Flashing on Everest: is it safe or sensible?

At a rough estimate, around 250 people reached the summit of Everest from the north side this year, climbing with a number of different operators. Of these operators, two seemed to get the lion’s share of the attention: Furtenbach Adventures and Alpenglow Expeditions.

Why? Firstly, slick marketing fronted by a pair of dynamic, media-savvy owners, Lukas Furtenbach and Adrian Ballinger. Secondly, both teams are pioneering a new approach to high-altitude mountaineering that involves shortening the amount of time spent on the mountain by acclimatising at home in high-altitude tents.

Everest Base Camp in Tibet: a nice place to spend a few weeks
Everest Base Camp in Tibet: a nice place to spend a few weeks

Both teams are currently targeting the luxury end of the market, with prices two or three times more expensive than low- to mid-range operators, and 50% higher than many of the other luxury operators. I’m going to examine these prices in next week’s post, but first I’m going to use this post to examine the concept of shortening your expedition by acclimatising at home. Is it safe and/or sensible?

I kind of did this in another blog post a couple of years ago. Most of that post is still relevant. This post is a follow up to it – an update in the context of what happened on Everest this year.

To summarise, when I wrote that post in 2016, Alpenglow Expeditions were offering shorter expeditions to the 8,000m peaks at a higher price, by sending their clients altitude tents to sleep in at home. The theory is that these tents simulate the reduced pressure and oxygen at high altitude, thereby providing an opportunity to pre-acclimatise.

You may well ask, what happens when the client wakes up and goes to work? Do they wear some sort of mask over their face that enables them to maintain the reduced pressure and oxygen while they sit in meeting or tap away on a computer, or do they immediately lose any acclimatisation they may have gained overnight? I still don’t have an answer to this question, and if anyone can enlighten me in the comments then I would be grateful. For me, this one of the fundamental flaws of the whole approach, though perhaps there is an answer I don’t know about.

Anyway, when I wrote that post in 2016 Alpenglow were the only operator in this space, but I predicted others would follow, some targeting less wealthy clients. To date, only one has followed, Furtenbach Adventures, and they are also targeting the luxury market with their ‘Everest Flash’ expeditions.

The Flash expedition goes a step further than Alpenglow’s ‘Rapid Ascent’ expedition by offering extra oxygen on the mountain, in addition to the pre-acclimatisation in altitude tents. Furtenbach claims their special regulators (which control the flow rate of oxygen from the cylinder) can dispense oxygen at a rate of 8 litres per minute (lpm).

Many operators provide enough oxygen for their clients to climb on 4 lpm, and I can confirm from my own brief experience that this can turn you into high-altitude superman. The more usual rate provided by most operators is 2 lpm. This is better than nothing, and certainly helps with combating frostbite, but does not enable a climber to race up the mountain in the way that 4 lpm can.

Griffith Pugh testing oxygen apparatus on Everest in 1953 (Photo: Royal Geographical Society)
Griffith Pugh testing oxygen apparatus on Everest in 1953 (Photo: Royal Geographical Society)

Interestingly, extensive research was done into oxygen flow rates as early as 1952. The scientist Griffith Pugh tested climbers at 6,100m on the Menlung Glacier in Nepal during Eric Shipton’s Everest reconnaissance expedition. The obvious assumption was the higher the flow rate, the faster a climber would be able to climb. Pugh tested different flow rates from 2 lpm right up to 10 lpm. He confirmed that the assumption was correct to some degree: the more they consumed, the better they felt, both during and after the ascent – the more easily they climbed, and the more quickly they recovered.

But another factor needed to be considered, and that was the weight of the equipment – the higher the flow rate, the more oxygen (and equipment) they would need to carry. There was a point where the weight of the equipment would counter the benefits of consuming oxygen, and Pugh discovered that climbers on 2 lpm climbed at the same speed as those who climbed without oxygen. And while those on 10 lpm did climb more quickly than those on lower rates, they had to carry so much more oxygen that the benefits were marginal.

Pugh concluded that the optimum flow rate of oxygen to weight carried was 4 lpm, and that is still considered the benchmark today (I have stolen all this information from Harriet Tuckey’s award-winning book Everest The First Ascent, which discusses it all in much greater depth).

That was in 1952. It’s likely that in 2018 the combined weight of cylinder, regulator and mask is less than it was back then, and so the optimum flow rate is a little higher (perhaps 6 lpm, but somebody will need to do more testing like Pugh to confirm this). However, the weight of the actual oxygen is never going to change, so eventually this optimum flow rate is going to reach a maximum, perhaps when cylinder, regulator and mask are all woven from silk.

I’ve digressed into this little discussion about flow rates because oxygen played a key part in events this year. While their use of altitude tents prior to the expedition is the main focus of both Alpenglow’s and Furtenbach’s marketing, it’s unclear how much of their success (or otherwise) is in fact down to the oxygen used when they’re on the mountain.

So what happened? I’ve used Alan Arnette’s peerless Everest 2018 season coverage as my principal source for this year’s events. On 15 May Alpenglow had to abandon their ascent at 8,500m on the Second Step because of equipment failure. Ten out of 39 regulators burst, allowing the contents of the oxygen cylinder to be released into the air. They weren’t carrying enough spare regulators for their clients to continue. They had to abandon their ascent, and were only able to descend safely after their Sherpas gave away their regulators to the clients.

Alpenglow were not the only team to experience regulator issues that day. Furtenbach’s ‘classic’ (i.e. ordinary speed, non-flash) team climbed the same day and put 5 clients and 5 Sherpas on the summit. The Transcend team of young Indian climbers, also climbing on the north side, put 11 clients and 14 Sherpas on the summit. Both of these teams experienced regulator failures, but were carrying enough spares for their climbers to continue.

Meanwhile, over on the south side, celebrity nice guy Ben Fogle described on Instagram how his regulator exploded at 8,100m and then again just below the summit. In both cases he was able to borrow someone else’s and complete his climb.

Testing oxygen apparatus on the Tibetan plateau (Photo: Edita Horrell)
Testing oxygen apparatus on the Tibetan plateau (Photo: Edita Horrell)

In some respects, Alpenglow were unlucky. Every reputable operator should inspect every bottle and regulator before carrying them up the mountain. Not all of them do, but Alpenglow said they inspected theirs at Advanced Base Camp, and the problems did not arise until they were well into the climb on summit day. This appears to be the case with the other teams as well, and there is a suggestion that the problem may have something to do with the warm, humid air on that particular day.

But in another respect, this issue highlights one of the major flaws of a shorter expedition. Despite the claims of the operators, it’s extremely unlikely that clients who use an altitude tent to acclimatise at home are as well acclimatised as those on longer expeditions who acclimatise on the mountain instead. While all teams rely on oxygen to help get their clients up the mountain, the shorter expeditions are relying on it to a greater degree.

