Inogen

[Pinecone]

3 minutes ago, Aaviationist said:

While I do t know for sure, those number have to be based on testing. How that testing is done, I don’t know, but I’m sure there is a reason they explicitly tell you not to use it as stated above. 

Or they just used what people have reported who have used them in aircraft.

But if they did actual testing, they had people using the system and measuring their saturation with a pulse oximeter.  Exactly the same as they do in the hospital.

But different people are different.  You may need more or less O2 delivered at the same pressure altitude as me.  So this is why most of us recommend using a pulse oximeter when on O2 whether from a concentrator or a tank.

A tank is not a magic bullet that ensures that you will have enough O2.

[Aaviationist]

7 minutes ago, N201MKTurbo said:

It is called CYA. There is no regulation.

So the FAA lets you ignore the manufacturers recommendations for required equipment?

 

it doesn’t matter where it came from. 

Edited Monday at 01:10 PM by Aaviationist

[Aaviationist]

15 minutes ago, N201MKTurbo said:

You are correct, I can’t find one.

The FAA brochure I posted says the regulations require a mask above 18000, then they post 91.211 but it doesn’t mention it. I have always been taught that, but where is the reg?

23.1447

which also states - there must be an individual dispensing unit for each person - which the aviation version of the Inogen has, but the medical one does not.

 

Provide effective utilization of the oxygen being delivered from the unit - which again for the Inogen - above 14k for 2 people it doesn’t matter where not, and for 1 person above 18k it doesn’t matter not. 

Edited Monday at 01:15 PM by Aaviationist

[N201MKTurbo]

25 minutes ago, Aaviationist said:

23.1447

which also states - there must be an individual dispensing unit for each person - which the aviation version of the Inogen has, but the medical one does not.

 

Provide effective utilization of the oxygen being delivered from the unit - which again for the Inogen - above 14k for 2 people it doesn’t matter where not, and for 1 person above 18k it doesn’t matter not. 

That applies to built in equipment. It doesn't apply to portable systems.

[N201MKTurbo]

At this point I have spent 23 years of my working life as an engineer for FDA regulated medical device manufacturers. Inogen is a regulated medical device manufacturer. They cannot recommend in any way that their devices be used for any off label use. I'm sure that is why they made an aviation version. It is probably not marketed as a medical device and therefore not regulated by the FDA. They cannot approve of anyone using any of there medical devices for aviation use, because that is not what it was designed and approved for.  Even if they are the exact same device. None of these regulations apply to the end user. if you buy one, you can do anything you want with it.

[Aaviationist]

19 minutes ago, N201MKTurbo said:

That applies to built in equipment. It doesn't apply to portable systems.

While that’s true, it really becomes a question for the FSDO. And I’d bet the FSDO gives you a solid no.  I’d encourage one of you to call and ask (and relay the full conversation, not just bits and pieces that only support your position)

 

8 minutes ago, N201MKTurbo said:

At this point I have spent 23 years of my working life as an engineer for FDA regulated medical device manufacturers. Inogen is a regulated medical device manufacturer. They cannot recommend in any way that their devices be used for any off label use. I'm sure that is why they made an aviation version. It is probably not marketed as a medical device and therefore not regulated by the FDA. They cannot approve of anyone using any of there medical devices for aviation use, because that is not what it was designed and approved for.  Even if they are the exact same device. None of these regulations apply to the end user. if you buy one, you can do anything you want with it.

Except they DID briefly make and support an aviation version that had 2 outputs. This is where those altitude limitations came from. Again, where has the FAA ever allowed you to use ANYTHING to meet a regulatory requirement that directly contradicts the manufacturer guidance?

 

never. 

Edited Monday at 01:58 PM by Aaviationist

[N201MKTurbo]

11 minutes ago, Aaviationist said:

While that’s true, it really becomes a question for the FSDO. And I’d bet the FSDO gives you a solid no.  I’d encourage one of you to call and ask (and relay the full conversation, not just bits and pieces that only support your position)

 

Except they DID briefly make and support an aviation version that had 2 outputs. This is where those altitude limitations came from. Again, where has the FAA ever allowed you to use ANYTHING to meet a regulatory requirement that directly contradicts the manufacturer guidance?

 

never. 

