Are these flow limits my problem?

[k888]

Greetings:  This is primarily – I think – a question about flow limits.  Over my first two months on CPAP, I have experimented with soft collars and collar management, and I have played with settings.  My AHI is, most nights, finally looking very good, and that is real progress, since I started with 30+ apneas/hour.  And I am feeling better, but still more sleepy than I think I should be.  (I have other health issues and age, so it's hard to know for sure what "normal" should be.)  I think I still have too many flow limits – is that true?  I am more sleepy when flow limits get higher, even with very good AHI.  And I don't see that raising the lower pressure has made much difference.  I have had EPR set at 3 from the start and have not experimented with it.  See below the results for various settings.  They are not 100% comparable, since I was working out various issues over time.  I am wondering 1) what my next step should be, and 2) what to tell the sleep doctor at next week’s mandatory Medicare follow-up.  I’m pretty sure she will say I am fully managed, and I’m not at all sure that is correct.  Thanks so much, k888

DATE, MIN - MAX PRESSURE, AHI, FLOW LIMITS
11/1:    7-12.4,    15.29,  .20-.33
11/5:    7-12.4,     2.42,   .14-.23
11/6:    8-12.4,     5.4,     .12-.21
11/11:  8.4-12.6,   .38,    .13-.23
11/16:  8.6-12.6,   .64,    .16-.31
11/17:  8.8-12.6,   .78,    .13-.25
11/25:  9-13.2,      .48,    .21-.54
11/21:  9.2-12.6,  2.25,   .08-.23
11/26:  9.2-13.2,  1.55,   .13-.3
12/1:    9.4-13.2,    .9,    .1-.22
12/2:    9.4-13.2,    .59,  .13-.26
12/4:    9.4-13.4,    .25,  .13-.26
12/3:    9.6-13.2,    .24,  .18-.34  sleep seemed good but sleepy by 8:30 AM
Here is last night's chart. 
   

[PeaceLoveAndPizza]

Overall things look good. Flow limits are high, but as long as sleep quality is good they are something to be watched.

It seems your flow limitations track pressure and as pressure goes up so do flow limits.

You are limited by your machines ability to provide more support than EPR 3, so we need to figure out an alternative. Consider setting your pressure to a fixed 9 with EPR 2 or 3. With the fixed pressure you will not get the FL’s from the pressure swings, and a bit of EPR should make things more comfortable.

If you don’t like that you can try dropping EPR to 2 and set your pressure range to 8-12. That will help with the flow limitations and pressure swings, but hopefully not cause more apnoeic events.

[gainerfull]

Have you considered switching to constant pressure mode? I'd be interested to see what a couple nights of constant pressure mode @ 12cmH20, EPR 3 and another couple nights of 13cmH20, EPR 3. Since you're essentially experiencing flow limitation all night it suggests you're undertitrated (pressure is overall, too low).

[k888]

PeaceLoveAndPizza and gainerfull,
Thank you for your suggestions.  I will give all these scenarios a try and report back.  Your help is much appreciated.  k888

[CPAPfriend]

There's a chance that higher pressure won't resolve the residual flow limitation. You may need a bilevel that allows for more PS if completely eliminating FL is the objective. Already, your OAs, hypopneas, and CAs are eliminated, so I have my doubts about increasing pressure further, but it's still something worth trying on the chance that you can tolerate it AND it eliminates what's left of airway resistance.

We know that flow limitation can cause disturbances in EEG backhground activity which is correlated with daytime sleepiness, so your observation that you feel more tired with more flow limitation holds up.

