With record-cold temperatures in much of the United States this winter, a high number of cold injuries have been reported. This podcast discusses prevention and treatment for hypothermia and frostbite. Brrrrr!
The GameChangers:
Host
Geoff Wall, PharmD, BCPS, FCCP, BCGP
Professor of Pharmacy Practice, Drake University
Internal Medicine/Critical Care, UnityPoint Health
Reference
https://www-nejm-org./doi/10.1056/NEJMra1800868?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
Pharmacist Members, REDEEM YOUR CPE HERE!
Not a member? Get a Pharmacist Membership & earn CE for GameChangers Podcast episodes! (30 mins/episode)
CPE Information
Learning Objectives
Upon successful completion of this knowledge-based activity, participants should be able to:
1. Differentiate between types of hypothermia
2. Discuss treatments for frostbite
0.05 CEU/0.5 Hr
UAN: 0107-0000-24-051-H01-P
Initial release date: 2/12/2024
Expiration date: 2/12/2025
Additional CPE details can be found here.
With record-cold temperatures in much of the United States this winter, a high number of cold injuries have been reported. This podcast discusses prevention and treatment for hypothermia and frostbite. Brrrrr!
The GameChangers:
Host
Geoff Wall, PharmD, BCPS, FCCP, BCGP
Professor of Pharmacy Practice, Drake University
Internal Medicine/Critical Care, UnityPoint Health
Reference
https://www-nejm-org./doi/10.1056/NEJMra1800868?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
Pharmacist Members, REDEEM YOUR CPE HERE!
Not a member? Get a Pharmacist Membership & earn CE for GameChangers Podcast episodes! (30 mins/episode)
CPE Information
Learning Objectives
Upon successful completion of this knowledge-based activity, participants should be able to:
1. Differentiate between types of hypothermia
2. Discuss treatments for frostbite
0.05 CEU/0.5 Hr
UAN: 0107-0000-24-051-H01-P
Initial release date: 2/12/2024
Expiration date: 2/12/2025
Additional CPE details can be found here.
Hey, CE plan members From CE Impact. This is Game Changers. I'm Jen Moulton and this week we're talking about a timely topic because, as I sit in below freezing temperatures in the Midwest, it is a real possibility, and that is frostbite. So with us today is Jeff Wall. Dr Wall, thank you so much for joining us on this very cold day to talk about this very cold topic.
Speaker 2:Not a problem. Yeah, no, I appreciate that. You know we had kind of talked about. This is a, yeah, as you said, very timely because of record cold temperatures across the US, including the Midwest. It has been absolutely freezing here, but I mean even in the Southeast you know my, my, a lot of my family lives in Nashville they had below zero temperatures which I'm sure they can't handle at all. They got nine inches of snow in Nashville too, which, again, I'm assuming after that snowfall it looked like an atomic bomb had hit in Nashville, because I'm sure it was just completely, you know, decimated, nobody on the streets and stuff like that. So, yeah, this is, this is absolutely a timely topic.
Speaker 1:Yeah, well, and what I've? What's so funny about that? We have some people on our team from Nashville as well and other places in the South that have gotten, you know, just crazy cold is they're not ready for it, like we know. You know we got, I don't know, 20 or almost two feet of snow, I think, which is the big deal, but when they get you know, a little dusting, they don't really know how to handle it. So everybody's talking about the weather. These days?
Speaker 2:Yeah, absolutely, I know, I'd my, my cousin and her husband. You know they got a lot of snow in Tennessee and they, you know my nephew and law goes. So when are the plows coming through? I'm like they don't have plows. Why would they, you know, keep plows and and have them under maintenance when they never get snowed, isn't it?
Speaker 1:Right, right, but then it's debilitating when they do.
Speaker 1:Exactly so yeah, so so I was reviewing the article that you're going to reference today, which is referenced in our show notes, and if anyone you, if anyone looks, there are some very disturbing photos.
Speaker 1:I had actually planned to share a frostbite story that I have, but then I felt a little wimpy when I saw those photos.
