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Gas Exchange and Altitude Acclimatization with Dr Patrycja Jonetzko
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In this science-focused episode, host Steve House sits down with Dr. Patrycja Jonetzko, a cardiothoracic anesthetist and high-altitude medicine expert, to explore the fundamental mechanics of gas exchange and oxygen delivery in mountain athletes. Dr. Jonetzko breaks down the journey of oxygen from atmosphere to working muscle, explaining the oxygen cascade, the critical role of partial pressure versus oxygen concentration, and why altitude performance is diffusion-limited rather than VO2 max-limited. The conversation illuminates why the body's adaptation to hypoxia is far more complex than simply producing more red blood cells.
The discussion moves beyond basic physiology into practical application, covering breathing techniques like pressure breathing, the importance of hydration for gas diffusion, and why slower, deeper breaths are more efficient at altitude than rapid shallow breathing. Dr. Jonetzko advocates for reframing "acute mountain sickness" as "altitude adaptation syndrome"—recognizing that most symptoms represent normal physiological adaptation rather than pathology. She emphasizes that while genetic factors play a significant role in altitude performance, pre-acclimatization strategies including hypoxic tents and intermittent hypoxic training can meaningfully prepare athletes for high-altitude objectives.
Drawing from both her clinical intensive care work and decades of Himalayan expedition medicine, Dr. Jonetzko reveals that success at extreme altitude ultimately comes down to energy management and self-awareness. The ability to maintain physiological efficiency while operating within narrow margins—controlling breathing rate, managing fear responses, and reading subtle body signals—often distinguishes those who summit from those who don't, regardless of baseline fitness levels.
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Transcript
Introduction to Overexertion and Fitness
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Speaker
Often the fittest people were the sickest and that's because they were pushing themselves too hard and they were not paying attention to how their bodies were trying to tell them to slow down.
00:00:13
Speaker
So it was almost like almost the opposite of what I was expecting.
00:00:25
Speaker
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00:00:43
Speaker
It's a great way to get a feel for how we train our athletes for big mountain goals. Check it out UphillAthlete.com slash Let's Go. UphillAthlete.com slash L-E-T-S-G-O.
00:00:58
Speaker
Welcome to the Uphill Athlete Podcast.
Podcast Introduction with Steve House
00:01:00
Speaker
My name is Steve House. We have a really exciting episode for all the science geeks out there that are fans of the pod. Today, we are going to go deep into understanding gas exchange and how oxygen goes from the air into the working muscles. And with us today, we have the incredible Dr. Janetschko.
00:01:24
Speaker
Welcome. Welcome. Lovely to be here. They say never meet your legends. Hopefully this is going to be ah different. Yeah, you get, you can that's a risk, right? You get ah could be disappointed by that. And i've I've had it go both ways myself. So hopefully we are ah where we we leave i leave a positive impression.
Gas Exchange and Oxygen Delivery Overview
00:01:47
Speaker
So um I wanted to frame this up for mountain athletes real quick, what we're doing. So whether you're As a listener, whether you're planning on climbing Denali or doing a ski mountaineering event, you're you're running in the mountains, your performance ultimately comes down to how efficiently your body can extract oxygen from the atmosphere and get it to the working muscles.
00:02:14
Speaker
Patricia Yuretsuko a cardiothoracic anesthetist whose daily work involves managing this oxygen delivery to patients in highly critical circumstances during surgery.
00:02:28
Speaker
she has about two decades of supporting all kinds of Himalayan expeditions as an expedition doctor and most recently was the expedition doctor for the historic Without Supplemental Oxygen Descent of Everest done by a fellow Paul Andres Bargiel just recently, just a few just like few, it wasn't that long ago, what, six months ago now or less.
Dr. Janetschko's Medical Journey
00:02:55
Speaker
So welcome, Patricia, and it's really great to have you here, and I'm really excited to dig into your knowledge.
00:03:03
Speaker
Thank you. So let's let's start off a little bit up with your background. You grew up as a competitive ski racer in Poland. Did that exposure to a life in the mountains lead you into medicine and then into being interested in health food physiology or was is that connected at all?
00:03:25
Speaker
um Yes, very much so. So, um yes, I did a lot of competitive skiing until the age of about 13. and then it ended because my parents didn't want me to go to a boarding school um for, you know, sports sort of boarding school. And I often say that's when everything went wrong in my life. Yeah.
00:03:49
Speaker
Because I remember having this conversation with my parents at the end of grammar school, secondary school, trying to decide what to do with my life. And basically, all I wanted to do was a ski patroller, you know, have a dog and be a ski patroller. And my parents said, oh, well, darling, you know,
00:04:07
Speaker
doing medicine and being a doctor is a little bit like that. You're helping people. um And I sort of went, oh, okay, yes, maybe I should go to med school. ah And I can tell you it's nothing like that. ah You know, you don't really get to be outdoors ah or hang out with dogs too much when you're a medic, especially in intensive care and cardiac surgery. um But I've been sort of trying to get back to the mountains ever since they were very success.
00:04:38
Speaker
Yeah, that's – having been a professional ski patroller for a couple of years of my life, um you know, my girlfriend at the time, she would let me – we'd get paid every two weeks. She would let me see my paycheck because I would get so just – I would get so bummed and worried because it's – but ah so I think you probably in some way, many ways, made it made a good choice. I see your parents' perspective and I see your perspective, especially the hanging out with dogs. As a dog lover myself, it's ah pretty great.
High-Altitude Medicine and Physiology
00:05:09
Speaker
your Your career has taken you through seven different countries for your medical training. You've worked in Afghanistan, Uganda, Nepal.
00:05:20
Speaker
Was there a particular experience along that journey that crystallized your focus on high-altitude medicine? I think there were two key factors. So once I grew up in communist Poland and until the age of, you know, 91, I'm born 77, we couldn't really leave or travel.
00:05:36
Speaker
So once I could do it, I just couldn't stop. You know, I found it absolutely fascinating and a huge privilege to be able to experience different cultures.
00:05:48
Speaker
um And i've the other thing is I've always loved physiology um and the understanding of how humans function. And then because I've always loved skiing, we don't have high mountains in Poland. You know, Tatras are not very high.
00:06:04
Speaker
But once I traveled in Nepal and sort of experienced altitude myself, i and I started looking into the the incredible way our body adapts to what is a very hypoxic sort of critical illness level.
00:06:21
Speaker
environment um that was it you know I was hooked and i was very lucky um to be offered a job in Machermo which is the parallel trek to um Everest trek in the Gokia region in the Himalaya and I spent a whole season working there as a doctor in the rescue station at 4600 and seeing a lot of altitude medicine daily you know it was um It sort of kept me hooked and interested um my whole life because it's so variable and our understanding of it is so poor.
00:06:58
Speaker
um yeah It's amazing to be able to sort of dig into it. I think that that that's an important point. And we completely concur that particularly our understanding of acclimatization and how the body responds to and adapts to high altitude is, i think we're really in the dark, but we're going to get it into that. So what kind of things were you seeing and treating and what did those things teach you about how the body responds to altitude?
00:07:30
Speaker
So I think that the you know there are many tracks coming through and I think the biggest surprise to me I remember at the time was um the fact that often the fittest people were the sickest and that's because they were pushing themselves too hard and they were used to driving themselves and they were not.
00:07:49
Speaker
paying attention to how their bodies were trying to tell them to slow down. So it was almost like, almost the opposite of what I was expecting. And very often people who are very, fit and not very fed or with medical conditions who are a bit more, maybe cautious or maybe listen to their guides a little bit more, oh,
00:08:12
Speaker
We're actually adopting we really well. So I think that was probably, ah for me, the main learning point. And also how scary it can be when things turn badly very, very quickly.
Basics of Gas Exchange
00:08:25
Speaker
We've had, you know, quite a few... patients clients with with severe high altitude cerebral edema and pulmonary edema also the the sort of acknowledgement that things can be very dangerous uh potentially and it can happen quite quickly yeah i've certainly seen that and but but i've been on both sides about myself in my own experiences in the high mountains Let's get into this core topic of gas exchange. So for those of us who haven't thought about this much since high school biology, could you walk us through the journey of an oxygen molecule going from the air outside of the body to actually being used in a working muscle? I mean, that's a huge question. But let's let's let's go just like kind of the summary and then we'll go into like some of the some of the different steps along in the ah oxygen cascade.
