Inogen

[Greg Ellis]

17 minutes ago, wombat said:

If you want to wear your underwear on the outside of your pants and fly around, I doubt the FAA's complaint would be that you were using your fruit-of-the-looms incorrectly.   No matter how much absolutely every one of us wishes you didn't do that. 

Maybe for Part 91 but what about for Part 141....

[Aaviationist]

1 hour ago, wombat said:

In some cases, I think it does.   For example, I think you are prohibited from using a nasal cannula above 18,000' MSL, if that device has been certified for aviation use and has a prohibition against use above 18,000'.  This is because the FAA has made the manufacturers prohibit it in order to be certified.   The way I see it, that's no different than exceeding VnE or max gross weight.    But instead of a cannula, if you literally stick the end of the hose up your nose, as far as I know, that isn't prohibited.  Is it a worse solution? Yes.  Is it legal?  Maybe?

 

Does every product you use have a requirement to be 'certified' or 'allowed' for use in the particular way you are using it in order to be legal?   No.....  If you want to wear your underwear on the outside of your pants and fly around, I doubt the FAA's complaint would be that you were using your fruit-of-the-looms incorrectly.   No matter how much absolutely every one of us wishes you didn't do that.  Or make up your own example of something that doesn't have a clearly defined use guideline.

What about using your Ferrari gloves for flying, when the manufacturer says "For use only when driving Ferrari automobiles." ?  I bet the FAA wouldn't violate anyone for that.  But it's closer to the oxygen concentrator example

What about using an oxygen concentrator that has been certified for non-aviation purposes?    Can you use that?  What if it says that it's usable by 2 people up to 10,000' and 1 person up to 14,000', but doesn't explicitly say it's prohibited otherwise?  What if it says nothing at all?  What if all there is for this is marketing copy but nothing in the manual?

Bah... All of this is pretty meaningless.   Unless or until there is some sort of problem, pilots are generally free to do what they want.  You want to use a concentrator?  You want to split it between two of you at 15,000' ?  Want to use a pulse oximeter?   Unless someone can provide authoritative guidance that says you can't, I say go for it.  Please be safe.

 

 

 

 

[citation needed]

https://www.fda.gov/news-events/fda-brief/fda-brief-fda-warns-about-limitations-and-accuracy-pulse-oximeters

 

https://pubmed.ncbi.nlm.nih.gov/27089002/

 

https://journals.lww.com/anesthesia-analgesia/abstract/2016/08000/the_accuracy_of_6_inexpensive_pulse_oximeters_not.9.aspx

 

[wombat]

2 hours ago, Aaviationist said:

https://www.fda.gov/news-events/fda-brief/fda-brief-fda-warns-about-limitations-and-accuracy-pulse-oximeters

 

https://pubmed.ncbi.nlm.nih.gov/27089002/

 

https://journals.lww.com/anesthesia-analgesia/abstract/2016/08000/the_accuracy_of_6_inexpensive_pulse_oximeters_not.9.aspx

 

#1: Does not support your claim in the slightest.

#2: The worst accuracy was 7.53% error and 1/3 of them met the medical requirements of < 3% error at all measured levels above 70%.   This is all perfectly adequate for our purposes.

#3: This is the same study as the second link.   Literally the same study by the same authors.

 

If you want to be extremely pedantic, you said "the most popular sensors" which has no actual definition.   

You also said "tend to be inaccurate" which also has no definition.    

 

But you know what?  I'll accept a random sample of cheap ones available for sale.

I'll also give you this study: https://pubmed.ncbi.nlm.nih.gov/34489238/ which did specifically measure popular pulse oximeters, and they showed a maximum mean absolute value error of 5.1%   And I'll quote the study here:   "Conclusion: Top-selling, direct-to-consumer pulse oximeters can accurately rule out hypoxaemia"

5% is adequate for our purposes.  At least for mine.   If any of us are trying to titrate their blood oxygen so closely that 5% one way or the other below 90% is critical, we're already doing it wrong.    

Check your O2 sat.... If it's below 90%, turn the O2 up a bunch!  If it's above 95%, and you want to save oxygen, turn it down a little.

 

[Aviationist]

You are saying my reference to a FDA article stating that cheap sensors are not accurate is not relevant to my comment that cheap sensors are not accurate?