If there is no regulation, then there is no regulation. You haven't shown me one yet. If you are curious, contact the FAA and ask them what the regulation is.

[Aaviationist]

Now I will give my opinion. 
 

if you want to rely and base your life, your family’s lives, and the lives of those that are underneath you on an oxygen source the manufacturer specifically says you should NOT rely on, then go for it. 
 

I think most people who will read this thread are smarter than that. 

[Paul Thomas]

On 6/22/2025 at 10:32 AM, Aaviationist said:

A lot of times that is the advertised price with Medicare. Especially when it comes to medical devices, you can’t just google something and use the ads that come up as a price. The cheapest I can find that I would trust sending money to Majorcpap - where it is 2k. Even then, 14k limit for 2 people is a non starter. 
 

the Inogen has a service life of 5 years. Compared to the cost of a hydro test (150$ last I did it) it still doesn’t make sense to justify the Inogen. 

(the below image is from the Inogen website, and if you buy one it comes with  warning in the documentation that says the same)

 

It doesn't appear to define the type of altitude. Is it AGL, density... you could get really picky if you wanted to give someone grief.

The manuals states it's approved for, but it doesn't say unapproved above those altitudes. To me, that's akin to max demonstrated crosswind or service ceiling. They are an interesting number but not a limitation and I have to figure out what works for me. The end goal of having oxygen on board is to maintain a certain saturation level and the best way to know if you are meeting that goal is to monitor you own personal saturation level.

[LANCECASPER]

Mooneyspace is a great source of information from people who have experience that we can all draw from. 

Occasionally someone signs up on here that really enjoys taking a contrary view about nearly every subject and has very little to zero personal experience on the subject they are arguing about. They never pay the money to be a supporter on the site and are here to stir things up and argue and don't contribute in any positive way. They get banned and then come back with another screen name. Most people who have been on here a long time have learned to ignore them and not take their bait to engage in endless debate. There's always the ignore option on their profile.

(Beechtalk's policy of people using their actual name as their screen name seems to help people behave better and not hide behind a random screen name.)

Personal observation: I've had an Inogen for close to 10 years. I bought it off of a Craigslist ad with 10 hours on it for $500 and although I have built-in oxygen I very rarely use the on-board oxygen.  My canisters on the Inogen are still good - I only use it for flying and the bottom line: it keeps my SPO2 where I want it. I end up using it on almost flight, whether it's 8000 or in the teens. Very rarely do I go into the flight levels, but when I do I plug into the on board O2 FL180 and above, with a mask. It has opened up options for me - if I need to climb higher I'm not restricted by how much oxygen is in my on-board tank. I still have my on-board O2 plus a few cans of Boost in the back pockets of the front two seats.

[Aaviationist]

1 hour ago, LANCECASPER said:

Mooneyspace is a great source of information from people who have experience that we can all draw from. 

Occasionally someone signs up on here that really enjoys taking a contrary view about nearly every subject and has very little to zero personal experience on the subject they are arguing about. They never pay the money to be a supporter on the site and are here to stir things up and argue and don't contribute in any positive way. Most people who have been on here a long time have learned to ignore them and not take their bait to engage in endless debate. There's always the ignore option on their profile.

Personal observation: I've had an Inogen for close to 10 years. I bought it off of a Craigslist ad with 10 hours on it for $500 and although I have built-in oxygen I very rarely use the on-board oxygen.  My canisters on the Inogen are still good - I only use it for flying and the bottom line: it keeps my SPO2 where I want it. I end up using it on almost flight, whether it's 8000 or in the teens. Very rarely do I go into the flight levels, but when I do I plug into the on board O2 FL180 and above, with a mask. It has opened up options for me - if I need to climb higher I'm not restricted by how much oxygen is in my on-board tank. I still have my on-board O2 plus a few cans of Boost in the back pockets of the front two seats.

So again, you’re just making things up and saying I don’t have experience?  Of course I do. 
 

For every argument of “it doesn’t say that” I posted the documentation to the contrary. Having the documentation itself in one place is useful. 
 

some people will do and believe what they want, grasping with all their might to the unscientific internet opinion when written facts and documentation is put in front of them. 
 

you can never change the minds of those people. You can only present the facts so when others click the thread everything needed for them to make an informed decision is in one place. 
 

