Season 4 | Episode 1
Title: Heat Stroke
Guest: Dr. Diane Birnbaumer, Emeritus Professor of Medicine at the David Geffen School of Medicine, UCLA, and Senior Clinical Educator for the Department of Emergency Medicine at Harbor - UCLA Medical Center
Joe McIntyre: Well, warmer weather is upon us, and everyone from athletes, to wedding guests, and parents of the elderly, are thinking about how to stay safe in the summer heat. Welcome to the Merck Manuals Medical Myths Podcast, where we set the record straight on today’s most talked about medical topics and questions. I’m your host, Joe McIntyre, and on this episode, we welcome Dr. Diane Birnbaumer. Dr. Birnbaumer is an Ameritas Professor of Medicine, at the David Geffen School of Medicine, at the University of California in Los Angeles, and she is a senior clinical educator for the Department of Emergency Medicine at Harper UCLA Medical Center. Dr. Birnbaumer, thanks for coming on the show!
Dr. Diane Birnbaumer: Oh, my pleasure. It's delightful to be here and it's very timely.
Joe McIntyre: Of course. Now, as we said it is summertime here in North America and the temperatures are rising. There seems to be a lot of confusion, often around heat stroke, heat exhaustion, or even dehydration, when being outside in the sun during high temperatures. Now, Dr. Birnbaumer, let's start off with a question that I'm not sure many of us even know the answer to: are heatstroke and heat exhaustion the same thing?
Dr. Diane Birnbaumer: Well Joe, thanks for asking and it is a really timely topic right now. It is ironic that I'm sitting here in fog along the California coastline at the moment, while 100+ million Americans are under heat warnings today. Records are falling right and left and we're really --and this is just the beginning of summer, we're not even in the heat of summer-- so it is really important that anybody listening to this podcast, really pay attention because we are all at risk of this heat stroke/heat exhaustion thing, but you really need to understand the difference. So, I really appreciate your asking. We see people throw around terms all the time in conversation. You hear it at the beach, you hear it at parks, and it's really helpful to understand what the terms mean. So, heat stroke is a true medical emergency. It's when the body gets overwhelmed by heat: either the heat that you produce because you're exercising, or the heat that you absorb because you're outside, or a combination of both. If people are hiking outside or they're playing outside at the beach, it can be a combination of the two. When your body gets overwhelmed by heat, your temperature rises, and it can rise to a level that becomes dangerous. And when you develop full blown heatstroke, this true medical emergency, people become confused. And that is sort of the key for those of us in medicine to be aware that this is now gone from, “I don't feel so great because I'm outside in the heat,” to “it is an emergency”. So that’s when people have to get treated right away. I know we'll talk about this a little bit later, but starting right then and there as soon as it's recognized. So emergency care is key starting right at the scene. Heat exhaustion is a different thing. Heat exhaustion is sort of like the warning sign. It's your body saying, “Get out of the heat, get something to drink, quit what you're doing. You're not feeling well. There's too much heat around here.” Your body gets overwhelmed by heat but not to the point where you're sick. Well, not dangerously sick. You will feel terrible. People with heat exhaustion feel like they have the flu. They're kind of achy and headachy and nauseated and sometimes they throw up, but they're not confused. If people can recognize that heat exhaustion part and intervene then, they can prevent someone going on to the full-blown heatstroke which is the emergency we worry the most about.
Joe McIntyre: Now we've seen, or probably a lot of us have heard, that heat stroke typically only affects people who are super young, maybe infants and children--babies, and the elderly. Is that actually the case?
Dr. Diane Birnbaumer: That is a myth. Now it is true that heatstroke is more likely in extremes of age, or they're actually more susceptible. It’s not necessarily more likely, they're more susceptible. And it makes some sense why, right? An infant who's lying there on the ground, your adorable, cuddly baby, can't tell you they're thirsty. They can't tell you that they're dehydrated. You're responsible for giving them fluids. And older people, especially older people who are kind of alone, or in an apartment, or they're just kind of not followed carefully, they may be a little confused, they may be frail, may not drink enough water either. So, they are definitely more prone– plus they have medical conditions that make them more prone to heat stroke. So definitely those extremes of age we worry more. But I will tell you anybody listening to this podcast, right now, literally anybody, can develop heatstroke. If you're out hiking in hot weather, you could develop heatstroke. Anyone can get this, and we see it in the summer, right? Sports, football games. People go down at graduations with this stuff, so anyone can get this.
Joe McIntyre: Now this may seem like a silly question, but I'm going to go for it anyway. Does heatstroke only occur in super high temperatures such as 90+ degrees or can it actually occur at lower temperatures even?