Speaker 1:But I had frostbite when I was in college, actually, when I was in pharmacy school, I was waiting for the can bus, so I went to the University of Iowa so we have what we call a can bus and I was on rotation at the dental building with Karen Baker back in the day. She's amazing, but anyway, I was waiting for the can bus and it was so cold and of course I was like dressed up, because it was, you know, rotation and I had, and of course it was like the early 90s, so I had these big, huge gold earrings in and as I waited for the bus, by the time I got home I could not feel my ears and I my ear lobes were red for months on end and I could not feel them. So I know that that gold was frozen to my ears and I had some frostbite and it was painful, like it tingles and it's painful, but if you look at the pictures on that article, that was nothing. So I'll let you get into it, because I know there's some very, very serious frostbite.
Speaker 1:what I had was very minimal, but I always remember it, so I'll let you take it away.
Speaker 2:All right. Yeah, no, that's. You know. My experience currently in my ICU at Arm tertiary care hospital has been pretty bad. We've had, you know, multiple admissions for severe hypothermia and we've had multiple patients who've had, as you've said, you know, black fingers, black nose, you know stuff like that from frostbite. So, yeah, definitely seen this quite a bit in the last three or four weeks and and and again, as you point out, you know, there's a lot of places that just aren't used to seeing this sort of stuff.
Speaker 2:So that's why we thought it would be a good time for a debate. There is no real gigantic like official guidelines. There is the wilderness medical society, and that's that's one of the articles that we referenced in the show notes, it you know. So you know they talk about a lot of stuff that has to do with wilderness medicine and of course, this is, this is one of them, but there's a lot of other sites you can use as well. American burn association actually has some pretty good stuff on frostbite, and so we're going to divide today's talk into the end of the two things. The first we're going to talk about, just you know, if we divide everything into cold injuries, we're going to talk about hypothermia, which in and of itself can be life threatening, and then move on to frostbite. So because we've certainly seen both here, back at a patient who was admitted to my medicine service two, two weeks ago, who had a core temperature of only 80.4 degrees Fahrenheit, to which I went, and he's still alive and he actually has frostbite but he made a good recovery. So I mean it was pretty amazing.
Speaker 2:So now, of course, as we all know, you know you're out when it's super duper cold. Obviously you'll use a loose body heat really, really quick and that's through a process called conductive cooling where, basically, you know you lose core, core heat in contact with any sort of external surface and, jen, that might have been what you were talking about you know with with, with, you know freezing cold, you know gold earrings, but the worst, of course, is water, right. So when you, when you have a body part that's submerged in water, the conductive heat loss is 25 times greater than an ambient air. And that's why you know when people are in, you know super cold water, you know they've been, you know, capsized or whatever in a shipwreck or whatever. They usually die from exposure. They don't die of you know shark attacks or anything like that. I mean they usually die of exposure because you, you know, you just can't tolerate being in that cold of water for that period of time.
Speaker 2:But it can occur even without that right and it just all, all waters, just accelerates the process significantly, or having having submerged water, sort of thing. So now, why is this? Why, you know, why do you get into all these sort of problems? It's because the body of course does a lot of things to prevent over overcooling it. It of course causes vasoconstriction, which pushes all the heat into, into the core, which is certainly what you want to do as well, though, interestingly, after a certain point of cold injury, you've got a phenomenon called cold cold induced vasodilation, which is a poorly understood phenomenon but probably has to do with local ischemic effects. So then you start to get micro plots in in the extremities feet, toes, you know, fingers, stuff like that and the body's response to that is is, of course, you know, trying to increase blood flow. So then you get this paradoxal vasodilation. The other thing that you see, of course, is a is a heat regulation mechanism of the shivering, which is of course an involuntary mechanism for heat generation, which actually does increase thermogenesis about sixfold. So when you shiver, you actually are increasing your core temperature significantly.
Speaker 2:Of course, it's also got its own problems associated with it, and anyone who has to deal with the hypothermia protocols and the ICU first. You know post-cardiac arrest patients or anything like that, you'll be able to deal with that as well. It's not incredibly common. I studied in 2008, found the incidence to be about 5.6 per 100,000 in the United States. But of course, you know, that only counts patients who actually go see a healthcare professional. Many times people do have mild hypothermia or frostbite injuries and they just don't ever see anybody about it. So the Wilderness Medical Society, you know, notes that once someone reaches a certain level of hypothermia, traditional thermometers aren't going to work. So tympanic thermometers or mouth thermometers are not going to work well to determine core temperature and they really shouldn't be used. They actually recommend epitempanic thermometers, which is a special type of tympanic thermometer which has an extended nozzle, if you will, and a cover, and that's actually better. And then, certainly, if they're hospitalized, and intubated.