00:09:23
Speaker
So I think the first key thing to say is, and it's something that I think we often forget, is that humans have adopted to life on the surface of Earth.
00:09:37
Speaker
Um, and you know, if the composition of our atmosphere changes, uh, we would not be able to survive. Okay. So we're very finely tuned to the, uh, to the air that we breathing that's around us.
00:09:53
Speaker
um Just the very basics. And I think without getting too political, if we can stick to kilopascals, which is the European way of doing pressure, just because it's easy. Yeah, let's use the metric system. It's also the standard for science. So let's let's see let's use the metric system. yeah So if you imagine the Earth is the bowl in the middle, and then you've got the atmosphere, which is essentially a mixture of gases rotating.
00:10:19
Speaker
Well, it's not rotating. The Earth is rotating, so most of the gases are rotating around the equator. It's the fattest bit of the atmosphere. And as you get closer to space, the gas mixture gets thinner and thinner and thinner, and eventually there is no gas. There is just space. There is nothing. Okay? Okay.
00:10:37
Speaker
So the mixture of gases that's sort of sitting on the Earth, the gravity holds it close to the Earth, exerts a centre set certain partial pressure. And when we talk about gas exchange, we shouldn't be talking percentages. I often hear, oh, 21% and, you know, third of that on Everest.
00:10:57
Speaker
The key thing here is partial pressure. So partial pressure of gas is what keeps us alive. And on average, when the weather is okay, it's 100 kilopascals. That's the total pressure of atmosphere. 21% of it, so 21 kilopascals, is oxygen, okay? So if we remember 21 kilopascals of oxygen from school, and then the rest of it is primarily nitrogen and a bit of noble gases like xenon and so on. But it's essentially oxygen and nitrogen.
00:11:30
Speaker
The other thing that always catches people out is... There is no carbon dioxide in the earth in the air that we breathe, okay? So that's why we need trees.
00:11:40
Speaker
Trees mop up the carbon dioxide and give us oxygen back, okay? We give them carbon dioxide, they give us oxygen back. If we cut down all the trees, apart from global warming and other, you know, like major issues, we will also rebreathe carbon dioxide, go into coma and all die, okay? That's another reason why we shouldn't be cutting the forest.
00:12:03
Speaker
so umm So when we take a breath, this mixture of gases essentially travels through to the 500 million bubbles called alveolies, which make up our lung.
00:12:19
Speaker
And if you take our lung out and stretch it, sort of alveolar thickness, so just one layer, it would be as big as a tennis court. You know, I always find that man-bumbling that you can have a huge surface area within our tiny, well, tiny bodies, right? Yeah.
00:12:37
Speaker
And this is, I think, the first key thing. um And people often wonder, well, what's the meaning of life? What's the meaning of life? Well, the meaning of life is simple diffusion, okay? Yeah.
00:12:50
Speaker
So we only stay alive because of simple diffusion. so And what what is diffusion and how how does it relate to the abeal life? Diffusion, essentially, it's a very simple physical process where if you have a high partial pressure of gas on one side and low on the other, the gas will travel down the gradient.
00:13:13
Speaker
And it will travel, you know, how fast and far it travels depends on what the gradient is, how thick the membrane is. Okay.
00:13:25
Speaker
um And that's pretty much it. So this little molecule of oxygen from atmosphere gets into the bubbles in our lungs and then travels farther, being carried by some hemoglobin into our tissues.
00:13:42
Speaker
And then it travels to what's called a mitochondrion. This is the engine of life in every cell. And it gets metabolized into ATP, which is the energy that keeps us alive.
00:13:54
Speaker
Okay. It's quite simple. It's not terribly efficient. And if the stars in concentrat if the starting pressure pressure of oxygen drops, then there comes a point where there isn't enough gradient to keep us alive, essentially. Does that make sense?
00:14:15
Speaker
Yeah, it does make sense. And so...
00:14:21
Speaker
People think about climbers on Everest and using oxygen masks um and then breathing ah more, like breathing a gas mixture that is higher concentration of of oxygen. And yet you also say it's all pressure. So how how do we understand the difference between like breathing and greater concentration of a gas at a low pressure, like what you have ah at the top of Everest, which is roughly a third. i like to use um kind of 5,000 meters is half an atmosphere of pressure, roughly, right? yeah so So like, and that's maybe more relatable. Mont Blanc is almost 5,000 meters, 4,800 meters. So um that's about half an atmosphere of pressure compared to sea level. So how does that how does that work? How do we understand that? Mm-hmm.
Oxygen Masks and Breathing Techniques
00:15:16
Speaker
So this is an excellent question and um i I would love to start using this more in that sort of altitude conversation. So what you're asking me right now is the difference the difference between Normal barric hypoxia and hyperbaric hypoxia. Okay?
00:15:37
Speaker
Yeah. So normal barric means normal atmospheric pressure. Okay? So let's say at sea level. Normal barric pressure. Normal barric. Okay. Yeah.
00:15:49
Speaker
So let's say I am at sea level at home right now. The pressure around me is 100 kilopascals. Okay, 21% of it is oxygens of twenty one kilopascals of oxygen,
00:16:03
Speaker
If you put me in a hypoxic tent or i make you use one of those masks people use for training, right? Essentially what these devices do, they increase the nitrogen concentration, okay? So you're dropping the concentration of oxygen.
00:16:21
Speaker
you get less percentage of oxygen, let's say 17%, but the total pressure is the same, 100, right? So it's 17 kilopascal. Now when you go to altitude let's say, let's 5,000, let's say Mont Blanc, more or less, you your starting point is no longer 100 kilopascals, there's 50 kilopascals, right? So 21%, so the mixture stays the same, but the kilopascals are less, between twenty because 21% of is right?
00:16:58
Speaker
yeah ah eleven or ten and a half and and this is why ah It's not just supplementing oxygen if you go to altitude because actually what keeps the bubbles in our lungs splintered is pressure. Okay, it's atmospheric pressure. It's not just supplementation with oxygen.
00:17:19
Speaker
So when people climb Everest, when they breathe... through the oxygen masks, okay? We increase the percentage of the mixture, so we add oxygen. So you might be breathing 30% oxygen mixture effectively, but the atmospheric pressure still lower, and that's the one thing we can't compensate for. So we're exposing our lungs to lower pressures.
00:17:47
Speaker
ah And that's why, you know, for example, in HAPE high-altitude pulmonary edema, it's not the oxygen component as much that causes the flooding of the lungs. It's the fact that the pressure that's splinting the lung is not enough to sort of keep it open or keep the the fluid out.
00:18:05
Speaker
And why can't someone just like hold their breath and like increase the pressure in their lung and pop all the veal oil? They can. They can. It's called auto-PEEP. Okay, and this is one of the methods, actually, there's a really good paper about using it to treat early pulmonary edema altitude. So essentially what you're doing is you're increasing your positive and expiratory pressure.
00:18:30
Speaker
And it's also, that is incredibly important in increasing the efficiency of your gas exchange at altitude, right? So when we're walking at altitude, ascending, let's say we want to walk so slow that we can keep a respiratory rate, um you know, essentially normal. That might not be possible, but as low as possible. So breathing in through the nose.
00:18:59
Speaker
Many reasons for that, I can go into it, but breathing out through like a fish mouth.
00:19:07
Speaker
sort of fish lips because that increases the positive end expiratory pressure in our lungs and it stops the lungs from collapsing. It also makes us less likely to develop pulmonary edema and it helps the parche the diffusion, simple diffusion in the lungs. So it helps the oxygen actually going into the ah circulation and then being picked up by hemoglobin. Yeah.
00:19:33
Speaker
And this technique has actually been around for as long as I remember. When I was a teenager, we i remember hearing about this, and they would call it pressure breathing. um And even for people climbing like ah Mount Rainier in the United States, which was that was the tip. That was like when you look first your lips and create resistance when you breathe out. And it was called the pressure. pressure breeding. I don't think that we had like a good understanding of whether or not it worked. I think that that was one of those campfire conversations. does that really do anything or not? I don't think it does. And now it's kind of coming around to where where I'm understanding that this may actually be a good idea.
00:20:20
Speaker
So there are many physiological reasons for this. So I think one thing that is also really important and key to understand for people is that your performance and altitude. So we're talking about exercising in hypoxic conditions, right? At altitude.
