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Hello there. I'm Jack Watson. I'm a GP in Cheltenham um and an exposition doctor and we're going to explore the busy heights of altitude illness. So sit down, get comfortable pen, pick paper and a nice cup of tea and let's go through things. So high altitude generally is defined as altitudes above 2500 m. Um As you go higher, the percentage concentration of oxygen in the atmosphere is the same, there's still 21% of oxygen, but the oxygen molecules are all further apart. So each breath of air you take in, you're getting AAA lot fewer, a lot less oxygen if you like. Um and the partial pressure has also dropped. So the the um as you go higher up, the pressure in the atmosphere is dropping, the oxygen molecules are further apart. And subsequently, it means that you're getting less in each time you breathe, which causes um physiological changes, some of which um are of interest to us because they can be uh very dangerous. Um So we're gonna be talking about um acute mountain sickness, a MS high altitude cerebral edema and high altitude pulmonary edema. So um it depends where you, you will be working on your um on your travels or, or what you, you do specifically. Uh But my personal experience from my attitude has mainly been in the Andes and on Kilimanjaro. Um Now achilles are very popular. Um almost entry level mountain if you like, but it's actually classified as just fitting into the extreme altitude section. So above 5800 m, um achilles at 5895 and um just a rough ballpark figure when you get above 5000, you've basically um half the amount of oxygen that you're taking in per breath. Um So you can imagine that found effects that can then have on your body. Um It, now if we have a little look at this, er, lovely mountain map of all the pick box dreams. Um Hopefully some of you have done Ben Es. Um I did Mont Blanc last summer. I done Kill Au is certainly a, a dream. And then Everest, you know, if anyone would be willing to, to sponsor a doctor up there, I'm sure there will be a few, a few up for going and doing it. Um But generally when you're getting that high, you're, you are kind of putting your body through some real extremes and MRI changes that have been done on Everest climbers has shown that um above 7000 m, you are getting changes on your brain and there's a reason why human beings generally can't live above about 5.5 1000. Uh, long term. Um, A MS and Hace can, can actually kick in as low as 2.5 1000. And, um, obviously in the UK, we're, we're pretty safe at Ben Levis, but, um, when you start to go into the Greater mountain Ranges, um, it is something that you really do want to be aware of. So, A MS, what is it? Um, it tends to be um quite normal for, for these symptoms. You know, most people do get them if you um I to altitude quickly. So I would expect at least kind of 80% of the group to be feeling some form of A MS on the first few nights in, on Kilimanjaro. Um high altitude headache, um very typical, often that's associated with fatigue, loss of appetite, nausea and dizziness. Um Often people can feel ok during the day they get somewhere. Uh It's only really later on when um when they start trying to get to sleep that the headaches really starting to kick in and, and they really get starting to feel dizzy and not feeling so well. Um What normally then happens is if you've got a, a good acclimatization profile, um you can stay there for 24 hours or so and the symptoms should settle and your body then acclimatizes to that, to that altitude. Um Now, to look into the, the diagnostic criteria around uh the Lake Louise score um can be very helpful for particularly for people who haven't been to high altitude before. Um It was important to say that this is a scoring criteria that was created to try and help researchers um kind of grade um altitude sickness. Um It was never meant to be a tool used for diagnosis purposes, diagnostic purposes. Um It was clearly just a research tool now similar to things like the Glasgow coma scale. Um, it then got taken up by um medics and non medics alike. You thought this is brilliant. We've got some way we can classify if someone's getting very sick with high attitude or not. And to some extent it can be very useful cos it, I, I've used it in the past particularly for monitoring people's own personal symptoms, cos from person to person, how they grade dizziness might be hugely varied. Um It was actually a very interesting paper that Doctor John Dallimore um did, um, when he was, I might have got, I'm not, it was 100% right. But he was basically had some students, uh kind of 15 and 16 year olds and a big um hike around Dartmoor and made them do the Lake Louise school um, each night. And er, I think his results showed that, you know, the majority had, according to the Lake Louise score had at least moderate A MS symptoms. Um, and that's because it was using things like you have poor sleep. Um Do you feel tired? Are you off your food? Which a lot of the time if you throw a bunch of school kids into a 400 m high altitude more, um, they aren't gonna be getting a MS symptoms, but they are gonna