Speaker 2:The other thing you can do, which is obviously the most accurate at all, is place an esophageal probe after you've intubated the patient. But the guidelines are pretty, in fact, that traditional thermometers that you can buy at a store are not good for measuring core temperature and should just basically not be used at all. Based on that temperature, we divide hypothermia into mild, moderate and severe stages and the symptoms that you get with them. So mild hypothermia is a core temperature between 89.6 and 95. So not that bad really. Patients are usually fine there. They may be, they may be shivering, but they are usually okay. They do reach a point where they can't care for themselves, because one of the big things that happens with all stages of hypothermia is mental status changes, and so you do reach a point where patients are confused enough that they won't be able to take care of themselves. So, even though they may not require, you know, intubation or ICU level care, they may need to be watched in an emergency department or something like that until they kind of warm up. Modern hypothermia is a core temperature of 82.4 to 89.6 degrees Fahrenheit and that at this stage most patients, though not all of them, lose consciousness. At this point, actually shivering ceases because patients lose their ability to normalize their core body temperature entirely and so the shiver response stops working. So the guidelines are pretty empathic about the fact that just because someone is in shivering you can't say that they're hypothermic or nonhypothermic, and I think that that's something that I did, though that was kind of interesting to note At this point. Mental status changes are pretty common, so a lot of cognitive dysfunction, dysarthria, ataxia and definitely hallucinations and other neurologic deficits. I don't know if anybody don't mean to plug a streaming service, but if anybody is watching True Detectives Night Country on HBO Max. It's about a murder mystery occurring in the Northern Arctic, in Alaska, and they actually talk many times about the fact that people who have significant hypothermia will often have hallucinations and things like that.
Speaker 2:Often these patients will develop various sundry EKG changes, including bradycardia and AB block, which of course can be life-threatening, and then severe hypothermia is a core temperature of less than 82.4. So the patient that I had that was found met that criteria. All these patients are unconscious, most of them have significant EKG changes and basically at that point we'll probably need basic life support, if not intubation. It's important to note that vital signs in these patients will be difficult to detect, like peripheral pulses of course won't work and things like that. So you definitely want to check carotid pulses and before you start doing resuscitative measures.
Speaker 2:The Wilderness Society of Medicine Society, as well as the Canadian government, have some pretty good resources If you want to check out their website. So, for example, the Medicine One website for Canada and then of course, the Wilderness Medicine Society website. Both has some pretty good resources on this, and they note that for hypothermia, the first thing you do is just basically assess mental state as well as temperature. So again divide them into that Again mild, moderate, severe hypothermia, and then assess whether their mental status is normal or has some sort of impairment with it, as well as shivering, to kind of figure out what's going on. And so they actually talk about OK, there's patients who certainly have been out in the cold for a long period of time but are not hypothermic. My guess is I probably fit this category several times than the last two weeks because, as Jen noted, I think we got something like 27 inches of snow in a week, which wasn't fun. And so they note that in these patients obviously all you need to do is reduce heat loss by trying to bring them inside, moving around and exercising to warm up, and with all of these they note that because of shivering and other heat loss, that high caloric food or drink is actually beneficial. So again, providing obviously something, maybe warm, with high calorie content is probably beneficial.
Speaker 2:Mild hypothermia, which again, I very well may have had in the last couple of weeks you want to have the patient sit down or lie down for at least 30 minutes. Obviously, try and get them out of the cold and if at all possible have some sort of vapor barrier, especially if you're outside. Apply heat to the upper trunk with blankets or heating pads, again giving high calorie food and drink, and monitor for at least 30 minutes before you let them do anything. And then for moderate hypothermia, again, most of these patients are going to be unconscious or have some sort of physiologic or neurologic deficits. They have to be horizontal, they should not receive food or drink because they can't control their airway. Again, giving heat to the upper trunk and if you have access to medical supplies and a medical center to actually use a warm saline intravenously so they actually heat saline to about 40 degrees centigrade, so about 101 degrees Fahrenheit, and go ahead and infuse that into the patient and that actually will rapidly get their core temperature up. And then for severe hypothermia, which they say that basically if you find somebody unconscious in the cold you should just automatically assume they have severe hypothermia. All the patients that I saw in our ICU in the last couple weeks were found down in the snow and all had severe hypothermia. Interestingly, most of them had some sort of alcohol or drug exposure that probably they lost consciousness or they went out into the snow and basically couldn't move after a period of time.