The big problem, as we have seen, is what happens when the equipment fails. Contrary to what many people suppose, if you are well acclimatised, you do not immediately keel over and die as soon as you remove an oxygen mask, and in fact Ben Fogle’s guide Kenton Cool continued to the summit after giving his to Ben.

But clients who are not well acclimatised and relying on oxygen to a greater degree are in a much more serious situation than those who are already well acclimatised. Alpenglow made the right decision to descend as quickly as possible, a point made graphically by climber and expedition leader Robert Anderson in a recent post on this subject:

And for a climber who has followed a minimal acclimatisation program, has less climbing experience and suddenly finds their most vital ingredient failing on a windswept ridge at -20c in the dark, they will very quickly realize they are a very long ways from home.

So that was Alpenglow. How about Furtenbach and their Flash team? The word flash in English carries a number of different meanings. As a verb it could mean to move or pass very quickly, or to expose one’s genitalia. As an adjective it means ostentatiously stylish or expensive, and as a noun it means a sudden or brief manifestation or occurrence of something.

It’s probably going to take a few more of these expeditions to see if the noun definition will follow. I’m presuming Furtenbach name their expeditions after one of the verb definitions (I’ll let you guess which), but their Facebook post on 21 May after all 4 clients and 8 Sherpas reached the summit, which may remind some readers of a certain world leader’s Twitterstream, suggests the adjective definition is equally appropriate.

So maybe the history of commercial, guided Everest expeditions has to be rewritten? At least a new climbing style was established to the Everest guiding community. Finally, after almost 40 years of standstill without any significant innovation. This is the first time that a whole guided team summited Mount Everest in such a short time (21 days from home) with the help of an acclimatizing program at home. This comes with an increase of safety and a 100% success rate. Not to forget that our Flash members are no professional athletes, they are dentists, consultants or entrepreneurs. With our own acclimatization program we acclimatized the whole team up to 7100m in non-standard hypoxic tents at home. Almost 15 years of experience with hypoxic acclimatization was essential for this project. Only 7 days after entering Tibet we made one safety rotation to the north col and then took a rest for the summit push. This is game changing. So we become the first and only operator that successfully achieved and can offer a 21 days door-to-summit Everest expedition. But what to do with the remaining time? Well, maybe a beach holiday with the family.

Thank you to all climbing community for all the criticism and skepticism, it kept pushing motivation to move on with this idea.

There are a number of things here that grate like fingernails down a blackboard. It’s not just the brash self-confidence of the writing (some people might use the word gloating). Let’s look at them one by one.

First, commercial mountaineering on Everest was in itself a significant innovation that occurred in the last 40 years (you can argue that it started when David Breashears guided Dick Bass to the summit in 1985, or when Rob Hall led a group trip in 1992, it doesn’t matter).

Second, this particular innovation of shortening an expedition by pre-acclimatising in altitude tents wasn’t Furtenbach’s. It looks to me like Alpenglow had the idea first.

Third, the assertion that the whole team were acclimatised to 7,100m before they left home is patent nonsense. It’s not yet known whether it’s even possible to acclimatise to 7,000m, or whether you just have to climb up and get down as quickly as possible. The high-altitude mountaineers Ralf Dujmovits and Nancy Hansen have recently been spending two weeks in a lab at a simulated altitude of 7,000m to find out what might happen.

Fourth, there’s no mention of how much oxygen their clients were using (Furtenbach have since said it was as much as 6 lpm). The jury is still out on whether these fast times are a result of the pre-acclimatisation at home or the oxygen used on the mountain.

Fifth, what self-respecting mountaineer wants a beach holiday?

But the biggest problem is what this post doesn’t mention – the final, most gaping flaw in this whole approach. The weather.

Furtenbach managed this record – and there’s no denying it’s an impressive record – during what was probably the most perfect Everest season there has ever been.

When I climbed Everest in 2012, there were only four good weather days, some of them marginal. This meant that everybody had to squeeze their summit ascents into those four days. My own summit day, 19 May, still holds the record for the most number of successful ascents on a single day (233). How much oxygen would the Flash team have needed if they’d got stuck behind those crowds?

Record numbers reached the summit of Everest on 19 May 2012. Here I am with just a few of them.
Record numbers reached the summit of Everest on 19 May 2012. Here I am with just a few of them.

This year there were 11 good summit days in a row, spreading out the numbers. Team after team reported summiting in perfect conditions, with warm temperatures and no wind. Some climbed so quickly that they were surprised to find themselves reaching the summit in the dark.

They may have got it right this year, but there is no doubt Furtenbach got lucky. It’s not usually possible to choose your summit day and go up to a predefined itinerary. You have to watch the weather forecast and wait for a window, and some years those windows are few and far between. It’s not unheard of to spend 21 days at base camp waiting for that window, and that’s all the time the Flash team had.

One thing you can be sure of, is that they won’t be that lucky every year. They would be wise to tone down the rhetoric. What happened to Alpenglow this season should serve as a warning not to get too cocky where Everest is concerned.

But I started this post by lamenting that two teams got all the headlines this year. What have I done, but spent the rest of the post talking about those same two teams. I’ve fallen for it. So I’m going to finish by contrasting their approach with one of the other teams.

On 24 May, Altitude Junkies, the team I climbed with in 2012, posted a dispatch on their website in tiny writing so small that it was barely noticed. They whispered that a number of their team had reached the summit, but due to privacy reasons they weren’t going to tell us who they were.

Two members of the team climbed to the summit and back to Camp 3 in just 5 hours on an oxygen flow rate of 1-2 lpm (bugger privacy, it was Phil Crampton and Kami Neru Sherpa). All of them descended to Advanced Base Camp (6,400m) the same day, using oxygen at rates of up to 3 lpm. To put these numbers into perspective, it took me 18 hours to reach the summit and stagger back into Camp 3 (8,200m) on a flow rate of 1-2 l/min.

The final part of the dispatch made a few nice points in a mock-style that will now look familiar (actually there’s a hint of Russell Brice in it too). It was written by expedition leader Phil Crampton. It came as no surprise to learn that he was one of the climbers to whiz up and down in 5 hours, but it was a surprise to discover his talent for parody. I couldn’t have written it better myself (although I have tried), so I’m going to quote Phil in his entirety.

We hope to exit Tibet tomorrow and be back in Kathmandu 31 days after departing. Below are a few points, which enable us to climb Everest in 30 odd days instead of the traditional 60-70 days.

We do not advertise our expeditions as “Everest Express” or “Everest Flash” but just plain old boring “Everest Expedition”.

We have realized over the years that entering Tibet at the start of April will not change the fact that the ropes will not usually be fixed to the summit until around May 15th.