 

Also, when it comes to O2 saturation, 5% id s HUGE discrepancy.

 

This conversation is about the Inogen, which do to limitations at altitude, you can't just "turn it up a bunch"

 

In the example previously provided of lets say 91% at 20k or whatever it was, that means you don't know if you are 88% or 94% (based on what they say the mean error was)  everything I'm reading says the average error makes the sensor read high, which suggests the lower number.

 

Those are NOT good numbers, and suggest the Inogen is NOT a good option for 2 people above the altitudes recommended by the manufacturer

[wombat]

I'm saying that your quoted article saying that sensors are affected by skin tone, health status, and fingernail polish but doesn't say anything at all about accuracy at low saturation rates doesn't support your claim that popular sensors do less well at low saturation rates.

As far as the flow rate goes, you can just turn it up until you reach it's maximum flow rate.   

88% to 94% isn't a huge discrepancy.  It's 91% +- 3%.    These are perfectly adequate numbers for our purposes. It's not as you say a "HUGE" discrepancy.

 

The differences between individuals' O2 concentrations at a given pure O2 flow rate are going to be relatively high compared to the measurement errors, so you don't really gain yourself anything by having measured and guaranteed flow rate but not a pulse oximeter.  You are better off with an unknown flow rate and concentration plus a pulse oximeter.

Also, any given person's response to a given O2 saturation is unique to that person and that situation and there is no good 'minimum' that is realistic for all people.   Learn your symptoms at multiple measured saturations for a given measurement device and operate accordingly.  Sure, you can say that 50% is bad for everyone.  And you can say that 99% is good for everyone.   But the saturations we care about are in between those two extremes.

If the inogen is a good solution for 2 people above the altitude recommended by the manufacturer is a factor of oxygen saturation and personal symptoms and responses, not a factor of manufacturer's documentation.

 

In your example, if you are not capable at 91% measured saturation, then turn the flow rate up and/or decrease altitude!  It's that simple.  I've found that I'm perfectly fine for many hours at that saturation, as measured by my oximeter.  But you might be different.

[Hank]

One big thing I learned from almost three decades' manufacturing medical devices:  every body is different. 

(NOT "everybody," but each and every body reacts slightly differently to the same injury and to the same treatment.)

So when it comes to oxygen saturation while flying, get a meter, see where you read and decide if you feel good at that level or if you want higher saturation. There's two ways to quickly raise your O2 sats--descend into thicker air, or get some extra oxygen from somewhere (O2 tank, a disposable bottle, a concentrator, somewhere), and see how much your reading changes and if you feel better; if not enough change, descend.

Easy easy, and simple enough for anyone to do. Personally, my C struggles to get high enough for me to start feeling bad. What I used to think was low oxygen headaches after 2-3 hours at 7500-9500 msl went away when I got an in-ear headset . . . .

[Marc_B]

If you read the research paper that CAMI produced (linked earlier), there are two aspects at play for oxygen concentrators and altitude: 1) that at a certain altitude/barometric pressure the FLOW rate declines; and 2) at a certain altitude/barometric pressure the oxygen CONCENTRATION declines.  The rate of decline and altitude it starts are unit specific and can NOT be generalized to every concentrator sold.

In the absence of testing form a third party (i.e. CAMI), you may only have manufacturer guidelines to assist you in determining where that barometric pressure ceiling exists.

BTW, this is also likely the reason that there is a difference in Inogen altitude recommendation based on 1 or 2 users...it's likely not driven by the oxygen concentration output, but rather the flow rate.

[wombat]

@Marc_B Strongly agree with you about this.

Since as we climb into the oxygen-needing altitudes the concentration and flow rate (and therefore capability to boost blood oxygen concentration) is less well defined.  

Each body's supplemental oxygen requirements are different as well.  Both just basic physiology as well as the way people breathe and the delivery hardware (cannula, mask, bare hose, etc)

5LPM of 60% oxygen is the same oxygen delivered as 3 LPM of 100% pure oxygen.  But 5 LPM flow rate might not make it into your lungs and bloodstream as well.  Or maybe it's better.   I don't know.

So the only way to know what's going on is to measure your saturation.

