O2 saturation at altitude

k9medic

k9medic

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I posted this here since most folks don't look into the medical threads much.

Recently I started flying a twin again and with that comes a little higher altitudes. My typical cruise altitude in the Cherokee 6 was around 7500'. I am now flying routinely at 9500' so I figured that I would buy a cheap pulse oximeter from Amazon just to see what my O2 saturations looked like.

WOW! As a Floridian, at sea level my O2 sats are 98% or so with a pulse rate of 66. At 7500' my O2 sats are 94% and the pulse is 88. When I get up to 9500' my O2 sat drops to 89% with a pulse rate of around 100.

I'm reasonably healthy with no meds...

Not sure what is normal but this was an eye opener for sure!
 
Crude measurements without the modern oxymeters, your vision slowly degrades, with color vision becoming faded even while black and white remains clear. When color is gone, so is your usefulness as a pilot. Descending to a lower altitude after reaching grey is a touch and go trip, and may not have the necessary response to any abnormality to make a quick enough response. At such degraded mental state, a gradually increasing bank could be such a developing emergency, that could have been coped withy at the edge of color vision.

This is not to say using color vision as a normal warning, but that if such does occur, immediate steps to get to a lower altitude are mandatory. Oxygen in the blood stream is like charge in a battery, it slowly decreases when the charge rate is inadequate. Even if your measured O2 is fine at the arrival at cruise altitude, it will be much less in half an hour or later. Flying out of a sea level area is particularly degrading to your altitude safety.
 
A friend of mine who used to fly with me had some medical conditions that we actually discovered as he would fall asleep anytime we were above 5000 feet.

The total saturation just caught me off guard.

My wife, who works out every single day and runs as well had a saturation of 92%.

I am aware of the benefits of supplemental oxygen above 5000 feet at night but I am seriously considering using it during the day.


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Even in my lowly Warrior I carry portable oxygen and generally use it above 9,000 feet. I’ve noticed my sats are about like yours and I titrate the O2 flow to keep it 90 or above. I want to believe it helps with “jet lag”, though, honestly, a 9 hour cross-country day wears me a bit regardless.

I bought a PreciseFlight system at OSH years ago - not exactly sure why I picked them at the time. All the big names sold at OSH seem reputable.

Getting them refilled can be either expensive or tricky. The best I’ve seen at an FBO for my 15 and 22 cu ft cylinders is $20 flat rate. Usually more - sometimes much more. I did find a welding shop that does it for $13. They just confirm I know it’s industrial gas (comes off the same manifold as medical or aviation) and generally say they don’t care that I’m using it to aerate my bait tank:)
 
I attended a hypoxia talk at Sun and Fun this year and some of the info imparted was enlightening/concerning. Basically they recommend O2 above like 7,000 feet plus monitoring. The take away was that O2 saturation at a certain altitude can be a moving target, you can be fine at 10,000 one day, and severely hypoxic the next. It is not something to mess with, O2 is relatively cheap. I'm much more careful above 7,500 and will hook up the cannulas if there for any length of time. Not worth the risk IMO. YMMV.
 
Monitoring is probably a good idea. If you can swing it, getting no joke training in an altitude chamber is something I know is worth while. It’s one thing to talk about losing your color vision, it’s another seeing everything turn gray and then the colors come back as soon as you take a hit of O2. They mention that everyone reacts differently to hypoxia so I think knowing your symptoms and experiencing it first hand makes you forewarned and forearmed.

I’ve heard of folks on the civilian side getting training through the FAA in Oklahoma City. Not sure if this is current but I think it would be worth looking into.

https://www.faa.gov/pilots/training/airman_education/aerospace_physiology/
 
Healthy 40something flatlander, had similar happen to me recently as well.
 
Andrews AFB, now joint base Andrews, has had civilian access to their altitude chamber at rare intervals in the past. I think it is a base commander initiative, and for short times. Training well worth doing if you can get a chance.
 