We do not have well-known, highly publicized, sponsored guides leading our trips but a single expedition expediter. Therefore there is less pressure to rush our schedule based on social media, tight schedule deadlines, live Internet interviews, etc. Our expediter is old and grumpy but is always looking to be sponsored with gear for himself and his Sherpa.

We spend a lot of time at base camp allowing our bodies to recover rather than rushing up to Advanced Base Camp and making folks sleep several nights on the North Col, depleting them of all their energy reserves and reducing their hard earned muscle mass. Climb high sleep low is the old adage.

We do not make our team members sleep in plastic tents over their beds at home. Really! The majority of the Everest industry folks know this does not work. I do not want to be the reason for unhappy husbands and wives sleeping on the sofa. Red blood cells need real altitude to reproduce, not a gimmicky tent at home.

And that goes some way to explaining why many of my 8,000m peak expeditions have been with Altitude Junkies. Regular readers of this blog and those who have read Seven Steps from Snowdon to Everest, will know that I value the journey more than the destination. While climbing Everest is a worthy ambition to have, the main purpose is to enjoy the whole experience. After all, nobody climbs all 282 Scottish Munros to annoy people in restaurants or at work by constantly reminding them that they’ve stood on top of 282 hills. They do it to experience many wonderful days out in Scotland.

If you can get the time off work, then I recommend a longer expedition that allows for sufficient acclimatisation, or even a pre-expedition with some trekking at high altitude. Don’t think of it as a chore to be endured, but as extra holiday to be enjoyed.

I believe there is merit in the concept of acclimatising at home before leaving for an expedition, if not to replace the acclimatisation time once you are there, then at least to augment it and give climbers a better chance of success. More objective research still needs to be carried out though, so that we can have a more balanced discussion.

At the moment there is way too much marketing hype by the two operators promoting the idea. This produces a backlash from other operators who might be open to it, and any balanced discussion gets blown to the Tibetan wind.

All of which brings us back to the title of this post. Flashing on Everest: is it safe or sensible? Absolutely not. That’s one part of your anatomy where you don’t want to get frostbite.

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33 thoughts on “Flashing on Everest: is it safe or sensible?

  • June 20, 2018 at 5:20 pm

    Congratulations to you and Edita, Mark! Wishing you both every happiness for the future. Not much gets passed my radar – I always look at the pictures first, so I’ll go back and read the rest of the article now 🙂

  • June 20, 2018 at 5:59 pm


    As an an anesthesiologist and critical care specialist, I’d like to comment on several aspects of your article.

    1. In anesthesia or critical care we rarely care about oxygen flows since they are mostly meaningless. We can give low flow anesthesia with 0.25 l/m (baseline O2 consumption rate) but that’s not a number we care about. What we are interested in is oxygen saturation. Is the flow we are giving allowing us to reach our target SpO2? (oxygen Hemoglobin saturation ). So if I’m on a mountain or sailplane, I target my flow to keep my O2% at greater than 80% at all times. And depending on my day and altitude , the flow rate needed will vary. (Do I have a mild respiratory infection today or allergies which cause mild bronchospasm? Do I have mild pulmonary edema from a bad night at high altitude?) From my viewpoint, discussions about adequate flow rates are meaningless. Your brain only works with an adequate O2 saturation, not a high or low flow rate that ignores your current O2 consumption or my lung status today. Ditto for your lung and brain vasculature that react to O2 saturation and not a flow you have blindly dialed on a regulator.

    2. Regarding hypoxic tents, there is little science and much hype behind these. They are not hypobaric. They simply add more nitrogen to your air and thus simulate hypoxic conditions. How much should they add to seek a measurable effect? Who knows. Again, they are not measuring your O2 saturation or Hemoglobin concentration throughout the process, let alone changes on your O2/Hgb dissociation curve. So who knows what is going on, and as you pointed out, they only use it at night and not at work. Personally I won’t trust them until we measure their effects. Nobody does that! I’ve tried to convince expedition leaders and even Hypoxico about simple measurements but I’ve met resistance.

    In short. Let’s use science and not hype when we talk about oxygen. Always use a reliable FDA approved pulse oximeter. (There are many bogus ones…) Always try to keep your saturation above 80 since below this number your O2/Hgb dissociation curve drops quickly. And forget about flows. That is NOT how to handle oxygen intelligently. And as a plus, you may be able to lower your flows and save on valuable O2 if you are saturating properly!

    Thanks for bringing this topic up.

  • June 21, 2018 at 12:29 am

    +1 for Dr Montejo. Iam also a MD and Agree 100%

  • June 21, 2018 at 7:45 am

    Can I just clarify what you are saying about oxygen flow rates, as the way you have phrased it is a little misleading. We know from the experience of thousands of climbers that in general the higher the oxygen flow rate, the better they are going to perform. This is also what Griffith Pugh discovered in 1952 – they climb more easily and recover more quickly. It’s therefore not true to say the oxygen flow rate is meaningless – it’s actually quite important.

    I believe what you are actually saying is the important statistic is not the oxygen flow rate out of the bottle, but the oxygen saturation of the climber receiving it. The optimum oxygen flow rate is therefore whatever it takes to get the climber’s oxygen saturation up to 80%, which is the safe level for a healthy person at sea level. This will differ from climber to climber, and is also dependent on their condition at the time. Do I understand you correctly?

  • June 21, 2018 at 9:29 am

    Thanks for that, very interesting reading, and I believe Monica Piris was Alpenglow’s expedition doctor for a time.

    In a nutshell, they are saying it’s unequivocally the supplementary oxygen that enables these compressed time schedules, not the altitude tents. If you do a lot of training, then they are even suggesting you don’t use them, because you won’t be able to train as hard after sleeping 8 hours in an altitude tent.

    I still prefer the more relaxing method of pre-acclimatising for your expedition with a high-altitude trek, but they don’t mention this one. 🙂

  • June 21, 2018 at 9:27 pm

    Thanks Mark. Trying to keep up.

  • June 22, 2018 at 10:16 pm

    Thank you for this article Mark. I am one of your regular readers. I like what you write because it`s funny and has substance. In this article you are directly tackling our expedition and our business, so I have to clarify some points that are either simply wrong or poorly researched. It would have been useful or fair to talk to me or Adrian to confirm the information you take 1:1 from different online sources without knowing their truth content. Your article shows me again that there is quite a number of people out there who feel obviously offended by our expedition style. That in itself is pretty disconcerting. We are talking about the style of a recreational pursuit.

    Before our Flash expedition most of the critcis had the same points why our expedition would either never work or would be absolutely life-threatening for our clients. Now that the expedition was successful, they are having again congruent points and reasons why it was only luck and coincidence for sure that nobody died and all members summited. And they all seem to have a very deep understanding (obviously deeper than mine) of why the so-called pre-acclimatization is actually not working at all and is only a marketing gimmick to sell an expedition with a higher O2 flow rate. I am always open for criticism and discussions. I was criticized for what I am doing since years now. I like to discuss my ideas and what I do. But if criticism is lacking objectivity and substance it reminds me of a certain world leader’s Twitterstream.

