Pulse oximeters

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Pulse oximeters

Postby nyker » Tue Jan 15, 2013 10:02 pm

Has anyone used a pulse oximeter as a predictive tool to gauge your acclimatization?..and then made decisions as to whether to ascend or wait depending on what your reading was?

For those who have used them with success, I've heard many have accuracy problems...are there mankes known to be better than others?

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Re: Pulse oximeters

Postby Scott P » Wed Jan 16, 2013 7:17 am

Yes. Not in Colorado, but on higher peaks. They are a useful tool, but every once in a while you can get an off reading, so it's best to take several before basing any kind of decision on them.

I got one when I started to take my kid to higher altitudes, as a precaution to monitor closely since I didn't want to take any chances with him. It has become quite useful.

I forgot mine on our last trip to the Himalaya, and although we didn't get sick (we acclimatized well and gradually), several other people we met did and several of them had low saturation levels. One person decided to go up anyway and when Kessler and I were climbing a nearby peak we saw a helicopter coming and immediately knew who they were coming to pick up.

So, yes, they are useful tools. Even if your readings are OK, you still shouldn't go up if you are showing any signs of altitude sickness. Pulse oximeters are just one indicator or tool and not the only one to base a decision on.

As far as brands go (I only have one), I don't know which brands are best, but I'd go with a hospital grade one. Prices have dropped dramatically in recent years. Ours was something like $300 in 2007, now they are much less.
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Re: Pulse oximeters

Postby jsdratm » Wed Jan 16, 2013 7:49 am

I work for Covidien in Boulder, which makes the Nellcor brand of pulse oximeters, and have been thinking of taking one of our devices up a 14er hike just to see how my SpO2 level is affected. You might be able to find a good deal on a portable medical-grade monitor on ebay or something. The biggest brands in the United States are Nellcor, Masimo, Nonin, and Datex Ohmeda. I have seen generic pulse oximeters sold in Walgreens, but I have no experience with them and they may be less accurate since they are not intended for patient monitoring.

As you ascend, I would expect the SpO2 (%) to drop, but how much I cannot say. Maybe I will get a chance to try it out myself this weekend.

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Re: Pulse oximeters

Postby jbchalk » Wed Jan 16, 2013 7:57 am

Never completely rely on pulse oximeters. Many times they are so very inaccurate. The best means of assessing someone's acclimitization is just to talk with them about how they feel and monitoring their movements. I've witnessed climbers with edema symptoms yet still with a reading in the high 80s at 21,000'. Personally, I never have one with me. We just go off how we feel, which in my opinion is the best measure one's acclimitization.

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Re: Pulse oximeters

Postby jeremy27 » Wed Jan 16, 2013 8:00 am

Two thoughts:
1. http://www.summitpost.org/expedition-medicine/675753 (there is a discussion of o2 saturation in this article)
2. I climbed Pikes with the AdAmAn group this new years eve. We got to the summit around 3 and after setting up the fireworks we had plenty of time to kill in the summit house. One of the members is a doc who carried a pulse oximeters. Most everyone we tested was in the mid 70 to mid 80 range - enough to put you on o2 if you were in the city. With a little pressure breathing we could get it back up to the mid 90s - maybe 2-3 minutes worth. We also used some of the o2 they have on the summit (for AMS suffering tourists) and it was really easy to get it back to normal.

Take aways:
1. Pressure breathing works.
2. Pulse oximeters are fun.

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Re: Pulse oximeters

Postby siop » Wed Jan 16, 2013 8:06 am

I haven't used a pulse ox on peaks, but my son has been on supplemental O2 for over 8 months so I use one all the time. They definitely can be finicky so I would just say don't rely completely on the readings. I've seen him blue and lethargic in the high 80s and happy and fine below 70. If you feel any signs of altitude sickness trust how you feel.
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Re: Pulse oximeters

Postby shearmodulus » Wed Jan 16, 2013 8:31 am

Trust your body's signals.

I always have to remind myself about 500-1000 feet below the summit, when looking up at the final pitch and thinking that I don't have enough gas in the tank to finish: "Yes, I'm supposed to be feeling this bad right now. Don't be a wimp."