We’ve been using an O2 concentrator (InogenOne) for about a year to provide supplemental O2 in our RV10 flying around east of the Mississippi. It works great at altitudes up to 13k supporting 2 people. We haven’t tested beyond that but we really don’t need it beyond that.

This is not the aviation specific model that’s been mentioned but the latest product for people needing supplemental O2.

It keeps our O2 levels at 95% with a simple T fitting. It’s an on demand system that interestingly seems to provide more O2 to each person on a T fitting that it does for 1 person on a straight fitting (hard to explain but makes sense when using). We don’t know it’s limits but it has more capacity than we are using.

We found it difficult and inconvenient to keep a small O2 bottle filled at airports east of the Mississippi. The price was more reflective of the effort to do the fill than the cost of the O2 (and occasionally FBOs will fill out tank for free just because). But with an O2 concerntrator hooked to the airplanes power, we have unlimited O2, on demand which makes using it a 7k and above a no-brained. Actually it is a yes-brained because our brains definitely work better with it than without it.

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PaulS said:
I attended a hypoxia talk at Sun and Fun this year and some of the info imparted was enlightening/concerning. Basically they recommend O2 above like 7,000 feet plus monitoring. The take away was that O2 saturation at a certain altitude can be a moving target, you can be fine at 10,000 one day, and severely hypoxic the next. It is not something to mess with, O2 is relatively cheap. I'm much more careful above 7,500 and will hook up the cannulas if there for any length of time. Not worth the risk IMO. YMMV.
Click to expand...

Paul, it probably was my presentation. Glad you remembered it. I also gave a similar talk at OSH, and at several online safety seminars. Here is a link to one I did that we recorded….

Scott
 
Bill Watson said:
We’ve been using an O2 concentrator (InogenOne) for about a year to provide supplemental O2 in our RV10 flying around east of the Mississippi. It works great at altitudes up to 13k supporting 2 people. We haven’t tested beyond that but we really don’t need it beyond that.
Click to expand...

Can you give more info? Model number, power requirements, etc?
 
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Bill Watson said:
We’ve been using an O2 concentrator (InogenOne) for about a year to provide supplemental O2 in our RV10 flying around east of the Mississippi. It works great at altitudes up to 13k supporting 2 people. We haven’t tested beyond that but we really don’t need it beyond that.

This is not the aviation specific model that’s been mentioned but the latest product for people needing supplemental O2.

It keeps our O2 levels at 95% with a simple T fitting. It’s an on demand system that interestingly seems to provide more O2 to each person on a T fitting that it does for 1 person on a straight fitting (hard to explain but makes sense when using). We don’t know it’s limits but it has more capacity than we are using.

We found it difficult and inconvenient to keep a small O2 bottle filled at airports east of the Mississippi. The price was more reflective of the effort to do the fill than the cost of the O2 (and occasionally FBOs will fill out tank for free just because). But with an O2 concerntrator hooked to the airplanes power, we have unlimited O2, on demand which makes using it a 7k and above a no-brained. Actually it is a yes-brained because our brains definitely work better with it than without it.

Sent from my iPhone using Tapatalk Pro
Click to expand...
Bill - any more details? Brand, model, cost, where to buy? Thx.

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I live at 8300', my O2 is usually 96 to 98 at home. I routinely fly 11,500 and 12,499 without oxygen. But I suspect someone from seal level would have a different experience.
 
Arm3 said:
Monitoring is probably a good idea. If you can swing it, getting no joke training in an altitude chamber is something I know is worth while. It’s one thing to talk about losing your color vision, it’s another seeing everything turn gray and then the colors come back as soon as you take a hit of O2. They mention that everyone reacts differently to hypoxia so I think knowing your symptoms and experiencing it first hand makes you forewarned and forearmed.

I’ve heard of folks on the civilian side getting training through the FAA in Oklahoma City. Not sure if this is current but I think it would be worth looking into.

https://www.faa.gov/pilots/training/airman_education/aerospace_physiology/
Click to expand...
Every once in a while, a local 99s chapter or pilot association will host the traveling high altitude chamber form a few days. It works differently from the OKC version. Instead of changing altitude pressure, it changes O2 levels. Check around your local area to see if its on a schedule. The New Mexico Pilots Assoc hosted it a couple years ago.