    Ok, I go through it point for point.

    You are talking about 250 “people” summiting Everest this year from the North side. It is sad to see that most western “people” still do not count Sherpas from Tibet and Nepal as summiteers. But that`s another story.

    “Altitude tents” as you call them do not simulate any change in pressure. Oxygen is filtered out of the air and that air is blown into a tent and that is simulating the oxygen concentration from higher altitudes. No change in pressure. But you are not alone with this misunderstanding, also Russel Brice was talking about “pressure tents”. We know from scientific studies that only the reduced oxygen is the factor that triggers the acclimatization processes in the body.

    Alpenglow in 2016 was not the first operator in this space. We have been on the south side in 2016 and acclimatized a whole team of clients with hypoxic tents (successful). I use hypoxic tents since 15 years and started as a subject in scientific studies. We did not follow Alpenglow but started at the same time to sell this kind of trip.

    Today the more usual oxygen flow rate on summit day is 4-6 liters, not 2 (that was a few decades ago). 8 liters is the maximum that the 200ml reservoir from summit oxygen`s facemask can handle at 8848m without significant loss. Our Flash members used flow rates from 2-6 liters. One member started to use oxygen at 8300m only. All of our members descended directly to ABC after summiting. The book where you took your information about flow rates is more than 5 years old and no more up to date. Our members did not use more oxygen than others. We provide more and have everything redundant but that does not mean that we use all of it. Again, one member started to use it at 8300m only. Yes, success on Everest depends on oxygen for most people. But that is for our Flash members and every other climber on the hill in the same way and extend. Our success was not more related to oxygen use than any other. As for an operator anything else than providing enough (basically unlimited) oxygen for O2 supported climbs would be irresponsible.

    All our Flash members had the same “acclimatization quality” as the climbers from our classic team that has been there one month longer, doing a classic acclimatization. Our Flash team did the first rotation to north col (7000m) seven days after leaving Kathmandu. Without oxygen. One member slept at the North col. Without oxygen. If they would not have been well acclimatized, they would have experienced problems. But not even a slight headache. Just nothing.

    There are scientific studies that show that acclimatization in hypoxic tents works as good as on the mountain. This is a proven fact. Why are reasonable, wise people still ignoring or denying that without doing a simple research? Simone Moro, Kilian Jornet, Ueli Steck and most other professional high altitude climbers use (Ueli used it) this form of acclimatization. That is for a reason. We have now done 3 successful Everest expeditions in 3 years where we acclimatized all members in hypoxic tents. I am using them since 15 years. We have first hand data and experiences. Who else has that? Of course we take data (O2 saturation, pulse) from all clients every day during the use of the tent. We even make regular hemograms. We can see how it works. And we could show that it works. There is also scientific proof. What else do you need? Why still criticism and skepticism? Is it just unknowing or ignoring? By the way, Monica Piris is still the Alpenglow expedition doctor. At least she was this year. The article she wrote together with Steve House is also not perfectly clean researched – 1) Kilian Jornet is very sure that his achievement on Everest last year was only possible due to hypoxic acclimatization (scientificly attended), 2) there are scientific studies, 3) hyoxic tents are never humid inside as the authors write. Dry air is a problem with these tents. Don`t know how these statements can happen.

    Even though we assume that the human body is not able to acclimatize higher than 5500m we can see that climbers that did not reach and slept at 7000m or above before the summit attempt have a higher risk of getting altitude related problems (some US operators know what I mean). That is why we “acclimatize” people to 7000m and let them sleep one night there.

    To shorten an expedition with so called “pre-acclimatization” tents or chambers was not our idea and was also not Alpenglows`s idea. It all started with the COMEX study 1992. Alpenglow and Furtenbach started in the same year.

    If the weather would have been in an statistic average, we would have had the same summit success. Maybe +/- 2-3 days for the summit day.

    Yes, we would have needed more oxygen if we would have got stuck in the crowds on summit day (we had enough). But not more than any other climber on the mountain (not all are having enough).

    In 20 years of expeditions I never spent 21 days at basecamp waiting for a weather as you say would be not unheard.

    All our Flash members summited 17 das after leaving Kathmandu. With ease. No accidents, no injuries, all alive. We will do it again this way. And yes, it`s Everest. There might happen an accident one day. There is still a risk related to climbing Everest, for every climber. Flash or Classic. But the less days you spend on the mountain, the lower your risk.

    A “balanced discussion” is what I wait for since 3 years. Your article will maybe not help.


    Lukas Furtenbach
    Furtenbach Adventures, Austria

  • June 23, 2018 at 3:26 am

    For Gaetano Zanon:

    That higher flow rates give you higher oxygen saturations is true up to a certain point.

    But you must understand that with a perfectly closed system (no leaks from your mask) after your flow rate matches your O2 consumption, a higher flow rate is useless.

    So yes, if I am not measuring SpO2 (oxygen saturation of the Hgb molecule) a higher flow rate is safer. But that means you will waste much valuable oxygen.

    My whole point is that by focusing on flow rates, you are trying to solve the wrong problem.

    To Lukas Furtenbach: Can you send me a link to the scientific studies proving that the hypoxic tents work as well as acclimatization on the mountain? I certainly have not seen them, and if they exist, I am interested in how the authors arrived at such conclusions. What parameters did they measure? Where they looking at O2/Hgb dissociation curves on climbers and on flashers? Did they follow blood gases on both groups? Where the authors blind to who used what technique? All that you mention is anecdotal. I have seen people at Everest base camp be flown out after 24h after being flown in from KTM after having used hypoxic tents. (BTW this is also anecdotal…) In short, all I am saying is that if you are on to something, let’s prove it with rigurous science and not anecdotal evidence.


  • June 23, 2018 at 6:10 am

    To Leo: I have seen people at Everest basecamp be flown out 24h after reaching basecamp in the regular 10 days trek in.

    There are people using hypoxic tents without professional advise and experience. Yes, accidents will happen with these tents! You have to know how long (how many hours of exposure every day and in total), in what intensity and progression you have to use them. And then of course it’s individual for each person.

    Yes, all what I mention is 100% anecdotal. I did experience all this myself, with my clients. I tell very transparently what we have done and what we experienced. Why do still know others better? Without having used the tents for themselves or their clients? What is it that they are afraid of?

    Send me an email for further exchange about the scientific part. I am happy to send you links to what I have got.

    The exact hypoxic program (hours spent in the tent and progression in altitude) we did with out clients this year is completely new. Of course there is no study specific to that. But I would be more than happy to host a study next year! Any idea for that?