00:20:36
Speaker
That is not VO2 max limited. Okay. So the how fit your cardiovascular system is essentially doest does not determine how you perform at altitude. So at altitude, any exercise is diffusion limited.
00:20:53
Speaker
So it's the mechanics and the state of your lung um That is key to how you perform. That's going to limit the
Efficient Breathing and Oxygen Absorption
00:21:02
Speaker
oxygen delivery. And if you think about it, every time we take a breath, we take about 450 mils of air mixture in. of it sort of wasted the the respiratory pathway so that's not gas exchange it's before you gets it before it gets to the 500 million bubbles okay where it can go into the yeah that's the air that's occupying your mouth and you know trachea and so on yeah
00:21:31
Speaker
So if you want to be efficient in diffusing, the slower you breathe, the better, because then you don't waste 150 mils every time you take a breath. You're much better expanding your lungs more because then you only lose the 150 mils once. you see what I mean? to take So taking bigger tidal breaths is better.
00:21:55
Speaker
And that the other thing that's key is... So the red cells take about 0.25 seconds to get loaded with oxygen in our lungs, but they stay there for about 0.75 seconds and at altitude you need a way longer time for equilibration. So actually big breaths expanding our lungs and then holding and slowing your heart rate down So the cells, you know, can sort of use the 0.75 seconds to pick up oxygen. It's much better. So it's almost like the opposite of people tend to do.
00:22:36
Speaker
People tend to push hyperventilate because they feel short of breath. You need to essentially slow your breathing down and slow your heart rate down as much as you can to make it more efficient.
00:22:48
Speaker
know that that tracks with you know even when it has a mountain guide and denali or places we would always be telling people to do like belly breathing you know move your belly out get a really fill the chest you'll fill the upper part of the chest like really fill the lungs make those big deep uh tidal breaths is your term um let's go back a little bit and So now the oxygen molecule, let's talk about this, let's say, moment, 0.25 seconds or however long it is, where the the oxygen molecule that's that's been pulled into the VLI and now it's getting transported to the red blood cell. Let's talk about that like little...
00:23:34
Speaker
or not so little, that very important interaction and exactly how that happens and and what kind of gets in the way of it and and what the what the limitations are there. So I think um oxygen cascades, okay? So how the oxygen sort of drops down from atmospheric partial pressure all the way to the mitochondrion.
00:23:57
Speaker
So every time we take a breath, um If we breathe through the nose, which is the most efficient way, nose does two things. It clears the gas mixture, so it stops you from soiling your alveoli, so the little bubbles where it all happens.
00:24:14
Speaker
In the nose and then in the pharynx, so the back of our throat, the air is also warmed up to 36 degrees. And what's added to the mixture is humidity, so water vapor. So it becomes 100% humidified.
00:24:31
Speaker
That's key for the sort of alveoli well-being. Without humidification and in the same temperature, diffusion is very difficult. So again, when walking, it's really important to not be mouth breathing because you then expose your alveoli to dirty air, cold air, and you lose a lot of energy rewarming the gas all the time. So this is where the atrium masks come in or having a bath on your face and making sure that you're always breathing, sort of you keeping the warmth and the humidification in your airways. You're not using energy to do it every time.
00:25:09
Speaker
um And then the air travels sort of through the trachea bronchi down into the alveoli. Now, what happens in the alveoli is we've got to have space for the water vapor. That's about five kilopascals.
00:25:27
Speaker
And also carbon dioxide shows up right? Because we're the ones, you know, mammals are the ones who are producing carbon dioxide. So the carbon dioxide comes out of the blood, and goes into the alveoli. And there is something called Boyle's Law. ah Divers will be very familiar with it. But essentially, it says that the total pressure of any gas mixture is constant, right? So if you suddenly have 5 kilopascals of carbon dioxide and 5 kilopascals of water vapor in the alveoli, there's less space for the other gases.
00:26:02
Speaker
So that's where the first major drop in oxygen happens and it drops about by about a third. So the oxygen doesn't have as much space, right? And this is key for altitude adaptation. So the main thing that happens when we go to altitude, we're suddenly hypoxic, we will be hyperventilating like crazy.
00:26:23
Speaker
And we're hyperventilating because we want to get rid of all of our carbon dioxide to make more space in the alveoli for the oxygen so it has a bit more partial pressure to actually go through.
00:26:38
Speaker
So it generates enough partial pressure to actually bind with hemoglobin. Okay? Okay. Can I pause you right there? Because I a i want to be clear. ah Can you explain why the hyperventilation you just versus what you just said had these deep tidal breaths? So make sure that people aren't getting confused on this point because I think it can be confusing.
00:27:02
Speaker
Well, it is very difficult. So we will all be hyperventilating. um And I just thought you should be taking very slow breaths, right? Or um it's very difficult to do. So um there is also a difference in how our respiration or breathing is controlled. So in hypoxic environment, which high altitude,
00:27:30
Speaker
ah hypoxia drives hyperventilation. Okay, so that will be something that will be very difficult for you to control. There is a degree of ah conscious control over ventilation, but it is quite difficult.
00:27:45
Speaker
And when you go to altitude, you will hyperventilate and you essentially keep your CO2 level at much higher. lower levels and you'll reset your control to a lower levels of CO2.
00:27:59
Speaker
But despite that, if you can add the deep breathing, so using of accessory muscles and splinting. So, you know, often if you're walking with a backpack, if you put your arms on the belt, because that allows you to fix the frame and then use your additional muscles, not just your diaphragm and your intercostals to breathe, that helps you achieve sort of higher volumes.
00:28:21
Speaker
So put your hands on your on the hip belt of your backpack to sort of support your... Yeah, sort of do this. Yeah, okay. Because if you fix this frame here, you can use ah your interscalings and your stoner clad muscles, which are up here, to aid your ventilation because what you want to do is expand...
00:28:43
Speaker
your lungs but as much as you can so your diaphragm will move by about 10 centimeters maximally but you can also lift your sternum and your clavicles if you use additional respiratory muscles and what helps that is you you essentially need to fix your arms to have a fixed frame to be able to do that
00:29:05
Speaker
Interesting. Super helpful. Okay. So now, I understand. So I think that's
Oxygen and Hemoglobin Dynamics
00:29:11
Speaker
clear now. Like, I mean, you, the goal is to take deep tidal breaths, but because there's, you know, a buildup of, correct me if I'm wrong, but because there's a buildup of carbon dioxide, you're triggered to like exhale that and that sort of triggers the hyperventilation. Is that, I understanding that correctly?
00:29:30
Speaker
Yeah, so I think the the, okay, this might be an easy way of understanding it. So hyperventilation essentially means increasing your minute volume, okay? Your minute volume, so how much you breathe a minute, essentially is your respiratory rate times the volume of each breath, which is the tidal volume, okay?
00:29:51
Speaker
So you have two ways of doing it, right? You can either do this... which is not very good at altitude because it's shallow. and It will increase your heart rate, your breathing through the mouth, so you use a lot of energy to warm up and so on. Or you can try consciously to take very, very deep breaths, so then you sort of achieve the same increase in minute volume.
00:30:18
Speaker
by moving bigger volumes rather than increasing the rates. Do you know what I mean? That's a way more efficient way of achieving hyperventilation. I think most lay people, when they you know hear hyperventilation, they assume it's fast breathing. It isn't. You can hyperventilate by increasing your minute total minute volume.
00:30:39
Speaker
Got it. Okay, yeah, that was my assumption. That was my confusion on this term. Okay, so...
00:30:49
Speaker
Like take us take us down to the red blood cell level where this you know the oxygen molecules diffuse across the aveli. Why is it attracted to, why is it diffused? Like what is that like negative pressure on the other side of the aveli in the blood that it that it's going from the air into the, to bond with the red blood cell? What what exactly makes that happen?
00:31:15
Speaker
I mean, it's the, i you know, Newton's apple, right? Gravity. Can't do anything about that. Okay? Physics. Everything is physics. um yeah If you have a high concentration of something on one side and lower on the other, it will travel.
00:31:31
Speaker
um it's not i understand that, but if it's if it's traveling from a from a gaseous form into a into the to bond with a red blood cell, like we're what is there What is the attraction? What is the what is creating the slope? It's non-intuitive to me that ah going from a gas into a liquid would create that negative slope. okay so Okay. any gas mix any partial pressure of gas above liquid... will make some of it dissolve in the liquid, okay? It depends on how soluble the gas is. And the interesting thing is that CO2 is 20 times more soluble, carbon dioxide is 20 times more soluble than oxygen, for example. actually, the transfer of CO2 is way easier, way less sort of pressure grade in consuming compared to oxygen. Now,
00:32:23
Speaker
The oxygen is super interesting because we have hemoglobin, which is this genius sort of molecule, right? um It's got four, each molecule binds four molecules of oxygen. It's got this special heme structure. It needs iron to work well. But essentially, hemoglobin is like...