One caveat...you may not participate if on Basic Med....must have at least,Class 3. I’ve discussed this with the previous FAA Surgeon with no success.
 
Llewtrah381 said:
Even in my lowly Warrior I carry portable oxygen and generally use it above 9,000 feet. I’ve noticed my sats are about like yours and I titrate the O2 flow to keep it 90 or above. I want to believe it helps with “jet lag”, though, honestly, a 9 hour cross-country day wears me a bit regardless.

I bought a PreciseFlight system at OSH years ago - not exactly sure why I picked them at the time. All the big names sold at OSH seem reputable.

Getting them refilled can be either expensive or tricky. The best I’ve seen at an FBO for my 15 and 22 cu ft cylinders is $20 flat rate. Usually more - sometimes much more. I did find a welding shop that does it for $13. They just confirm I know it’s industrial gas (comes off the same manifold as medical or aviation) and generally say they don’t care that I’m using it to aerate my bait tank:)
Click to expand...
I was under the impression that the only thing special about aviator's breathing oxygen is that it doesn't have the moisture that is added for medical use.
 
Palmpilot said:
I was under the impression that the only thing special about aviator's breathing oxygen is that it doesn't have the moisture that is added for medical use.
Click to expand...
There's no water added in the cylinder... that happens at the bedside bubbler. All oxygen is water free in the cylinder, as it comes from <-100F liquid oxygen... the water's all frozen early in the process.
 
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Palmpilot said:
I was under the impression that the only thing special about aviator's breathing oxygen is that it doesn't have the moisture that is added for medical use.
Click to expand...
I think you’re right. Moisture in aviation oxygen apparently raises the risk of icing up
 
PaulMillner said:
There's no water added in the cylinder... that happens at the bedside bubbler. All oxygen is water free in the cylinder, as it comes from -100F liquid oxygen... the water's all frozen early in the process.
Click to expand...

Llewtrah381 said:
I think you’re right. Moisture in aviation oxygen apparently raises the risk of icing up
Click to expand...

Which is consistent with what I have previously heard.
 
I’m not surprised. I live at some altitude and I choose to go on O2 if I climb and stay much above 10,000’. A 7 or 10k foot change from your normal living altitude is pretty huge.

Hypoxia has different symptoms for different people. As an aside, I know I’m getting a little hypoxic when I start getting paranoid. It’s the worst - suddenly I can’t stop focusing on the engine sounds or feeling like a wing is going to fall off. If I go on O2 the feeling almost instantly evaporates.
 
AA5Bman said:
I’m not surprised. I live at some altitude and I choose to go on O2 if I climb and stay much above 10,000’. A 7 or 10k foot change from your normal living altitude is pretty huge.

Hypoxia has different symptoms for different people. As an aside, I know I’m getting a little hypoxic when I start getting paranoid. It’s the worst - suddenly I can’t stop focusing on the engine sounds or feeling like a wing is going to fall off. If I go on O2 the feeling almost instantly evaporates.
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I'm exactly the opposite. I get this feeling of total calmity. I stop thinking about what can go wrong. I get relaxed and get this feeling that I am a great pilot. It's really seductive. Fortunately I am aware of this. It is weird to feel so good and yet know that something is going terribly wrong.
 
kyleb said:
Can you give more info? Model number, power requirements, etc?
Click to expand...

It’s an Inogen G5 (their latest as far as I can tell).

Runs off 12volt (or AC) and or battery. It cost $2000 minimally configured with smallest battery.

I power with a 12volt cig lighter fixture (ugh). Only accessories required are nasal cannulas (get the standard ones versus soft because they tend to crimp around headphones).

They are widely sold but the difficulty is that they are sold as medical equipment so they are kind of Rx items. I Mother had COPD and used them so I piggy backed on that. YMMV.