Dr. Birnbaumer: So that’s a really good question. The reality is absolutely most of them occur at high temperatures and/or high humidity. So, humidity turns out to be a really important part of developing heat illnesses. Your body needs to sweat, and you don't evaporate sweat very well when it's humid outside. But the reality is anyone can develop heatstroke even in relatively temperate temperatures. And that depends a lot on what you're doing. If you're running a marathon and you're not hydrating very well and it's, you know, 75 or 80 degrees outside but you're generating a lot of heat, you can still develop heatstroke, so it isn't just high temperatures. It is significantly more in high temperatures and high humidity but really any temperature, it can happen. Not necessarily when it's super cold outside. That's kind of a different end of the spectrum but anything temperate or above, it could certainly happen, especially depending on your level of activity.
Joe McIntyre: Now, I think we all know that sweating helps our bodies cool down. It's a pretty effective tool of doing so. What happens if you stop sweating? Does that mean your body has effectively cooled itself down enough where it doesn't feel like it needs to sweat anymore?
Dr. Birnbaumer: Oh, that's such a good question. So, people will say oh look, I'm good. I'm not sweating anymore. From a - from a medical person standpoint, that is like Red Flag Warning. Warning, Warning, Warning. That means you don't have enough fluids in your body to sweat. You're absolutely right. Sweat is magic. Sweat is magical. If you think about what we do when we're hot outside, you spritz yourself with your little fan and your little spritzer. You see it at football games all the time and when people are out hiking, and that dehydration, or excuse me, that evaporation feels so good because it's cooling you down. But boy if you don't have enough fluids in your system to sweat, you've just lost your most adaptable rapid way to lose heat. That is, stopping sweating is an alarming finding.
Joe McIntyre: When it comes to heat stroke, is there a specific temperature that your body has to reach for that to happen? Is it just over 98.6 or is there some sort of exact temperature that it needs to hit?
Dr. Birnbaumer: That's a good question as well. So, we think about temperatures in all kinds of different ways. Like the assumption that if you have an elevated temperature, you have an infection, which we will talk about a little more later, I know we're going to address that a little bit. But heat stroke does mean your body is overwhelmed. It is basically absorbing or generating too much heat and it is overwhelmed. So, for true heat stroke, people's temperatures are often over 104 or so, and they can go really high. I've seen people as high as 109 degrees, who had heatstroke. It is basically, your body is cooking. It's just overwhelmed by heat. Now I’ll tell you, no infection gets you that high. If you're super high like that, that is heatstroke or some other condition. It's not an infection. So, there is no specific temperature for heatstroke, but you tend to be high. It's something you would notice. It’s not like I feel a little feverish. It's like, wow, you feel really warm. You would notice that.
Joe McIntyre: You mentioned a few of these early on, but what are some of the most common signs and signals of heatstroke that people need to look out for if they are going into high temperatures or outside for a while and they're just generally not feeling well during the high temps?
Dr. Birnbaumer: Right, so heat stroke - we're talking about the big deal here. Heat stroke is somebody with an elevated temperature, and they have something wrong with how they're thinking. They're either confused, they may even frankly go into a coma. And what's interesting about heatstroke is, you would think it would be sort of gradual. Now you're out hiking with your friends, and they would say I'm not feeling so great. And then they would get you know, sick slowly. This can be very abrupt, and it can be particularly abrupt in the very young and the very old. So, your baby can seem fine or your grandma can seem fine when you're at, you know, in the backyard at a picnic, and then suddenly grandma's really confused. It can happen quite abruptly. So that's one of the things I want to dispense with this myth of, you know, “Oh, I have a warning that it's coming,” - you may not, and confusion is the key here. Remember, heat exhaustion is that step one down from that. You're not super critical yet, it's not really an emergency, but you don't feel good. That again is a warning sign. But heat stroke, it is characterized by an elevated temperature and confusion or coma. Altered mental status is what we call it, in medical terms.
Joe McIntyre: And then how about just heat exhaustion? When that starts to happen if someone starts to feel really, really hot, or really, really sick?
Dr. Birnbaumer: We tend to see this in people that are sitting outside in the heat, or it happens quite frequently in people that are active in the heat. So, they know that they've already been drinking some fluids, they already kind of know they should be hydrated. They're out and about, they start to feel queasy. They may get a headache. They may actually vomit or have just an abrupt episode of diarrhea. You're out hiking and it's like “Oh, I gotta go.” That's your body saying, “It's time to get out of the heat.” You're not - you haven't crossed the threshold and your body temperature may be normal. At that point, your body's trying its best to adapt, to help you sweat, etc. And it's warning you that things aren't going so well. That's the time to get out of the heat. Once you get to the point where your temperature does rise and you're getting a bit confused, now that's an emergency. Now you've got to get to care.