be getting a lot of these symptoms you're gonna get from being outside your normal environment. And we see that a lot anyway, on Kilimanjaro. So recently they updated the late Louise score and they took sleep out of it completely. Um So the school has uh the symptoms of a headache has to be there. As long as at least one of one other of these categories, they're all graded from naught to three according to sort of how severe they are. And um as I said, when I've been on Kilimanjaro before I've made people do the score twice a day and seeing how they're adapting to it. And if they're starting to show signs of a MSI might start them on Diamox, so they're not already on it. And it's quite useful kind of seeing the trend, seeing if things are improving or not. Um Now it is important to say that it's the Lake Louise school is sensitive but it's not actually specific. Um and it can be confused with other symptoms, er, or other things that are causing it. So just in your back of your head, you wanna be considering things like migraines or upper respiratory tract infections. Uh, alcohol can certainly do a lot of this. I know when I flew into Ecuador in November, I was a doctor for a group hiking around Co Apax. Um, and there's a bunch of Canadian real estate agents who hit the bottle pretty hard. Um, the first couple of nights before I actually had even got out to join them and, um, one of them was bed bound. Um, you know, Keto to be fair is, is quite high. I think it's about 3000 m. But um there was a bit of a concern about whether we can even begin the g the hike with one of the ladies. But um once she'd kind of rehydrated and stayed off the bottle for a night. Um her hi, she had a dizziness, fatigue and lack of appetite. All were actually improved and she did absolutely fine the rest of the trip. So something to consider um exhaustion, dehydration, carbon monoxide poisoning. Always something to think about, particularly in, um, you know, intense when you're cooking inside and that sort of thing. So, acclimatization, um normally after 2.5 1000 m, it's important that you're going slowly. Um The W MS the Wilderness Medicine Society guidelines, um very clear suggesting that 300 to 500 m elevation a day, your sleeping height um shouldn't really be um exceeded um to allow your body time to adequately acclimatize. Having said that Mount Kilimanjaro at 5895. if you actually went to that sort of speed you'd probably be climbing it over about 2, 2.5 weeks. Um, people, they pay quite a lot per day for a park fee, which is why we see so many, uh, so much higher illness on K, um, it's a great place to go if you, you wanna see these things in person and I've sort of treated, um, patients with a MS there a lot. Um And there's an element where ethically should they be climbing the mountain so fast. Um When, you know, actually this is fast than guidelines and just because you have a doctor there doesn't mean it's safe. Um So some of the routes will be, um, try and do it up over about four days. I would really recommend if you ever climb it, try and go on something like the La Mosia route where you have about 77 or eight days to, to, to climb it. Um, but climb high sleep low has always been the kind of age old mountaineering adage. Um You can go up to 1000 m in elevation um, in a day as long as you drop back down for sleeping. Um, and certainly places like an Everest um, base camp can be quite helpful cos you can go up and down the valleys so you're going up and then coming down again. Um And Diamox acetaZOLAMIDE has been plenty of trials. Have clinically proven that it works very well for um preventing a MS and preventing high altitude illnesses. Um So it certainly should be considered. And the most recent W MS consensus guidelines said that on mountains like Kilimanjaro, they'd recommend it for everyone to take some Diamox, given the um rapid ascent profiles. So this is an example of, of a good assent profile if you're looking at, you know, taking a group somewhere or being a doctor or medic there, um It is something you want to be considering, you know, it is an incent profile, you feel safe. Um If it's not, can we change it? Can we alter it? Whereabouts? Why might be we be getting problems? Um But as you can see there, they've got sort of a few rest days after every couple of days generally. So if someone gets a MS um the gold standards is that they don't ascend any further, um You want to be giving people Diamox. Um The treatment dose for it is 250 mg three times a day. Um Paracetamol and Ibuprofen can certainly help with the, the headache and Ibuprofen itself has shown to have um some effect at reducing the attitude illnesses. Um Prochlorperazine is often used for nausea. Um If option is available, it can certainly help and help people feel better. Um And if there's no improvement in symptoms, then you want to be looking at ascending. Um and always important to be monitoring for signs of hace and tape, which we'll go into in a little bit. Uh Diamox. Um a little bit on this cos it is the most commonly used altitude medical drug. Um Even if you're not a prescriber yourself, people will often come