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fear
Ice climber
hartford, ct
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Also why people who enter say, a confined space filled with 99% Nitrogen often pass out with only a few breaths and die shortly thereafter...
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Al Barkamps
Social climber
Red Stick
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^^^^
exactly.....but they will "gasp" for breath during their slow death. Which is why in toxicology, nitrogen, like other inert gases are known as "simple asphyxiants".
Similar kinds of things used to happen (and probably still do in developing countries) when workers enter large metal storage tanks to clean them out. If they're not wearing SCBA or the tanks are poorly ventilated, they will die; the O2 has been chemically bound up in rust or some other oxide leaving the atmosphere depleted in O2.
Years ago, 3 workers were killed when two of them lowered themselves into an empty storage tank to de-scale the surfaces. Seeing them unconscious at the bottom of the tank, their supervisor went in, also passing out and dying. They thought enough to test the air for poisonous fumes, but not for oxygen content.
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fear
Ice climber
hartford, ct
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So why is it you can hold your breath for several minutes with a little practice? Back in my whitewater Class 4+ days I got to 110 seconds.
Is it the residual O2 still in that last gulp of air that sustains you for that long?
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Al Barkamps
Social climber
Red Stick
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That's a "low oxygen atmosphere", different than a "low pressure atmosphere".
"Low Pressure" is irrelevant. Consider the use of supplemental oxygen at altitude. The demand regulator releases pure O2 into the mask attached to your face. The pressure in the space between your face and the mask is exactly the same as the pressure outside of the mask. If it weren't, oxygen would constantly be forced OUT of the seal between your face and the mask.
Low pressure atmosphere, if I remember my Charles Houston correctly, does funky stuff to other parts of the body, but when it comes to oxygen diffusion across capillary walls, has no effect. It's all about that O2 partial pressure.
edit: Fear- Maybe you were practicing to hyperventilate....which flushes the lung's residual volume of "stagnant air" with fresh air. Which is, in itself, sorta dangerous, as it fools the brain into not wanting to flush accumulated CO2. Out on a limb here, but I think people die every year doing solo breath-holding contests, unsupervised, in a pool.
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matisse
climber
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At high elevation pulmonary edema is caused by low atmospheric pressure outside that is insufficient to keep blood and fluid from being pushed into the alveoli by normal internal pressure.
Sue wanders in for the first time in ages and pulls specs off the top of her head plops them on her nose and sighs. hmmp hmmph. leave for a while and you rabble get completely out of control. cheese louise................All kinds of nonsense in this thread.
Short answer : Um no.
Longer answer:
A quick lesson on what we think is the pathophysiology of HAPE:
First of all the biggest predictor of who will get HAPE in the future is a past history of HAPE and because of this we can study people who have had this quite rare condition.
You have two circulations for blood the systemic circulation out to your body and the pulmonary circulation to your lungs. The systemic circulation has a relatively high pressure (i.e around 120/80 mm Hg) whereas the pulmonary circulation is a low pressure low resistance circuit (~15/5 mmHg). This is a good thing because the walls of the pulmonary capillaries are very thin to allow for gas exchange and aren't very strong. High pressures in the pulmonary circulation can cause the capillaries to rupture and that isn't a good thing. It's called "Stress Failure".
When your systemic circulation encounters hypoxia, it vasodilates..i.e. the blood vessels relax and the local pressure may fall, but the pulmonary (lung) circulation is the opposite. When the pulmonary circulation encounters hypoxia it vasoconstricts, a phenomena known as hypoxic pulmonary vasoconstriction or HPV. What happens with HPV is that muscle in the blood vessel walls located upstream of the capillaries constricts and this causes the pressure in the lung blood vessels to go up. Fortunately the capillaries don't see this pressure because they are down stream of the constriction, in the same way that if you kink a garden hose the pressure before the kink is high but after the kink is low.