00:32:43
Speaker
this Maserati for oxygen transfer. Okay, it's highly, highly attractive to oxygen. And when you exert hemoglobin molecule to partial pressure of dissolved o two in the plasma or in the blood, which depends on the alveoli pressure pressure of oxygen, it will change its shape and mop up all the oxygen molecules it can.
00:33:10
Speaker
Okay, and how much Hemoglobin mops up depends on what the partial pressure of oxygen is in your blood, which depends on the air mixture that you're breathing and how much is in the alveoli.
00:33:24
Speaker
And the other thing that's incredible about hemoglobin is that it can shift its affinity for O2 so we can adapt and sort of make itself more sensitive to oxygen at lower pressure, you know, at lower partial pressures. And that's where a lot of the adaptation to hypoxia and altitude comes in.
00:33:46
Speaker
And it does it by various things. So, Let's say if you if our CO2 levels are increased or we're very acidotic because we've just exercised, it will make itself more sensitive to take more oxygen because it's getting all these signals that we might need more.
00:34:04
Speaker
It also develops this 2,3-DPG. dpg which is a ah like this special cocktail that makes it more sort of sensitive to oxygen. So a lot of the hypoxic training or intermittent hypoxic exposure in exercise or when people bring themselves just to the anaerobic threshold of exercise, it will be essentially...
00:34:26
Speaker
sort of stimulating the hemoglobin A production, so hyperproduction, but also making the hemoglobin a bit more sensitive or a bit more keen to take oxygen at lower partial pressures.
00:34:40
Speaker
Okay? And most of oxygen that's in our body at any given time is bound to hemoglobin. So we're talking 80-90% of oxygen is transported with hemoglobin. If we don't have hemoglobin, we cannot stay alive. So just the dissolved oxygen in blood is not enough to keep us alive. Okay, that's why hemoglobin is key.
00:35:03
Speaker
um to to our survival and people with low hemoglobin levels, so you know acute hemorrhage ah or a very severe iron deficiency, you know will struggle with hypoxic or critical environment or critical illness. And then the hemoglobin travels through the circulation, right? So six liters per minute, we're pumping blood on average. That then goes to the tissues, to the capillaries,
00:35:34
Speaker
And the environment in the capillaries is such that the hemoglobin is more keen to get rid of oxygen. So it sort of dumps oxygen. And then again, simple diffusion is everything. Okay, so whether or not the single mitochondrion that you need in your big toe will get oxygen depends in the peripheries on simple diffusion. And the key factor here is how dense your capillary network is because that determines the how far the oxygen has to travel, you know, from the capillary to the mitochondrion in the single cell. And, you know, professional athletes or people who are very, you know, who train a lot, a lot of their adaptation will be increasing the density of the capillary network, essentially.
00:36:23
Speaker
And then in the mitochondria, um some of us are... just better
Genetic Factors in Hypoxia Adaptation
00:36:32
Speaker
at adopting to hypoxic conditions. I'm sorry, we can't control. I know you're training people. There's a yeah genetic component. No, I mean, it's 100% true. There's a genetic component where yeah some of us are less likely to die if we're critically ill with shock and intensive care.
00:36:53
Speaker
So we're just more able to deal with what is, you know, the hypoxic sort of challenge to to our organism. And a very interesting point in the mitochondrion is so-called Pasteur's point.
00:37:09
Speaker
So if your partial pressure of oxygen drops to below 0.3 kilopascal in the mitochondria, that's when you go into anaerobic exercise, okay? So that's the sort of cut-off point.
00:37:23
Speaker
So maybe write just one more thing and I'll try not to make it too complicated, but essentially there are these things called hypoxia inducible factors. There are quite a few of them.
00:37:35
Speaker
um And we have very little understanding of what they actually do and how they work. But um they trigger an expression of over 200 genes in our body. I mean, that's how complex adaptation to hypoxic stimuli is.
00:37:55
Speaker
Okay. It's incredibly complicated. Yeah. Yeah. Before we go into hypoxic-conducible factors, want back up and kind of summarize some key points for people.
00:38:06
Speaker
One is that the oxygen is diffusing from the gas inside the VLI into the blood before it is bound to the hemoglobin, which is part of the red blood cell.
00:38:21
Speaker
It's... It's always been my mental model that somehow the oxygen went – like I wasn't thinking about the gas trends um ah we're transfusing. What's the right word here? Diffusing. Diffusing. Sorry. I wasn't thinking about the oxygen – i Diffusing into a liquid, and just thinking of the blood is a liquid. So that also brings up the point of how vital hydration is and what a big role hydration can play. Because if we get dehydrated, especially but on the more extreme ends, our blood volume is affected and the blood becomes less dehydrated.
00:39:07
Speaker
less liquid, more viscous, more thick. And that also affects the ability of the oxygen molecule to diffuse across that barrier into the liquid in order to get picked up by the hemoglobin. Is that correct?
00:39:20
Speaker
That is correct. And it's um um incredibly important. So there was a whole science of flow called rheology and it has to do with how efficient flow is and it that's incredibly important at altitude because um we get dehydrated for many reasons um or um maybe not just dehydrated the how thick our blood is increases a lot at altitude it's because we're producing a lot of new red blood cells.
00:39:58
Speaker
So our blood becomes more dense. But there is also a point where if you compare blood flow to a very busy, you know, like an American highway, right? You've got five lanes and imagine the red cells are cars, right? There comes a point if it gets too busy, it gets very inefficient, it gets slow.
00:40:19
Speaker
So you need to have, it's called a hematocrit, which is sort of, it's the proportion of cells versus plasma in the blood, right? You don't want it to be too high because then it's too slow, too thick. It increases the risk of clots as well.
00:40:38
Speaker
and And if you think about flow through the pulmonary capillaries, essentially pulmonary capillaries are wide enough to accommodate one red cell. So you need to have enough sort of, you know, and it needs to be viscous so it can pass through the capillaries without getting stuck, right? Yeah.
00:40:58
Speaker
Our body's amazing at sort of regulating this, but yes, hydration is key. And this is where I would say, you know, people who tend to use acetazolamide or Diamox, um what Diamox essentially does is bicarbonate wasting. So it makes you wee out bicarbonate, but you lose a lot of fluid with it because you need fluid, you know, pe with to wee the bicarbonate out. So this is where if you're using it, ah you know, it will help your adaptation, but you sort of need to compensate for, for you know, for being dehydrated. Yeah.
00:41:33
Speaker
Absolutely. Absolutely. Can I just add one more thing? Because I um i also think it's relevant. So your at the atmospheric pressure also varies a lot depending on where you are on the on planet Earth.
00:41:49
Speaker
So because the sort of at the that the atmosphere, because of rotation, is the thickest around the equator, That's why we can climb Everest without oxygen. Okay, so the closer you are to the poles, the atmosphere is thinner.
00:42:04
Speaker
Okay, and that makes a bit different. So people tend to think, oh, well, winson Vincent is not so high or Denali is not so high, but get quite sick. That's because... there is a little bit of atmosphere above us when we're closer to the poles. And also seasons can make a big difference. So, you know, the spring and summer in the Himalaya is much better because atmospheric pressures tend to be higher um on average than in the winter. And when you're operating within margins, you know, that like that might make a difference.
00:42:39
Speaker
Yeah, 100%. Okay, so... okay so um Let's talk about red blood cells and hemoglobin a little bit more.
00:42:49
Speaker
There's this perception that the body's ability to create and generate new red blood cells and mature them and get is a major part of acclimatization. This is what we're all taught. but We also are taught that this takes a long time, you know, from from the...
00:43:08
Speaker
from there erythropoietin in the being, which stimulates the birth or the generation of new red blood cells to the red blood cell being quote unquote mature. And I would like you to explain what that means to us is like so six weeks, you know, and at most expeditions are only six weeks long. yeah.