Speaker 2:If they have moderate hypothermia, the important thing is to check vital signs. Many times these patients again will not have a peripheral pulse, so make sure you check a carotid pulse. If they do not have that, you should immediately start CPR and, of course, get them to a medical center for intubation and evaluation very quickly. Now one of the things that we talk about in the guidelines is is rewarming and interestingly there is an initial period during rewarming where there's something called a circumfo rescue collapse which can occur and it's not fully understood. It basically is a state of lightheadedness, syncope or sudden death occurring around the time of a cold water rescue in particular, where or heating may occur too quickly.
Speaker 2:So and again, it's not. It's not a really well understood process, but probably has to do with cardiac arrhythmias and so making sure, again, patients stay horizontal and not immediately getting their core temperature to normal. But but you know, raising it over time can help decrease the risk of this, of this rescue collapse that occurs in these patients. They note that that, again, you know external heating with with. You know blankets if that's all you've got, but there's a heating pads. We have things called in the hospital, called bear huggers, and it's not bear like a, like a bear in the woods, it's actually the name of the company and they're basically just heated pads with, with heated air and then that you literally just wrap around the patient and again it does a really good job of bringing core temperature up.
Speaker 2:So there's, a couple of ways you can approach. You know, increasing core temperature in patients with moderate severe hypothermia. Obviously they're going to need a telemetry monitoring or EKG monitoring at that point and making sure you're monitoring them for the development of cardiac arrhythmias. Now in the field, if someone has severe hypothermia it may be very challenging to get an IV line placed, which I guess kind of makes sense, because if my peripheral pulses aren't working, trying to find a vein to stick a needle in is probably going to be pretty difficult. And so they note that that in those cases that if you have access to the right equipment, interosseous access actually works pretty good. That surprised me. I didn't think you could give heated saline via the intraosseous route, but it has been done apparently. So I thought that was kind of interesting as well. The ACLS protocols if you have someone again with severe hypothermia who has had a cardiac arrest, is something to think about. They actually recommend that you should not give medications in the ACLS algorithms until a patient has a core temperature of greater than 30 degrees centigrade, because basically they're not going to get the drug. The drug will not actually get to the heart because of poor perfusion, also due to decreased metabolism. Sedative drugs should be used at reduced doses because again, the patient won't be able to metabolize the medications very well. They emphasize the use of warm IB fluids to really really help. And then there's some detail which I think goes kind of beyond the scope of this pod, talking about deferbulation and treatment of other arrhythmias. I think for the pharmacist out there, suffice it to say that epinephrine and basepressin and amiodarone all the stuff we would use in an ACLS circumstance would probably be held until the core temperature is greater than 30. Of course, the other piece too is that and we certainly saw this in this patient that I saw in the unit the patient may not look like they're alive because again, they have minimal vital signs and things like that. You really have to warm the patient's core temperature to normal before you can determine whether in fact they have passed. And I get one of the truisms in the ICU is that no one dies cold. And again that just basically means that you can make a pretty significant recovery in a patient that looks like they're morbid and they've kind of reached the end of the line. That's actually you can bring these patients back because of the severe cold. So you have to be very careful about that. So that's hypothermia.
Speaker 2:Now we can kind of switch gears and talk about frostbite a little bit. Again saw this several times. It's a freezing injury, of course that results in cellular damage and death. Frostbite requires freezing temperatures but it doesn't interest in the require like below zero severe temperature. In fact many frostbite injuries occur at just below 32 degrees Fahrenheit. So again, I think we tend to think about frostbite occurring in subarctic temperatures, 30 degrees below zero, and that certainly happens. But it actually can occur at temperatures. I think, especially if you live in the Midwest, you'd go, oh, that's not too bad, our temperature warmed up just last couple days to 30, and everyone's like, oh, this is not too bad. Again, the Midwest mindset, you know, isn't too bad Anyway. So frostbite in the northern part of the hemispheres is not uncommon. In Sweden, for example, it's been estimated about 1.5 cases per 100,000 in the general population. It is of course more common in patients who have to be out in the cold because of their job or patients who have, who are homeless, things along those lines.
