"Personally, I would never fool with Diamox for anyplace as low as 10,000 feet, but that is just me. Everybody has a different ceiling. I came to the conclusion that about 80% of the symptoms that others report from high altitude are mainly from simple dehydration, but I've seen well-hydrated hikers get pretty sick in a hurry at 16,000 feet. It isn't pretty."

I would agree with Bob that everyone is different and some people have little trouble with AMS while others can have a lot. I was backpacking with a group from Ohio last September in the Winds and one of the group came down with definite AMS that began for him at around 10,000 to 11,000 feet. He had been higher than this in past and no prior problems. He toughed it out but got increasingly short of breath with activity and eventually even at rest, despite the fact that our sleeping altitude was never higher than 11K. We decided when he became short of breath at rest that he was probably in mild HAPE and descended with him to a lower altitude trailhead so that he could get a ride out to Pinedale. After 2 days in Pinedale just taking it easy (Pinedale is about 7.5 K)he was pretty much back to feeling normal.

So I learned from this to not make assumptions about how high you need to go to get AMS. Its less predictable than it ought to be, unfortunately.

Robert, absolutely right.

I have heard of little old ladies with a heart condition stepping off a tour bus in Yosemite Valley (4000 feet) and started developing altitude problems immediately. But, that is not a normally healthy backpacker.

Years ago a healthy 40-year-old physician drove from sea level up to 8500 feet in Yosemite, strapped on his backpack, and headed up to Cathedral Lakes (around 10,000 feet). That was too much of a rush, so he was feeling poorly by that evening. By the next morning, he had all of the classic early symptoms of HAPE. Somebody else went for help, and they had a helicopter evacuate him before noon. By the time he had been sitting in Yosemite Valley for an hour, his vital signs were normal.

--B.G.--

"I seem to recall the increased permeability of lung tissue (something helps deliver oxygen to the tissues but that can go awry in HAPE) was in the 1-2 week range."

With HAPE, according to a text I read a long time ago, the difference in pressure between the blood and the atmosphere at higher elevations can cause fluid to leak into the lungs in susceptible individuals. I can't remember where I got this offhand, but it makes sense and should be easy to validate with a few queries. FWIW.

"With HAPE, according to a text I read a long time ago, the difference in pressure between the blood and the atmosphere at higher elevations can cause fluid to leak into the lungs in susceptible individuals. I can't remember where I got this offhand, but it makes sense and should be easy to validate with a few queries."

I agree. Guess what forces the blood pressure to be abnormally high to cause this to happen.

If the victim is very dehydrated the capillary fluid coming past the lungs is very thick, and little micro-clots happen. Well, if just a couple of micro-clots stack up there, you won't notice much. However, when those tiny capillaries are clotted and closed, that forces the fluid to flow more into the capillaries that are still open, which forces them to have even higher pressure with even more risk of micro-clots and leakage into the alveolar membrane, and that is another vicious cycle. The key to prevention, of course, is to never let yourself get very dehydrated.

Too many climbers get dehydrated. They don't want to carry any more water weight. They are maybe up too high in direct sun, so they don't realize their body temperature. The air is dry, so they have a lot of water loss to the air. Maybe their stove for melting snow isn't so efficient. That brings us back to Larry Penberthy and MSR.

--B.G.--

Small airplane pilots with unpressurised cabins are required to use oxygen above a certain elevation, I believe it is 8000 ft. I was told by the maker of oxygen supplies
for these craft, that several hours at 8000 ft can give one the same symptoms as spending
one hour at 13000 ft (headaches, fuzzy mind etc.)

While it might take a month or more to get all the red blood cells you might need for
altitude, it only takes about 3 days for you body to get rid of them when you return to
lower elevation. Your lungs and other adaptions last longer.

FAA regs. Sec. 135.89 Pilot requirements: Use of Oxygen.
(a) Unpressurized aircraft. Each pilot of an unpressurized aircraft shall use oxygen
continuously when flying—
(1) At altitudes above 10,000 feet through 12,000 feet MSL for that part of the flight at
those altitudes that is of more than 30 minutes duration; and
(2) Above 12,000 feet MSL.
======================================
I don't know that your body "gets rid of" red blood cells three days after returning to lower elevation. I think it simply quits replenishing them until it gets to normal concentrations. The average life expectancy of a red blood cell is 21 days or so.