00:43:31
Speaker
We're going to go into sort of pre-acclimatization strategies and some of that. And I think that this is important to lay this foundation for like how that process works, how important are red blood cells, what conditions should we create within our bodies in terms of nutrition and hydration and exercise to to make sure. sure that we are producing the healthiest, highest quality, most abundant red blood cells? And is there an upper limit, like where we have too many red blood cells? And is that possible without ah going going into, you know, using strong med medications that yeah are aren't usually not accessible or legal? Yeah. Well, this is ah this is a huge subject. Yeah. um
00:44:19
Speaker
So I think the first thing I would say is… um
00:44:24
Speaker
If there's one blood test that one should have before sort of planning any major expedition, I think it's full blood count, including you know hemoglobins, ferritrin, transferrin, and iron studies, because it's a simple thing to do. And it would be really silly to to try to generate your own red cells if you don't have enough iron. okay So there are many there might be people who, let's say, have normal hemoglobin levels, but the iron stores are depleted.
00:44:55
Speaker
So they're not depleted enough to show in the hemoglobin level. But when you suddenly have a huge stimulus to produce lots of more cells, you need a lot of sort of iron stored in your body to to be able to do that, to be able to generate them.
00:45:13
Speaker
and So it's always worth checking that. In terms of increasing your HB levels, the best way to do it is for your body to do it on its own. Because the cells that you produce then are of highest quality.
00:45:33
Speaker
So, um and a lot of it has to do with, um so sort of intermittent chronic hypoxia is a really good stimulus for your body to produce hypoxia.
00:45:48
Speaker
well-functioning
Training for High Altitude
00:45:49
Speaker
cells that are sort of sensitive to O2 and will work better at altitude. So this is where, you know, either sleeping in a hypoxic tense or intermittent hypoxic training or training where you're just bringing yourself into the anaerobic threshold essentially has the same effect will be will be very good.
00:46:09
Speaker
um Traveling to altitude frequently um also does the trick. um Now, any pharmacological fixes, you know they always sound great.
00:46:24
Speaker
But the issue is that ah the cells that are produced might not be ah of good quality. And transfusing cells essentially gives you sort of fairly average red blood cells because the way we store them makes them deplete of 2, 3-DPG and make them work not very well. So there if you compare oxygen capacity, let's say, of transfusers versus cell stick we grew ourselves, um it's you know it's like So
00:46:57
Speaker
essentially There are no quick fixes. Mm-hmm. Mm-hmm. And I want to sort of reiterate just from my own experience some of the things that you said and how those manifest. And one of the things is...
00:47:15
Speaker
people often get really discouraged when the first time they go to altitude and they think, oh, I'm not good at altitude. I don't acclimatize. Well, I can't do that. And they they check out, they do something else. And I, first time I went to 5,000 meters, I got sick as a dog um and was like, yeah, really sick, really like almost had a hard time walking to get myself down.
00:47:40
Speaker
So, But i and I just also noticed through myself, the more I went to altitude, the better my body got. It became at acclimatizing. And I noticed that with other people that I would climb with that were more experienced than I was as a young climber. I'd be like, wow, how come they're so fast at altitude, et cetera, et cetera. And it's like that is earned. That's part of the process of becoming an altitude high altitude mountaineer or mountaineer in general is you're just going consistently as you said intermittent hypoxic exposure you're repeatedly asking your body to do something it's just like the training effect like we're asking our body to build a capacity to do something like move uphill for a sustained amount of time and it will build that capacity we can't expect it to
00:48:25
Speaker
built a capacity that it's never been asked for before. It's like giving somebody a test on on a subject they haven't studied, they're they're going to fail, right? So I think that that's ah really important. And I think it connects back to the the the philosophy ah behind a pill athlete, which is, you know, that this is not... um These sports and these activities, being in the mountains, it's not something we do like, you know, one week a year. It's part of our lives. It's part of our our whole trajectory of our life of of becoming a person that can do these things like climb high mountains.
00:48:59
Speaker
And I think that that's super important. And I also want to get into a little bit something that you said because I've seen some of the, from Dr. Robert Browning, and we've discussed this briefly offline,
00:49:14
Speaker
who has been doing these studies, which she hasn't been able to publish yet because they're ongoing, just just the sheer scale of the ah the the way that the human genome reacts to high altitude is is really mind-boggling. It's like you said, it's it's hundreds of switches on our modern genome are either up or down regulated. Yeah.
00:49:41
Speaker
by a simple exposure to high altitude. And a lot of these switches, we don't even know what they do yet, right? So there's all kinds of things. what What does that make you feel as a physiologist and as a physician?
00:49:55
Speaker
are you Are you excited at the prospect of how much there is yet to to know and understand about how we can better planetize? And what how do you think about that, where we are on the sort of the evolution of ah human knowledge around this topic?
00:50:15
Speaker
Well, it makes me feel ex excited, I guess. You know, it's um you never stop learning, right? And um I think all the methods that we currently have to help people adapt are fairly crude.
00:50:30
Speaker
um i think a lot of the work will be probably about individualizing the process because people react in such different ways. You know, they there are,
00:50:46
Speaker
um there are people where you recommend certain things but it might be the opposite of what they need so because the process is so complex and um and but I also think it opens huge new opportunities. And I think the key thing for me is that there's so much crossover in what I do in my daily work. So essentially, most of my patients, you know, are trying to deal with critical levels of hypoxia in one way or the other. And that is very similar to being at altitude in a way. So finding new ways of being able
00:51:28
Speaker
to support people is is very, very exciting. And I think just going back to what you said, how awfully how awful you felt doubted it the first time around, I really wish we could relabel acute mountain sickness as you know, adaptation, altitude eye adaptation syndrome, because it does my head in, you know, sickness suggests that A, there is a pathological process, something you need to be worried and scared, worried about scared of and a bug, you know, a bacteria, virus. Oh God, I have AMS. I have to take drugs. Please help me.
00:52:08
Speaker
You know, All the symptoms that you describe are essentially physiological symptoms of your body gradually, slowly adapting to it, right? It's only the escalation that's a problem. So, you know, when you've got a little bit of a headache and you feel crap and you don't want to eat and you haven't slept well... That's a Lake Louise score of, let's say, you know, not so high.
00:52:35
Speaker
That's altitude adaptation syndrome. And that's what everyone, 80% of people will have. And it's completely normal. It's just your body telling you, ooh, you know,
00:52:48
Speaker
this is not the environment I'm used to i feel a little bit short of oxygen here, but actually i can cope with it. Give me time. Let's take it slowly and we will be okay.
00:53:02
Speaker
Yeah. I really think we should sort of try to change the way we think about it. I like that a lot. I like that a lot. Um, I want to skirt in this conversation because there's so much others else to talk about the idea the the the discussion around altitude illness and stay focused on the gas exchange idea. So to go back in summary,
00:53:31
Speaker
The oxidant is bound, the oxidant is binded to the hemoglobin. Hemoglobin is part of a red blood cell. The EPO, the erythroplatin is key to, it's the key trigger that tells our body to increase the red blood cell count. and we need to have good iron stores on board before we start building correct new red blood cells. Okay, we got that. everybody or i've I've summarized those and I'm and i'm on track.
00:54:06
Speaker
Now I would like to shift. as I think this is a good segue because we talked about like you talked about how we should reframe mild, what we currently call acute mountain sickness, to um altitude adaptation syndrome syndrome or process.
00:54:28
Speaker
And so a lot we we can agree that frequent ballots, whether it's in the Alps or the Cascades or you live in Colorado or you know in those places you're going to have access, even California to a certain extent, you're going to have access to 4,000 meters, let's say.
00:54:46
Speaker
But if you live in Poland or you live in the UK or you live in york New York or ah Florida, you don't have access to that. You live...
00:54:58
Speaker
I've had the challenge and the and the pleasure to coach athletes who are living in Mexico City and they had ample opportunity to get this intermittent exposure to altitude. But also I've had athletes, one guy laughed I worked with last year, he climbed K2 without supplemental oxygen and he lived in Singapore.
00:55:20
Speaker
He never went above the top, you know, the highest altitude he reached was the top of a building, which was probably 100 meters above sea level. So, A lot of people are bound by their location that's far from real altitude. So let's talk about some of the hypoxic training methods that might help us at low altitudes. And there's a few different ones. you want kind of summarize what some of those different modalities, potential modalities are, and maybe we need to come back to that idea that you touched on earlier, normal baric hypoxic conditioning um versus hyperbaric hypoxia.