[k888]

Hi all,
This is an interim report - I tried two protocols based on suggestions:

1) pressure 9-12, with EPR changed from 3 to 2.  Flow limits worse.  Felt like I slept well, but sleepy shortly after getting up.
2) flat pressure of 13, EPR 3.  Bad night. In the first part, I went to sleep but apparently managed to chin tuck in spite of heavy duty collar and believing that my chin was in the right spot (I try to check it regularly.)  Made collar tighter after waking up.  That worked for position, but it took me a long time to go back to sleep.  I kept getting up to check if the positional business was improving.  So I don't know exactly when I went back to sleep but suspect it was when the tidal volume went down and flow limits went up?   Also, I had some leaks and got way too much air in my system.  Let's just say its a good thing I didn't have to be around a lot of people this morning.  I don't know what to make of these results – should I try a flat 12 with EPR 3 or repeat flat 13 to look for cleaner results?

Anyway, I know this really is not enough data on flat pressure, but tonight I have to go back to my prior sweet spot for a little better sleep.  (9.4-13.2, EPR 3)  That has been a mixed bag, but after three nights poor sleep, it is my best chance to get a little more clear headed and my eyes higher than half mast.  Then I will be ready to try again.  Thanks again for your advice, k888
       

[gainerfull]

What does your sleep look like / feel like without the collar? Have you tried different collars? If I wear my soft cervical collar too tight I get some episodes like yours because I think I'm sleeping on my side and pinching my airway off when my head leans to the sides.

The interesting part with your sleep is your machine senses obstruction all night and just bounces off the 12cmH20 maximum pressure all night when using APAP mode. Do you have any prior nights with higher maximums like 16cmH20 that we can see?

[PeaceLoveAndPizza]

When you set your pressure support (aka EPR) to 2 it caused more flow limitations which drove your presure to the ceiling max. That is not the way we need to be taking your settings.

You can increase pressure to handle the hypopnoea’s, but that may not make much difference in sleep quality.

I think you need to consider a bilevel, specifically the ResMed AirCurve 19 Vauto, to get more pressure support as it looks like a max of EPR 3 is not going to help you in the long run. Until your flow limits are under control you will continue feeling like a dog’s breakfast.

You can of course continue with your current workable settings of 9.4-13.4 EPR 3 full-time. I doubt that will make much difference in sleep quality other than a low AHI. 

If you are buying out of pocket there are a number of Suppliers that sell new and used machines. You can also find them on Facebook Marketplace or Craigslist, but you be careful and be sure you are protecting yourself with PayPal or other service that will refund your money if the seller is pulling a scam.

If using insurance we can help with what to tell the doctor to grease the skids to get a bilevel.

[k888]

Gainerful,
Without the collar, it is positional apnea all night long.  I have tried multiple collars and seem to need 4" even though I am small.  I have gerd and often a stuffed nose, so I sleep high and apparently exert too much downward pressure on the collar.  I have caused several to fail that worked for a few days and then, incrementally, didn't.  I have always liked to sleep on my back, and now I really can't sleep on my side due to stent placement on left and rotator cuff on right.  I am a very still sleeper.   So I can't rule out the collar itself causing a problem – I certainly find it rather uncomfortable and tighter than I want, but I do know I can't do without a collar.  I am trying to deal with the stuffiness and to lower my pillow height.  Re pressure, I have tried higher pressure, but above 13, I get big leaks and the blowing air onto my face disturbs me even when the machine is not registering significant leaks.  I have an Evora FF with the smallest attachment, and it works well up to a bit over 13, then not, both because of leaks and air into my system.  

I am attaching one of my best nights:  lovely AHI of .59 at pressure 9.4-13.2, EPR 3.  Flow limits of .13-.26, which I know is not good, but is about my best.  k888
   

[k888]

PeaceLoveAndPizza,
In answer to your comment, I would very much appreciate knowing whether a bilevel is called for here, and whether insurance might actually cover it, given that I (mostly) can get my AHI pretty low.  I have my "mandatory Medicare" follow-up appointment with my sleep doctor next week.  They have been mostly unhelpful, but any advice about how best to move forward would be appreciated.

If I do need a bilevel, I think I need a prescription to get a different machine, with or without insurance, right?  k888