--B.G.--

When climbers go too high to fast, they make themselves susceptible to altitude sickness in one of its forms. If you are with somebody else who seems a little sick this way, how can you tell? The answer is: it depends.

If they have cardiovascular problems, then it will likely show up in their blood pressure or pulse. You probably don't have a blood pressure cuff along, but at least you can count their pulse against your wristwatch. It helps to know what their normal sea level pulse is, or maybe what their pulse was at the trailhead. Generally, once they arrive in camp and rest for an hour, if the rest pulse is above 110 or 120, that is a bad sign. You can listen for respiratory problems like wheezing, and you can look for pink sputum that they may be coughing up.

The easy test is one of brain function. Some of us are glad to have any at all, but I digress... When your blood oxygen saturation starts dropping, some of the first signs are at the brain. Ataxia is the loss of balance, like a drunken driver. The test that I like can also be performed at a drinking party. You can tell who is really drunk and who is just a bit impaired.

Here is a graphic that needs to be printed in color. Have the subject look at the graphic, but not read the words as spelled. Instead, speak the colors of the words. Then watch the fun begin. Maybe print the correct response on the back side of the graphic so that the subject sees the graphic and you see the correct response. The subject must be able to concentrate a little in order to get them correct at all. If the subject is impaired, he might not be able to get any correct.



The correct response is:
Red, White, Blue, Brown, Green
Blue, Red, Green, White, Brown
White, Green, Red, Blue, Brown
White, Red, Blue, Green, Brown
Green, Blue, Red, White, Brown
Blue, Red, Green, White, Brown
Green, Brown, White, Red, Blue
Blue, Green, White, Red, Brown
Green, Blue, Brown, Blue, Red

Have fun.
--B.G.--

"If the victim is very dehydrated the capillary fluid coming past the lungs is very thick, and little micro-clots happen. Well, if just a couple of micro-clots stack up there, you won't notice much. However, when those tiny capillaries are clotted and closed, that forces the fluid to flow more into the capillaries that are still open, which forces them to have even higher pressure with even more risk of micro-clots and leakage into the alveolar membrane, and that is another vicious cycle. The key to prevention, of course, is to never let yourself get very dehydrated."

Interesting info. Thanks for the update.

It's amazing how many unpleasant conditions have dehydration as the cause or as a contributing factor! AMS, hyperthermia, hypothermia, just plain fatigue and a lot more!

One friend of mine had to have kidney dialysis as a result of dehydration combined with a large dose of Tylenol.

--B.G.--

I became incredibly exhausted going on an overnight to Paradise Valley (kings canyon). That couldn't have been much more than 7000 ft. I barely ate anything that night and pretty much stumbled out of there the next day. I slept at 6500 feet the night before.

On another trip it took me 8 hours to walk 3 miles to Monarch Lakes from Mineral King where I slept.
I turned around the next day after I fell over a few times walking up Sawtooth Pass. I was becoming very confused at my surroundings, getting blurred vision, and I pretty much starting to lose consciousness with every step. A sad end to a planned 5 day trip.
I also slept a night car camping at 8,000 the night before.

Apparently, I get it REALLY REALLY BAD. And I desperately want to get over it so I can do some backpacking trips in the high sierras this summer.

Justin, you might want to have a talk with your physician. You may either have to sleep up high another night before you start, or else get a prescription for Diamox (acetazolamide). Still, you need to take the Diamox pills for a day or so before you head up to the mountains. Then, you generally continue the pills until you hit the high point of your trip.

I know some guys who gobble that stuff down like it was candy, and I'm not sure that is good, although it gives them good results in the mountains.

--B.G.--

Thank you Bob.
I think it was you, or maybe someone else who recommended me Diamox in another thread but I had forgotten the name of it. I am going to talk to my physician eventually.

Justin, your physician will probably ask you if you are allergic to any sulfa drugs. Diamox is one of those. If your regular physician is not familiar with it, typically a travel medicine clinic will be familiar.

