CA events - Advice

[lukewpc]

Hello everyone, I'm new here!

I was recently diagnosed with sleep apnea through two 'WatchPAT One' sleep studies:

• First study: AHI 21.9
  
• Second study: AHI 4.7
  

I'm not quite sure why there's such a big difference between the two studies, all the events are showing as obstructive but not sure I trust the WatchPAT CA / OA algorithm?
For some context, I'm a 26-year-old male, lean build, physically fit, and have no other known health issues. I don't smoke or drink heavily, and there are no known structural issues that could be causing the apnea.

I've been using CPAP for almost two months now, initially with the P10 mask, but switched to the F40 to fix some mouth leak issues.
I'm using OSCAR to view my data, almost all of my events showing are central/clear airway.

Here are the settings I've tried over the last few nights - I've attached screenshots of these:

• Pressure: 6 - 8 cm, EPR: 3 → AHI 11.4
  
• Pressure: 7.2 - 8.4 cm, EPR: 1 → AHI 4.9
  
• Pressure: fixed 7.4 cm, EPR: 0 → AHI 6.3
  

I've noticed that turning EPR up causes a significant increase in CA events, but turning EPR off results in more flow limitations and slightly higher AHI compared to EPR 1.
So far, it seems like keeping the pressure low (6-8 cm) with EPR set to 1 results in the lowest AHI and best sleep, but I'm still averaging around 5 AHI.
I'm also seeing hypopneas and a waxing and waning pattern in my tidal volume—I'm not sure what's causing this even with EPR off.

Any guidance or insights would be greatly appreciated!

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EPR 1 screenshots

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EPR 3 screenshots

[SarcasticDave94]

Well, you're onto a few hints with the problem with dealing with CA. Therapy settings to diminish CA will oppose all the other events. I call it the teeter-totter effect, as in CA and settings to reduce are on one side while all the other events and their settings to reduce are on the opposite end.

Note that CA will be consistently inconsistent. They are stubborn and will be up, down, absent but will return for any reason, sometimes with no setting edits.

Would fixed pressure 8 do any better for you? An attempt to reduce Hypopnea and OA events should reduce overall events.

I'm guessing your watchpat test didn't monitor CA. These are probably treatment emergent, as you're likely relatively new to CPAP. The CA should naturally diminish over a bit of time getting used to CPAP, unless you know for certain that your sleep test identified a predominant style of the Central Apnea.

[lukewpc]

Well, you're onto a few hints with the problem with dealing with CA. Therapy settings to diminish CA will oppose all the other events. I call it the teeter-totter effect, as in CA and settings to reduce are on one side while all the other events and their settings to reduce are on the opposite end.

Note that CA will be consistently inconsistent. They are stubborn and will be up, down, absent but will return for any reason, sometimes with no setting edits.

Would fixed pressure 8 do any better for you? An attempt to reduce Hypopnea and OA events should reduce overall events.

I'm guessing your watchpat test didn't monitor CA. These are probably treatment emergent, as you're likely relatively new to CPAP. The CA should naturally diminish over a bit of time getting used to CPAP, unless you know for certain that your sleep test identified a predominant style of the Central Apnea.

Thanks for your response, Dave.

I understand the need to find a goldilocks zone between opening the airway but not over-ventilating and triggering CA events.

I'll set to fixed 8cm and try to get a solid period of data with those settings. Would you recommend EPR on 1 to avoid flow limit or 0 to reduce treatment emergent centrals?

So the waxing and waning I see even without EPR will likely diminish by itself, is this a form of periodic breathing caused by CPAP?

[SarcasticDave94]

You can trial both EPR 1 or off to find what's better right now.

It's not periodic breathing in what I'd call it. It can be an actual Central Apnea as in it's not Obstructive based, it is over 10 seconds with no flow (Apnea). What we've come to understand on this board is that some new CPAP users have to deal with extra CO2 being exhaled due to CPAP pressures, and your Central nervous system hasn't yet recalculated a better breath need anticipation. The unexpected low CO2 removes the breath trigger from the equation. This will equal a Central Apnea in the new to CPAP user.

[Phaleronic]

Hi lukewpc , Dave's spot on with his assessment here, I would also suggest maybe turning EPR back on to 1 for a bit and letting your body adjust to the treatment for a few more nights and I'm also an advocate of fixed pressure when it looks like it will help (and I think it will in your case). I'd suggest 8.6cm cpap pressure (since your 99.5 is hovering around 7.6) one bar over that for a little headroom with EPR @ 1.

[lukewpc]

Thanks very much both, I'll be keeping it at fixed 8.6 with EPR 1. I'll keep an eye on the numbers, hoping to see events dropping off over time and will report back if that doesn't happen