This unit is the smallest with the most O2 production capability I’ve seen on the market. Older units go up to 3Liters/whatever but his goes up to 5 as I recall. I run at 3L for 2 people in the examples I gave.

They require some kind of periodic filter type maintenance but I haven’t run one with my Mother or my plane to run into that yet.


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In my younger years, I was acclimated to high altitude flying. I grew up in Albuquerque, and its elevation is close to a mile above sea level. In my teen years, I could be found skiing in Colorado, on ski areas that were almost all above 10,000' MSL.

I also flew hang gliders, mostly on the Sandia mountains. The takeoff at Sandia Crest was 10,400'. With favorable conditions on summer afternoons, it was possible to ride thermals up to 13,500'. It was more common to fly around 12,500', and I could stay at those altitudes for hours. I never felt any effects from oxygen deprivation, but I imagine being young, in good physical condition, and acclimated to those heights was the reason.

Now I've lived in Texas for over forty years, elevation 750'. When I go back to Albuquerque to visit my Dad, I get dizzy after climbing two flights of stairs.

:D
 
PaulMillner said:
There's no water added in the cylinder... that happens at the bedside bubbler. All oxygen is water free in the cylinder, as it comes from -100F liquid oxygen... the water's all frozen early in the process.
Click to expand...
This. Go talk to your local gas supplier. If he's honest he'll tell you that the medical, aviation, and industrial o2 come out of the same tank. There's different requirements for purity, but it's cheaper to meet the highest standard than to segregate different grades.
 
Bill Watson said:
It’s an Inogen G5 (their latest as far as I can tell).

Runs off 12volt (or AC) and or battery. It cost $2000 minimally configured with smallest battery.

I power with a 12volt cig lighter fixture (ugh). Only accessories required are nasal cannulas (get the standard ones versus soft because they tend to crimp around headphones).

They are widely sold but the difficulty is that they are sold as medical equipment so they are kind of Rx items. I Mother had COPD and used them so I piggy backed on that. YMMV.

This unit is the smallest with the most O2 production capability I’ve seen on the market. Older units go up to 3Liters/whatever but his goes up to 5 as I recall. I run at 3L for 2 people in the examples I gave.

They require some kind of periodic filter type maintenance but I haven’t run one with my Mother or my plane to run into that yet.


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Click to expand...
From the little research I did on these it looks like the Inogens are the best by far. There are surprisingly inexpensive ones on Amazon but they’re really limited in their ability to concentrate O2 - and it falls of to near zero above about 10,000 feet, so useless for our needs.

The one thing I’ve heard about all of them is that they’re designed for people who need them continuously. Very intermittent use is apparently not ideal for the cartridges. So, it seems like someone with a turbo doing frequent cross-countrys in the upper teens would be a good candidate. Otherwise, even at $30/refill, it’ll take a lot to repay the investment.
 
Llewtrah381 said:
From the little research I did on these it looks like the Inogens are the best by far. There are surprisingly inexpensive ones on Amazon but they’re really limited in their ability to concentrate O2 - and it falls of to near zero above about 10,000 feet, so useless for our needs.

The one thing I’ve heard about all of them is that they’re designed for people who need them continuously. Very intermittent use is apparently not ideal for the cartridges. So, it seems like someone with a turbo doing frequent cross-countrys in the upper teens would be a good candidate. Otherwise, even at $30/refill, it’ll take a lot to repay the investment.
Click to expand...

I believe there are a lot of them floating around the marketplace because the technology/performance was improving rapidly during my Mother’s use of them. Smaller and lighter was desirable for personal transport. Battery life was critical to using them on the airlines because the airlines were strict about battery life vis-a-vis length of flight and volume of O2 required. Maximum O2 production was critical for those in more urgent need of the life giving gas.

For unpressurized aircraft use the main factor is the ability to produce enough O2 at altitude. That is not a published spec and still and unknown by me. Use by 2 at 13K appeared to work fine but I need to fill my O2 tank before more testing can be done.

