does any APAP algorithm have an "ignore flow limitations" option?

[cathyf]

I have an Airsense 10 that I've been using for my six years of being on CPAP. I'm thinking about getting a new machine because I'm kind of nervous about what happens if this one fails -- nothing lasts forever, and it's a mechanical device. That means that I can actually consider the advantages and disadvantages of all of the various machines.

My main problem with the A10 is that, at least for me, "flow limitation" is a five-syllable exact synonym for "asleep". I was a kid when I first noticed that as long as I'm awake I can breathe with my mouth closed, but as soon as I start to doze off my nose shuts off and I have to open my mouth in order to continue breathing. Now that I have a machine that has recorded 16000 hours of me breathing, it is very obvious how my breathing works: as long as I lie there awake, the "flow limitation" graph is completely flat at zero. As soon as I fall asleep, it jumps up and down all jagged. This causes the pressure to rise to whatever the max is, and stay there pegged as long as I stay asleep. If I arouse partially the pressure might fall but then as soon as I'm asleep again it's pegged at the max again.

I read the description of the "for her" algorithm (which my machine doesn't have) and it sounds even worse. The "regular" A10 algorithm raises the pressure by 3 cmwp at every 3rd asleep breath, while the "for her" algorithm raises the pressure by 2.5 cmwp for each asleep breath.

(3-1/2 years ago I tried the experiment of setting my min/max pressures to 5/6. Through the entire time I was asleep, the "flow limitations" took the same wild up and down that happens at the higher pressures, and it instantly drove the machine up to the max. For the 90% of the night I spend in non-REM sleep, no apneas or hypopneas at 6, but as soon as I hit REM sleep the events come one right after another. After about a week of the experiment, it was clear that there was nothing that I could do to make my machine an APAP, and as long as I'm asleep it's a straight CPAP pegged at whatever my max pressure is. I set the machine back to 7/14 and it stays at 14 as long as I stay asleep, and 14 eliminates events even during REM sleep.)

From the description of the algorithm, as soon as I fall asleep, the machine marches the pressure up, so breath-by-breath it's 7,7,7,10,10,10,13,13,13,14,14,14,... and then it stays there at 14 unless and until I wake up. If I get the for-her, I'm guessing it's going to be 7,9.5,12,14 -- all the way to the max in four breaths instead of ten.

Are there any APAPs out there that have algorithms that only react to apneas and hypopneas, and ignore "flow limitations"? Or is this just hopeless and I'm just going to have to live with a machine that's going to function as a fixed-pressure machine?

[Wulfman...]

In my opinion, your only solution would be to switch to a straight pressure......CPAP mode......with a pressure that works best with your therapy. As far as I know, ALL APAPs use Flow Limitations to trigger pressure increases.

It seems to me that I remember you posted some years ago with a similar question/issue. And, I believe my suggestion was the same as it is now.

Good luck.

Den

.

[Dog Slobber]

Sounds to me like your settings are badly misconfigured.

You really should post some graphs.

Because you haven't posted graphs, all we can do is guess, but it seems your minimum pressure is considerably too low for your needs and your maximum pressure is artificially limiting where the machine needs to go.

Asking for the ResMed algorithm to ignore flow limitations doesn't make sense.

The algorithm monitors various indicators (Snores, FLs and events) and then responds. Snores and FLs start occurring as the airways start to collapse, the algorithm increases the pressure to prevent apneas.

Post some graphs and there's a pretty good chance your therapy can be improved.

[Pugsy]

Are there any APAPs out there that have algorithms that only react to apneas and hypopneas, and ignore "flow limitations"?

No.

There is a reason that all auto adjusting algorithms will go increasing the pressures when flow limitations are present.
Flow limitations are widely accepted as early indications that the airway is trying to collapse...early warning signs of impending OAs and hyponeas. The auto adjusting algorithm's job is to try to prevent this sort of thing from happening.