  • June 25, 2018 at 3:11 am

    To Mark:

    Yes, that is correct. Forget flow rates per se and instead target SpO2 (oxygen saturation) which will vary depending on many factors. I target 80% because if you look at an O2/Hgb dissociation curve, the curve is still fairly flat at that %. Below, depending on your genes it can drop quickly and get you into trouble. In short, dial your flow rate to achieve a specific result and not because it’s an anecdotal number that seems to work.

    Also, a HUGE issue commonly overlooked in this discussion is how well your mask fits and your leak. The higher the leaks, the higher the flow rates you will need. Again, measure what your brain sees (O2 saturation) and not a high flow rate.

    Taking your mask off at the summit for a selfie IMHO is not too smart since you are exposing your brain to a sudden O2 deprivation.

    To Lukas:

    I’ll send you an email on the subject, and yes let’s work together to confirm that hypoxic tents and flashing work (or not) by using a scientific approach.

    At this point, as a person who works with O2 every day in a laboratory environment (the operating room) I am skeptical, but I will be happy to be proved wrong!

  • June 25, 2018 at 11:39 am

    Hi Lukas, thanks for commenting. I’m glad you enjoy reading the blog (apart from this post, obviously) and congratulations on a very successful expedition this year.

    Firstly, I know that both you and Alpenglow are highly experienced and successful operators, and I admire you for trying something a little bit different. You should understand that you are trying something that goes against tried and tested methods. People are naturally going to be sceptical about anything new until it’s proven or otherwise. You therefore need to have a thick skin and expect some criticism.

    Secondly, this is an opinion blog, written from the perspective of a commercial client. I’m happy to correct anything that’s inaccurate, but at the end of the day, we may still end up disagreeing, because we have different goals: yours is to sell your trips, while mine is to inspire readers and provide advice to help them enjoy the mountains. I’m open to the idea that pre-acclimatising in an altitude tent will help people perform better at high altitude; it’s not going to change my opinion that it’s far more fulfilling and enjoyable to take a longer holiday and acclimatise by spending more time in the mountains.

    So let’s between us correct some of the facts in my “poorly researched” article.

    – Let’s start with my understanding of how altitude tents work. As both you and Dr Leo point out, it does not simulate the pressure at high altitude; it simply adjusts the ratio of oxygen and nitrogen in the air. Kindly noted. I don’t think this changes any of the points I am making though – if anything it means that altitude tents are slightly less effective because it does nothing to help the body adjust to the reduced pressure at high altitude?

    – I said that the more usual oxygen flow rate provided by operators is 2 litres per minute; you say it is now 4 to 6 litres per minute. Again, noted. Things have probably moved on a bit since I climbed Everest in 2012. I can well believe that operators are now providing more oxygen for their clients. We can probably all agree that this is leading to increased success rates. One of the points I am making in this article is that your use of supplementary oxygen may be a bigger factor in your ability to shorten your expeditions than your use of altitude tents.

    – You say that your Flash members went to the North Col 7 days after leaving Kathmandu, and they were not using supplementary oxygen? This was entirely due to their use of altitude tents before they left home, they did not acclimatise elsewhere beforehand, and there were no adverse side effects, not even a slight headache? Are you sure about this? This is a very bold statement. Forgive me if I am sceptical. To put it into context, I reached the summit of Aconcagua (about the same altitude) in 12 days from sea level, and would certainly not recommend anyone going to 7000m from sea level in only 7 days. That’s not to say that it can’t be done with the use of altitude tents, but we need to be totally convinced this is safe before providing any recommendations.

    – You say there are scientific studies that show that acclimatisation in hypoxic tents works as well as on the mountain, and that you will send information about them to Dr Leo in a private email. Feel free to provide further information about them here as well if you like.

    – Alpenglow and Furtenbach started using altitude tents in 1992. I had no idea either of you had been around for that long. Do you mind my asking your age? Adrian must have started using them when he was 16 years old. Are you sure this is true?

    – We will have to agree to differ about the weather. Unless you have many extra contingency days in your itinerary, then there will be some years when you don’t get an opportunity to make a summit attempt. And yes, I have heard at least one example of a team waiting for 21 days at base camp.

    As you can see, I’m happy to be corrected where necessary, but I’m still sceptical about some of your statements. However, I understand that you are upset that I didn’t contact you or Alpenglow before posting. In fact, I sent Adrian a list of questions – at his suggestion – when I first addressed this subject a couple of years ago, but he never responded to them. As I mentioned in the post I intend to write a follow up post about the cost of these expeditions. I am still a little unclear why they are so much more expensive than longer expeditions, so if you are willing to answer a few questions about the price then it would be very much appreciated, and extremely helpful to both myself and readers.

  • June 25, 2018 at 11:02 pm

    Hi everyone,

    Wilderness medic here.

    Mark: Thanks for another insightful piece about the latest trends on the big hill. As always well written and thought provoking.

    Dr. Montejo: Absolutely agree with you re flow rates when treating in hospital. We treat based on the patient presentation and actual blood gases not on some arbitrary number. However, this advice does not translate well to the wilderness setting. There is no possible way to accurately measure SpO2 in real time on an Everest summit push. The finger pulse-ox is notoriously inaccurate and unreliable. Even if it wasn’t, we cant have climbers taking of their gloves during the push to titrate their flow rates for adequate saturation-it’s impractical and dangerous. Until we have solid science we need proceed based on experience, ie 2-6 lpm

    Lukas: Thanks for commenting and giving insights into your experience. I, like Dr. Montejo, am not aware of any scientific studies (recent or otherwise) that show hypoxic tents to “work as good as on the mountain” and I certainly have never seen any that present it as a “proven fact”. I am more than happy to be wrong on this if you can provide some citations. The main issues as I see them with pre-acclimatzing in hypoxic tents is the difference between normobaric hypoxia and hypobaric hypoxia. As far as I am aware (again very happy to be wrong here) there are no studies contrasting the two. Discounting the effects (or non-effects) of differences in pressure is not based on any hard scientific evidence. In addition, Mark mentioned the time one is not sleeping in the tent (ie going to work), what about travel time to KTM? Surely it takes even your fastest client from Europe or NA at least 2 days to get to KTM. How does that effect acclimatization in your opinion?

  • June 26, 2018 at 4:10 pm

    Thanks, Dan. I came across this article in Runner’s World while googling normobaric hypoxia and hypobaric hypoxia:

    I don’t know if you’ve seen it, but it describes a study where participants under normobaric hypoxia (i.e. fake altitude) were shown to exhale more nitric oxide than participants under hypobaric hypoxia (i.e. real altitude). I understand this is significant because nitric oxide plays a role in dilating the blood vessels (which I’m guessing means oxygen passes around your body more quickly).

