APAP to CPAP - clear airways disappear?

[zeleni]

I've been on APAP for over a year and still have high AHI (typically over 8, often up to 15). The majority of these events are clear aways, with some hypopneas, and few obstructive apneas. I also have RERAs of about 4 an hour. I recently had another sleep test which showed very low AHI (around 2) with a total RDI of 12.

Last night I changed from APAP mode to CPAP (which is how I was tested). I also turned off flex mode. My clear airways completely disappeared and my RERAs dropped below 1/hr. My obstructives increased significantly though. This was my first night with absolutely no CAs.

Does the machine algorithm on APAP detect CAs and RERAs differently? Can CPAP mode even detect CAs? Or could the APAP and A-flex really aincrease these events?

[archangle]

I've been on APAP for over a year and still have high AHI (typically over 8, often up to 15). The majority of these events are clear aways, with some hypopneas, and few obstructive apneas. I also have RERAs of about 4 an hour. I recently had another sleep test which showed very low AHI (around 2) with a total RDI of 12.

Last night I changed from APAP mode to CPAP (which is how I was tested). I also turned off flex mode. My clear airways completely disappeared and my RERAs dropped below 1/hr. My obstructives increased significantly though. This was my first night with absolutely no CAs.

Does the machine algorithm on APAP detect CAs and RERAs differently? Can CPAP mode even detect CAs? Or could the APAP and A-flex really aincrease these events?

Don't put too much faith in one night's results.

If your pressure is higher with APAP, you might get more centrals.

AFlex might affect your centrals. It's worth experimenting with.

CA detection shouldn't change, but I'm not sure about RERA detection. I have a vague recollection that PRS1 Auto machines detect something differently in terms of RERA or flow limitations in Auto vs. CPAP mode.

[Pugsy]

I have a vague recollection that PRS1 Auto machines detect something differently in terms of RERA or flow limitations in Auto vs. CPAP mode.

It's only the Flow limitation thing. CPAP mode doesn't flag flow limitations at all. Everything else is pretty much the same no matter which mode.

[Sheriff Buford]

Some folks respond positively to straight cpap mode vs autopap and vise versa. Most time the "how you feel the next day" normally determines which mode they use, but there have been cases where lower AHI numbers are achieved in either apap or cpap modes. I have always contented that for me, I felt better on the cpap mode because the cpap mode worked at keeping my airway open all night as opposed to waiting for apap to respond to a closed airway. I have recogmended folks to swith to the other mode once or twice a year to see how they felt. I switched to the apap mode over a week ago, and I found I've felt much better, so I'm staying with it for now. Six months from now, I'll switch back to cpap mode and see how I feel. As Advil stated, you may want to give it a little more time. Be wary of responding to a "one night" event without giving it more time. We all have bad nights and good nights here and there.

Sheriff

[zeleni]

Thanks for the feedback. I'm not putting much stock in it. I did have absolutely zero clear airways detected, which has never happened in the 400+ days I've used it. Overall still not a great night, since I had an AHI of almost 12 (nor do I feel very refreshed). Will keep fiddling with it!

[zeleni]

Two more nights. One with APAP, no A-Flex and one with CPAP, no flex. Both nights, no clear airways. I'm thinking either the flexes encourage events or the flex somehow gets read as centrals instead of obstructives. Still have fairly high AHIs (9 and but better than before. I wish I had experimented with this sooner!

[archangle]

Unplug your machine from the power to reset the processor. It doesn't sound likely, but sometimes the computer gets confused and powering it off may fix it.

Do your centrals happen when the pressure is higher? It's not at all uncommon for centrals to increase with pressure.

[Pugsy]

It's possible that the "Flex" exhale relief is a low level sleep disturbing factor and maybe causing little mini arousals that get read as clear airway events.
Some people do better with no exhale relief. Some people do better with exhale relief.
I did an experiment a while back where I turned off my exhale relief. Horrible results that I documented here.
viewtopic.php?f=1&t=67883&p=631376&hili ... mb#p631376

I do better with exhale relief but there is no reason that you might not do better without it. Everyone is different and respond to even minor changes differently.

[patrissimo]

Do experiments. That's how you learn. But it takes more than 2 nights of data to learn something, usually .