“there’s no reg that says you need a mask above 18k”. There is and I posted it. 
 

“there’s nothing in the Inogen documentation that says not to use it above 14k for 2 passengers and 18k for a single user” there is, and I posted it

 

”there is no guidance on what the FAA says is a suplimental oxygen source” there is and I posted it. 

[Marc_B]

I think that this topic is difficult without scientific data and clear regulatory data, because the basic goal of supplemental oxygen is to avoid hypoxia and we have a clear way to define this with a pulse oximeter.  But not all equipment is the same (pulse demand, continuous, tanks vs concentrators, cannulas vs oxysaver cannula vs mask vs mask with reservior, etc.)

Typical recommendations from FAA have been 1LPM flow rate for every 10,000 ft altitude.  Typical oxygen concentrators can deliver anywhere from 1.5-20 LPM flow at 87-99% oxygen concentrations (vs 21% FiO2 at sea level ambient air).  Most medical devices are tested up to 10,000 feet so you'll often seen this as a "standard".  However, the goal of certification of medical device is different than what might be considered for aviation device...i.e. there is no prescription for 2LPM continuous "dosage" for pilots, but rather it is self titrated to avoid hypoxia.

Nasal cannulas entrain ambient air in addition to the flow from the cannula, and opening your mouth/speaking also entrains more ambient air, which is why above 18,000 feet you are required to use a mask that covers the mouth and nose.  Above 18,000 feet the partial pressure of oxygen is low enough that a standard nasal cannula is no longer effective for most.

However, I'm not sure if it has been well studied what the service ceiling of pulse demand portable concentrators are and if you can "override" the drop in oxygen concentration with increased flow rate.  I would suspect that this would depend on the units efficiency (i.e. some units likely have lower ability/service ceiling) and I also suspect that at some altitude, the oxygen concentration output drops and cannot be accommodated with flow increase.  I'm also not sure if the differential effects of using a face mask vs cannula with a pulse demand oxygen concentrator have been studied. i.e. what flow is required for a face mask vs using a simple cannula?  and does the "service ceiling" of the concentrator change with use of a mask vs cannula?

I reached out to the FAA CAMI (Civil Aerospace Medical Institute) to see if they've performed any testing with this and if they have a recommendation on who I could speak with.

 

The answer is that there is some regulation on the use of oxygen devices in aviation.  But it's clearly not exhaustive with current technology.  However the goal being normal oxygen saturation is clear and easily defined with an accurate pulse oximeter.  Of course not all pulse oximeters are equal, and not all show a wave form to tell you they are reading accurately.  So you CANNOT just assume that you're fine if the number reads over 90%.  They can also give false readings with CO poisoning as well.

 

[Marc_B]

TLDR:  pulse demand oxygen concentrators may not have the same "efficiency" as each other and some may have more "horsepower" to continue to maintain adequate oxygen concentration output with lower partial pressure of oxygen at altitude.  But I don't think that the "service ceilings" of these devices have been well defined.  So I think that you're left more with manufacturer recommendations rather than FAA regulations with these devices.  That's not to say they don't work, and have well proven benefits with portability and ease of use.

[Paul Thomas]

3 minutes ago, Marc_B said:

Of course not all pulse oximeters are equal, and not all show a wave form to tell you they are reading accurately.  So you CANNOT just assume that you're fine if the number reads over 90%.  They can also give false readings with CO poisoning as well.

 

Marc,

I've used oxygen once and it was 15 years ago. I don't recall the last time I flew above 10k.

I do have a pulse oximeter and I did assume that I was fine as long as I'm above 90%. I'll have to check mine to see if it shows wave form. Can you please expand on why we can't assume we fine? What type of false reading would we get with CO poisoning? I am thinking of getting supplement oxygen even though I've yet to see any of my symptoms (and I know what to look for as I've gone in the chamber).

 

Paul

[Marc_B]

@Paul Thomas A pulse oximeter estimates the oxygen saturation of blood (SpO2) and pulse rate by shining two different wavelengths of light (red and infrared) through the fingertip and measuring how much light is absorbed/transmitted. Oxygenated and deoxygenated hemoglobin absorb these wavelengths differently, allowing the device to calculate the percentage of hemoglobin that is saturated with oxygen.