I would suggest that the cost is less of a factor if you fly a lot and consider safety and comfort important. In the east in non-turbo charged planes it’s rarely worth getting much above 10 or 11K let alone 13k. It’s also a pain trying to find O2 refills when traveling. The price and the difficulty of refills means that staying around 10k and going without is less trouble (and expense). And who is going to consistently fly with O2 at 7k given the difficulty? But at the same time, flying. at 9,10,11k is where the sweet spot is for me in my RV10. So having the concentrator unit means I’ll use it consistently while not having it means that my O2 tank tends to stay full just in case I want to go high. At 9 and 10k, I just won’t use it much. But at 67yo, using it at 7 and. 8k is getting very desirable.

The frequent use thing I’ve kind of heard about but don’t have any real facts about. I’m waiting for the self diagnostics on the Inogen to let me know some service is required. We’ll see.


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Bill Watson said:
We’ve been using an O2 concentrator (InogenOne) for about a year to provide supplemental O2 in our RV10 flying around east of the Mississippi. It works great at altitudes up to 13k supporting 2 people. .

We found it difficult and inconvenient to keep a small O2 bottle filled at airports east of the Mississippi. The price was more reflective of the effort to do the fill than the cost of the O2 (and occasionally FBOs will fill out tank for free just because).
Click to expand...
A couple of comments from a common layman about O2. I have not heard of any in flight problems with the InogenOne. I think its a good idea. Military A/C use a similar O2 generator. The Military bases may one day retire the Oxygen trucks that cruise the base's ramps. As I understand the principle, a pump draws in air and passes it through a filter. The filter blocks nitrogen (78% of the atmosphere) and dumps it on the cockpit floor. Some military A/C duct the nitrogen to fuel tanks to inert them. The other gases pass on through the canula and up your nose. Oxygen (21%) and CO2 (0.3%) are the important ones.
Just asking; If you had a tightly sealed cockpit, could you build up nitrogen and exhaled CO2 to dangerous levels?
BTW, CO2 is important in that the trace amount causes the body's breathing response. I picked that up in Army Medic class. Hospitals used to add it to the O2 supply to the beds.

I live in Florida and not many FBOs refill small O2 bottles around here. However, there are many SCUBA divers around here. If they want to dive on the Oriskany, the carrier that was sunk 20 miles out, they use a rebreather rig that scrubs the air and uses a tank of O2. Most of those guys get their tanks filled at a local welding supply company. The same one I use for my oxyacetalyn welding gasses. Aviation, medical and industrial O2 is about the same.
 
Maxnr said:
Just asking; If you had a tightly sealed cockpit, could you build up nitrogen and exhaled CO2 to dangerous levels?
BTW, CO2 is important in that the trace amount causes the body's breathing response. I picked that up in Army Medic class. Hospitals used to add it to the O2 supply to the beds.

I live in Florida and not many FBOs refill small O2 bottles around here.

Most of those guys get their tanks filled at a local welding supply company. The same one I use for my oxyacetalyn welding gasses. Aviation, medical and industrial O2 is about the same.
Click to expand...
There’s nothing tightly sealed in light aircraft cockpits. I thing there is zero chance of Nitrogen and CO2 buildups.

The hassle and liability of refilling O2 bottles is the crux of the problem for light aircraft pilots in the east wanting to use O2 on a more frequent basis. It’s what makes concentrators so attractive.

From many discussions I’ve seen online, there’s only 1 grade of o2 sold - pure, dry, O2. Same for aviation, medical and welding. Makes sense from all perspectives. Still hard to get a small tank filled.


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After thought ( and a little off topic). Back when I was flying 135 Haz Mat classes were once a year. One of the case studies stuck with me.

A bush plane crashed and killed all aboard. Post mortem only showed elevated CO2 levels for all. Not CO, but CO2. Where did that come from? It came from a cooler chest that had contained frozen food or game. It had been packed with dry ice. Dry ice is frozen CO2. Dry ice does not melt. It sublimates. Goes straight from a solid to a gas not leaving a trace.

Many families load up the car, close the windows and head out. If there was a container with dry ice on the seat. It could cause an accident that may be written off as "Driver dozed off".
 
