Mt Whitney Zone Forums The Chat Room O2 Saturation & AMS, Long, Bear with Me

I'm not sure where this will go but thought I'd post it out of curiosity and hopefully get some interesting information.

I recently bought an oximeter and tested it out on my last trip to the Sierra. I'm VERY prone to AMS and do not deal with the altitude well. If I go too fast, I definitely will be stumbling like a drunk on something as "low" as San Jacinto or San Gorgonio here in Southern California. So, I wanted to measure my O2 saturation level and hopefully compare it with others to hopefully glean some information, and if not, just for fun.

Here's how my last 3 trips to the Sierra went:

1) May- I drove up with a friend to the HSM in the morning to acclimate, and went to Trail Peak. I was feeling fine until going down where I got a massive headache. It subsided when we went to the Pizza Factory for dinner. It returned that night while we camped at the HSM again. It disappeared the following morning. I had no issues going to E-Ledges later on. The day after that, I was fine on the North Fork until reaching Iceberg Lake, where I felt a strange "tingle" in the back of my head. By the time we reached the Notch, it was a massive headache. By the time we reached the summit, I could hardly take 5 steps before stopping and gasping for air. It came on suddenly like a sledge hammer even after 2 days at altitude.

2) Fast forward a few months I went to Langley by myself and summited with no issues after acclimating for 2 days. I only had a subtle headache on the way down. I met my friend the following day where we slept at the Glacier Lodge Rd for the night before starting up to Middle Palisade the following morning. I felt like a million bucks that day and the next as we went up. Strangely enough, I had a bad headache coming down that didn't subside until we were back at the parking lot. The following day, we headed up Agassiz. Again, felt fine until I hit the summit and got a minor headache on the way down which perplexed me after basically being at altitude for about 5 days.

3) Last month- I did the same thing, acclimated (with Diamox this time) and went up Langley with another friend. This time, I took some readings. He was doing better than me after only acclimating 1 night while I had 2 days and nights. No headaches whatsoever going up, but had a slight one while coming down and I took 2 Ibuprofens. That night and the following morning I stayed at the Portal before going to the South Lake trail head for some R&R before backpacking to the Palisade Basin the day after. No issues that day. The following day, we went up Thunderbolt and Starlight Peak. Again, no issues, not even the slightest bit. I felt like a million bucks. The following day, I woke up with a slight headache which got worse and worse as the day wore on. I went to sleep with a headache that dissipated overnight. The day after, we headed up North Palisade and Polemonium without the slightest hitch. I thought I was at the beach the way I was breathing. The trip out the following morning was also enjoyable and free of drama.

Anyhow, here are the numbers from the last Langley trip:
Day 1- Horseshoe Meadows @ 5-ish PM- 93/73 O2 Sat/Pulse
Day 2- Horseshoe Meadows @ 8-ish AM- 95/75
Day 2- Horseshoe Meadows @ 5-ish PM- 97/68
Day 3- Top of Old Army Pass @ 9-10 AM- 91/109
Day 3- Langley Summit @ Around noon- 85/110
Day 3- Whitney Portal @ 7-ish PM- 96/85
Day 4- Whitney Portal @ 7-ish AM- 98/80
Day 11- Home @ 3:00 PM- 99/61

By comparison, my friend's O2 saturation on the summit of Langley was fluctuating around the mid-90s, and his heart rate was in the mid-80s.

Can any of the WZ doctors make heads or tails of this, or am I just wasting bandwidth? :grin:

My quick interpretation:
Normal Sat for you is about 99 (as for most people)
Note the drop to 93 on day 1, but gradually going up the next two days, as you are acclimatizing. But you aren't there yet.

Your heart rates for those days are elevated above your baseline of 61....your body is compensating normally by increasing heartrate.

At NAP, a significant elevation gain, your Sat drops accordingly, and your heartrate is up even higher (assuming you've rested long enough for it to come down from your effort)

On the summit, your sat drops even more from decr oxy. Your Heartrate is still up compensating.

Down at 3 Whitney Portal, you have continued to acclimate, so your Sat is now almost normal, and your HR is still up, compensating.

At 4 WP, your sat continues to approach normal, and your HR is continuing to drop. Were you to stay longer, it would continue down until finally reaching your baseline in the 60's

That's my "quick and dirty" look at it.

I do think those 02 sats are pretty much are in line with what one would expect at those heights. Those small O2 drops in saturation do not tell the whole story. There is something else going on with a much larger drop in pressure. For example, while the O2 sat might drop 10% at say 12,000 ft, the pressure drop is more like 30%.