    BTW, here in Europe we can catch an evening flight and be hydrating in Sam’s Bar the following afternoon.

  • June 26, 2018 at 9:23 pm

    Thanks for your comment Mark.

    I wrote that our Flash members did not use more oxygen than the average climber in a modern commercial Everest expedition. If as you say our use of supplementary oxygen would be a bigger factor in our ability to shorten our expeditions than our use of altitude tents that would by implication mean that all the other climbers on the mountain would also have been able to summit in 21 days from home, without doing any acclimatization? I would strongly recommend not to try that…

    Yes, our Flash members went to the North Col 7 days after leaving Kathmandu, and they were not using supplementary oxygen. This was entirely due to their use of altitude tents before they left home, they did not acclimatize elsewhere beforehand. And yes, this is a bold statement. That is why I used the word “game-changing” in my Facebook post that reminded you of a certain world leader’s Twitterstream. If properly acclimatized with our hypoxic acclimatization program you can easily climb to 7000m within a week. If I would not be totally safe about that, I would probably not sell this and put the lives of my clients at risk. As written, this comes after 15 years of testing and experimenting.

    Of course we did not start to use hypoxic tents in 1992. The Comex study took place in 1992. I wanted to say that Alpenglow and Furtenbach Adventures started with a fully pre-acclimatized commercial group on Everest in the same year, in 2016. Sorry for that misunderstanding, I am not a native English speaker. I personally started to use hypoxic training for pre-acclimatization for expeditions about 15 years ago. I am 40 now.

    We have more than a full week as weather contingency days in our itinerary. As far as I know in the last 30 years there have been only two spring seasons (2014 & 2015 – icefall accident with Sherpa strike and earthquake) on Everest with no summits in the most successful 7-day period in May. This 7-day period is our targeted window in our itinerary.

    If a modern expedition on Everest in spring season spends 21 days waiting at basecamp because of the weather something went fundamentally wrong with this expedition (or the leader).

    You say that you are still a little unclear why these expeditions are so much more expensive than longer expeditions. I am sure that you are aware that the main cost factors on Everest are western guides (1:4 in our case), highly qualified and well paid Sherpas (2:1 in our case plus a team of backup rescue Sherpas), oxygen (unlimited in our case) and the transport of the oxygen up and down the mountain. Beside that in Tibet we have to pay for working permits for our Nepalese Sherpa staff, which is not the case in Nepal. By the way, guides, sherpas and O´s are also the main success and safety factors. $ 85.000 was the normal price for decades for an expedition meeting these standards. No one of the operators that sold Everest at this price tag for decades is now a billionaire. So your questions should go out to the low-budget operators, not to Adrian or me. Here you should look for answers, why they can offer an Everest expedition at $ 28.000. We know the reasons of course. But we obviously don`t want to see them.

  • June 27, 2018 at 2:18 am

    To Don:

    Thanks for your comment. Check out http://wicis-sports.com. We have been doing what you think is difficult with our solution for quite some time.

    Or look at our twitter feed where you will see how we can monitor from California, live, every second, vital signs from anywhere in the world:

    From Everest C4 – https://twitter.com/WiCisSports/status/866528632319098880
    Live Data from K2: https://twitter.com/WiCisSports/status/757207208866172928
    From Everest C2: https://twitter.com/WiCisSports/status/865399166561730563
    Sherpa in Upper Mustang, Nepal https://twitter.com/WiCisSports/status/996734793210445824
    Inner Mongolis: https://twitter.com/WiCisSports/status/875375112152903682

    So had you writtten this a couple of years ago, I would agree with you 100%. But times have evolved, and I can follow your vitals from a bluetooth pulsox, sending data to your smartphone in your pocket, to your Iridium Go or Thuraya, (or 3g) and then to anywhere in the world with a 1 second delay. Or I can of course track SpO2 and HR on myself, including body temperature, another one of my favorites.

    And that is how in fact I follow myself while on the mountain! In fact, where I have seen more problems is when climbers settle in for the night in their tents. The climber lies down. The diaphragm is then pushed up by the intestines in his abdomen and maybe 10% of his alveoli now collapse. This is called a shunt situation, and it is then that saturations drop to dangerous levels.

    Finally, you should not take a single shortcut when protecting your brain up at altitude. For those who believe in the heroics of no-oxygen in the death zone, check this article out:


    Look at the MRIs and decide whether you want to take risks with what Woody Allen called his second most favorite organ…

    Sorry to sound like an alarmist, but I make a living working with oxygen and have also spent countless hours in labs testing subjects and pulse oximeters where we bring the inspired oxygen down by adding nitrogen (technique used by hypoxic tents).

    Best regards.

  • June 27, 2018 at 10:21 am

    Thanks, Lukas. Some good answers. You’re not ducking the questions, and for that I take my hat off to you.

    So, we’re left with this statement:

    – Furtenbach Flash team members went to the North Col (~7,000m) seven days after leaving Kathmandu, without using supplementary oxygen, without pre-acclimatising at high altitude, but after using altitude tents before they left home.

    If this is true, then it would indeed seem to be true that altitude tents are extremely effective.

    Why are we still sceptical?

    – This is not a small improvement on traditional acclimatisation schedules, but a very significant one (we’re talking 7 days vs. 12 days, so almost half as short).

    – If it’s not true then this dangerous, so we have to be careful.

    – We know you’re convinced it works based on your own experience, but others don’t have that experience, so you’ll have to forgive us if we don’t want to take the word of 1(2) operator(s) who have trips to sell in this era of fake news (since you seemed to like that particular joke of mine 😉 ).

    – While your expeditions have been successful, we’re still waiting to see the science to back it up – you say it exists, but specialists in this field (e.g. Leo, Dan, Monica) say they haven’t seen it.

    – There are still some puzzling things here that have not been explained, such as why people don’t lose their acclimatisation when they get out of bed, leave the tent and go to work.

    – There is a certain amount of hyperbole in some of your statements (e.g. “we acclimatized the whole team up to 7100m in non-standard hypoxic tents at home” and “scientific studies that show that acclimatization in hypoxic tents works as good as on the mountain”) that are naturally going to encourage scepticism.

    So while you may yet be proved right and you’ve had some success using these methods, these are just a handful of expeditions out of many. If this is ever going to become accepted practice then there’s still a little way to go.

    Anyway, thanks for the info on costs. That’s helpful. There are just a couple of things about this I’d like to clarify with you, so I’ll send you these in a private email.

