warm and if you kept your trunk warm your extremities would sort of take care of themselves. But you're sort of saying, no, those hand warmers are important too.

Dr. Amalia Cochran: Yes, it's both. You need to keep your core warm because of the risk of hypothermia, but when you're looking at a risk for frostbite you need to look at keeping your extremity areas, your fingers, your toes, even your nose is an area that's at risk for lower blood flow when you get really cold.

Interviewer: So those face warmers too.

Dr. Amalia Cochran: Yes.

Interviewer: Well, Dr. Amalia Cochran, thank you so much for being my guest today.

Dr. Amalia Cochran: Thank you, Dr. Lee.

Announcer: We're your daily dose of science, conversation, medicine. This is The Scope. Ï㽶ÊÓƵ of Utah Health Sciences Radio.