Normal pulse oximeter reading

[aggie06]

I picked up a pulse oximeter to use while flying at night and at higher altitudes and was having trouble figuring out what "normal" is. Everything I've found online indicates 95+ being normal on the ground, but then info gets scarce for altitude. For example, should I be worried about something less than 95 on the ground (even if I'm not planning to fly)? What if it dips to 85 in the air? Should I assume my decision making ability is impaired? Will the fact that I was a smoker until 15 years ago make a difference?

I completely understand that everyone is different, so really looking for some guidelines.

 

[Clark1961]

I think the "magic" number is 90. If it goes below that for very long then add O2.

Smokers have carbon monoxide in their red blood cells which fools the sensor. 15 years of non-smoking has prolly gotten the carbon monoxide out of your system.

 

[citizen5000]

What if it dips to 85 in the air?

Do not let it get below 90 as a benchmark. Oxygen is recommended if below 90 on the pulse ox.

 

[FORANE]

I concur with the 1st 2 replies.
Yes, you should assume that at 85% your decision making will be impaired.
Smoking 15 years ago may effect your % today but not the accuracy of the % today.
The acceptable % doesn't change with altitude. generally 90% or greater is acceptable and below 90% you should use oxygen in the plane.

 

[bgdriveway]

What's your normal? If you normally run 98, by time you are getting low 90's you should start thinking about it. Drawing the line at 90 seems good to me. End tidal CO2 with 02 sats are a better way of determining efficiency of respirations, but that gets into some expensive med equipment. How are you feeling, how is your breathing? I feel fine to 11-12k feet. But I recently rode to the top of Pikes Peak and was getting winded sitting in the car. Maybe I need to get a pulse ox and check my sats at 11k.

All the pulse ox is measuring is how saturated your red blood cells are. Carbon monoxide has an affinity for those red blood cells 4 times what oxygen has. So it's going to bump the o2 cells out of there. So there is potential to have 100% sats and still be really hypoxic. Especially in how we do heaters in planes. It's only one part of the picture. Just like you can't just say my blood pressure is 120/80 I have no medical issues. Maybe so, maybe not. It's not the whole picture.

 

[Rykymus]

General rules are fine for a start, but everyone is different. If you live at a higher altitude, your body becomes accustomed to the lower O2 saturation. I don't find my thinking impaired until I hit 85%, and I grew up and lived most of my live at sea level. However, I still where the nose hose if I'm going to be above 10k for a prolonged period of time, as it helps tremendously at staving off fatigue.

 

[citizen5000]

You cannot self-assess hypoxia for most symptoms. Which is why it is so dangerous. A pulse ox doesn't care if you live at sea level or 10,000 feet. The reason to wear one is precisely because you cannot tell if you are hypoxic unless you know what level you are registering.

 

[Vance Breese]

You cannot self-assess hypoxia for most symptoms. Which is why it is so dangerous. A pulse ox doesn't care if you live at sea level or 10,000 feet. The reason to wear one is precisely because you cannot tell if you are hypoxic unless you know what level you are registering.

I feel time in a hypobaric chamber will help to identify the symptoms of hypoxia for each individual without an oximeter.

I find it easy to identify the feeling of euphoria brought on by hypoxia.

I find the color of my fingernails changes when I experience hypoxia.

I find that anything to do with memory is more challenging when I experience hypoxia.

 

[citizen5000]

I feel time in a hypobaric chamber will help to identify the symptoms of hypoxia for each individual without an oximeter.
I find it easy to identify the feeling of euphoria brought on by hypoxia.
I find the color of my fingernails changes when I experience hypoxia.
I find that anything to do with memory is more challenging when I experience hypoxia.

By the time you 'notice' purple fingernails or feel euphoric it's too late. That's part of the point. You will lose focus and possibly miss a critical flight function before you notice symptoms. The chamber is a great way to experience the extreme and deadly levels while on the ground. They take you to 30k feet and have you remove your oxygen mask. Some last a few minutes. Some only a few seconds.

 

[Vance Breese]

By the time you 'notice' purple fingernails or feel euphoric it's too late. That's part of the point. You will lose focus and possibly miss a critical flight function before you notice symptoms. The chamber is a great way to experience the extreme and deadly levels while on the ground. They take you to 30k feet and have you remove your oxygen mask. Some last a few minutes. Some only a few seconds.

That has not been my experience.

