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Strange Flow Rate Pattern
#1
I've been having this strange flow rate pattern during the night that has started to show up over the last 6 weeks or so. I've been on CPAP for 3 1/2 months now. It doesn't happen every night, but does happen most nights. Any ideas what this is?

The problem seems to occur for ~10-15 minutes at a time. You can see the really high respiration rate on the full night graph. Basically, it happened twice last night. I've got a fairly zoomed in, and a completely zoomed in view of the area.

[Image: JEe4Xli.png?1]
[Image: Tk8DOMX.png?1]
[Image: MEIsE1e.png?1]
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#2
The high resp rate is an artifact of that odd flow pattern. The machine counts breaths from zero crossings in the flow waveform. You have a bunch of zero-crossings in that wiggle after a true breath.

What's the pressure at that time?
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#3
Just looking at your summary report on the left side column, Your pressure is low for what is needed. You need to open up the top end of the range a bit. Maybe try to open it to 15cm.

Without looking at the pressure curve, I can't say if you need to raise the start of the range from 9.
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#4
I'd like to see if this resolves with the use of EPR. You will need to keep your minimum pressure where it is or increase to 10.0, but turn on EPR at 3, which will relax exhale, and provide more support in inhale. Be sure to increase the maximum pressure to 15.0 cm and give this some room.

The second chart shows an almost stair-step pattern where inhale rises until a strong exhale cycle begins, and this is where I think the EPR is going to help even things out by preventing air from stacking up in the lungs. Very unusual, but in general, your tidal volume looks great.
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#5
(02-28-2017, 08:30 AM)justMongo Wrote: The high resp rate is an artifact of that odd flow pattern.  The machine counts breaths from zero crossings in the flow waveform.  You have a bunch of zero-crossings in that wiggle after a true breath.

What's the pressure at that time?

The pressure at the time was 11.5cm. I was just referencing the respiration rate, because it denotes this strange oscillating pattern without needing to zoom into the data. I'm really just trying to understand what the root cause of that weird oscillating breathing pattern is from.

(02-28-2017, 08:31 AM)AshSF Wrote: Just looking at your summary report on the left side column, Your pressure is low for what is needed. You need to open up the top end of the range a bit. Maybe try to open it to 15cm.

Without looking at the pressure curve, I can't say if you need to raise the start of the range from 9.

Here's the screen shot with the pressure graph. I had been operating at a fixed 9cm, based on the doctor's choice. I did try some higher pressures for a short time, but didn't really see any noticeable improvement in AHI or flow limitation. I did have some awakening issues from having a large pressure range too. Plus, I struggle with aerophagia, even at 9cm. Most of the time it is just a little gas. Other times, it can become quite painful.

[Image: 3FQoGa8.png?1]
(02-28-2017, 09:42 AM)Sleeprider Wrote: I'd like to see if this resolves with the use of EPR.  You will need to keep your minimum pressure where it is or increase to 10.0, but turn on EPR at 3, which will relax exhale, and provide more support in inhale.  Be sure to increase the maximum pressure to 15.0 cm and give this some room.  

The second chart shows an almost stair-step pattern where inhale rises until a strong exhale cycle begins, and this is where I think the EPR is going to help even things out by preventing air from stacking up in the lungs.  Very unusual, but in general, your tidal volume looks great.

I will try turning EPR back on. I had it on for a couple of weeks initially, because of the aerophagia. I had read or heard somewhere that it's not a good idea to use this for the long term. Maybe that's not right. Anyway, I'm obviously still learning and searching for a good setup.

I've never been able to get my AHI down below about 1.5. It's typically ranging from 2.5 to 3.5. My flow limitations have never gotten better than what is in this night. I'm not sure if this is expected, but it seems like I've seen significantly better results from others who have posted their data.
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#6
The aerophagia history raises a new possibility on your graph.  The wavy lines at the end of exhale may be air leaking into your stomach as the lower esophageal sphincter opens and closes.  Had I known this was a problem I would have recognized it sooner. You can see at the end of exhale, the flow returns to the zero line, then dips as air "exhales" into your gut. Your inhale shows signs of flow limitation. 

NOTHING wrong with EPR, especially in your case.  The lower pressure at exhale until you initiate the next breath will be essential for your comfort.  What we want to see, is now low can we go before OA becomes too much of a problem.  9/6 is looking really good to me in light of the aerophagia.  Once you turn on EPR, let's look at another chart and see if the air is still dumping to your gut.

[Image: JEe4Xli.png?1]
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#7
Thanks for that insight. That makes a lot more sense. I was trying to figure out what kind of breathing pattern would cause that. But it sounds like it is an artifact of the secondary air escape path into my stomach.

Are you suggesting to go back to the fixed 9cm or keep trying the APAP 9-12cm or 9-??cm? Thanks. I'm just trying to continue to see if I can improve the flow limitation and overall AHI. Haven't had much luck with those though.
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#8
The strategy with aerophagia is twofold. To find the highest pressure that is tolerable so you don't fill up with air, and the lowest pressure that controls OA and other problems. In the graphs above, the missing chart is pressure, but I presume that strange flow pattern occurred at or near your maximum pressure of 11 to 12. I think you need to put EPR 3 back into the settings, then you decide where the pressure is tolerable and give decent results.

You indicated that higher pressure did not result in a noticeable improvement in AHI or flow limitation, so going back to 9 with EPR at 3 is a known baseline. How was the aerophagia there? Is there any benefit to going lower? Based on your own findings, a maximum pressure of 9 with EPR at 3 is where you should be. If you put in a minimum pressure of 7, how much would that change things? I would guess not much. In spite of the flow limitations, your tidal volume and other respiratory metrics are very good. I think you need to back it down and get some relief for the aerophagia. In any event, now that you know what the signature is for air going to the stomach, you can probably go through your data and find a threshold where that happens and use that to your advantage.
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#9
I set EPR to 3 with a fixed pressure of 9cm for last night. Here are my results. Overall, the respiratory rate, which signifies some of the artifacts in the breathing pattern, are cleaner overall. However, there was still an area with the oscillating pattern from 2:10am to 2:40am. I did wake up with a little less aerophagia, but could notice more air in my stomach vs my intestines. I think the EPR did help, but there seems to be more going on, because the flow limitations are still not great, even though the AHI looks reasonable. If you see all the spikes in flow rate, those seem to indicate some sort of arousal, even though I don't remember any. I definitely did not wake up feeling refreshed today. But I couldn't fall back asleep either, because of some of the stomach discomfort.

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#10
Looks great...if you're ready, drop to fixed pressure at 8 EPR 3.
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