An important tool for any SpO2 reading is plethysmography tracings or "pleth" or "waveform" which is a measure of volumetric changes associated with pulsatile arterial blood flow.  Inconsistent or distorted pleth may result in changes to the computer calculated value resulting in artificially HIGH or LOW SpO2 reading.  Therefore, plethysomography ensures reliability of the calculated oxygen saturation.

With carboxyhemoglobin (i.e. carbon monoxide poisoning), the abnormally bound hemoglobin has similar absorption spectrum as when O2 is bound...so it can be falsely interpreted by pulse oximeter as "saturated" even though you are actually hypoxic and have a LOW total amount of oxygen in the blood.  CO binds to hemoglobin MUCH more strongly than oxygen and so carbon monoxide actually displaces oxygen from your hemoglobin.  This is why it concentrates over time and longer duration is a more damaging effect as more and more CO is bound and less and less oxygen is carried in the blood and delivered to tissue.

Here's a great medical site going deeper into the details:  https://medicine.uiowa.edu/iowaprotocols/pulse-oximetry-basic-principles-and-interpretation

[Marc_B]

6 hours ago, Aaviationist said:

23.1447

which also states - there must be an individual dispensing unit for each person - which the aviation version of the Inogen has, but the medical one does not.

I think the FAR is defining a dispensing unit as the mask or cannula.  i.e. I have one oxygen cannister built in, but I have 4 outlets that allow 4 cannulas (one for each occupant).

[Aaviationist]

4 minutes ago, Marc_B said:

I think the FAR is defining a dispensing unit as the mask or cannula.  i.e. I have one oxygen cannister built in, but I have 4 outlets that allow 4 cannulas (one for each occupant).

In a pulse system like the Inogen it would not be unreasonable to say that using 2 cannulas attached to one output counts as 2 dispensing units. Again, that’s a question to ask to FAA. I personally think it is unreasonable to think splitting the output of a single pulse based output is a good idea. 

[Marc_B]

22 minutes ago, Aaviationist said:

I personally think it is unreasonable to think splitting the output of a single pulse based output is a good idea. 

I think what you mean is that "homerolling" your own cascade might be problematic. (i.e. if resistance/length/tube diameters/etc weren't considered you might get differential flow rates) However, I think if you used a cannula cascade that was designed for equal flow then I think it's feasible. 

If you consider that you're using one oxygen canister with standard built in oxygen, using one canister with a Precise Flight or Mountain High portable oxygen set up....

But you also have to realize the failure points with ANY oxygen system you use.  The failure points of each set up has it's own merits...built in, portable, pulse demand vs continuous flow, etc.

But for people using supplemental oxygen at 10-15,000 ft MSL...the FAA Time of Useful Consciousness is indefinite.  Meaning the FAA won't care what oxygen equipment you use below 15000 ft MSL.  You have more likelihood of CO poisoning than significant altitude (hypoxic) hypoxia at these altitudes.

Time of Useful Consciousness
15,000 feet — Indefinite
20,000 feet — 10 minutes
22,000 feet — 6 minutes
24,000 feet — 3 minutes
26,000 feet — 2 minutes
28,000 feet — 1 minute
30,000 feet — 30 seconds
35,000 feet — 20 seconds
40,000 feet — 15 seconds

 

[N201MKTurbo]

52 minutes ago, Marc_B said:

@Paul Thomas A pulse oximeter estimates the oxygen saturation of blood (SpO2) and pulse rate by shining two different wavelengths of light (red and infrared) through the fingertip and measuring how much light is absorbed/transmitted. Oxygenated and deoxygenated hemoglobin absorb these wavelengths differently, allowing the device to calculate the percentage of hemoglobin that is saturated with oxygen.

An important tool for any SpO2 reading is plethysmography tracings or "pleth" or "waveform" which is a measure of volumetric changes associated with pulsatile arterial blood flow.  Inconsistent or distorted pleth may result in changes to the computer calculated value resulting in artificially HIGH or LOW SpO2 reading.  Therefore, plethysomography ensures reliability of the calculated oxygen saturation.

