Sucking in on bilevel

[ahuman]

I switched to an AirCurve 10 and am still tweaking things. I'm also trying a new masks. Using an N30i nasal cushion, it at times feels like I'm trying to breathe in against resistance - sort of like breathing in before the air is there. I feel the mask being sucked toward my nose. I'll check the mask by loosening it and there's obviously pressure and flow. This can get bad enough to cause me to remove the mask. 

Is this a trigger sensitivity issue or a mask fitment issue - maybe the mask holes don't align well with my nose or the frame is restricting airflow in certain positions? I did not experience this with Dreamwear and I'll test switching back. It also could be that the filtered exhalation port on the N30i is somehow a problem for me. 

This feels similar, but also different from when CPAP pressures are set too low and there's a sort of gasping result. To start the AirCurve, I'm running VAuto with the pressures increased by one from the AirSense and PS at 4 versus EPR at 3. Perhaps this is giving me too much EPAP (increased by two, one directly and one from pressure support) even though the machine is adjusting up to have 95% EPAP and IPAP ranges using most of that additional unit of pressure which is a little odd as the AirSense was adjusting to and reporting one cmH2O less. The adjusting algorithms might not work very well with narrow pressure ranges as there's not much runway for the machine to use?

[SarcasticDave94]

You should post an OSCAR chart to help us guide in this.

OSCAR is free to download. It only takes using an SD card in the machine to store the data overnight. The SD card is standard form factor, any brand, 2-32 GB capacity, and formatted to FAT32. Sometime after sleeping, you insert the SD card into your computer card reader to upload into OSCAR. There you'll see all the data charts, with the ability to screenshot and from there attach to posts.

It would really help us in helping you to have this. It sounds very much like settings needing edited.

[ahuman]

Think that last part is either after I pulled the mask off or from my trying to adjust the mask airflow.

Some of the leaks were from mouth breathing as I think I was trying to figure out the airflow problem. One thing which is different with bilevel is I can kind of breathe through my mouth without air blowing out my mouth as with CPAP.

https://lh3.googleusercontent.com/drive-...dTdA=s1600

[Sleeprider]

I tried the N30i and it was a fail for me. I swapped the nasal cushion for a P30i nasal pillow and I got better flow. The mask is interchangeable, so it's easy to try. I recommend a larger size if in doubt to increase flow. We're seeing a median flow limitation of 0.50 on your results which is unexpected with bilevel at PS 4.0. I think it's fine to increase to PS 4.6 and you can try trigger sensitivity on high if you wish. I do think you may find the PS increase won't be needed if you swap for a pillows cushion.

[ahuman]

median flow limitation of 0.50 on your results which is unexpected with bilevel at PS 4.0.

Where are you seeing this? I see 95% of 0.05 and median of 0.00. That's still high as the day before the 95% was 0.01 over a longer period. Maybe the mask had some sort of fit issue or is just not a good fit for me.

I've not used pillows much and will try again. It seems drier on my nasal passages, or perhaps there's just an adjustment.

[Deborah K.]

I hated the N30i and loved the P30i. I think you will find it much more comfortable to use.

[Sleeprider]

ahuman, I misplaced a decimal. .5 would be extremely high, but I have seen it. 0.05 is borderline, and most bilevel keeps the 95% FL below 0.02. I think most of the problem is from the mask with the N30i cushion. With both the N30 and P30 the pressure flows directly to the nose, so I don't see how one would be more drying, however, it is much h harder for the cushion to be misaligned.

[ahuman]

I looked over some older data. For 95% flow limits, it's somewhat bimodal with some nights at 0.00-0.02 and others at 0.05-0.06 even with no OA/H events. Does this generally mean the EPAP pressure is too low or is something else happening given flow limitaions are sometimes ok?

[SarcasticDave94]

There's a progression from flow limits, to hypopnea, to Apnea. Each step has a greater obstruction. So if you see flow limits, it indicates you consider increasing the minimum pressure.

[ahuman]

Can flow limits be positional then too?

Went back to a Dreamwear cushion to remove some variables for now. I did notice at least one sensation of sucking in the mask so it may be something to do with the bilevel machine settings as well. I also opened up the pressure range and bumped the PS a tad. 

https://lh3.googleusercontent.com/drive-...aafQ=s1600

Should I increase the EPAP some? With bilevel do you generally want to increase IPAP along with EPAP in order to allow the machine the range to float up while keeping the pressure support? I tend to get flow limits when the machine is auto-adjusting which I had with APAP too which led me to use a narrow pressure range of only 2 cmH2O. Perhaps I should work toward fixed pressures if I'm sensitive to the adjusting or maybe I'll eventually get used to it?