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Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
#81
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
Right, thank you!

So this way, my UARS and CA are treated, but as the CA decreases, UARS manifests and I up minPS if my flow rate indicates I need it.

The other way starts without treating the UARS, but is a bit more intuitive for titrating and reading the graphs.

In theory, a handful of months from now when the minPS is high enough to treat UARS, could I switch off of ASV smoothly if I don't get centrals or they're very rare? I understand I might never fully adapt and then the ASV is necessary for centrals, and I'd stay on ASV in that case.
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#82
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
How do you know PS of 3 doesn't treat your UARS? Do you have polysomnogram data to back up that claim, proof of RERAs etc? Or are you assuming that some lingering symptoms are still due to UARS?

At fixed PS of 3-3.5 you had the odd central apnea and your data looks decent. The idea was to remove the handcuffs from your machine (by raising max PS) which in theory should allow it to increase PS when necessary to fight off the odd central you were having. Instead of fighting the odd central the first night averaged 4.25 PS and your AHI increased to 10. Removed more handcuffs and second night was better but it had nothing to do with removing the handcuffs, it was better because the average PS was only 3.75. Then the next night the machine went off the rails and averaged PS of 10 leading to AHI of 36. And on the last night turned on backup rate after realizing it was off and your AHI dropped but your respiratory drive was depressed the entire night at an average PS of 6.3.

You seem to think you still have untreated UARS but all of your data suggests CO2 being washed out and having central apnea issues whenever PS goes above 4. Centrals and respiratory depression that appear to be a much more obvious issue which is supported by your reports of tiredness later in the day etc. I still don't get why but this machine seems to blow up PS at times causing this central apnea issue to worsen but my theory is that increasing PSmin to 3.5 triggered some central apneas causing hyperventilation and the machine getting stuck on a higher TV target which is why I recommended trying PSmin of 3 to try and avoid the machine targeting too high of ventilation. The machine will still increase PS when necessary to maintain TV and this will help fight UARS unlike before when you used a fixed PS. When using a PS range you don't need to use as high of a PSmin to be effective.

If you want to use a higher PSmin then it appears you appear to be better off sticking to a fixed PS so the machine doesn't start over ventilating you like it has these couple nights. If you used the fixed 3.5 PS but with backup rate turned on (was previously turned off) then that could help fight off the odd centrals you were previously having.
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#83
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
I would add that the backup rate for you needs to be found, so it can be set to function without that CA combat ability being missing. If you don't I'm quite sure the CA are going to trigger reactions from the SV Auto that knocks you of the rails and prevents you from using and getting results you want and expect. Maybe try 8 as backup rate or something like that. Auto didn't work out so well, so put in an actual value.
Dave

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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#84
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
(08-22-2021, 01:28 PM)Geer1 Wrote: How do you know PS of 3 doesn't treat your UARS? Do you have polysomnogram data to back up that claim, proof of RERAs etc? Or are you assuming that some lingering symptoms are still due to UARS?

At fixed PS of 3-3.5 you had the odd central apnea and your data looks decent. The idea was to remove the handcuffs from your machine (by raising max PS) which in theory should allow it to increase PS when necessary to fight off the odd central you were having. Instead of fighting the odd central the first night averaged 4.25 PS and your AHI increased to 10. Removed more handcuffs and second night was better but it had nothing to do with removing the handcuffs, it was better because the average PS was only 3.75. Then the next night the machine went off the rails and averaged PS of 10 leading to AHI of 36. And on the last night turned on backup rate after realizing it was off and your AHI dropped but your respiratory drive was depressed the entire night at an average PS of 6.3.

You seem to think you still have untreated UARS but all of your data suggests CO2 being washed out and having central apnea issues whenever PS goes above 4. Centrals and respiratory depression that appear to be a much more obvious issue which is supported by your reports of tiredness later in the day etc.  I still don't get why but this machine seems to blow up PS at times causing this central apnea issue to worsen but my theory is that increasing PSmin to 3.5 triggered some central apneas causing hyperventilation and the machine getting stuck on a higher TV target which is why I recommended trying PSmin of 3 to try and avoid the machine targeting too high of ventilation. The machine will still increase PS when necessary to maintain TV and this will help fight UARS unlike before when you used a fixed PS. When using a PS range you don't need to use as high of a PSmin to be effective.

If you want to use a higher PSmin then it appears you appear to be better off sticking to a fixed PS so the machine doesn't start over ventilating you like it has these couple nights. If you used the fixed 3.5 PS but with backup rate turned on (was previously turned off) then that could help fight off the odd centrals you were previously having.