Joe McIntyre: Is it possible to be properly hydrated and still suffer from heatstroke or do they just kind of go against each other so strongly?
Dr. Birnbaumer: You can. So actually, some of the best sort of research about this has come out of contained populations like the military. So, for instance, military recruits going through boot camp --especially in super warm places like the desert-- they know to hydrate, they know to just take gallons of water, often before – and by the way, it's just a good practice anyway, to drink plenty of water before you go exercise in the heat. But if you are now really exercising and you're carrying around a 60-pound pack on your back, and you're traipsing around in the desert, you can develop heatstroke even though you're well hydrated. So, it's one of those things again, it's generating too much heat or absorbing it, or both, that can get you into the heatstroke range. You can be hydrated well and still develop this for sure.
Joe McIntyre: Now let’s say we are out hiking or at the beach and getting inside is not really an option, kind of difficult to do. How does someone cool their body down when they're feeling not very well whether it's heatstroke or just heat exhaustion?
Dr. Birnbaumer: So first of all, stop what you're doing. If you're exercising, quit making more heat, like, don't give that to your body. If you can, at least get in the shade. And if there's no shade around you, have somebody makes shade for you. So, take your clothes off, down to your undies. Have somebody hold something over you so that you're in the shade, and then if you have water with you, get yourself wet. Let evaporation work for you if you're starting to feel queasy – drink, certainly, make sure you're hydrated. Don't waste it on your skin, put it in your body, that's probably better. But if you have the ability to get moisture on your skin, do! Let it evaporate. I'll tell you; we use evaporation on purpose in the ER to help cool people down, we will get people wet with towels; we’ll blow a fan over them. We use it on purpose because it's a very effective way to bring down your temperature. So, try to get into some sort of shade. Stop what you're doing. Strip yourself down to as stripped down as you can be, get your skin as moist as you can, and hydrate. Those are the things you can do to kind of help, and often that will get you feeling enough better that you can kind of get back and stop doing what you're doing and go sit in an air-conditioned room somewhere. If it crosses the threshold, though, where you get confused, then you got to get 911 involved to get people to the hospital.
Joe McIntyre: When people do go to the hospital, what are some of the techniques that you use in the emergency room to get people feeling better again?
Dr. Birnbaumer: So, we make them naked. That's one of the things we basically do is make them naked. Strip people down and we will cover them with either damp towels - not sopping wet damp, you squeeze them damp or sometimes even spritz them – we have little spritzers sometimes and use a fan. So, we use evaporation on purpose. In the extreme, we can do more invasive things. We would do things like use ice baths both inside you and outside you. Sometimes, we'll put a tube in your nose into your stomach and give you cold water in there. Or we'll actually put a tube into your bladder and put cold water in there. So, we use your body's sort of, surfaces, on purpose in the emergency department. And by the way, if you come to the hospital with heatstroke, it doesn't mean we're going to do any of those things. If you find that those things are heinous, you just will never want anybody putting a tube anywhere, it doesn't mean we're going to do that. It just means we're going to definitely induce evaporative cooling, and sometimes we will go on to --if somebody's really terrible, like that person that I saw with 109-degree temperature-- we may do an ice bath. And I mentioned ice baths because --you'll see it on the internet, and you'll see it sometimes at the side of a stadium, a football stadium, or in a big, huge gathering/mass gathering like a big concert venue outside. Ice baths are really for medical personnel to use. Because there's a window – remember, somebody's confused with heatstroke -- and if you put them in any kind of pool of water, and you take your eye off for a second, they can theoretically drown. You don't want that to happen. So, we use these on purpose in health care because we can bring your temperature down if you are really dangerously high. But in general, we don't need to do that we often will just use evaporative cooling when it comes to the emergency department.
Joe McIntyre: What effect does sunburn have, if any, on someone's ability or on someone's body to kind of get too hot? Obviously, we sometimes can wait too long and realize we have sunburn later once we get back to the beach house or wherever. But what affect does sunburn have?