I've had Diamox prescribed on three trips, but I actually only consumed it on one trip. Some people claim that they get a good effect out of half of the standard dosage. You might discuss that with your physician. The advantage of half is that you will likely have reduced or zero side effects. But then if you have to go really high sometime, go for the full dosage.

The standard side effects include (1) increased urination for the first few days, (2) slight tingling in the extremities, and (3) strange taste of carbonated beverages. That will kind of mess up the post-trip beer.

--B.G.--

Justin -

Some advice I received and followed for a Nepal trek was to take a half tab (125 mg) at bedtime every night as a preventive step once I arrived in Kathmandu and continue doing that unless/until I started to have any mild AMS symptoms, at which point I should increase to a full tab (250 mg) two to four times a day, depending on symptom level.

I took the preventive dose until our party got to about 13,000 feet (day 4 or 5, as I recall), at which point I started to get headaches, which are not common for me to get. At that point I went to a full tab twice a day and continued that until I got back to 13,000 feet. For me this worked very well. I got as high as 18,200 feet and slept as high as 17,100 on this 14-day trip. We ascended for the first 9 of the 14 days and descended in remaining 5 days.

Just to confirm the variability factor, my brother (8 years younger) needed about twice the Diamox that I did, and my son (30 years younger) needed none. I was 54 at the time.

"Incidentally, if you drive too far from sea level up into the mountains for your first night, you might trigger this whole problem right there before you ever get onto the trail. That's why sleeping in your car at some 11,500 foot trailhead might not be smart."

Which is what I did for New Years Day this year. Drove straight from Bakersfield (About 408 elevation), slept at the Little Lakes Valley trailhead (About 10,200 elevation), got nausea/vomiting all night. We were gonna camp in Little Lakes Valley somewhere, but my friend just dayhiked and I drove down to Tom's Place the next day where I recovered.

One night wasn't enough for me for that White Mountain trip. Slept at that lower campground which is around 8k, I think? Never had enough time for staying 2 days at a somewhat high elevation before heading in.

Attempting High Sierra Trail + Whitney and a loop back with a friend this summer. Hoping I'll be acclimated enough by the time I get to Guitar Lake, but I'd like to have Diamox just in case.

Edited by TRAUMAhead on 03/24/2012 21:49:45 MDT.

So, Robert, I guess you were the old guy who made it up Kala Pattar? Congratulations.

The last time that I was there, I think I was the only one in the group of twelve that was not taking the Diamox.

For the next time that anybody is going on a trek to high elevation where part of the group might be taking Diamox and part won't be taking it, it would be neat if some statistics could be gathered. Have each group member record their rest pulse rate first thing in the morning before they get up. Then record whether or not they are taking Diamox, and if so whatever the dosage is, and any altitude symptoms that they may have. Then at the end of the trek, gather all of that and see what kind of correlation there is between Diamox and non-Diamox. I tried to get all of that done on my last trip up high, and only one out of eleven turned in the data. On another trip, Diamox gave climbers some advantage, but it was sure no guarantee of success.

--B.G.--

After reading the various stories of altitude-related issues, I feel luck to have had so few. The only time I can recall even a bad headache was driving from 2k' directly up to Tioga Pass at 10k', then immediately climbing Mt Dana at 13k'. All my other experiences have been that one night spent above 8-9k' is enough for me to be good to go all the way up to 14.5k', with no issues. I did live at 4-5k' from birth to age 17, I wonder if that would have any impact?

"I did live at 4-5k' from birth to age 17, I wonder if that would have any impact?"

Probably zero.

The native people in the Andes have lived up high for enough generations that there is a bit of adaptation. They get more of a barrel chest, and that is thought to make for bigger respiratory volume.

Yes, Mount Dana is a typical place to have altitude problems. We pulled a similar stunt there 25 years ago, and the hiker with me was almost crippled from a headache.

--B.G.--

I have found that physical fitness prior to a high altitude trek is key. Preparation is always key. Also hydration is a major component as I'm sure you all know. However, keep in mind that to fully hydrate your body take 4 days. Focus on hydrating in the 5 mornings preceding a trip as your body is like a sponge in the mornings and makes most effective use of your intake.

Finally, and I know its tough... but cut out the celebratory drinking session prior to your to the day you embark on your trip.

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Edited by rcaffin on 03/27/2012 14:47:05 MDT.