out with them already and you often get 100 questions before a trip or whether they should take it or not. Um I always say that your body generally naturally acclimatizes. Sometimes it takes people, you know, three days rather than one at each altitude. But um Diamox just helps speed up that process to some extent, it basically helps to acidify the blood, which then means that you breathe faster because you're going to be blowing out all your carbon dioxide to, to help to um balance out the um metabolic acidosis. Um It also works as a bit of a mild diuretic and has an effect on the kidneys. Um So the main way that your body acclimatize anyway is by helping to increase your breathing rate. So that although you might be breathing in less oxygen particles per er minute, you'll, if you breathe faster, you end up getting the same amount over the minute. Um The same with uh the body also looks at diuresing to some extent and that causes some fluid shifts so that you increase the concentration of hemoglobin in your blood vessels. Um And that's some ways that the Diamox can help. Um It's been used to always be used as a diuretic initially. Um But now this is almost one of its main uses. Um It's important to say that um it can cause some side effects and it's not uncommon for people to find some of these quite unbearable. Um So often real tingling in the peripheries in the hands and the feet. Um that's partly due to the um the effects of the Diamox and it also can cause people to pee a lot. So they're taking a dose at night, they might be up three times a night. The temp zip are going, waking everyone up in the campsite as they're going out for another pee. So it's, um, uh it's important for people to stay hydrated as well, make sure they're drinking plenty on it. And I normally recommend trying a little test dose in the UK first um, before they go abroad and to make sure that they tolerate it fine. And if they're allergic to sulfa drugs and sulfonamides, um, it's important to avoid taking it, but generally, uh the Diamox dosing as research comes out, it keeps been reduced further and further and the side effects tend to be reduced with that. Um, current recommendations as prophylaxis is 100 and 25 mgs twice a day, which is normally about half a tablet twice a day. Um There was a paper a few years ago showing that possibly a quarter of a tablet. So 62.5 mgs twice daily. Um was uh enough in a non inferior trial, preventing um high altitude um sort of preventing a MS symptoms and um potentially looking at, you know, whether we can extrapolate that into the kira environment and whether a lower dose might be enough to stop all the side effects or reduce the side effects a lot but still be effective. So we'll uh we'll watch this space. Um ok, So now on to high altitude cerebral edema. Um so this is basically where due to the effect of altitude on the body, um we aren't completely clear why, but we think it might have an impact on the um on the membrane between the blood, the blood brain barrier and the probability of that. And um and the kind of the fluid shift that go on can cause um a lot of headache, nausea, disorientation, and confusion. Um and some believe that attitude headache may be part of a um of the process that can lead up to Hace. Um Having said that I have had a patient with Hace who didn't really have a headache at all beforehand and caught me a bit unaware. Ok. Um So poor coordination uh is, is one of the key signs that you'll see um severe tiredness, um altered consciousness um and often it develops over a few hours. Um So it may be seen with altitude pulmonary edema as well. They tend to get can often go hand in hand and if you can treat someone for hape you off for hate as well, just as a prevention. Um, it's uh if someone has a, any signs of um, uh poor coordination. So if they can't, um, walk heel to toe across the room and they've got very severe headache, then it's important to consider and treat it as haze um, with the gold standard of descent alongside dexamethasone. So to treat hay, it's critical that um you stop. Um the patient has to rest oxygen if it's available should be given. Um Normally with portable oxygen tanks, you don't want to be using a big non rebreathe mask cos it won't last longer than 20 minutes. Um But from experience using just the nasal prong oxygen with one or 2 L of um oxygen flow is often enough to help improve the symptoms. Uh dexamethasone can be given if the patient's vomiting, you might want to look at the intramuscular or intravenous route. Um Otherwise oral dexamethasone of 8 mg followed by 4 mg four times daily. Um I see the zolamide is often given hand in hand with that. Um There's been one paper showing that treatment for a MS type symptoms and um Hace hate and A MS all tend to go together. Um The ghost sound though is, is descend and it's critical that they do try and get them down. Um And that they don't reascend because it's like the symptoms will just return. Um Now, a portable altitude chamber is um something worth talking about. Now, these tend to weigh around 5 kg and um are becoming more popular to be taken to remote high altitude