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.