Dr. Birnbaumer: That's interesting. So, sunburn, I want to kind of dispense with a term that I hear out there that I would like people to kind of learn to be a smidgen more specific in their terminology. So, there’s a term you hear called sun poisoning, where people talk about “Well, I was out in the sun and I have sun poisoning. I had these little blisters on my skin, and I don't feel good.” That's kind of combining a little bit of apples and oranges. So, your skin's response to the sun, we all are aware of this, right, we have SPF 1000 out there. I mean we have these crazy SPFs, which is good actually, it's protecting our skin. Your skin is your first kind of absorptive level of sun. It absorbs UV rays and it's damaging to your skin. There's no question. Sunburn just means that at the skin level of your body, you have exposed yourself to too much UV light. It's not necessarily the heat part. It's the UV light part of this that your skin has absorbed. And it causes damage versus just that red thing, and then it can cause blistering. Some people actually do develop sort of what people call a sun allergy. It's not - it's actually a specific medical condition that people have that the sun will make worse. But in general, the sunburn itself doesn't affect heat illness, which is another thing. Whether you actually become hot or become systemically body sick from being out in the in the heat, that's a different thing. So, I kind of want to split it into sun problems and heat problems to help people not use a generic term that kind of lumps two things together that are actually approached quite differently.
Joe McIntyre: What about Tylenol or other medications? I think people use Tylenol or you know other sorts of acetaminophen or whatever to lower their body temperature. Would that work in this case?
Dr. Birnbaumer: So, you would think it would and it doesn't. I'll tell you why. And this is helpful for people to understand. So, we all have a knee jerk right, “Oh, my temperatures up some. I'm going to take some Tylenol or whatever and bring my temperature down.” That does work, for infections. So, infections, when your body has an infection, your body knows it needs to try to fight it off. And there are lots of different ways it does that. So, it does that by recruiting some white cells in your body, and it does that by immune things. And it also does that by resetting a little place in your brain that sets your temperature, and it will just basically say “Make me a little hotter, I might be able to kill off some of these viruses and bacteria that way.” What Tylenol does is it goes to that little set place in your brain and says “Chill, just cool it, do not do that.” When you develop heatstroke, there's no resetting of your brain. This is just an overwhelming of your body. So, Tylenol does nothing for heatstroke. Absolutely nothing. And, I think for people that are listening to this, if you can get that sort of understanding the difference. It's your body absorbing too much heat versus saying I'm going to fight an infection, then it makes sense why it works and why it doesn't.
Joe McIntyre: What about for people who may not have air conditioning in their home? Is it possible that in your own home with you know, no sun beating down on you, you could suffer from heatstroke or heat exhaustion?
Dr. Birnbaumer: Without question. So, anybody listening to this podcast, if you have someone you love, who is in an apartment or some sort of living space where they have no air conditioning, and it is record breaking heat like it is today, please check on them. Make sure they have plenty of fluids. In fact, we have every summer – and Chicago gets the biggest rep on this because there are a lot of people in small apartments in Chicago-- somehow Chicago gets a lot of deaths of older people that are stuck in their apartments in heat waves during the summer. There were 1000s of people who died in Paris years ago in a heatwave who were just stuck in un-airconditioned apartments. It is really important, especially as we have more and more heat, to keep track of those people and if it’s just your neighborhood or your apartment building - check on your neighbor. And they are opening air conditioning centers for people to go to so they can stay cool when things get so crazy hot. And people worry about paying their bills, they may have air conditioning but not turn it on because they can't pay their bills. So just keeping track of one another and the people you love will really help minimize people at risk at home when they're kind of stuck in their in their living space where it's too hot.
Joe McIntyre: So, we've talked a lot about heat stroke and heat exhaustion when the temperatures are super high. Let’s flip that a little bit. What is hypothermia? When it's super cold, how does that affect your body? Is it the same type of type of thing?
Dr. Birnbaumer: It's actually ironic, considering its so hot outside today. It's kind of fun to think about being cold. It's kind of a nice thing to think about. It's going to be months before we're back into that position, but it's kind of fun to think about that. So cold illnesses, like we have this whole heat illness category, there's a whole category of cold illnesses, and we call them accidental hypothermia. So, it's basically if you get cold because you're outside in the cold, and that is only because sometimes we use making people cold on purpose in medicine for medical things. So, we call it accidental hypothermia. And the range of things is similar in that you have skin things that happen when you're cold. Just like you have skin things that happen when you're hot. That would be sort of the Frostbite, Chilblains, that kind of thing that you get when you're cold. And then you also have the total body things, the systemic things, that happen when you're cold. Being cold actually is not quite as damaging to your body as being hot. It just sort of slows things down. And people can stay cold a long time and still get resuscitated. We have cases - we have all these sorts of rules about when we stop resuscitating somebody who might even be in a full cardiac arrest if their body is cold, so you can kind of withstand it. I don't recommend you go out and get cold on purpose, but you can withstand that a little better than heatstroke. Heatstroke is literally, every minute that you are in a state of heatstroke, every minute counts because there's damage being done every minute. Getting cold is like taking, I don't know, those of us who remember records you know and turning the speed down so it's slower or playing a tape more slowly, where everything just kind of slows down and eventually it stops. So, it's like you have a little bit more of a buffer with that. The skin stuff can be very damaging though with cold. Very damaging. It's like having a burn like a thermal burn from heat, but from cold instead. It damages the layers of the skin for being out in the cold.