00:56:00
Speaker
I mean, I hope I'm not going to say anything too controversial. um I think there are many, many modalities that we can use. None of them as good as are as good as going to altitude. And the reason for that is that essentially the the way we can generate hypoxia at sea level is...
00:56:22
Speaker
by
Hypoxic Training Methods
00:56:23
Speaker
adding more nitrogen to the air that we're breathing. So we are still at normal barracks or normal atmospheric pressure. We just have the oxygen, the the gas mixture has less oxygen in it.
00:56:37
Speaker
Isn't it kind of the opposite of like using an oxygen mask and breathing a higher... concentration of oxygen having the oxygen that's on everest you're breathing an oxygen mask and you're breathing 30 it is exactly the opposite so on oxygen so and that's displacing nitrogen and now we're taking nitrogen and displacing the oxygen molecule so it's the the opposite of that it is essentially the opposite of that and however You know, if you look at what you can modify before you travel to altitude, you know, if you look at the EPO response and the making of the new cells, as you said before, that takes most of the time. Okay, so that's the thing that's really worth doing before you go.
00:57:20
Speaker
Because you are sort of starting the process that you would be having at altitude anyway. You're just starting it sooner. ah And red cells tend to live for 21 days.
00:57:33
Speaker
So a lot of it is about timing as well. um And this where you know the the main modalities we have essentially is sleeping in hypoxic tents.
00:57:44
Speaker
yep So you either have a tent on your head or you have a a tent that your whole mattress is in. ah Before going to Everest this year, I slept in a hypoxic tent. ah I absolutely loved it because there's a lot of white noise. There's the constant buzzing. It's nice and warm.
00:58:01
Speaker
but um Some people hate it because it's too loud. So again, you know, this, how you cope with this depends very much on whether or but or not you get on with the technique. But I think here we say that you need to sleep in it for at least 250 hours. So, you know, we're talking four, six weeks of of eight hours ah of of sleeping in a hypoxic tent and you can go up to as high as 6,300 in these tents. Okay? So you monitor your SATs overnight um and it works very well for some people.
00:58:37
Speaker
um The other thing you can do is You can have short hypoxic bursts at rest. I think most of us feel that um it is much better to do hypoxic bursts exercise, that that tends to work better in stimulating EPO than just doing it at rest. So that's the classic you're on a treadmill exercise.
00:59:01
Speaker
And you have a and nitrogenator next to you and you have a mask and then you breathe, you know, again, ah mixture with higher nitrogen concentration. And all these things, essentially what what it does, it it stimulates the HIFS, so hypoxia-introducible factors, and it mostly stimulates your EPO into generating your own red cells.
00:59:23
Speaker
Yeah. Many athletes I know or work with sort of can sense it when they're getting themselves to that point. So if you think about it, you know, if you train and you bring yourself into the anaerobic threshold...
00:59:41
Speaker
but not so far that you get a lot of lactic acid. So, you know, you don't, um you will know more about this than I do. But essentially, people can sense when they just get to that point and they do it intermittently many times, you know, that's sort of similar to breathing a hypoxic mixture.
00:59:59
Speaker
and So, you know, Andrea, who I work with, You know, he just has this incredible innate intuitive ability to know when he's hitting that point and he will be doing it intermittently and actually, you know, doesn't use a tend, but essentially achieves the same thing, right? It's the continuous sort of hypoxic inducible factor stimulation. Yeah.
01:00:23
Speaker
and So, you know, all of these are great. um And I'm sure with more research, there will be more things that we might be able to do to prefer prepare better to climb safer, essentially.
01:00:38
Speaker
And this is something that we've worked with at Apalasi. We have a ah a program that runs parallel to our existing coaching where we will do the hypoxic, normal barric hypoxic,
01:00:52
Speaker
adaptations And we've done it with people in tents, as you described. with the and And interestingly, like I had an athlete that I worked with on this couple of years ago, Climb k two also without supplemental oxygen.
01:01:07
Speaker
We couldn't get a tent to Australia ah because they don't have a distributor there. So we only used the exercise training. induced um you know with ah with a nitrogenator on on the stationary bike and also used a ah breathing or restricted breathing mass on some of his ah other other workouts. And it seemed to work really well. And he he did really, really well in the mountains. So there there is certainly some so It takes a lot more effort than for those that live in the mountains and have the ability to go up to the top of Mont Blanc or whatever easily. That's ah that's ah relatively easily. That's always always better, as you said. But it's it's remarkably effective.
01:01:54
Speaker
I have to say, like i and I've said this on the podcast here before, where you know I first tried 2001, believe, two thousand and one i believe No, it was 2003 for an expedition to go to Mashabrum, which is about 7,800 meters.
01:02:10
Speaker
And it didn't feel like it worked. Like it was a lot of work ah to do the thing. I was in the tent for a couple, like eight weeks. I think that back then the problem was it took us 10 days to get to base camp.
01:02:24
Speaker
It's just like it by the time I got to base camp, I hadn't been in the tent for over two weeks. You know, I'd been traveling. I'd been and buying potatoes in the market. I'd been doing all the things that you know, have to had to do for expeditions, especially a small, low-budget expedition back then. And by the time I got to base camp, there was probably not much of the acclimatization left. And it didn't feel like I was any better than I I felt like I was the same.
01:02:49
Speaker
And so I was for a long time for that reason kind of like, you know, dismissive of the technique. yeah But I think one thing that's happened is we've gotten much better understanding, like you said, how many hours do we need of these different stimuli? What are we actually doing? And so now I want you to talk about the hypoxic inducible factors and what those are and what we understand about them because I've I think we can agree there's probably a bunch of things going on that we don't understand, but there are some good ones that we've understood. And we and where we've come a long way, I'd say, in the last...
01:03:26
Speaker
for sure 10 years, but even in the last three years, I feel like in the in our sort of community of practitioners in this space,
Role of HIFs in Acclimatization
01:03:34
Speaker
we've come a long way in understanding what these hypoxic inducible factors, the HIFs are and how we are affecting them, what this what what what stimulus we're giving the body through the the let's say fake altitude or the stimulated altitude and what reaction we're getting out and how highly individual it is. So let's talk about that.
01:04:00
Speaker
There are people in the community um who might have chronic illness, whether it's heart failure, whether it's severe you know chronic obstructive pulmonary disease, pulmonary hypertension. So theyre you know there are people out there who are able to adopt and and sort of survive that in in conditions or, you know so so on the edge in terms of where they are with their oxygen delivery that if you if, you know, if you put you and me in that situation acutely, we would just die, right? So, um and that's achieved through the sort of chronic stimulation or a chronic hypoxia.
01:04:48
Speaker
And all the different adaptations that that happen that allow our body to function. And that's why we can function at high altitude. You know, apart from what we've talked about, which is the hemoglobin, right? That's that's ah a really, you know, big part of it. But...
01:05:09
Speaker
Also, the way, let's say, even if you look at how um our ventilation and ah the function of our cardiovascular system and is controlled, that sort of learns and adapts as well. So, you know, you... um Let me just find a good example. um I think what I'm trying to say is that it's... it's You know, there's so many levels at which...
01:05:38
Speaker
they work that it's almost impossible to explain. Is there like a, are there layers? Is there like a base that like is a mostly hemoglobin? And then the next thing is like, I don't know, like, um, uh, blood acidity, a pH, uh, like other, like, has a, has a way or you can break it into layers. I mean, you'll be adapting, you're sort of adapting at every level. So you'll, you know, the way you're,
01:06:06
Speaker
your central nervous system ah controls your respiration and your cardiovascular system sort of resets, right? So it's almost like AI. It learns to and sort of and act to different triggers, right? So let's say if you...
01:06:28
Speaker
and in you have very high CO2 levels because your lungs are not very good, then the sort of acidity of your brain changes, but your brain will learn to sort of reset its control to a different pH levels and at different CO2 levels.
01:06:47
Speaker
um It will, ah the way your lungs work will adapt. um But I think that the other, you know, key thing is that... um For example, your mitochondria will reset for a different like like a different level.
01:07:06
Speaker
They can learn to function in a more hypoxic environment. yeah we We don't have any good ways of measuring this. This is maybe the you know the other important thing. It's like that EPO you can measure, hemoglobin you can measure, but yeah we we don't really have a good way of measuring what HIFs do.
01:07:30
Speaker
and So like you can use lactate thresholds, but that's a very crude way of measuring it.