In my experience it is a slow process and it is not hard to recognize the onset.

I have recognized symptoms of the onset of hypoxia as low as 10,000 feet density altitude.

 

[citizen5000]

That has not been my experience.

Did you try the FAA hyperbolic chamber test? They have you count backward or write the same phrase over and over with the mask off. Most can't tell they are unable to count backward, they think they are doing fine. And the paper ends up with random scribbles but they swear they were writing it perfectly.

The subject is complex. But the lesson is clear. Hypoxia is dangerous largely because the symptoms are not self-assessed often before it's too late. This is why the FARs are strict in regard to when you must use oxygen despite how you may 'feel.' Some do use oxygen at lower altitudes than the regs require. But if you do not use a pulse oxy at or near the restricted levels and/or the readout is below 90 and you do not get oxygen or descend then you risk a disaster.

 

[colojo]

Here's an interesting data point. My wife and I live in Denver (5300' above sea level) and just last week returned from a trip to Peru. While in Peru we stayed at Lake Titicaca for 3 nights, elevation 12,500'. Upon check-in at our hotel they took our pulse oximeter readings. Mine was 93 and my wife's was 91. At check-out they did so again; mine was 87 and my wife's was 88. Oxygen was available in our room but we never used it.

 

[Tantalum]

@aggie06 thanks for asking, I've wondered myself

While in Peru we stayed at Lake Titicaca for 3 nights, elevation 12,500'. Upon check-in at our hotel they took our pulse oximeter readings. Mine was 93 and my wife's was 91. At check-out they did so again; mine was 87 and my wife's was 88.

I'm surprised it went down, I would have thought the body would acclimate and it would stay the same or improve. BTW, jealous! Have always wanted to visit Lake Titicaca.

This discussion reminds me of

 

[citizen5000]

My wife and I live in Denver (5300' above sea level)...we stayed at Lake Titicaca for 3 nights, elevation 12,500'.

You guys are blood doped.

The reason those who live at altitude do better at higher altitudes is the body acclimates by making more red blood cells but it takes several weeks to make them.

Some sea level dwellers will use oxygen flying as low as 8k well below the minimum 12,501 level in the FARs. Other factors also play like age and lung function damage due to pollution and smoking (which includes marijuana).

 

[Rykymus]

If you ever worked an ambulance you'd know how to recognize hypoxia. But being hypoxic doesn't necessarily mean your ability to reason and react is actually impaired by an appreciable level. That is where each person is different. The reading on the pulse ox by itself is simply a number and has no real meaning. I've seen COPD patients with a PaO2 reading in the low 80s that were just fine.

 

[Clark1961]

@aggie06 thanks for asking, I've wondered myself


I'm surprised it went down, I would have thought the body would acclimate and it would stay the same or improve.

For Denver the body takes about 6 weeks to adapt. I suspect they were a little excited to arrive so their O2 was up a bit. On checkout they were a bit more relaxed so breathing was slower.

 

[X3 Skier]

When I took my chamber rides back in the day, the instructor said the symptoms you experience will likely stay the same for life. In my case it was feeling very hot and flush. (no snide remarks). I think I still have the squiggles somewhere that resulted from allegedly copying a clearance.

My usual reading is around 97-99 wether I'm at 1000' in OH or 7000' in CO.

Cheers

 

[steingar]

I picked up a pulse oximeter to use while flying at night and at higher altitudes and was having trouble figuring out what "normal" is. Everything I've found online indicates 95+ being normal on the ground, but then info gets scarce for altitude. For example, should I be worried about something less than 95 on the ground (even if I'm not planning to fly)? What if it dips to 85 in the air? Should I assume my decision making ability is impaired? Will the fact that I was a smoker until 15 years ago make a difference?

I completely understand that everyone is different, so really looking for some guidelines.

I hate to be insulting, but the answer to this is one of the easiest I've had to fathom in recent days. You take a reading of yourself on whatever ground level you call home. Better yet, you take a bunch and develop an mean and standard deviation. That is your "normal". If you want to really be scientific about it, have a buddy on O2 take you up to where the air is thin while you do math problems. When you can't do the math problems anymore you check your reading. That's the one where you experience hypoxia. If you want to be really scientific you can that a bunch of times and get a mean and standard deviation too.

 

[aggie06]

If you hate to be insulting, you should probably work to not be insulting. The point of my question was more about figuring out whether 92 on the ground should worry me. No reason to insult me by telling me how to figure what it usually is on the ground.

