Flow not responding quickly enough

[coolbranch]

I have a new Autosense 11 that I have only been using for a few days. I have been tweaking the settings by looking at my Oscar data daily. Last night I noticed a 38 second OA with zero leaks from mask. My therapy pressure is set 10-15. The machine responded with increasing pressure only at the end of the OA. When I looked closer at the pressure graph there is a several second red line displaying rather than green. Machine glitch?

Screenshot 2022-07-26 131202.png (3.64 KiB) Viewed 2682 times

[earlvillestu]

I have noticed the same thing, also with an Autosense 11. I'm a Newby, so I figured this was probably normal.

[Pugsy]

ALL machines that are in auto adjusting mode will NOT do anything during an actual apnea event.
They can't generate enough pressure fast enough to move the airway tissues that have collapsed and blocked the airway.
So they do nothing until AFTER the apnea event (OA or hyponea) has resolved itself and THEN it will decide based on what just happened and some other criteria if it needs to increase the pressure a little bit in an effort to better prevent the airway from collapsing again.

So what you see...the machine waiting until AFTER the event has ended to increase the pressure is actually the normal and to be expected response.
It's because it simply can't do anything else.

I have no idea what the red/green line means. Sorry.

Repeat...these machines do not/cannot respond DURING the airway collapse making up the apnea event. They all sit back and twiddle their little thumbs until the airway opens back up and then they decide what it is they want to do to best try to PREVENT the next collapse from happening.

[coolbranch]

Thanks. I just switched from the Airsense 10 which was 8 years old. I can't remember when I had this long an OA in quite a while.

[Pugsy]

If that long OA is a random and rare happening I would just shrug my shoulders and move on.

[Tec5]

The machine responded with increasing pressure only at the end of the OA.

The device is responds AFTER a OA is observed. By defination, an OA is cessation of >10 seconds, so a pressure increase after the OA flag is ususal
What might be unusual is that you say the OA (flow cessation) went on for 32 seconds, one would have expected the OA to be flagged at 10 seconds, immediately followed by a pressure reaction.
As to the red line, I see that occasionally when the pressure and the EPAP values are not exactly the same.
Could you post the 32 second flow cessation and the pressure graphs together?

[Pugsy]

The machine responded with increasing pressure only at the end of the OA.

The device is responds AFTER a OA is observed. By defination, an OA is cessation of >10 seconds, so a pressure increase after the OA flag is ususal
What might be unusual is that you say the OA (flow cessation) went on for 32 seconds, one would have expected the OA to be flagged at 10 seconds, immediately followed by a pressure reaction.
As to the red line, I see that occasionally when the pressure and the EPAP values are not exactly the same.
Could you post the 32 second flow cessation and the pressure graphs together?

You would be expecting wrong. Doesn't matter how long the apnea event lasts the machine cannot and will not increase the pressure until the airway has opened up. If it lasted 2 minutes...the machine still would wait until the apnea event was resolved and the airway was opened up and then it would respond based on the event and other criteria that needs to be met to have the machine want to increase the pressure. There's more to the criteria than just one lone OA.

These machines simply cannot push enough air to move sagging airway tissues...they just can't so they don't try.
It's part of the auto adjusting algorithm and expecting it to do something that isn't part of the algorithm is going to mean you are going to wait forever because it just won't happen.

[Tec5]

These machines simply cannot push enough air to move sagging airway tissues...they just can't so they don't try.

How does that square with:

APAP therapy works by the air pressure acting like a splint. When the patient has an obstructive apnea, the APAP machine increases pressure just enough to return breathing to normal. https://www.aastweb.org/blog/pros-cons- ... %20events.

The phrase " return the breathing to normal" suggests that the airway is no longer obstructed due to the pressure increase (e,g, sagging tissue has been splinted / resolved)

What am I misunderstanding?

[Pugsy]

These machines simply cannot push enough air to move sagging airway tissues...they just can't so they don't try.

How does that square with:

APAP therapy works by the air pressure acting like a splint. When the patient has an obstructive apnea, the APAP machine increases pressure just enough to return breathing to normal. https://www.aastweb.org/blog/pros-cons- ... %20events.

The phrase " return the breathing to normal" suggests that the airway is no longer obstructed due to the pressure increase (e,g, sagging tissue has been splinted / resolved)

What am I misunderstanding?

I guess you don't seem to understand my explanation of how auto adjusting algorithms work.
You don't believe me.
Fine. Your choice. I am 100% certain as to the accuracy of what I said.

You need to do a lot more research and dig deeper....documentation as to what I said is out there. I won't do your homework for you.
I also will not argue with you about it. You won't believe me anyway and I am not going to waste my time with you.

You are again making assumptions erroneously about something and coming to the wrong conclusions again.

Have a nice day..

[GrumpyHere]

The phrase " return the breathing to normal" suggests that the airway is no longer obstructed due to the pressure increase (e,g, sagging tissue has been splinted / resolved)

What am I misunderstanding?

The APAP doesn't resolve the obstruction. Your brain does.

Once an apnea happens, your brain panics, sends signal to excrete adrenaline, which wakes you, which restores the breathing.

Meantime the APAP records the event.

Once airflow return to normal because of your brain, the APAP increases the pressure in attempt to prevent the next apnea.

If successful .

If not, then it again waits for your brain to restore breathing.

Rinse and repeat.

[Tec5]

What am I misunderstanding?

The APAP doesn't resolve the obstruction. Your brain does.

Once an apnea happens, your brain panics, sends signal to excrete adrenaline, which wakes you, which restores the breathing.

Meantime the APAP records the event.

Once airflow return to normal because of your brain, the APAP increases the pressure in attempt to prevent the next apnea.

Thanks, that makes sense.
The original OA only gets resolved by an arousal (initiated by the brain) - that clears the “sagging tissue” .
Then the APAP increases the pressure to hopefully splint (stabilize) that tissue to prevent further OAs.
Do I have that correct?

[GrumpyHere]

Not just the first OA.

The APAP will ATTEMPT to prevent the next OA by increasing the pressure incrementally.

If it is unsuccessful, you will be repeatedly aroused until there's enough pressure to successfully splint the tissue.

[Tec5]

Thanks again, but it sounds like you and I are saying very near identical things, that is the incremental pressure increase (following the original OA) is intended to prevent the tissue sagging into the airway. That incremental pressure may or may not be sufficient to prevent future tissue sag (occlusions).

Right?

[dataq1]

BTW, Tec5, by the nature of your questions, it sounds like you are an engineer, Amiright?

[ozij]

Thanks again, but it sounds like you and I are saying very near identical things, that is the incremental pressure increase (following the original OA) is intended to prevent the tissue sagging into the airway.

Right?

Right, very near identical.

Not just the first OA

This is not a "quibble". Incremental pressure increase may also occur when "partial obstructions" -- hypopneas or flow limitations -- are indentified. Not only when an obstructive apnea occurs.

That incremental pressure may or may not be sufficient to prevent future tissue sag (occlusions)

Correct. Furthermore if the algorithm is the regular (not "For Her") Autoset, and the minimal pressure is too low, the pressure my drop to where new obstructive events are no longer prevented.
Hence the importance of a minimal pressure not being set too low.