Speaker 2:There are several classification schemes for frostbite. The most common one, the clinical classification scheme, divides frostbite into four degrees, see a first, second, third and fourth degree. First degree is just basically superficial and the findings are really just reduced sensation and erythema and burning after rewarming. So sounds like Jen, you may have had that. Fortunately there's no sequelae, so you know there's no damage, permanent damage to tissue or anything along those lines.
Speaker 2:Second degree frostbite affects the dermis and you'll often get clear blistering of the affected tissue with later slopping of the necrotic skin. And one of the keys for these a couple of degrees is that there's significant pain on rewarming and, while permanent damage doesn't always happen, lasting cold sensitivity to the exposed may develop. Third degree is where you start really getting into trouble because now you've now you've affected the full thickness of the skin. You'll often get blue-gray discoloration of the affected body part, blisters that are clear or hemorrhagic and there's significant pain on rewarming. Unfortunately, these patients may develop full thickness skin wounds which may require plastic surgery to fix or in some cases even amputation, and in children this can lead actually to damage to growth plates, which obviously isn't good.
Speaker 2:And then the most severe type and the type that I saw a couple of times in the last couple of weeks is fourth degree frostbite, which is where you get damaged tissue beneath the skin, including muscle, tendon and bone. The skin is actually gray or blue and, interestingly, because of this point, you have damaged the nerves badly enough that there actually is no pain with rewarming. Most of these patients will develop necrosis of the skin, as well as sometimes underlying bone and deep tissue, and so you might imagine a surgical options to fix that or take care of the damaged tissue is pretty common. The pathophysiology of this is not only from just basal constriction, but also because of ice crystal formation in the tissues that damages skin cell membranes and then that basically causes them to die and you get more damage. Interestingly also, small mesotorombosis has been reported, and that kind of leads to some of the treatments we may be talking about.
Speaker 2:So how do you approach these patients? They say that, first up, obviously you're going to slowly rewarm the frozen body part, but they also note that if there's a risk for refreezing before you reach definitive treatment, that you should just leave it frozen, because the freezing, thawing, freezing re-injury is actually worse than a prolonged single freezing injury. So again, keeping that in mind, in the field they'll do things like anti-inflammatory agents and things along those lines. But again, there's not a lot of data about medication therapy to treat these patients, with exceptions of what we're going to be talking about in just a second. In all cases, if the limb is frozen and cold, once you reach a place where it'll stay warm, active external warming becomes the way to go and then, once fully thawed, you can actually examine the patient for reperfusion and you can look at cap refill. Obviously, in this case, doppler is going to be a pretty good test you can use Once you estimate how long they may have been out. Then you can start thinking about therapies, and probably the therapy that's been studied the best is an anticoagulant and antithrombotic therapy, and I've seen this used a couple of times. We actually did not use it in the patients I had in the ICU, but there is evidence to support its use, and so the theory, of course, is thrombolysis will take care of some of those small clots in the exposed tissue and may improve outcome.
Speaker 2:Interestingly, there is a ton of data Like I'm not surprised. I don't know how you would do a randomized control trial of this in a condition that's relatively rare. So really most of the data comes from case reports, case series and stuff like that, the largest one being a case series that came out a few years back but looked at 208 patients who did receive thrombolysis for frostbite injury that was either stage 3 or 4. They noted in this case series that without a control group it's hard to tell how much things improved. But there did seem to be some more rapid in the 24 hours following thrombolysis improvement in infusion. So again you have to weigh risk versus benefit. But if the patient especially in fingers, then they note that most of the most of the status in frostbite fingers, that it may be reasonable to consider systemic thrombolysis. But if you feel like the risk may outweigh the benefit, also a local thrombolysis and getting interventional radiology or vascular surgery involved may be a treatment as well.
Speaker 2:A lot of expert opinion also suggests that anticoagulant therapy, with or without thrombolysis, may be beneficial.