People who have had HAPE have exaggerated HPV, so when they become hypoxic the pressure in the pulmonary circulation rises to a much greater extent than normal people. There is very good evidence (very, very, very good..I think someone should get a noble prize for this brilliant research if I do say so myself) that HPV in people who are susceptible to HAPE is UNEVEN: some areas get constricted so the overall pressure rises but some areas don't constrict and they see the pressure. This causes small areas of capillary ruputure (stress failure) and then you get an inflammatory response and then you get a bigger leak and a cascade of events that leads to HAPE.
wanders off to her dusty lab again....
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fear
Ice climber
hartford, ct
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yeah..... what she said...
What about for HACE? Similar reasons for leakage inside the poorly designed pressure vessel?
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High Fructose Corn Spirit
Gym climber
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Topic Author's Reply - Dec 8, 2016 - 07:19pm PT
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Sue, your post seems to imply then that any general hypoxia (not just at HA) over some length of a time (eg, a number of hours) would lead to PE (pulmonary edema) by these mechanisms. Do I have that right?
Well, at least for those with "exaggerated HPV," that is.
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matisse
climber
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Fear. I'll try to get to your question tomorrow. I'm tired and it isn't a simple answer.
HFCS. As a physiologist, I tend to think of hypobaric hypoxia i.e. that from high-altitude, and normobaric hypoxia, that induced by giving lower inspired oxygen concentrations to breathe are equivalent. However, there is some research that suggests that the effects of hypobaric hypoxia are more marked for reasons that we don't understand. I'm not talking specifically about the pulmonary circulation, but as a general effect of altitude/hypoxia on the body.
I'm not sure anybody has really done the definitive study to answer your question, which would be to take people that were HAPE susceptible and stick them in a hypoxic tent (not hypobaric) for two days maybe exercise them a bit, or exercise them a lot and see if you could induce HAPE in that setting. There may be some indirect evidence out there, where people were looking at different things but I don't recall any off the top of my head.
Years ago there was a study called operation Everest II in which they simulated an ascent of Mount Everest inside an altitude chamber and made a large number of physiologic measurements on a small group of research subjects. One of those subjects developed HAPE and had to leave the study, so we know that you don't have to be out in the real world to get it.
We know that exercise is important in the development of HAPE and a group from UCSD several years ago showed that something like 70% of climbers who ascended rapidly to over 4000 m had some evidence for very mild pulmonary edema, however only a couple of those had overt HAPE. I also think that probably cold temperatures may be important too for reasons that nobody really seems to understand. We see a lot less HAPE in California compared to Colorado and one factor is that it tends to be a lot colder in Colorado. Of course it just could be that the California climbers/skiers are vastly superior physical specimens. :p
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High Fructose Corn Spirit
Gym climber
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Topic Author's Reply - Dec 9, 2016 - 08:18am PT
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Matisse, thanks for the elaboration, interesting stuff.
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Rockies Obscure
Trad climber
rockiesobscure.com....Canada
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I have climbed a few Andean peaks, but only two times I had illness strike....
Poorly acclimatised in Ecuador after being on the coast, spending little time around Quito, and going to climb Chimborazo. Made it to the summit fine, but on the descent started developing "gurgly lungs". Near the rock feature at the bottom known as "El Castillo" the gurgling lung sound intensified and i started spitting up blood into the snow. Coughing like crazy and more blood- took me forever to get to the hut. Got flu like symptoms overnight back in the city, the blood stopped very soon after driving down to lower altitude. Coughed non-stop for weeks, went to the doc and he said i had bronchitis, something I never had in my life.
About 18 years before that I was well acclimatised for Huascaran, but around the 6000m level stated to hallucinate over night in the tent and next morning we boogied out of there and i was seeing images and my head couldnt figure out how to tie a figure 8.
Other Andean adventures I had no problems.
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Reilly
Mountain climber
The Other Monrovia- CA
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The temperature relationship is counter-intuitive given that warmer temps result in a higher
'density altitude'.