Let's say I go through your process and find that my normal is 92. Then the question becomes when do I need to be worried at altitude? Is it at an arbitrary number like 89? Is it after some predetermined drop from preflight reading? Or maybe at some difference from my normal? I don't have a buddy and an oxygen bottle ready to go, so I can't do step 2 of your plan.

Now if we could discuss guidelines since I already admitted everyone is different, that would be helpful.

 

[citizen5000]

The reading on the pulse ox by itself is simply a number and has no real meaning.

Pulse oxys better work. They are the tool pilots in non-pressurized planes use to manage oxygen.

 

[Cooter]

That has not been my experience.

In my experience it is a slow process and it is not hard to recognize the onset.

I have recognized symptoms of the onset of hypoxia as low as 10,000 feet density altitude.

The onset depends on the rate at which the pressure drops. If you're climbing at 600 fpm then you have plenty of time to recognize it. If you're climbing at 6,000 fpm then the symptoms may not be a sufficient means to identify hypoxia. I'm like you in that I'm pretty confident that I'll catch it and I have several times, but I also missed it once. I don't know how available training opportunities are on the civilian side, but I highly recommend it for anyone that can do it in a controlled environment.

 

[Checkout_my_Six]

I hate to be insulting, but the answer to this is one of the easiest I've had to fathom in recent days. You take a reading of yourself on whatever ground level you call home. Better yet, you take a bunch and develop an mean and standard deviation. That is your "normal". If you want to really be scientific about it, have a buddy on O2 take you up to where the air is thin while you do math problems. When you can't do the math problems anymore you check your reading. That's the one where you experience hypoxia. If you want to be really scientific you can that a bunch of times and get a mean and standard deviation too.

there are more degrees of freedom in your experiment....add stress and behavior to it. If one is talking....add that too. It all affects our body's response....

 

[coloradobluesky]

Its how you feel. Have a pilot who is on oxygen take you up until you start getting light headed, then suck on oxygen and feel the difference. Thats what matters.

 

[Van Johnston]

I went to the hypoxia workshop at Oshkosh last summer. The MD who gave the presentation said there is no one size fits all number. He said to measure your baseline saturation where you live; the coast, Death Valley, Leadville, wherever. Then when flying, if you go five points below that normal baseline you should consider getting on oxygen.

 

[steingar]

there are more degrees of freedom in your experiment....add stress and behavior to it. If one is talking....add that too. It all affects our body's response....

That's why the replicates and the statistical analysis. Blood oxygen isn't a one size fits all kind of thing. If someone actually gives you a number for "normal" that's the first clue that he or she doesn't know the first thing about it.

I really do apologize to the OP if I came off as arrogant or insulting . I honestly don't want to be. But if you want it know the baseline of an instrument you go use it and find out. Do you let someone tell you how fast your airplane goes or how high it can climb, or do you go find out for yourself?

 

[Vance Breese]

My typical reading on my oximeter sitting at my desk at SMX is 95 to 97 and 75.

When I recognize the symptoms of hypoxia I add a little oxygen.

I don’t wait till I see it on the oximeter and I don’t typically wear the oximeter flying.

At night I find I can see better with a little oxygen.

 

[GRG55]

Did you try the FAA hyperbolic chamber test? They have you count backward or write the same phrase over and over with the mask off. Most can't tell they are unable to count backward, they think they are doing fine. And the paper ends up with random scribbles but they swear they were writing it perfectly.

The subject is complex. But the lesson is clear. Hypoxia is dangerous largely because the symptoms are not self-assessed often before it's too late. This is why the FARs are strict in regard to when you must use oxygen despite how you may 'feel.' Some do use oxygen at lower altitudes than the regs require. But if you do not use a pulse oxy at or near the restricted levels and/or the readout is below 90 and you do not get oxygen or descend then you risk a disaster.

There is that "other" solution.

Place an order for a Vision Jet and after about a five year wait, voila, problem solved.

 

[Checkout_my_Six]

My typical reading on my oximeter sitting at my desk at SMX is 95 to 97 and 75.

When I recognize the symptoms of hypoxia I add a little oxygen.

I don’t wait till I see it on the oximeter and I don’t typically wear the oximeter flying.

At night I find I can see better with a little oxygen.

That's about my experience and what I do....