01:07:38
Speaker
There's no measurement for like the efficiency of the mitochondria's use of oxygen in a hypoxic environment or in a non-hypoxic environment for that matter, right? Like there's no there's no chest strap that we can put on that would measure measure that. Oh, the other thing that I think is important is how much oxygen we extract.
01:08:04
Speaker
Because people, I don't think people know that there is a lot of oxygen in the venous blood as well. So we cannot extract more than 50%. in, so the hemoglobin is always, there's always some oxygen on hemoglobin.
01:08:22
Speaker
Yeah. Yeah. And and that that's interesting, right? I mean, i think that when I learned was a kid and learned CPR, that was one of my first questions. Like, how how does breathing into this person help them give them oxygen if I already pulled all the oxygen out of the air? doesn't.
01:08:40
Speaker
But it doesn't, right? Like, we're we're actually pretty… why we don't do it anymore. Yeah, yeah, yeah. Okay. Yeah.
01:08:49
Speaker
We just do chest compressions because you have enough. You still have some, unless it's, you know, avalanche vario because the asphyxia might be a big part of it. So you tend to give it a sweet hand. okay. Well, so I'm so out of date on all my medical stuff.
01:09:04
Speaker
So, look yeah, like why don't you walk us through… The oxygen extraction and how we measure that. And, you know, these people are obsessed with their O2 sat measurements and they all everyone's carrying a little O2 sat measure around the neck these days or on their watch.
01:09:24
Speaker
Let's talk about that. Tell me about oxygen extraction how that works. So as we said before… most oxygen content or carrying capacity is determined by how much hemoglobin you have and how well that hemoglobin functions how how healthy your red cells are essentially yeah The interesting thing is that, so if you have enough partial pressure of oxygen in the plasma, then 100% of your hemoglobin gets saturated, right?
01:09:58
Speaker
So that means that all the binding sites on hemoglobin are saturated with oxygen. So that's oxygen saturation. um And this is the what we often measure, what our watchers measure is ah oxygen saturation. Now, the way that's measured is by shining an infrared light through tissues.
01:10:21
Speaker
And so oxygen saturated with chemoglobin absorbs some of the red er infrared lights. So then, you know, the clever computer calculates sort of how much oxygen of the infrared got absorbed and it gives you a fraction. So oxygen saturation is a fraction.
01:10:39
Speaker
and What most people don't know is that venous blood also carries a lot of oxygen. So in normal conditions, at rest, we only extract about 25% of oxygen that's bound to hemoglobin.
01:10:55
Speaker
So your venous saturation is 75%. And the venous blood is the blood returning to the heart and lungs. Returning the lungs, yeah. So that the the that's the blood that's sort of given the oxygen to the tissues, to the mitochondria, and it's returning to the lungs to pick up more.
01:11:13
Speaker
And um the way we can tell how sick people are or how critically challenged from the hypoxia point of view they are is by testing venous saturation so maximum human body can extract in the peripheries in the tissue is 50% so venous saturation of 50% means you've just ran the marathon climbed really hard or you're critically ill essentially
01:11:44
Speaker
okay um and But the O2 sat meters are measuring venous saturation or arterial saturation? Arterial. They're very clever. So they can tell the difference between a pulsatile signal and a constant signal. So venous sats have a constant signal because it's non-pulsatile flow and arterial sats have a pulsatile flow.
01:12:10
Speaker
Okay. So um the measuring device can tell the difference. So it only only tells you the saturation of the pulsatile flow. So the arterial saturation.
01:12:22
Speaker
Now, important to understand about pulse oximeters is that there are huge limitations to what they measure. So let's say if you have one on your finger,
01:12:36
Speaker
that does not give you the full body picture. It gives you, you know, the O2 saturation in that finger, okay? So if your blood flow is not good, let's say you're cold, you're dehydrated, ah you know, you might have a little thrombus here, then the reading that you're getting might not actually represent what's happening in the body. And that's where the sort of holistic assessment happens how the climber is or your patient is is really really important
01:13:10
Speaker
um And often, i see it very often that people get very hyper-focused on one number. And, you know, a question that I get often is like, well, well what O2SAT would you be worried?
01:13:25
Speaker
And I'm like, I can't answer that. I mean, i would look at, you know, is someone conscious? Do they look like, does it work? Like they're working really hard. Their work of breathing is through the roof, you know.
01:13:38
Speaker
Do they make sense? Either tachycardic, what's their blood pressure, what are the other things doing? You know, I wouldn't just sort of say, based on this one number, that someone is sick or not sick.
01:13:50
Speaker
It's ah more about trends. Yeah. If someone's at ah at, I don't know, Everest Base Camp and they or Camp 3 for that matter, and they have a certain O2 sat compared to, you know, and it's, let's say, relative to their other climbers, it's higher or lower. Does that correlate to someone's acclimatization status? Is someone acclimatizing better acclimatizing worse? Or is it, again, just one data point among many? It's one date upon a point among many, which has, you know, a sir fair amount of measurement error.
01:14:27
Speaker
And I think this is where having experienced guides is so, so important. I mean, I often say you don't need a doctor on an expedition. You just need an incredibly experienced guide who can tell that someone's cognitive function is worse.
01:14:48
Speaker
They're starting, to beginning to trip. They're sort of starting to lean, and you know, against walls, maybe losing coordination a little bit, right? When people, what, is there a big difference between the different devices? Because you can order these things on Amazon or something for $10 these days.
01:15:07
Speaker
Are there medical grade? Are there non-medical grade? Is the, is the, um, pulse oximeter on your Apple watch work as well as something on your finger. I mean, understanding that it's limited to measuring the O2 sat at that point of measurement, whether it's your finger or your wrist, but is that something that people need to be concerned about in terms of selecting a device?
01:15:30
Speaker
I think most of them, i mean, it's it's sort of, it's been around for such a long time and it's so simple that most of them work very well. I don't think you need, you know, um you need anything too sophisticated. I mean, they are helpful, I think, if people use O2SATS to guide their adaptation process, I tend to say, you know, please take the measurement at the same time of day in similar sort of circumstances. Let's say after breakfast in the morning, when you're sitting in the warm tent and you're at rest and then compare, compare a day to day. So you have comparable trends, you know, do it along Lake Louise score.
01:16:10
Speaker
And let's say, what's your heart rate variability, which is probably a better marker of how stressed your body is at the time. ah And, you know, monitor these trends every day and and then we can have a conversation.
01:16:27
Speaker
I mean, clearly if someone is an extremist and they're sat at 65 and they've got frothy, you know. Yeah. Yeah.
Monitoring and Managing Oxygen Levels
01:16:35
Speaker
They're coughing up sort of frothy spute, you know, that that's life-threatening. But I think that and a number on a to its own, it tells us very little.
01:16:46
Speaker
You've worked with elite climbers, but you're also frequently working with patients, as you said, in various states of hypoxia. Are there things from your clinical practice that you have learned that apply well to the high-altitude medicine practice?
01:17:06
Speaker
I think so. I... ha so For me, I think it all boils down to expenditure or energy management.
01:17:20
Speaker
Okay, so it's like, how much is your body paying to get to where you want to be? Okay, so...
01:17:31
Speaker
is the the effort and the sort of O2 energetic cost of you going higher such that it is actually making you ah unwell?
01:17:43
Speaker
And that's the the very fine balance where... If work with people who are critically unwell or who have severe heart disease and need operations, you become, I think with time, you know, it's sort of pattern recognition. You become it you become very sensitive to picking up ah The little clues when people are, you know, sort of almost going over the edge because ah it's, um how can I explain it? So so let's just let's let's just take work of breathing, okay? So when I'm sitting here now talking to you, I am a little bit stressed, but essentially I'm at rest, okay? Okay.
01:18:30
Speaker
So my work of breathing right now is less than 5% of my total O2 consumption or what what my body is using. But if I am in a hypoxic environment exercising or trying to ascend or if I'm critiquing unwell, work of breathing itself can be more than 30% of all all of your O2 consumption.
01:18:57
Speaker
You know, that pretty much means that even the effort of of respiration can take you over the edge and make you sort of fall off the cliff, right? If you're operating within very small margins.
01:19:12
Speaker
And it's all about... explaining to people that you work with or at work treating treating the people, you know, treating the patients to to sort of pull them back to a slightly more comfortable position.