With carboxyhemoglobin (i.e. carbon monoxide poisoning), the abnormally bound hemoglobin has similar absorption spectrum as when O2 is bound...so it can be falsely interpreted by pulse oximeter as "saturated" even though you are actually hypoxic and have a LOW total amount of oxygen in the blood.  CO binds to hemoglobin MUCH more strongly than oxygen and so carbon monoxide actually displaces oxygen from your hemoglobin.  This is why it concentrates over time and longer duration is a more damaging effect as more and more CO is bound and less and less oxygen is carried in the blood and delivered to tissue.

Here's a great medical site going deeper into the details:  https://medicine.uiowa.edu/iowaprotocols/pulse-oximetry-basic-principles-and-interpretation

It has been a while since I studied how pulse oximeters work, but from my recollection, they cannot get a solution without correlating the transmissions of the individual wavelengths with the pulse cycle. That’s why they are called pulse oximeters, not just oximeters. That’s why they all give your pulse rate, because they need it before they can give you an SpO2 reading. The way I understood the process, it can’t really be wrong. It is either no reading or the correct reading. The process has been known for a long time and is easy to implement using a fairly basic microcontroller.

[N201MKTurbo]

A good review of current pulse oximeters:

https://docreviews.me/2023/04/18/top-10-pulse-oximeters-of-2023-a-comprehensive-guide-to-choose-the-best-pulse-oximeter

 

[Aaviationist]

6 minutes ago, N201MKTurbo said:

A good review of current pulse oximeters:

https://docreviews.me/2023/04/18/top-10-pulse-oximeters-of-2023-a-comprehensive-guide-to-choose-the-best-pulse-oximeter

 

I’m noticing this list gets much less accurate the less you spend. Including the ring. 
 

what I have learned from your post is that cheap sensors, like those most of us probably have(including the ring) are not accurate at all. 
 

you need to spend at least 100$(after tax and shipping) to get something you can trust. 

[Marc_B]

16 minutes ago, N201MKTurbo said:

That’s why they all give your pulse rate, because they need it before they can give you an SpO2 reading. The way I understood the process, it can’t really be wrong. It is either no reading or the correct reading.

That's not what I experience with hospital equipment. I'll routinely see an inaccurate number with a poor pleth, that improves with a better pleth (or vice versa).  Sometimes it's poor distal perfusion, hypotension, or cold fingers.  But if you don't see a good pleth, you can't trust the number that's displayed.  So you'll commonly hear someone say "they were 82% with a good pleth" meaning it was accurate.

In terms of the background programming to not show a reading if a wave form isn't sensed...I'm not sure the detail of how the portable units are programmed.

[N201MKTurbo]

1 hour ago, Marc_B said:

That's not what I experience with hospital equipment. I'll routinely see an inaccurate number with a poor pleth, that improves with a better pleth (or vice versa).  Sometimes it's poor distal perfusion, hypotension, or cold fingers.  But if you don't see a good pleth, you can't trust the number that's displayed.  So you'll commonly hear someone say "they were 82% with a good pleth" meaning it was accurate.

In terms of the background programming to not show a reading if a wave form isn't sensed...I'm not sure the detail of how the portable units are programmed.

But is that the fault of the Pulse Ox, or the patient, or how it is on the finger?

We can assume we are in good health when we go flying.

[N201MKTurbo]

I think the pleth wave has always been calculated internally, but I see the new ones display it. I think if you were getting a stable and reasonable pulse, you would have a good pleth wave.

[Marc_B]

35 minutes ago, N201MKTurbo said:

But is that the fault of the Pulse Ox, or the patient, or how it is on the finger?

You'd be surprised.  We routinely check pulse ox on everyone from critical ill to standard vitals for a sprain in an otherwise healthy patient.

Skin pigmentation, fingernail polish, poor circulation, cold fingers...even healthy people have fingers that might not always read properly.  Most problematic I'd think would be use of fake nails/nail polish and vasoconstriction from just being cold in the winter or at altitude.  Some people also have hypersensitive vasoconstriction to cold (i.e. Raynaud's) and might not get a great reading at times.

This is why I think it's important to establish your baseline for what "seems right" for you and what seems like somethings "off".  Most of the decent portable pulse ox's that I've seen have a bar that beats up and down showing wave form.  If that's not correlating with your pulse, then it may not be accurate.  Some newer units have an OLED screen that actually show wave form.  Its a good idea to have a rough idea of where you "trend" at various altitudes as there are lots of variables in each of our "high altitude" physiologies.