Meaning of Flow Rate Shapes

Hi Everyone,

I'm wondering if there's something good/bad to be gleaned from a pattern I see in my flow rate graphs in OSCAR. For some stretches of the night my flow rate does this mountain range type pattern where I gradually breathe more or less shallow.







Other times it's much more regular and flat




Is the wavey pattern something that would indicate a need to adjust my pressure or other settings?

Thank you!

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I think the first graph shows light sleep or dreaming. The second graph shows deep sleep. I think the general shape of each wave indicates you are sleeping. If you were awake, it would look more like a sine wave or U shaped peaks and valleys.

Hello, spacemustard. That's a stretch of waxing and waning breathing. To interpret it will take more context. Could you do a couple of things?

First, right-click where the flow-rate graph label is, select Y-axis, and modify it to around +50 to -50. While your there, also select Dotted Lines and put one at zero. These actions will make your flow-rate graph easier to read.

Second, please provide a screenshot for the whole night. Include the left panel with the calendar turned off (little triangle to the left of the day's date) and include just the following graphs:
Events
Flow rate
Pressure
Flow limitations
Snores
Leaks.

If you need to squeeze the graphs to fit them into a single screenshot, just grab the grey bars that separate them and push them up.

Third, please provide a zoomed in view of this same stretch of breathing, but with all the graphs showing.

Thank you Miss Emerita!


Here is a stretch of waxing and waning breathing zoomed in with those changes you requested. I should note that this period was while I was using the f30i FFM, which is not my normal mask. A little later that night I ended up taking it off and switching back to my normal Dreamware Nasal Cushion Mask.



Here is that whole night.


And here is last night where I was using the nasal cushion the whole night. I woke up many times. I think that only 3 of the 7 CAs were legit, the rest were arousals.


I was trying the f30i because I feel like I wake up a lot with the nasal cushion and I wanted to see if a FFM would help me not wake up as much at night. I have no idea if it'll help but I wanted to give it a try. I have a deviated septum, and although I can breathe through my nose I do wake up with a dry throat some of the time.

Thank you!

Great job on the charts, thanks.

I'm not seeing anything to suggest that the waxing/waning pattern is problematic. Our trigger to breathe is a build-up of CO2 in our blood, and heavier breathing can wash out enough CO2 to diminish or suppress the "breathe now" signals. So these patterns can appear: heavier breathing (washing out some CO2) followed by diminished breathing, until the CO2 builds back up enough, at which point heavier breathing ensues. Rinse and repeat until your breathing settles down.

By the numbers, you are doing very well, but your report of frequent wake-ups, along with the bristly appearance of the flow rate for both full-night charts suggests that your quality of sleep is not yet where it needs to be.

Do you want to try an experiment? You already have a very tight range between your minimum and maximum pressure. You could see whether setting min = max would be even more restful for you. Some people are quite sensitive to pressure changes, and you might be one of them. What pressure should that be? I would recommend 8.2, which is roughly where you are a lot of the time anyhow. I would also suggest turning off the ramp, unless that makes you miserable.

I see that you increased your EPR from 1 to 2. Why don't you go ahead and increase it to 3 while you're at it? Normally your minimum should be increased by the same amount as an increase in EPR, but I don't think you need to, given that your numbers are so good, and you would be increasing your minimum a little anyhow.

Your leaks are fine with both masks, at least as far as your therapy goes. Stick with whichever mask is most comfortable for you over all.

You know, I realize I don't know how long you've been using CPAP. Could you tell us that?

Thank you so much for all the detail in your reply. I really appreciate it.

I've been using CPAP for around 2.5 years and almost always have my AHI under 1.5 with treatment. I had only 5 complex apneas an hour during my sleep study but I didn't sleep much so I don't know how accurate that count is. What I do know is that before CPAP I was a mess and now I'm at least somewhat improved.

Over the last two years I've used pillows, nasal masks, and FFM at various times and have had mixed success with all of them. I wear my mask all night but often feel like sleep is low quality. What I realized a few months ago is that my pressure range (originally 5-15) was a big part of the struggle and I started adjusting it to be narrower. Aerophagia has also been a struggle but EPR helps.

I will definitely try your idea and set max=min at 8.2 and see where that gets me.

Good, and do consider raising the EPR as well. Keep us posted, would you?

Last night was a little rough. The EPR of 3 felt very dramatic and might have been too much for me. It felt like my nasal cushion was ballooning in and out from the rapid pressure change between inhale and exhale. I also woke up with pretty bad aerophagia. It's possible that the aerophagia is due to diet, I have bad gerd, but it could also be from the CPAP settings. The aerophagia is intermittent so I haven't been able to pin down an exact triggers yet.

I'm planning to try a few more nights with max=min but with EPR=2 and putting my pressure back to 8.2.

spacemustard wrote: ↑

Sun Nov 08, 2020 2:56 pm

nov_7_cpap.jpg


Last night was a little rough. The EPR of 3 felt very dramatic and might have been too much for me. It felt like my nasal cushion was ballooning in and out from the rapid pressure change between inhale and exhale. I also woke up with pretty bad aerophagia. It's possible that the aerophagia is due to diet, I have bad gerd, but it could also be from the CPAP settings. The aerophagia is intermittent so I haven't been able to pin down an exact triggers yet.

I'm planning to try a few more nights with max=min but with EPR=2 and putting my pressure back to 8.2.

it may be better for you to make one change at a time. that way you'll know precisely what change you make makes any change in your results.

good luck!

I see waxing and waning in my flow graph too. If I zoom in to see the waxing and waning, then use the left and right arrow keys to move through the day, I find that it starts and then fades out. I usually see flow limits, even small ones, showing up when it starts.

Having EPR at 2 felt much better than 3. Mask didn't feel like an unstable balloon.

I was able to sleep with fewer arousals (I think) but I did still wake up earlier than desired and with aerophagia. As far as I can tell nearly all of the CAs were actual central apneas, which I suppose is better than before min=max when many of my CAs were arousals. Looks like I goofed when setting my max pressure and had it at 8 instead of 8.2.

Have you tried lowering your min. pressure by e.g. 1 cm? Often works well for aerophagia - worth the tradeoff in AHI.

Definitely having fewer arousals with the static pressure and EPR 2. Waking up an hour before I'd like to, but that could just be my body refusing to acknowledge daylight savings. Aerophagia still a problem so I might try lowering pressure a bit but keeping it static. I might also try my chinstrap or FFM again in a few days if my leaks keep up.