So now we’re gonna switch gears a little bit and talk about another cold related problem.
So in this case, we have a 46-year-old gentleman
who comes into the Emergency Department with bilateral foot pain.
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.
It’s February and there’s snow and slush on the ground, so his shoes are getting wet.
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.
So he’s got some swelling and he’s got some blue discoloration of all of his toes.
What’s the diagnosis for this gentleman?
Unfortunately, this man has frostbite.
So risk factors for frostbite include obviously, low temperatures.
You don’t get frostbite when it’s warm out.
Also, high velocity wind, exposure to water or snow, and that’s very, very important.
Remember, we mentioned that you lose much more heat through conduction when you’re wet.
So anytime you have digits that are exposed to water or snow,
the risk of frostbite increases significantly.
Wearing clothing that’s wet, constrictive, or inadequately insulating
increases your risk and of course, anything that impairs your judgement.
So alcohol, drugs, fear or panic in a wilderness setting
can raise your risk of developing frostbite.
So you can get frostbite anywhere on the body
but we see it most often in peripheral areas that have relatively poor vascularization.
So fingertips, toes, the tip of the nose, the tips of the ears, and the penis.
I do wanna mention also that occupational exposures can lead to frostbite.
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.
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.
So there’s four different phases of frostbite.
So there’s the period before the tissue actually freezes when it’s gotten very, very cold
but has not yet formed ice crystals.
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.
Then, there’s the freeze-thaw stage.
So at that point, ice crystals begin to form in the tissues.
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.
After the freeze-thaw stage, you develop vascular stasis.
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.
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.
Clinically speaking, frostbite can be divided into three phases.
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.
When you examine them, they might have relatively few findings on their physical exam.
So just like the picture we saw of our patient’s slightly discovered blue toes,
that might be all you see.
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.
The middle phase of frostbite is gonna involve basically complete sensory loss.
The patient is gonna be numb and insensate in the affected area
and that’s because the nerve endings are actually frozen and killed.
They’re of course gonna lose dexterity as well
because they’re not gonna have normal neurologic function in the affected extremities.
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.
Finally, in the late phase, this is where the patient really begins to experience pain.
So they’ll have throbbing pain and it can persist for weeks or months
well after the tissue damage has actually stopped evolving.
This is the phase in which we’ll start to see tissue loss.
We’ll see demarcation of the area that is no longer viable and development of dry gangrene.
And here’s some pictures that illustrate the progression of frostbite.
So early on, you see that blueish discoloration
that you can see in this patient on the toe and on the heel.
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.
And then, in the final picture,
you see demarcation and dry gangrene of all of the affected digits.