But then again, I'm usually slogging a 50-pound pack in the winter, so I like pain.
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Re: Pulse oximeters

Postby tenpins » Wed Jan 16, 2013 10:08 am

jeremy27 wrote:2. Pulse oximeters are fun.


pulse ox readings can also be affected by low circulation in cold fingers. you cant rely on them soley up there. The real value of them is to put one one a subject complaining of AMS symptoms, then administer oxygen. If the spo2 readings do not go up in a few minutes, there may be an underlying problem more serious than typical AMS

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Re: Pulse oximeters

Postby MountainMedic » Wed Jan 16, 2013 2:24 pm

Personally, I think it would be a waste of your money unless you're climbing at altitudes above 20K and don't really have time to acclimate properly AND you're very well versed in high altitude physiology. Pulse oximeters are fairly inaccurate in the first place - even the best ones. Furthermore, the data is quite complicated. Your SaO2 will change considerably with sleep and activity. I've read a bit on the subject and consider myself fairly knowledgeable; I would not know how to use this information were I to have it. In Denver, if you have a patient below 95%, they go on oxygen, and below 90%, they go on a lot of it. If I'm not mistaken, we're around 80% on the summit of a 14er - and most of us feel fine. Our sea level and first-time climbers may also be at 80% on the summit, but they might feel like crap.

Ultimately, SaO2 is kind of beside the point. It's dependent on your altitude and the barometric pressure more than it is on your acclimation. The oxygen dissociation curve allows well maintained SaO2 up to about 10,000 ft, after which improvements are largely dependent on hypoxic ventilatory response (HVR). HVR is just a fancy way of saying that you breathe faster/hyperventilate, which increases oxygen exchange and thus SaO2. Diamox (acetazolamide) works through enhancing HVR. Hypoxia will manifest itself clinically - that is, with clear symptoms (cyanosis, lethargy, altered mentation) - and should be evaluated on these grounds. Numbers are relative, and unless you take serial readings, meaningless.

Anyway, Denver Paramedics use the Lifepak (Physio-Control) oximeters. The Nonin Onyx is portable and decent in cold temperatures (I used it in Vermont). Bottom line, IMHO: not worth the money. If you're looking to spend money on medical supplies, I recommend buying books...Auerbach's Wilderness Medicine is the bible. Also, I'd invest in Diamox way before I'd invest in an oximeter.

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Re: Pulse oximeters

Postby Derek » Wed Jan 16, 2013 5:17 pm

I met a guy on Longs a few years back and we ended up descending to the TH together. He had brought along a very large hospital unit. (I seem to recall that he was an anesthesiologist...) He brought it from his work just to play around with. The entire way down, he would ask people if they would mind letting him check their levels. (It was Longs...so no shortage of participants.) It was really interesting to see the different %'s people would show.

MountainMedic wrote:If I'm not mistaken, we're around 80% on the summit of a 14er - and most of us feel fine. Our sea level and first-time climbers may also be at 80% on the summit, but they might feel like crap.

I dont recall exactly, but 80% seems to be about the average of what everyone was ringing in at. I do recall a couple people's came in VERY low, one low enough that the guy I was with commented that had they been in the hospital, the doctors would've been freaking.

I would never use something like that for a real purpose, prefer to go by how I feel. But it was interesting!

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Re: Pulse oximeters

Postby nyker » Wed Jan 16, 2013 8:40 pm

Interesting feedback, thanks.

The main reason I'd be using it would be for higher peaks, 17k and up that might be in the future. I wouldn't make blind decisions purely based on a number that might be quantifying my acclimatization and thus to some extent my physiological preparedness to climb higher, but would be using it for certain instances; for example, there have been a few times where inexplicably, I've suddenly felt like crap (nausea and GI distress, primarily) higher up for no obvious reason and when having done nothing differently from prior successful peaks. At those times, I would like to see what my saturation level is and see what the correlation is if any and use it as another tool. I wish I had one last month in Mexico, where one day I felt pretty bad which impacted by ability to climb well, but felt fine all the other days.

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Re: Pulse oximeters

Postby elhombre » Thu Jan 17, 2013 8:51 am

It was touched on in an earlier post , but I think think it should be emphasized more. The finger pulse ox, when used while on the trail, is not a good indicator because it measures the blood in the fingers. One, when it is cold, the blood flow to your extrimities is reduced so it is not a true sample of the blood in rest of your body. It would be more accurate at base camp while sitting in your warm tent. Also, while hiking, holding onto hiking poles for hours will cause a decrease in blood flow to the fingers because the lack of flexing your fingers. Finally, if you don't have hiking sticks, ever notice how your fingers swell up due to the blood being held in them by gravity and the swinging of the hands below the heart level.

In the EMS service I work in, it is all about LOC - Level Of Conscious. When it comes to the first sign I see the most (or feel myself) in the mountains, it is anxiety. I see friends start to get short with each other. Just have to reconize it for what it is.
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