Joe McIntyre: Yeah, how does kind of frostbite exactly work? What is the process, I guess, in your body that causes that to happen?
Dr. Birnbaumer: So, frostbite is basically freezing. It's the freezing of your skin and it basically starts from the outside and goes in. It’ll start with just the very surface of your skin and frostbite can be anything but let me back up. Frost nip, we call it frost nip (cool term), is basically just when things get really cold, but no permanent damage is done. And we’ve all had that, right? It's like “Oh shoot, I should have worn my mittens, I didn't, my hands are killing me. I come inside and it really hurts when I put them in the water…” but they're fine. Frostbite is where you actually freeze. Frostbite, when it's more superficial, it freezes, and you can develop blisters that are clear. The more deep that the freezing happens, you get to what we call the deeper structures of the skin. Your skin is really cool, by the way, all kinds of really interesting things in your skin. It freezes deeper and the blisters end up sometimes bloody. As that goes even deeper it becomes to a point where it can't heal. So, what people will do with frostbite - we call it frostbite in January and then we do whatever procedures in July. Because what will happen is your body will demarcate: it'll make a line where the damage is permanent. It's, whatever the structure is, is not coming back. And what is salvageable. Your body sort of does that on its own. And I'm sure you've seen pictures and it makes sense which parts of your body are at risk: your fingers, your toes, your nose, your ears. And if you read a book like Into Thin Air by Jon Krakauer there are people on this hike to Everest who survived that rather ill-fated trip and had parts of their body get frostbite. And so, there’s pictures of people missing the tip of their nose, missing their ears, missing a certain finger, so you gotta make sure you keep yourself warm and your parts as well.
Joe McIntyre: How long does it take typically, for someone to suffer from either frostbite or how do 23 know when that damage becomes more severe and serious?
Dr. Birnbaumer: So, it really depends on the conditions and what you’ve worn. It really depends on the conditions. So, there's reasons that people can go to the top of Everest and back and never develop frostbite. Right? They're adequately prepared, they're adequately warm, they know sort of when to watch for things. We tend to see frostbite more in people who are unprepared, so they don't have the right kind of warm things. They end up stuck out in the cold in their car, and that's when we tend to see it more. So, it's not specific. I can't say, “10 minutes and you develop frostbite”, it really is more situational. But I will tell you, if your extremities are cold or if you are cold and your fingers are cold, if you can't feel your fingers and toes, please find a way to get them warm, tuck them in your armpits, put them in your pants, whatever. Find a way to get them warm.
Joe McIntyre: Dr. Birnbaumer, we've talked about a lot of different topics here. And I'm sure there's much more that people want to learn. Where should people go if they do have questions about heat stroke, heat exhaustion, or even hypothermia? Where would you recommend?
Dr. Birnbaumer: Oh, boy, there's lots of ways. I'll tell you; the Internet has changed everything for the good and the bad. To be honest, you can find things that aren't so true on the internet as well, but there's a lot of great resources for you out there on the internet. This is a Merck podcast, and the Merck Manual is free to everyone, you know, there's a version for the people in your home, you can just look it up, that's really worth that and I'm just gonna put in a little plug. That's something that I've actually edited. So, I highly recommend that one. But there are also other resources there are things like e-medicine, WebMD, those are all very useful. There are certain societies - The Wilderness Society has all kinds of great recommendations if you're going to go out into the wilderness and you want to know how to protect yourself or go out into the heat and know how to protect yourself. So, there's great resources out there. Make sure it's reputable, though, don't go to folk remedies. Don't go to - make sure you go to something that has a true sort of staff, that is people who know what they're talking about in this sort of thing. So those are the sorts of things I recommend. Be careful with folk remedies. Those things don't work very well. In the end, especially with something like heatstroke, it could theoretically get you into trouble because that can be life threatening.
Joe McIntyre: Well Dr. Birnbaumer, thank you so much for joining us on this episode here. Obviously, as the temps are rising, people are getting warmer, people want to go outside more, but it's super important that people manage their body temperatures and know what they're getting into. So, again, thanks for joining us and I’m gonna leave our listeners with something we always do with the Merck Manuals.
Dr. Birnbaumer: Medical knowledge is power. Pass it on.
Joe McIntyre: Thank you so much.