You can die with 100% oxygen at 40,000 ft. military pilots must use pressure masks there. Pressure is what drives the "oxygen cascade" into the cells for utilization, not just O2 itself.

headache of AMS is well known to be independent of O2 sat. Plenty of people get headaches with appropriate O2sats, normal O2sats, or O2sats like others with no symptoms. The exception might be someone who is really sick like HAPE with, say, 02sat under 75 and they have multiple symptoms. Lowest O2 sat I have ever experienced up high above 20,000 was 62. With an hour of rest and 2 liters of hot tea it came up to 75. Felt far, far better there, but to put it in perspective, all of us at 75 if in the hospital would have been put in the ICU.

Oh, I'd also mention that small changes in Sat are really not to be trusted. I'm not sure that a unit can reliably distinguish between a couple of points.

More important is a trend over time.

I really appreciate the responses guys. Biggest issue for me has always been altitude. Literally scares me, so much more than a potential fall. I think the biggest fear factor is that I can't seem to find a trend or discern what brings it on in order to get a handle on it. It seems to be very random and sporadic when it comes.



Harvey, there's a joke with a few friends now that I'm the canary of the Sierra, instead of toxic gas, I keel over when bad weather is imminent. For case #1 above with Whitney, when we went up Whitney it was clear, but we could see it coming down hard on the East side over the White Mountains in the distance.

For #3, when I was at the Palisade after coming off Thunderbolt and Starlight, this was right before a storm system came in. The following day rain came in the evening and lasted throughout the night. My headache literally got worse with the weather. Coincidence? I'm not a meteorologist, but doesn't storms bring a low pressure system? No climbing was done that day and I was "bed ridden", but was 100% fine the previous day huffing and puffing at 14k ft, and the following day doing the same thing.

Also, good to know that my numbers are not "off" from normal.

Thank you both again for your insights.

Someone else, or was it you?asked about barometric changes with weather impacting the risk of AMS. I answered something like that is significant at , say Denali, but is not so-recognized at lower mts. On the other hand, Boeing has increased the pressure in its new model Dreamliner to equivalent altitude of 7k rather than 8k (the official threshold of altitude illness) because there is evidence that some travellers illness is AMS. Yes, some people are canaries!

The DreamLiner (787) also allows for increased humidity. (Humidity is controlled to a low value in tin jets, due to corrosion.)

The other huge improvement is using electric compressors rather than bleed air from the engines. That air is in contact with some rather exotic lubrication chemicals. Probably a good research paper on travel sickness there...

"The internal cabin pressure of the 787 is increased to the equivalent of 6,000 feet (1,800 m) altitude instead of the 8,000 feet (2,400 m) on older conventional aircraft. According to Boeing, in a joint study with Oklahoma State University, this will significantly improve passenger comfort. Cabin air pressurization is provided by electrically driven compressors, rather than traditional engine-bleed air, thereby eliminating the need to cool heated air before it enters the cabin. The cabin's humidity is programmable based on the number of passengers carried, and allows 15% humidity settings instead of the 4% found in previous aircraft. The composite fuselage avoids the metal fatigue associated with higher cabin pressure, and eliminates the risk of corrosion from higher humidity levels. The cabin air-conditioning system improves air quality by removing ozone from outside air, and besides standard HEPA filters which remove airborne particles, uses a gaseous filtration system to remove odors, irritants, and gaseous contaminants as well as particulates like viruses, bacteria and allergens."

I tend to do better than most at high elevation, so I'll toss in a few words on my experience for comparison.

I'm 63 and I have been playing in the mountains for 25 years. I live at 5,000 feet, which is clearly an advantage, but I think it's a small one. I get above 10,000 feet nearly every week and have never had any symptoms except mild Cheyne-Stokes breathing on Denali. I never take extra time to acclimatize, but I try to sleep as high as possible (usually at the trailhead) before climbing. It's common for people to kick my butt at relatively low elevations and then watch me return the favor up high. Some might say that I'm perpetually acclimatized, but I still felt fine when I have gone up high after several months away from the mountains. I think I'm just one of the lucky ones.

Having said all that, I've only used a pulse oximeter once at altitude. Saturation was 93% about five minutes after reaching the summit of Middle Palisade (14,040). Pulse was in the low 90s. We had slept near Glacier Lodge the night before.

Color me green with envy Bob.

My unscientific belief is that your resistance to the effects of altitude is genetic and not because you live in Reno. I'm new to this, but the two buddies that I go into the mountains with have been doing this for about as long as you have. They both live at sea level, both hardly acclimate (one night at the trail head like you), and neither have ever experienced the debilitating effects of AMS.

Earlier this year, I've tried to see if being at higher elevation periodically would help build up my resistance or tolerance for lack of better words. Went to San Jacinto and used the Skyline trail or Marion Mtn trail on a weekly basis for about 4 months...didn't work.

If they weren't so awfully expensive, I would be tempted to try out one of those altitude tents...but the cost is ridiculous for my pay grade.