01:19:29
Speaker
And I think that's key. And the elite athletes that I work with Their skill is, I think, intuitive sort of energy expenditure management where, you know, if you think about Andrzej climbing, start you know, he was above 8,000 meters for 16 hours.
01:19:51
Speaker
You know, he is right on the edge of what is humanely achievable if you look at physiology. But he he can manage his own sort of exercise expenditure budget like minimum budget well enough to be able to sort of continue with what he's trying to achieve and that is the that is a very difficult thing to do because once you sort of cross over it spirals out of control very very quickly and I think that's maybe the crossover for what I do in my daily work and and working with with clients at altitude is like how
01:20:33
Speaker
how to keep someone in that comfort zone, which is, you know, that's a very limited space, but it is there and you can find it. Very interesting.
01:20:44
Speaker
So let's let's wrap this up with kind of a lightning round of a couple of questions that I want to ask to sort of summarize some of the key things that that you communicated today. um First off, give me a good summary of the oxygen cascade concept.
01:21:03
Speaker
Okay, so the oxygen cascade concept essentially is the flow of partial pressure of oxygen from atmospheric to mitochondria.
01:21:16
Speaker
Okay, so we take a breath, we expose our lungs to atmospheric pressure of oxygen, starting with 21 kilopascals, that's 21% of 100 kilopascals at sea level.
01:21:32
Speaker
The air gets warmed up, so water vapor squeezes in, CO2 squeezes in. By the time we're at the alveoli membrane, partial pressure of oxygen is about 13. So, you know, we have a full of a third by the time we get to the alveoli.
01:21:50
Speaker
That determines how much binds to hemoglobin. that travels to the peripheral tissues. And then by the time hemoglobin offloads in the tissues and it gets to the capillaries and then to the mitochondria, which is where it has to get you, get to to keep you alive,
01:22:08
Speaker
It's about three kilopascals. So, you know, I will often ask people, well, would you buy a car that essentially has seven fold?
01:22:19
Speaker
Full, you wouldn't. It's not a very efficient engine, isn't it? If you're starting with 21 kilopascals and then you're down to three and the three kilopascals is what keeps you alive.
01:22:31
Speaker
you probably wouldn't. So it's a very fine balance. And that's why our adaptation to the conditions on Earth is so important.
Acclimatization Processes and Risks
01:22:40
Speaker
Give me a summary of acclimatization and the process of acclimatization and what that means to you.
01:22:49
Speaker
So acclimatization is essentially a physiological, so a normal natural process in which your body will, if given time,
01:23:01
Speaker
slowly adapt to hypoxic environment, to not having enough oxygen. And it will happen at so many levels, it's of which most of them we don't even understand, but the primary thing will be hyperventilation, so getting rid of CO2 so you have more space for oxygen in your alveoli.
01:23:26
Speaker
You will then increase your oxygen-carrying capacity, In many ways, that has mostly to do with red blood cells and hemoglobin.
01:23:37
Speaker
You will increase the capillaries, so your peripheral resistance will be less. There'll be more capillaries closer to the mitochondria, so there's less road to travel to get there for oxygen.
01:23:50
Speaker
And through the hips, your mitochondria will cleverly increase reset to function at a lower partial pressures of oxygen.
01:24:01
Speaker
And a lot of his a lot of it is genetically genetically predetermined in how you're going to adapt. But there is there are big areas where that's modifiable. And the more time you give your body to achieve that, the better it will be. So it's the acute...
01:24:19
Speaker
hypoxia, that's a problem, you know, that's critical illness or a climbing Everest without acclimatization with six liters of oxygen, suddenly you lose your bottle or your apparatus freezes. You know, you're in the worst case scenario where you're essentially not pre-acclimatized in a hypoxic environment.
01:24:41
Speaker
Yeah, great. Summarize for me so the individual factors in a conversation and what some of them, what some of the big variations are between individuals and how that changes over time.
01:25:00
Speaker
So the individual factors, I think, This is what we know today, and I'm sure there will be much more and hopefully we'll be able to do genetic testing for this one day. It would be very exciting, is um so-called hypoxic ventilatory response.
01:25:20
Speaker
That is essentially how much your minute ventilation increases when you're exposed to hypoxic environment that predetermines how you will adapt or whether you'll be able to adapt to altitude.
01:25:41
Speaker
um Other individual factors, obviously, if you have certain diseases like pulmonary hypertension, it's a no-go, you can't go. um um a lot of the genetic adaptation, again, that is something that's predetermined. We can't do much about it.
01:26:01
Speaker
But I've... so i've taking many people with very severe diseases to altitude people with bone marrow transplants. And I think if you go slowly and carefully, you can actually achieve the objectives if if you do it sensibly. So a lot of it is about monitoring the response, what I call, you know, altitude adaptation syndrome, essentially response and and slowing things that things down if we if if you need to.
01:26:31
Speaker
um i don't know, does that answer the question? Yeah, yeah, no, that's, that's great. And I think ah the last question I have is the role that self-awareness plays in going to altitude.
Self-awareness and Mental Control at Altitude
01:26:48
Speaker
So this is, some I think this is probably the imperceptible, you know, sort of non-technical skill, you know, the human factor, which is key.
01:27:02
Speaker
it's And that's why how you cope mentally with that exposure is so important in your drive.
01:27:13
Speaker
um And the ability to keep your body quiet, not sort of sympathetically overstimulated, to keep your respiratory rate down, you know, despite the fact that your brain is screaming, please hyperventilate.
01:27:32
Speaker
And trying to keep your you know your heart rate down so the cells have load longer time to load and in in the lungs, right? If you're able to do that, you actually can master that ah environment. Yeah.
01:27:48
Speaker
You know, the interesting thing is like the the way we control ventilation, part of it is sort of conscious. A lot of it is automatic. Again, at central level, chemo, baroreceptors, receptors in the lung and so on. But emotional state also has huge impact. So, for example, you know, what fear will make you hyperventilate, very difficult to control. And we talked about it already that actually increasing your respiratory rate is not the most efficient way of doing it.
01:28:18
Speaker
So, you know, if you're able to contain your fear and slow the rate down by making the tidal volumes bigger, that's actually way more efficient. So it's the the fine ingredient of being able to manage an environment where you are...
01:28:36
Speaker
not in a happy place, right? Because you're short of breath, but you're able to stay calm and and continue and be reassured that sort of you can do it is, I think, probably key.
01:28:47
Speaker
And that's why, you know, Messner could do it. Messner was not an elite athlete. There was a brilliant paper comparing his VO2 maxes to, you know, other people. he He's not superhuman. He just has that...
01:29:02
Speaker
incredible ingredient where he can work with his body, his own body and recognize where he is and, and yeah sustain that challenge.
01:29:13
Speaker
yeah and dial it like if the maximum is 10 he can set it 9.9 and stay there all day right like it knows where that is like what you were saying with with andre but also the consistence i think the consistency of that you know what i mean to be able to maintain it for prolonged periods of time and this is where i think training comes in and you know, using heart rate variability, using heart rate zones as as a guide to, okay, how stimulated am I? Can I bring, tone this down a bit and actually, you know, go calmer but more efficiently?
01:29:55
Speaker
Very cool. Yeah. How can, i well we will put in the show notes some links to some of the places where you're showing up online and you you do a mountain high altitude medicine course ah that you offer. You work with the Altitude Center in London, which whom we also have us a partnership with. And you are also at Altidoc.com.
01:30:20
Speaker
dot ord where you're consultations for people going to high altitudes or treks or expeditions, expedition medical services. And i think that that's, you know, for for a lot of people, that's ah a really great service for them to be able to connect with you for that individualized support. Because a lot of times...
01:30:44
Speaker
What I tell people regards to training is there's easily 50% of the people that want to train just need a training plan and they can follow the training plan and they kind of do it themselves. and then But as you like get into the other 50%,
01:31:00
Speaker
There's more people that have, you know I don't know, whether it's ah um a medical issue or a historical you know ah it experience with high-altitude illness or any kind of variety of things. You may need some more individualized support, and they can they can find you for that. so i think that's great. Thank you for bringing your expertise today and all your think decades of of knowledge. And it's been, and I'm sure we're going to chat again.
01:31:29
Speaker
Thank you so much. Thank you so much, Steve. Thank you. Thank you for listening to the Uphill Athlete Podcast. We're not just one, but a community. Thanks for listening.
01:31:53
Speaker
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Speaker
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Speaker
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