environments. Um They don't um beat the gold standard of descent, but where descent isn't possible, um it can sometimes help to improve the casualty enough so that they can um descend um on on their own 2 ft without having to be stretchered off, which can be very difficult and hazardous. Um They work by um basically a big and face bag that they put the casualty inside, uh important to monitor them closely and not to put them in there. They're vomiting due to a risk of um aspiration. Um You can then use a foot pump to help to increase the pressure inside the bag, which then is meant to help to stimulate a um lower altitude environment. And um you then intermittently continue to use the foot pump to help to blow out any of the carbon dioxide that the patient is um breathing. And um you should find that often. It does work quite well and there's good evidence that it can help to improve symptoms. It as I said, it helps to buy valuable time, but it's not seen as a replacement. Well, as we can see on the graph here, um if a patient develops high altitude illness at 5.5 1000 m, um if you then simulate um the pressure to two psi inside the bag. Um that then is theoretically meant to lower the pressure to um the equivalent of 3.5 1000 m. So if they've been previously well acclimatized to that, then they should, you should notice a notice of improvement using the bag, high altitude pulmonary edema. So hace tends to affect maybe not 5 to 1% of people who go above 5000 m. Whereas um Hape will go from around 6% may be affected at about 4.5 1000 m up to as high as 15% at 5.5 1000. So the higher you go, the more likely the risk of getting Hape um as I mentioned before, um from people who have hate, you want to creep for hate as well. Cos around 20% of hate sufferers will have hate will have hate and for those who have hate, who have had uh unfortunately have died from it. Um At autopsy, around 50% seem to have um signs of haze as well. So it's um again, they're not entirely clear what causes it, but it's thought to be due to um I know the body's reaction to the hypoxic environment. Um the capillaries which are the small blood vessels inside the lungs um will um vasoconstrict in response to the hypoxia but they won't or do it evenly. Um And where some of vasoconstricting, some aren't will cause little stress um uh in the alveoli membranes, um which can then cause leaking. Um This then causes leaking of fluids um into the alveoli and your lungs are then basically filling up with um with fluid. Um, this thing causes difficult to breathe and um the the typical HPE symptoms. So these include with breathing a lot faster, um difficult to carry out simple tasks such as tying a shoelace, um a dry cough, which then later on may become wet and um poor exercise tolerance. So you, you find that although they were doing very well, they start to really slow down and really struggle. Um Laser signs tend to be more sort of pink frothy sputum coming out really raise heart rate and very fast respiratory rate. And occasionally you get a bit of a mild um fever which can diffuse things a little bit. It's worth saying that it's thought that I if you have an upper respiratory tract infection, um your, your risk of hate goes up quite significantly. Um So to treat it, you wanna make sure that you're sitting the patient upright that Nifedipine um which is a type of BP medication um is given orally. Um It's a set dose and then um regularly afterwards. Um a modified release dose can often be better cos it can drop your BP a lot and complicate things further, really important again to descend immediately, give oxygen and you can use a port out um, al two chamber if oxygen's not available, um Things like frusemide diuretics don't work at all. So it's best to avoid that. Um I think one other thing just to add with high altitude is that you're more likely to suffer from hate if you've, if you've had it before. So anyone who's kind of had these symptoms, sometimes you can be on prophylaxis like Nifedipine to help to treat you when you go to high altitude in the future. So generally, um if someone's getting very well at high altitude, you should treat it as A MS until proven otherwise, but always have those other differentials in the background. Um Don't ascend if someone's already got symptoms of A A MS cos it will just keep getting worse. Um ha ha are potentially fatal and must be treated as an emergency and try and take part in expeditions that are on um ascent profiles that are in line with internationally recognized guidance. Um Always good to discuss plans and discuss evacuation procedures and descend early if any concerns. Fantastic. I'm very happy to talk to anyone on the course about um kind of high altitude experience and kind of patience, treated altitude. Um And we can always explore things a bit a bit further. Um If need be, this is very much just a more of a whis spot stop tour if you're interested. Again, the world's medicines consensus guidelines um recently updated um has a lot of good information on this and can also talk about some other medicines that have some evidence like Tadanafil or, um, smear. Um.