  • June 27, 2018 at 11:50 pm

    Mark: Yeah that’s a great intro into the NH vs HH debate. If you really want to get into the weeds (like 30min lecture into the weeds) watch Dr. Millet (2013) explain some of the other differences researchers have described in the literature: https://www.youtube.com/watch?v=u24Zg5e-8dQ

    One of the more interesting differences is postural stability (ie balance) in HH and NH. Described by Degache in 2012, only HH deteriorated postural stability vs. NH and NN (normobaric normoxia). To me, this further points to a fundamental difference in the physiology of adapting to HH and NH. Now whether these differences actual mean anything with respect to acclimatization and performance at altitude, who knows.

    Dr. Montejo: Very interesting stuff. Correct me if I’m wrong, the climber still has to take off their gloves to use the bluetooth pulse ox, correct? I’ve heard some of the new generation smartwatches are going to integrate pulseoxs, but if climbers have to remove their gloves it’s still impractical and dangerous during a summit push. It sounds like it’s a great solution for monitoring sleep and when climbers get into camp, but during the actual summit push I just cant see it. When I was working Everest a couple years ago I could barely get my climbers to respond on the radio. What we should do is use your technology to run a study to describe the effect of different flow rates on performance/vitals next season.

  • June 28, 2018 at 4:00 pm

    To Mark – Of course it is true what I say. One member even slept at the col 7 days after leaving Kathmandu (without oxygen).

    Yes, the hypoxic tents are extremely effective for our purposes when used in the right way. And I can say, the right way of using them as a preparation for a Flash expedition is not the one that is stated in the manual. We also did not use the standard system but modified generators and modified tents.

    Yes, it´s a significant improvement. Game-changing in Everest guiding as I used to say and the first real innovation since 40 years of classic, supported Everest expeditions.

    Ok, what we did this season is obviously neither fake nor just a personal experience. It really happened and all other people on the mountain could see and experience that. It did not just work for one of our staff or one single member, it worked for ALL members. And they were not professional mountaineers or athletes.

    The last puzzling thing – also about the practical use of these tents studies exist. They show how many hours per day one should spend in the tent to have the physical processes and effects triggered to begin. We know today, that you don’t have to be exposed to real or simulated altitude for 24h / day to have all processes of acclimatization running in your body. Also the traveling from home to the mountain does not affect the acclimatization.

    Regarding the studies – Dr. Monica Piris (and others) are asking for peer-review studies. All other studies are obviously nonsense or have asters as “non existing”. I quit my own scientific career when a computer generated nonsense paper was pulled from a peer-review magazine. For me “peer-reviewed” doesn’t mean a sh.. Of course you have to look closely to the study design but peer-reviewed is not my criteria for convincing results. I am Everest operator, not a scientist so maybe simply have no idea. The studies I mentioned exist and are open to public. All critics, sceptics and competitors are free to do their own research to find them. All the doctors in this discussion should know how to find them. I will not take the work out of their hands. A small hint – look over to the old rusty continent on the other side of the big ocean. A little bit of this planets knowledge goes back to here.

  • June 28, 2018 at 11:31 pm

    Lukas: You’re charging people to sleep in gas filled plastic bags (that you now say you modify and dont use as the manufacturer suggests). We need to further investigate if and why this works.

  • June 29, 2018 at 4:36 am

    Hello All:

    This is how we practiced simulating lower oxygen concentrations at the lab in Silicon Valley:

    1) Anesthesia type machine which allows one to mix Oxygen + Nitrogen from calibrated flowmeters.

    2) On the output circuit and before the tubing reaches the subject, we measure % Oxygen coming from the mixture (note we care little about flows, and again what we are looking for is FiO2 (inspired fraction of oxygen) since regulators or flowmeters can fail.

    3) This mixture is taken to a mask with a tight seal to the subject. (No subjects with beards – since beards are sources of big leaks. Take note, those of you who grow a beard and use Oxygen – this is not a good idea…)

    4) One to four pulse oximeters from different companies, are connected to the subject, along with EKG and BP.

    5) On certain subjects we start an arterial line on the wrist so as to be able to draw blood gases and correlate these with the pulse oximeters for further accuracy.

    1) We lower the FiO2 slowly (by increasing Nitrogen flow and leaving O2 steady) and sometimes do plateaus where we stop at pre-determined oxygen saturations. For instance: 100 -> 92 -> 82 -> 75 -> 70

    2) We wait until all pulse oximeters stabilize before continuing down to any plateau.

    3) We rarely took the subjects below saturations of 70%.

    4) The whole descent took some 10 minutes, and at the end we went back to 100% O2.

    1. We were able to see how humans react while being monitored with EKG, pulse oximeters, BP, to acute desaturations of Oxygen. (This is more what goes on when you summit and you take off your mask for the selfie with the big (hypoxic?) smile.

    2. We learned that all pulse oximeters give false data below 60%. In other words, if your pulsox is showing a lower number than 60, disregard its accuracy – just interpret as “things are bad”. Blood gases are the gold standard.

    3. We were able to construct O2/Hgb dissociation curves for subjects and we re-tested these subjects sometimes up to 5 times.

    4. The O2/Hgb curves, to my surprise, were not always the same for each subject when we repeated a session. In other words, you could have a good day or bad day when looking at this curve. This is important because this means that a climber can have a good day and feel great, and then 3 days later on a second ascent, be doing poorly because his curve has changed. This curve plots how readily the hemoglobin releases the O2 to the tissues, and shows how different parameters such as alkalosis (breathing quickly), temperature, and 2-3 DPG affect it. (Note that if you are cold, your Hemoglobin will be less apt to release O2 to your tissues (brain) and therefore you will be in more danger.

    5) In our studies Asians, especially women (think Sherpas?) had the flattest O2/Hgb dissociation curves making them the most resilient to O2 deprivation. In other words, at lower pO2’s they would saturate higher than for instance white males, and they would drop off less quickly. I’ve yet to see a book in mountaineering discuss this curve, and my opinion it is this plot that is key in understanding how one acclimates.

    Other thoughts:
    1) For me to go into a tent (plastic bag with gas as per Dan) where I don’t know the exact FiO2 (measured with a sensor, and not calculated by flows) is dangerous. This is like diving into a cave, where I surface, and I have no idea what I’m breathing. There have been many diving accidents where people surface in a cave after a dive and die with a smile… I surmise that we have not seen this with the “tents” because of luck and because they never increase the Nitrogen too much. (I’ve yet to see a protocol on this btw).

    2) To further remain inside a plastic bag, without knowledge, of the subject’s oxygen saturation AT ALL TIMES, is again dangerous and something I’d never do.

    In my discussions with manufacturers of such tents in the US, I have not seen them take these precautions, so in my opinion, sooner or later, an accident is bound to happen where the subject in the tent may not even know it occurred. (Think of a hypoxic seizure where you will not know it happened unless you also had loss of sphincter control in your bed.)

