Question for Pugsy: FLOW LIMIT?

[Passport in-hand]

Background:
55 y.o. Male
On PAP since 2014, Chronic OSA
Use, Resmed Aircurve VAuto. Eaon Nasal - Since 2017
Sleep Quality: Good to Above normal

Recent Events:
- Sept 2020: Throat Surgery (a) UPPP reduction (b) Adenoidectomy and (c) tonsillectomy. To mitigate OSA
- Dec 2020 to May 15 2021, lost 35 pounds (Keto). Goal for this year is to loose 20 more!

Refer to the attached ’screen shots’
ITEM 1: STATISTICS
A. My Setting for several years was on VAuto PS 6.0 over 4-18.
B. Since throat surgery and weight loss I’ve seen my AHI improve.
C. From Feb to May I’ve reduced my settings gradually (VAuto) - With improved outcome. I’ve learned this trough reading several CPAP forums, etc.
D. May 10, (once again self experimented) I change my settings to CPAP mode, from VAuto, thus regulating the pressure to ‘constant’. I Used a FIX pressure of 12.0, due to statistics from Feb2021-May2021 whilst on VAuto mode.

MY OBSERVATION AND QUESTIONS:
ITEM 2 & ITEM 3
Comparing May 2 vs May 14: I notice my FLOW LIMIT HAS increased, or more spontaneous than previous.
All other indicators within Oscar show negligible change.

QUESTIONS:
Why has my FLOW LIMIT INCREASED? Based on the evidence provided, is this good or bad? And can you expand the significance of FLOW LIMIT with all the changes I’ve mentioned.
I have been influenced to ‘get-off’ VAuto mode and change to CPAP or S-mode. Is this a reasonable change for me?
What would be the benefits of S-Mode? Most Google search do not provide a clear delineation between the 2 settings.

If you require other screen-shots, please ask - and I’ll provide.
Thanks for you comments and insights!

[Pugsy]

Assuming the flow limitations are NOT related to nasal congestion...if you are experiencing much nasal congestion we need to have a different discussion.

Flow limitations...the airway is slightly compromised and the air flow is reduced but not to the point of earning an OA or hyponea flag.
I think of them as baby OA/hyponeas that just haven't grown up yet.
They may or may not be clinically significant though. Sometimes they cause big problems and sometimes they don't.
They are an important part of any auto adjusting pressure algorithm though and the algorithm will try to prevent the airway from becoming restricted or collapsing ever so slightly.
This is why you see the variations in pressure when you are in auto mode...the machine is on a mission to kill those FLs. That's it's job.
You have more FLs when using fixed mode because the machine can't kill the FLs with more pressure.

Now do they always have to be killed? It depends. Are they causing a problem and actually disturbing the sleep enough to impact sleep quality or how a person feels the next day.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4688581/

https://www.youtube.com/watch?v=-gie2dhqP2c

S mode is just fixed bilevel or CPAP mode with greater options for PS (EPR)...VAuto mode is just bilevel and the machine can go hunting/killing whatever it feels it needs to kill.
Some people do better with a fixed pressure and others do better with auto adjusting pressure.

We don't sleep the same each night so pressure needs can also vary during the night for any number of reasons.
Example. My OSA is worse in REM stage sleep to the point it is 5 times worse and I often see the pressures need to go 6 to 8 cm higher ONLY during what is probably REM stage sleep. REM amounts to about 20% of the night. If I wanted to use fixed pressures and deal with REM OSA optimally I would have to use 6 to 8 cm more pressure ALL night instead of part of the night. While I could do it...it's not pleasant to use 14 or 16 cm all night long when I can use 7 cm most of the night and let the machine go to 14 or so only when needed.

Which mode seems to offer you the most refreshed sleep? That's what I would go by.

You can get a better looking FL graph in fixed mode simply by having a higher minimum EPAP or exhale pressure.

CPAP with EPR...is bilevel but EPR is limited to 3
S mode is essential CPAP but you can use more than 3 difference between inhale and exhale. PS is nothing more than EPR backwards.
EPR comes off inhale...PS is added to exhale.

[Passport in-hand]

Assuming the flow limitations are NOT related to nasal congestion...if you are experiencing much nasal congestion we need to have a different discussion.

Nasal congestion, not an issue since throat surgery. Allergy responses (although was never a problem) are few and far between. Since the surgery, I've been in a a habit of performing NASAL WASH (with saline packs) 2x/week. If I had known this earlier, I would've never had occasional congestion. Besides, it feels good afterwards.

S mode is just fixed bilevel or CPAP mode with greater options for PS (EPR)...VAuto mode is just bilevel and the machine can go hunting/killing whatever it feels it needs to kill.
Some people do better with a fixed pressure and others do better with auto adjusting pressure.

I'll experiment with S-mode as using 6.0-12.0, with 'easy breath' turned ON.
As I continue to loose weight (hope and pray I do) continual adjustments with absolute be necessary. My adjustment periods (change settings) is anywhere from 5-days to 2-weeks - or based on 'feel'.

Any other word of advice or comments or comment are welcomed!
Thanks!

[Passport in-hand]

Assuming the flow limitations are NOT related to nasal congestion...if you are experiencing much nasal congestion we need to have a different discussion.

Nasal congestion, not an issue since throat surgery. Allergy responses (although was never a problem) are few and far between. Since the surgery, I've been in a a habit of performing NASAL WASH (with saline packs) 2x/week. If I had known this earlier, I would've never had occasional congestion. Besides, it feels good afterwards.

S mode is just fixed bilevel or CPAP mode with greater options for PS (EPR)...VAuto mode is just bilevel and the machine can go hunting/killing whatever it feels it needs to kill.
Some people do better with a fixed pressure and others do better with auto adjusting pressure.