Speaker 2:So a lot of the experts who practice this sort of thing again in Alaska or the Nordic countries do suggest that 72 hours of heparinization so again on therapeutic doses of unfractionate heparin may be beneficial in these patients. So that's something to consider. But again, every paper I read in preparation of the pod said it's basically just we think this helps, there's some empiric evidence it helps, but there's no randomized trial data and there probably never will be. So it's something to consider. There are some reports in Europe of using the vasodilator illoprost and it seems promising but unfortunately that is not available in the United States. So again, if you happen to be in a place where you're listening to this pod, where that is available, there are some small case series that say you can get rapid reperfusion with intravenous illoprost, but again that's not available in the United States. After the initial injury, then of course, assessment for reperfusion, injury and the need for surgical intervention, and again this is where plastic surgery as well as regular surgery, orthopedic surgery can get involved.
Speaker 2:Unfortunately, many of these patients will require amputation if they have stage four frostbite of some of the affected areas. But again, sometimes you can get some reperfusion and they actually will usually wait. They won't go right to amputation. They'll wait at least a week, sometimes more, before they make that assessment because again you can get delayed reperfusion and you may get some tissue back rather than waiting the other piece that I've seen a lot of in these last couple of weeks and again other patients as well.
Speaker 2:Again is this retina or thawing pain. As you might imagine, when you have stage three or four frostbite the pain can be pretty bad because of damage to nerve endings and because this is neuropathic pain, I tend to recommend drugs targeted toward that. So I've largely used things like tricyclic antidepressants and GABA, pentam it's. Again, I have not a lot of data to support that, but it seems reasonable and certainly the papers I read suggested that that's the way to kind of attack that pain. But unfortunately that pain can be severe and it can be quite long in coming. So again, that's something else to think about is what are you gonna be your treatments for pain as time goes on in these patients? Because that it's probably one of the biggest things the patient's gonna complain about, and traditional pain medications like opioids are probably not going to be very effective, even though they have severe pain.
Speaker 2:So bottom line is that this is an interesting, if not very common, set of diseases and you might think, well, I'm in Arizona, I never have to worry about this, and Arizona that may be true, but again, I think in the United States, the Southeast, got a cruel reminder that even when you're fairly, if you're closer to the equator, it does not necessarily mean you're not going to see patients with hypothermia and cold injury. So that's kind of what I got. Jen, again, something I've seen, something I hope we're rounding the corner on. I'm hoping we got all our winter and kind of one big blast and maybe we can not be so bad for the rest of it. So yeah, that's what we're dealing with.
Speaker 1:Yeah, yeah, I hope so too. Thank you so much, Dr Wall. As is often for our game changers topics, this is something I don't often think about, but it's so interesting.
Speaker 1:And as you were talking. You know I think about it in terms of an accident. You know you get in a car accident you didn't anticipate being outside and you know you get frostbite or hypothermia or whatever. But I remember a few years ago there was actually a student in a college town nearby who had gone to work out and so was sweaty and, you know, wet, and walked back to the dorm and didn't make it, had hypothermia and ended up dying. So you know it can happen in even in circumstances where we don't think about. So be careful out there.
Speaker 2:Absolutely Elite athletes are actually at fairly high risk. I certainly even here, when we had two feet of snow, we're seeing people running outside when it was 15 degrees below zero, and I'm just you know, every time I drive out people are like. That can't possibly be good for people. I don't think humans were designed to run a half marathon on a 15 degrees below zero, but on the other hand, they're in much better shape than I am, so maybe they know better than I do.
Speaker 1:Yeah, yeah, well, never know, I guess treadmill yes, exactly, yeah, yeah.
Speaker 2:What's what's wrong with treadmill? Exactly.
Speaker 1:Right, right. Well, as always. We appreciate your partnership with us on this podcast, and I personally appreciate learning so much from you every week on topics that I didn't know I wanted to learn about.
Speaker 2:So thank you again for another one of those weeks. I don't know, I'll probably make it interesting and different. Thank you.
Speaker 1:So that's it for this week, and if you're a CE plan member, be sure to claim your CE credit for this episode. So, as always, thanks again, dr Wall, and have a great week and keep learning. Talk soon.