And the only way to know if a given measured saturation is appropriate is to understand your condition at that saturation.

 

[1980Mooney]

1 hour ago, wombat said:

@Marc_B Strongly agree with you about this.  Since as we climb into the oxygen-needing altitudes the concentration and flow rate (and therefore capability to boost blood oxygen concentration) is less well defined.  

Each body's supplemental oxygen requirements are different as well.  Both just basic physiology as well as the way people breathe and the delivery hardware (cannula, mask, bare hose, etc)...

So the only way to know what's going on is to measure your saturation.  And the only way to know if a given measured saturation is appropriate is to understand your condition at that saturation.

Exactly.  I guess most here are too young to remember the 1968 Olympics in Mexico City at 7,434-ft. altitude.  Each athlete's body oxygen requirements and acclimation were different. 

[NickG]

Wow, this thread went down a Rabbit hole... here the OP's question:

"Okay guys and gals. How did you get an Inogen? I have been trying for years to score one of those but keep running into the same problem. Called the company and they say you need a doctors script. Go to my family doctor and he says that I don’t have breathing issues so he won’t write a script. Called AOPA and they told me to get a bottle. Told them I didn’t want a bottle. So what’s the secret?"

LOL

[Pinecone]

Welcome to the Internet.

The other factor is, the manufacturer recommendations are based on worst case.  So MOST people are good with an Inogen One G3 and two people up to 14K and one person to 17K.  But SOME people may be able to fly higher.

Heck, my last trip I was on ships O2 at 17K outbound and had to go to the F2 setting on my O2D2.  But on the trip back at 16K, I was fine on N5 setting.    So MY PERSONAL needs change from day to day.

[wombat]

56 minutes ago, NickG said:

Wow, this thread went down a Rabbit hole... here the OP's question:

"Okay guys and gals. How did you get an Inogen? I have been trying for years to score one of those but keep running into the same problem. Called the company and they say you need a doctors script. Go to my family doctor and he says that I don’t have breathing issues so he won’t write a script. Called AOPA and they told me to get a bottle. Told them I didn’t want a bottle. So what’s the secret?"

LOL

Hah.  Thanks for bringing us back on task.

To answer your question:  

• Facebook Marketplace
• Craigslist

Example: https://bellingham.craigslist.org/hab/d/bellingham-inogen-one-g5-portable/7854022558.html

[wombat]

From a co-worker:

Last year, I bought a new Inogen unit from Main Clinic Supply. They asked me for a copy of a prescription and I just sent them a copy of my pilot's certificate, and then they shipped me a unit without any further conversation about it.

[Pinecone]

2 hours ago, wombat said:

From a co-worker:

Last year, I bought a new Inogen unit from Main Clinic Supply. They asked me for a copy of a prescription and I just sent them a copy of my pilot's certificate, and then they shipped me a unit without any further conversation about it.

That is what I did. 

[Will.iam]

Wow this thread blew up since I made my post on 2 people above 14k. For the Karen that wouldn’t use an Inogen for 2 at 14k I will just leave the picture attached showing that LEGALLY I can fly at 14k for the whole trip and I am not required to give my passenger ANY oxygen at that altitude for part 91. And that 91% is unsafe I am positive he has never used a pulse oxy meter to read his values without oxygenation at 12,500ft because I know it would not be at 98% or better.  89% is the suggested lower limit but I have measured passengers and pilots on commercial flights that were below 88% at just a cabin alt of 8500ft!!! And all of them felt fine and were shocked to see their number so low and never would have known if it wasn’t for me giving them an oxymeter to test their levels. I have 2 meters and for the Karen that screams they are some times not accurate,  for the pilot that was at 87% he put on his oxygen mask and within one to 2 breaths the oxymeter reading shot up to 99% so oh yes that cheap oxymeter I had was reading his o2 stats just fine. If you sit up and do some deep breathing you can improve your percentage by 2 or 3 points with the best improvement one guy got 6 points better with his focused breathing. Get a baseline reading first. Hell you could be hypoxic on the ground if you are terribly out of shape or have a medical condition. But by inogen saying only to 14k for 2 people and a passenger doesn’t have to have any oxygen supplement at all at 14k really shows it’s a lawyer legality as the inogen can produce a bolus every 6 seconds and most people do not breathe that fast at rest so some oxygen will get to the passenger even though they don’t need any at all from the inogen. But the oxymeter will give you feedback as to whether it’s working or not for you. 