I'll experiment with S-mode as using 6.0-12.0, with 'easy breath' turned ON.
As I continue to loose weight (hope and pray I do) continual adjustments with absolute be necessary. My adjustment periods (change settings) is anywhere from 5-days to 2-weeks - or based on 'feel'.

Any other word of advice or comments or comment are welcomed!
Thanks!

[Miss Emerita]

I would guess that the biggest reason for the different FL results from these different settings lies in the amount of pressure support. In CPAP mode, your getting the equivalent of these VPAPAuto settings:

Min EPAP = 9.
Max IPAP = 12.
PS = 3.

Compare that to your settings in VPAPAuto mode:

Min EPAP = 5.8.
Max IPAP = 15. [But you're mostly around 12 max.]
PS = 4.8.

The lower EPAP didn't lead to an increase in OAs, which is great. So you don't really need a higher EPAP, it seems to me. What you do seem to benefit from is the greater PS, which gives you a pressure boost when you inhale. In turn, that boost helps you complete your inhalation more smoothly, without the need for extra effort to overcome flow limitation. Possibly you also do better without pressure variation during the night. I know I do.

As Pugsy says, it's an open question whether the FLs mess with your sleep or not. They can have subtle effects on sleep architecture, preventing you from getting as much deep and REM sleep as you need. Or not. People do differ.

So I would suggest you set your PS to 4.8, your min EPAP to 5.8, and your max IPAP to 10.6 (4.8 + 5.. This will eliminate pressure variation and provide the pressure support you seem to benefit from. You could even consider creeping up on the PS over time, making sure to raise the max IPAP too, to see how you feel with that.

[Passport in-hand]

Miss Emerita,
Thanks for the response; and the settings recommended and I appreciate you interpreting my data precisely.

So I would suggest you set your PS to 4.8, your min EPAP to 5.8, and your max IPAP to 10.6 (4.8 + 5.. This will eliminate pressure variation and provide the pressure support you seem to benefit from. You could even consider creeping up on the PS over time, making sure to raise the max IPAP too, to see how you feel with that.

However, as I'm using Resmed AirCurve 10 VAuto on 'CPAP mode' - This particular model (whilst on CPAP mode) only allows for a IPAP fixed setting: I used '12', precisely as you interpreted - 'an average', from my statistical data (whilst on VAuto mode). In addition the VAuto model does not allow for EPAP, only EPR with a maximum of 3. The EPR of 3 'is' the EPAP settings.

MY THOUGHTS: Should I revert back to VAuto mode and adjust the settings to 5.8/15/PS 4.8? Your thoughts and advice are greatly appreciated.
The 'S-mode' (spontaneous mode) within this model does allow for this variant and adjustment - however, I've tried and failed on S-Mode. Th EPAP is way too aggressive for the identical settings. On the other hand, I might be mis-using the S-mode? Who knows, but I do need additional 'hand holding for that if I continue with S-mode.

Reference note: The Resmed AC10 VAuto includes 3-settings (a 3-in-one machine),
1- VAuto (BiPAP) - Good Success ,
2- CPAP - improved AHI but questionable FLs - adjustments limited to IPAP only and EPR
3.S-Mode, spontaneous mode - fail ! Way too much EPAP no matter what the setting.

Min EPAP = 9.
Max IPAP = 12.
PS = 3.

I have been on this setting for less than a week, as mentioned. With an AHI outcome lower than on VAuto . I will continue onwards with my settings, then re access my data.

Many Thanks!

[Miss Emerita]

Sorry, yes, I meant you should use VAuto mode rather than CPAP mode so you can use the suggested settings to see how they work for you.

[Passport in-hand]

Miss Emerita,
Thanks for the response.

MY PATH FORWARD on CPAP-mode: I am seeing gradual improvement on the FLs since. (reminder: I've only been on CPAP mode for 1+ week). I intend to continue on this mode until end May, a self-experiment if you will - and we shall see what happens. If the FLs continue to improve - then, 'hey' we may just have a new setting for the near term. If not, then I will revert back to VAuto and experiment with the settings recommended.

Since December '20, I've lost all the weight I've gained since 2014. 2014 is the same year I started on CPAP, however I am physically 'better' from the throat operation in 2020 and other regimenting factors in physical improvements. It feels so good to wear the jeans I bought in 2013! My goal is to loose another 5 pounds by end June (very realistic!) - and another 20 lbs by November, my 56th Bday. Ultimately get down to my weight when I graduated high school. Possible? Time will tell.

My physical and mental changes will eventually reflect on how I sleep. I will continue to use the PAP and have NO plans in stopping. Experimenting with settings, on multiple 'modes' will also continue.

THINGS TO REFLECT ON: In 2014 I was recommended to get a sleep study - and sure enough I did within the month. Diagnosed with OSA (as most of us in this website are) I was prescribed my first CPAP. Much like most of us, the first 6-months was discomforting! I wake up with it off, I would forget to put it on, etc. - and for a couple months, it just stayed in the bag! Until I forced myself to do so, I immediately got the quality sleep I so desired. Like much of us, we tend to procrastinate. Looking back, I'm very delight and fortunate I did not procrastinate with sleep study and PAP therapy when advised. Now, 5-months into my weight loss, I understand I was in procrastination mode for weight loss. I was fully aware of weight gain - and denied it. Not until I looked at my medicine cabinet and reflected on 'why' I was taking these meds. Reason: it all pointed weight gain! Yes, I will die someday - and so will all us! How I will live, my quality of life, and how do I effect the people around me between now and then is up to me. I'll leave it with that.

Again Thanks!