    In short Lukas, while you may be on to something, your methods across the pond make me wonder whether you are less stringent than we are forced to be here due to our legal system. If you are following the safety methods that I’ve enumerated above, than I take my hat off. But I doubt that your tents have constant FiO2 and SpO2 monitoring while the subjects are inside them. I also doubt that you are measuring Hemoglobin concentration on a weekly basis to see whether you are triggering natural erythropoetin and higher hematocrits on your subjects. Finally, I doubt that you are measuring HR and Resp Rate changes throughout the several weeks that they spend in the tents, looking for certain goals. (In other words, there are no targets or goal oriented methods here – “just stick your head in the plastic bag for a few weeks, and you’ll be able to climb big mountains quickly…)

  • June 29, 2018 at 6:04 am

    Leo, we measure FiO2, SpO2 and HR inside the tents and we were measuring Hemoglobin on a weekly basis. Grab a beer and take your hat of Leo! We are working an measuring Resp Rate change as studies (haha, studies again) show that resp rate and respiratory response are more significant indicators for the progress of acclimatization than anything else. Our „methods“ are just practical, we are no scientists but of course we get advise from scientists and doctors. And we read the latest studies. Even the ones that are not peer-reviewed. Our goal is not a peer-reviewed study but safety on the mountain for our clients. But as I said before I am open to host a study. Get funds, switch from our competitor to Furtenbach Adventures and let’s do this.

    The reason why there was not a single accident in one of these tents after almost 20 years of thousands of people using them may be that in normobaric hypoxic environment HAPE or HACE are very, very, very unlikely to happen (also studies for that).

    And very important – we do not work with adding nitrogen in the „plastic bag“. Even me would consider that dangerous and leave it to the guys in silicon valley. I know that some climbers are experimenting with adding nitrigen. We are lowering the oxygen concentration (and therefore raise nitrogen) by filtering oxygen out of the air.

  • June 29, 2018 at 3:47 pm

    I’ve not been able to follow everything in this conversation, but thank you Leo for the very useful advice concerning beards. We start to understand why the great alpinists such as Messner and Bonington had such an aversion to using oxygen. 😉

  • June 29, 2018 at 6:12 pm

    Very interesting post! I am not tempted by Everest at the moment, but I have to say that personally I perceive the overly US American brash style as unprofessional and would be unlikely to trust guides who don’t display a more measured understanding of this mountain environment with my life.

    With regards to altitude tents: I can’t comment on to what extent they provide useful acclimation for high altitude mountaineering and how it compares to acclimatisation, and it looks like the jury is still out on this and awaiting further research results. With regards to the time question (do you loose the benefits during the day outside the tent), I would be surprised if that was the case. Any adaptation of our bodies is caused by a stressor, and research shows that for example athletes preparing for performances in hot environments can do so successfully even in winter with fairly limited time spent in saunas, so clearly the stressor does not have to be maintained in order to cause the body to adapt. I don’t know of any research specific to altitude adaptations that compared true acclimatisation with short bouts of acclimation, but I would be surprised if the body’s adaptations were triggered differently here.

  • July 3, 2018 at 2:32 am


    I sent an email to your web page with my contact information. I’d be more than happy to work with you on sorting out the science for your project!

    Let’s work together to implement, with data, this new chapter in mountain climbing.


  • July 5, 2018 at 1:45 am


    Messner et al were having such great leaks with their beards that most of their O2 was probably bleeding out and never getting to their lungs or brains. They thus learned how to climb with little oxygen, and at one point they must have thought – the hell with it – I can’t tell the difference (and rightly so since I bet that if we had measured their SpO2 with and without O2, we would have seen little difference). And so they climbed Everest without it.

    In anesthesia, when we wish to mask somebody with a thick beard, we sometimes add KY jelly to the mask (water based lubricant) which helps with the gaps created by the hair. But it never works well, and anesthesiologists are always uncomfortable when they see a Yosemite Sam type beard!

    So yet another reason, to disregard O2 flows when you are climbing a mountain and instead monitor SpO2 (Oxygen Saturation). And I could go on an on… But this thread seems to have exhausted itself.

    Lukas, I never heard from you. I’m ready to work with you and your customers at any time to minimize risks and create a scientific protocol for your Flash Program.

    Regards to all.

  • July 11, 2018 at 4:34 pm

    Hi all, really enjoying the spirited discussion. For the sake of brevity I’ll just add small points.
    1. Alpenglow Expeditions first used pre-acclimatization techniques with hypoxic tents with a full team of clients on Makalu in autumn 2012 (when we flew a full team direct from essentially sea level to ABC at 18,700ft, with no issues). Since then every spring Everest trip (starting in 2013) and every autumn 8000meter trip has been Rapid Ascent with pre-acclimatization in hypoxic tents. So we are 7 years, and 13 x 8000meter expeditions, in.

    2. Since 2014 we expanded Rapid Ascent to Aconcagua, and since 2016 on to 6000meter peaks like Cotopaxi, Orizaba, Elbrus, Ama Dablam, Alpamayo, etc. With these lower peaks we have now had hundreds of clients, guides and friends utilizing pre-acclimatization on peaks with and without supplemental oxygen (I significantly shortened my Everest no-O’s climb through pre-acclimatization). Our success rates have significantly increased since our switch from “traditional” to “Rapid Ascent”.

    3. Dr. Monica Piris is still Alpenglow’s expedition doc and manages all of our pre-acclimatization plans, schedules and success. Monica, I, and Alpenglow do not see a conflict between Uphill Athlete’s focus (low-intensity endurance training) and pre-acclimatization. We recommend both since they do completely different things – low intensity endurance training is training, pre-acclimatization is acclimatization. Monica’s focus in Steve’s article was reviewing past scientific studies, which as has been stated in this discussion, have not yet been done effectively to show hypoxic-tent pre-acclimatization works for high altitude climbing (although they have shown significant positive effects for endurance sports).

    4. On Everest my clients (with Russ/HimEx from 2009 to 2012 and with Alpenglow 2013-present) have always used 4 liter flow. This was standard for our teams all the way back to 2009, and it remains standard today (we have seen no need to increase to 6 liters although our regulators have that ability).

    5. Mark, I still owe you answers to your questions! Want to send an updated list?

  • July 12, 2018 at 10:07 am

    Thanks for posting, Adrian, and thanks for your offer to answer another set of questions. Sadly those questions that took me some time to write are a little out of date now (I know I said there was no rush, but I wasn’t anticipating that it would take 2 years 😉 ). Happily for me, Lukas has been very responsive at answering my questions, so it’s his company I will be focusing on again in my follow up post about costs.

  • July 31, 2018 at 5:30 am

    The hyperbole and bombast of that Furtenbach summit conquest post/advert……. Uggggh

    I suggest a some humility, context, and caution be added to the emptiness of those trumpet blasts.

    It’s Chomolungma for god’s sake, not the Bundesliga,….. she will be back.

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