Due to my recent covid experience I have learned more than I ever wanted to know about oxygen saturation. Couple things to comment on in this thread.

1. All pulse oximeters are not the same, and neither are your fingers (or ears). The cheap pulse oximeters don't always give the most accurate readings, and the reading can vary greatly from finger to finger. (even with the ones in the hospital) Try it. I can get 98 on one finger, move the meter to the next finger over and it reports 91. In asking the doc, it has to due with everything from thickness of the finger (no jokes) to how hydrated you are, to skin condition etc. A more accurate reading is always made with a medical grade meter on your ear, at least that is what the doc said.

2. Even a little bit of O2 (1L-2L ph) can make a huge difference on your saturation.

3. All the FAA approved oxygen concentrators are "approved" based a cabin alt of 8000 feet. They work really well from 8-10k) based on my experience, but the columns (google it) need to be in good shape. When they are getting old or a lot of time on them you will see the low oxygen errors on the Innogen. If you buy a used one factor in columns being replaced in your budget when purchased, and then about every 1-2 years depending on use. They are around $100-$120

4. My post covid saturation bounces from 97-91 on a "normal" day. We flew from Columbia SC to Nashville Saturday. At take off my reading was 96, at 4k it was 93, at 6k it was 91 and I put on the cannula and fired up the Innogen set for 2L ph. My saturation improved to 95 and was was between 93-95 at 10k for the entire trip.
 
Personal flatlander experiences 55 - 60 year old: an hour ride with a friend @ 10K, landing, then another hour @ an altitude I'm not sure of - went home really tired, with a headache. 2nd time - short trip with sons at 6500 MSL - noticed the same tired headache-y feeling, just to a lesser extent. Due to these, am planning to rig up some sort of O2 system for future longer trips.
 
Live at 5500AMSL. I get tired if I fly above 9500 without oxygen. So I always use it above 9500. It makes a huge difference. I fill up my Mountain high tanks at the local dive shop. Initial investment in equipment was eye watering but I have it now - makes no sense not to use it.
What most don’t realize is that the impairment is for the most part subtle. Those living high have physiological adaptations of haemoglobin-oxygen binding to improve oxygen uptake so we should have better oxygenation at any given level (up to a point) than lowlanders..
 
Altitude tolerance varies enormously. Ed Viesturs has summited all 14 of the worlds highest peaks WITHOUT supplemental oxygen. I have spoken with him and his intelligence seems quite normal.
 
Snowmass said:
Altitude tolerance varies enormously. Ed Viesturs has summited all 14 of the worlds highest peaks WITHOUT supplemental oxygen. I have spoken with him and his intelligence seems quite normal.
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i’m sure he is. although the caveat here is that the the functional impairment that occurs is subtle and only present during the time when you’re at altitude. the slopes of those highest peaks are littered with the corpses of those who couldn’t make good decisions.

but 100% agree that tolerance to altitude varies. i still don’t want to be experimenting with my tolerance with my family in a SEP……
 
Arm3 said:
Monitoring is probably a good idea. If you can swing it, getting no joke training in an altitude chamber is something I know is worth while. It’s one thing to talk about losing your color vision, it’s another seeing everything turn gray and then the colors come back as soon as you take a hit of O2. They mention that everyone reacts differently to hypoxia so I think knowing your symptoms and experiencing it first hand makes you forewarned and forearmed.

I’ve heard of folks on the civilian side getting training through the FAA in Oklahoma City. Not sure if this is current but I think it would be worth looking into.

https://www.faa.gov/pilots/training/airman_education/aerospace_physiology/
Click to expand...

Way back in ancient times when I flew a lot, the FAA had a program for this using military facilities around the country. As a pilot you could sign up through some FAA program for courses that were offered periodically. I took my chamber ride and physiology course at Langley AFB, on 1 June 93. Totally worth the effort of registration, and then some! I learned a bit too from the physiology course that applies to non-aviation stuff too...nutrition, driving long trips, etc...

Do they not have this program now?
 
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