00:01
So now we’re gonna switch gears a little bit and talk about another cold related problem.
00:05
So in this case, we have a 46-year-old gentleman
who comes into the Emergency Department with bilateral foot pain.
00:11
He’s homeless and he spends most of his time walking around on the street wearing sneakers
which is the only pair of shoes that he owns.
00:17
It’s February and there’s snow and slush on the ground, so his shoes are getting wet.
00:23
He’s been in our waiting room for about 7 hours
and by the time we see him in the care area,
you can see that his feet look like what you see here in this picture.
00:33
So he’s got some swelling and he’s got some blue discoloration of all of his toes.
00:39
What’s the diagnosis for this gentleman?
Unfortunately, this man has frostbite.
00:46
So risk factors for frostbite include obviously, low temperatures.
00:52
You don’t get frostbite when it’s warm out.
00:54
Also, high velocity wind, exposure to water or snow, and that’s very, very important.
01:00
Remember, we mentioned that you lose much more heat through conduction when you’re wet.
01:06
So anytime you have digits that are exposed to water or snow,
the risk of frostbite increases significantly.
01:13
Wearing clothing that’s wet, constrictive, or inadequately insulating
increases your risk and of course, anything that impairs your judgement.
01:21
So alcohol, drugs, fear or panic in a wilderness setting
can raise your risk of developing frostbite.
01:29
So you can get frostbite anywhere on the body
but we see it most often in peripheral areas that have relatively poor vascularization.
01:40
So fingertips, toes, the tip of the nose, the tips of the ears, and the penis.
01:46
I do wanna mention also that occupational exposures can lead to frostbite.
01:51
So for people who work with supercooled substances
like in the air-conditioning industry for example,
they can have frostbite as a result of exposures to those substances.
02:02
So the way frostbite works is basically, when your tissue actually cools below the freezing point
and ice crystals form in the tissue, that’s what leads to frostbite.
02:14
So there’s four different phases of frostbite.
02:18
So there’s the period before the tissue actually freezes when it’s gotten very, very cold
but has not yet formed ice crystals.
02:26
So the tissue cools, it vasoconstricts which causes ischemia,
and then, there’s inflammation related to the ischemia
that leads to endothelial leakage and tissue damage from inflammatory mediators.
02:39
Then, there’s the freeze-thaw stage.
02:42
So at that point, ice crystals begin to form in the tissues.
02:45
The cells become dehydrated because the water that belongs inside of them
is now inside of ice crystals and cells die as a result of that.
02:56
After the freeze-thaw stage, you develop vascular stasis.
03:00
So basically in the region of the body that’s frozen,
you start to get microvascular thrombus formation
which occludes the vasculature and further exacerbates ischemia.
03:11
After that, there’s the late phase which is called late progressive ischemia,
and basically, as a result of all of the other things that we’ve talked about,
you see hypoperfusion of the tissue in the region,
a lot of inflammatory change, and tissue necrosis.
03:26
Clinically speaking, frostbite can be divided into three phases.
03:30
So early on in the course of frostbite, the patient will complain that the affected area feels cold,
it’s painful, they’ll often complain of paresthesias.
03:39
When you examine them, they might have relatively few findings on their physical exam.
03:47
So just like the picture we saw of our patient’s slightly discovered blue toes,
that might be all you see.
03:53
Sometimes it’ll be a waxy or still texture to the tissue as well,
but it can actually look more benign than it is early on.
04:02
The middle phase of frostbite is gonna involve basically complete sensory loss.
04:07
The patient is gonna be numb and insensate in the affected area
and that’s because the nerve endings are actually frozen and killed.
04:14
They’re of course gonna lose dexterity as well
because they’re not gonna have normal neurologic function in the affected extremities.
04:22
In the middle phase when you examine them,
you’re gonna start to see blister or bullae formation,
and they’re gonna start to desquamate or slough their skin.
04:31
Finally, in the late phase, this is where the patient really begins to experience pain.
04:38
So they’ll have throbbing pain and it can persist for weeks or months
well after the tissue damage has actually stopped evolving.
04:48
This is the phase in which we’ll start to see tissue loss.
04:51
We’ll see demarcation of the area that is no longer viable and development of dry gangrene.
04:58
And here’s some pictures that illustrate the progression of frostbite.
05:02
So early on, you see that blueish discoloration
that you can see in this patient on the toe and on the heel.
05:08
As you move into the middle phase,
you can see formation of bullae and blisters over the affected area
and this patient as these bullae rupture will begin to desquamate.
05:20
And then, in the final picture,
you see demarcation and dry gangrene of all of the affected digits.