[Will.iam]

To test your oxymeter just hold your breath you can see your O2 drop as you keep holding your breath. I used to be able to hold my breath for 3 mins but with age I’m struggling to hold past 90 seconds which is the first dip and my o2 went to 83% before rapidly recovering with just 2 breaths then i laid down and was able to hold my breath for 130 seconds or 2 mins 10 seconds and again it hit 83% before bouncing back up. But the O2 ring is very quick reacting to my levels. Just some more info and a data point. 

[donkaye, MCFI]

So I ran a test on my new Inogen Rove 6 today on the way to Rapid City from Oshkosh.  It worked pretty well at the PPP in Cheyenne where my student and I used it at 10,000 feet.  O2 saturation levels were about 94% at setting 4.  That pretty well worked for me, although I prefer to have saturation levels of 96%.

Today at 10,000 feet I couldn't get above 94% even on the highest setting go 6.  Shirley maintained 96% so I kept her on the Inogen and I went back on ship's O2.  My saturation level immediately went back up to 98%.  At 12,000 feet even she went down to 90% so I put her back on ship's O2.  So for low altitude we'll consider using the Inogen, but most of the time we are flying at 15,000 feet, so we won't be using it.

I also reexamined using the O2D2.  Previously I had a 5th outlet installed that allowed for a diluter demand mask.  This outlet bypasses the altitude compensating regulator of the installed O2 system so I realized that this is what the O2D2 requires.  I was hoping I could get a higher sat reading than my previously max of 93% at max setting.  Once again even on the highest setting I couldn't get above 93% ever.  Other people seem to have had success, so apparently even though I am in good shape my physiology precludes my use of the O2D2.

When all is said and done, ship's built in O2, while more expensive to use, for me works the best, so that's what I'll be using.  It's disappointing.

[Will.iam]

I wonder if your breathing shallow beeaths abd the full bolus of O2 is not reaching your lungs? I find when i get to higher altitudes my breathing gets shallower until i notice the drop or my o2 ring buzzes then it reminds me to sit up not slouch and take deliberate deep breaths and that improves my o2 sat 

[Will.iam]

Also heard but not tried yet, to take apple airpod rubber ear pieces as they will slip over cannula  nose tips and then seal in your nostrils thus when you breathe from your nose you get 100% of the O2 in the cannula by avoiding outside air slipping around the cannula tips and diluting the O2 mixture. Will have to try that sometime just haven’t had the need to yet as taking full breaths have worked so far for me in mitigating low O2 levels. Might also help o2d2 devices as well since it would reduce the air diluting there as well. 

[dkkim73]

1 hour ago, Will.iam said:

I wonder if your breathing shallow beeaths abd the full bolus of O2 is not reaching your lungs? I find when i get to higher altitudes my breathing gets shallower until i notice the drop or my o2 ring buzzes then it reminds me to sit up not slouch and take deliberate deep breaths and that improves my o2 sat 

I wonder the same. I was puzzled by Don's experience. I almost didn't get the O2D2, but am happy I did.

Interestingly, I believe I have the same (or similar) altitude-compensating regulator (IIUC) in the factory system in the Acclaim. Mountain High's guy (Eric, I think, whoever is the main person who helps you select a product) said the system will actually provide too *high* a pressure and, to get it to work correctly, I needed to inline a regulator upstream: https://www.mhoxygen.com/product-category/regulators/regulators-reducing-ilr/ 

So, I suppose the system might not work correctly if the pressure is too high. Though I think in a previous post Don detailed that he worked with the company on this and so presumably this has been tried. 

It seems plausible that the depth of inhalation could cause this issue, since the puff comes early on. Whereas a continuous flow will give you close to the same mix, except maybe when using a mask. 

Anyhow, I find my own results vary a lot with breathing technique, either free-flow or O2D2. I get a lot of variability with the cannula, similar to what someone described above, sometimes fine on D5, occasionally needing to switch up to F2. Might be physiologic state that day, who knows. I would have the same problem I think using a cannula with any system. 