A trip I was on we were flown from low altitude to over 12,000' to our base camp. Daytime
temps were very warm resulting in a density altitude of about 15,000'. Three of the six of us
came down with HAPE to varying degrees, one very seriously.
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High Fructose Corn Spirit
Gym climber
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Topic Author's Reply - Dec 9, 2016 - 09:40am PT
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"Near the rock feature at the bottom known as "El Castillo" the gurgling lung sound intensified and i started spitting up blood into the snow. Coughing like crazy and more blood- took me forever to get to the hut. Got flu like symptoms overnight back in the city, the blood stopped very soon after driving down to lower altitude. Coughed non-stop for weeks..."
Rockies Obscure, thank you for this description.
So I imagine you probably think that if you didn't get relief from going down this "gurgling lung sound" would've intensified even more to the point of serious horror and incapacitation?
Thank goodness you didn't lose your cough and swallowing reflexes during this event. (I hear during PE events in general, this may happen, then it becomes impossible to clear the airway.)
"went to the doc and he said i had bronchitis, something I never had in my life"
as you probably know, generally speaking "bronchitis" means inflammation of the bronchi, the inflammation probably a result of your trouble (not the cause).
...
"but only two times I had illness strike...."
:)
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Rockies Obscure
Trad climber
rockiesobscure.com....Canada
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hi Fructose,
No i did not know that info about bronchitis, the doc may have told me but I may have forgotten.
The coughing did certainly intensify and if we didnt return within a few hours, as we did, to much lower altitude I think it would have gotten worse for sure. I was certainly very worried about this sudden condition that overcame me. I paid a tourist who hiked to the hut, like $10 to carry my backpack from the hut to the where cars park.
Of course I was tired from climbing, but wearing the pack made it worse.
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matisse
climber
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The temperature relationship is counter-intuitive given that warmer temps result in a higher
'density altitude'.
Cold activates the sympathetic nervous system and that seems to be the most plausible, but nothing really has been studied. I'm not sure it has anything to do with density altitude. (whatever that is)
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Al Barkamps
Social climber
Red Stick
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The temperature relationship is counter-intuitive given that warmer temps result in a higher'density altitude'.
A trip I was on we were flown from low altitude to over 12,000' to our base camp. Daytime temps were very warm resulting in a density altitude of about 15,000'.
Reilly, your brain has been afflicted with higher density attitude as this makes zero sense.
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Reilly
Mountain climber
The Other Monrovia- CA
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You guys really don't know about density altitude? Mr Google is yer friend.
I do realize it may be more germane to hypoxia but it seems to me it could
also effect HAPE.
I was just guessing but I just ran the numbers for our basecamp and the
density altitude was more like 16,000' for the conditions at 12,400'.
The air density was about 0.0463 lb/cu ft and the absolute pressure was
18.75" Hg.
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Al Barkamps
Social climber
Red Stick
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You mean "pressure altitude", and you have it backwards.....perhaps by an order of magnitude. Remember, the bong is not always your friend.
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Reilly
Mountain climber
The Other Monrovia- CA
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Mr Bongkamp, I told you to Google it, don't dig yerself a deeper hole.
Pressure altitude is not the same as density altitude. I guess yer not
in possession of an ATP license, are you?
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matisse
climber
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Reilly,
Ahh. Now I know what you are talking about.
You are conflating concepts. This is not aviation. Density altitude is irrelevant for this discussion. This is because by the time the inspired air clears your upper airway it is fully saturated with water vapor, and is at body temperature. What it is in ambient air plays no role in the physiology with the exception that you will have less heat and water loss out of your upper airway when you breathe warm wet air than cold dry air.
The one thing that is relevant is that for a given altitude barometric pressure will vary: with weather as a high or low pressure system blows in, seasonally and and with latitude. The barometric pressure at a given altitude is on average less at the poles than it is at the equator.
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Reilly
Mountain climber
The Other Monrovia- CA
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That's all I was implying - that at the same altitude as the temp rises
you get less O2 per lungful, just like an airplane engine unless it is
turbocharged. :-)
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