With a mask, it consistently works flawlessly regardless of attention and effort. 

The real game-changer with the pulse-delivery systems is that it makes fills so infrequent that: 

1. you just use oxygen whenever it makes any sense at all (I usually just go D5 on any XC, and always at night)

2. you don't have to plan ahead on fills, which I had to do using the factory system at continuous flow

I imagine the concentrator gives a person a similar sense of freedom. 

An aside: a person above mentioned how hard it is to hold your breath long enough to drop your SaO2 at sea level. That's because your primary respiratory drive (if healthy) is from too much CO2. Less CO2 at altitude makes it easier to not breath enough. Also, fun fact, this is why it's dangerous to hyperventilate prior to a long underwater swim, you can fight your air hunger long enough to pass out from lack of O2. 

I think we, collectively, may have found a replacement for the "lean of peak" discussion topic

 

[Will.iam]

2 hours ago, dkkim73 said:

I wonder the same. I was puzzled by Don's experience. I almost didn't get the O2D2, but am happy I did.

Interestingly, I believe I have the same (or similar) altitude-compensating regulator (IIUC) in the factory system in the Acclaim. Mountain High's guy (Eric, I think, whoever is the main person who helps you select a product) said the system will actually provide too *high* a pressure and, to get it to work correctly, I needed to inline a regulator upstream: https://www.mhoxygen.com/product-category/regulators/regulators-reducing-ilr/ 

So, I suppose the system might not work correctly if the pressure is too high. Though I think in a previous post Don detailed that he worked with the company on this and so presumably this has been tried. 

It seems plausible that the depth of inhalation could cause this issue, since the puff comes early on. Whereas a continuous flow will give you close to the same mix, except maybe when using a mask. 

Anyhow, I find my own results vary a lot with breathing technique, either free-flow or O2D2. I get a lot of variability with the cannula, similar to what someone described above, sometimes fine on D5, occasionally needing to switch up to F2. Might be physiologic state that day, who knows. I would have the same problem I think using a cannula with any system. 

With a mask, it consistently works flawlessly regardless of attention and effort. 

The real game-changer with the pulse-delivery systems is that it makes fills so infrequent that: 

1. you just use oxygen whenever it makes any sense at all (I usually just go D5 on any XC, and always at night)

2. you don't have to plan ahead on fills, which I had to do using the factory system at continuous flow

I imagine the concentrator gives a person a similar sense of freedom. 

An aside: a person above mentioned how hard it is to hold your breath long enough to drop your SaO2 at sea level. That's because your primary respiratory drive (if healthy) is from too much CO2. Less CO2 at altitude makes it easier to not breath enough. Also, fun fact, this is why it's dangerous to hyperventilate prior to a long underwater swim, you can fight your air hunger long enough to pass out from lack of O2. 

I think we, collectively, may have found a replacement for the "lean of peak" discussion topic

 

I have heard before about the trigger to breathe is off of co2 and not o2. Had not thought about hyperventilating before a big breath to dive could setup you up for running out of o2 before the co2 level forced you to breath again. I do know for rebreathers they have Co2 scrubbers and your exhaled breath has so much oxygen left unused that very little from the O2 tank is injected that the rebreather is time limited on the co2 scrubbers filling up before the O2 tank runs out.by a factor of 3. Also why giving CPR and breathing into the patient still has enough O2 for them to survive on. I would have thought hyperventilating would get enough co2 flushed out that the lungs could use more effectively (efficiency) the O2 in your lungs since it would take longer for the CO2 to build up forcing another breath. I added another 40 seconds to that breath hold above by hyperventilating before the breath hold so flushing out the CO2 does delay my urge to breath for longer. I wonder why the body triggers off of CO2 need instead of O2 need? Seems the priority is backwards. 

[Hank]

22 minutes ago, Will.iam said:

I wonder why the body triggers off of CO2 need instead of O2 need? Seems the priority is backwards. 

Because our bodies are adapted to life at ground level. Think of cavemen staying warm during the Ice Ages, CO & CO2 from the fire would trigger breathing well before running out of O2, so he would have the strength to exit the lower levels of the cave and reach fresh air. Once you run out of O2, you're done, so waiting that long is not good for survival.