I believe I have UARS at PS3 because I have flow limitations, and my flow rate looks awful, with almost constant jagged tops, cliffs, flattening, etc. I'll attach three examples here, if you want to see more then let me know.

Not only does a PS of 3 not treat these super-commonly occuring issues, but a PS of 3.5 and 4.0 doesn't either if I remember correctly. I can't check the data right now. 

Why would a fixed PS with BPM help with centrals? I thought that an ASV was for centrals when wanting a higher PS. I'm a little lost I think. 

Lets say I had a minPS of 3 - what would you recommend for maxPS for maintaining TV? Maintaining TV = treated UARS?

(08-22-2021, 04:06 PM)SarcasticDave94 Wrote: I would add that the backup rate for you needs to be found, so it can be set to function without that CA combat ability being missing. If you don't I'm quite sure the CA are going to trigger reactions from the SV Auto that knocks you of the rails and prevents you from using and getting results you want and expect. Maybe try 8 as backup rate or something like that. Auto didn't work out so well, so put in an actual value.

Thanks Dave. Apparently my machine more or less stayed at 10, why 8? 

So there's three opinions so far. Gideon says try my current settings for a week. Geer says lower minPS and maxPS. You say set BPM to 8, and see what happens. 

I think that it's best to gather data after changing one variable, right? So I'll see if I can finish the week as per Gideon's plan, since we've already started, and then I'll try Geer1 and your suggestion, one at a time. This seems the most "scientific" and sensible way to approach it all?

Also just to have the information here for Gideon's plan:

Day 1 with Auto BPM:
AHI = 0.63
FL = 21
H = 6
Timed Breaths = 5129

Day 2: 
AHI = 0.26
FL = 9
H = 2
Timed Breaths =  970

I realise two days doesn't establish any trends or conclusions or anything, but even so: With 5x less timed breaths, I had blocks of time without timed breaths. Flow rate was good at parts, with small issues in others. I woke after 7.5 hours of sleep, still struggled to wake up and had lots of brain fog, but I couldn't go back to sleep! This is very unusual for me, I can easily sleep 10-12+ hours if I don't fight to stop myself. As for how I feel, it was a better than average day in subtle ways, but I can't say it's significant enough to be beyond placebo, or a fluke, or due to the excitement of a big novel change to my settings or whatever. Guess we'll find out!

Anyway just a reminder again that the three attachments aren't last night, just typical flow rate stuff from random previous nights at a constant PS of 3.


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#85
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
The reason I chose 8 was that 10 you mentioned, making non spontaneous backup rate a bit lower than your normal median.

Just to simplify, go with Gideon's suggestion. We've a bit too many cooks in the kitchen and you're getting confused. All the info/suggestions are valid, but to lessen confusion, forget I said anything for now.
Dave

OSCAR
Standard OSCAR Chart Order
Mask Primer
Dealing With A DME
Soft Cervical Collar Wiki
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#86
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
Oooh, I'm a bit slow today it seems! I think I get it now, the constant triggering could be because i just naturally have a lower BPM so a trigger of 10 is constantly triggered, but 8 might not be.

I didn't mean each suggestion was invalid, but that I/we might miss insight if multiple suggestions are implemented at once as opposed to seeing how one change impacts the whole. I definitely agree simple is good! But if Gideon had replied saying that I should do what you two suggest alongside this week-long adaptation then i suppose I would. 

I'd just be doing us all a disservice to be jumping between suggestions if that wasn't a good idea and obviously I'm not knowledgeable enough to make that call! 

In any case, thanks for being patient and understanding. I'm lucky to have found this forum when I did!
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#87
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
(08-22-2021, 06:26 PM)ldinks Wrote: Not only does a PS of 3 not treat these super-commonly occuring issues, but a PS of 3.5 and 4.0 doesn't either if I remember correctly. I can't check the data right now. 

Why would a fixed PS with BPM help with centrals? I thought that an ASV was for centrals when wanting a higher PS. I'm a little lost I think. 

Lets say I had a minPS of 3 - what would you recommend for maxPS for maintaining TV? Maintaining TV = treated UARS?

So PS of 3 doesn't treat it, nor does 3.5, nor does 4 and over 4 creates central apneas. What makes you think higher PS will fix these issues? Perhaps PS won't fix them and that is why the machine targets too high of a PS some nights? 

These machines are very simple and they only really have 3 capabilities. First capability is EPAP pressure which is used to treat obstructive apnea by holding airway open/prevent it from collapsing. You don't have OA issues so EPAP is fine at a low value.

Next capability is PS (difference between IPAP and EPAP). PS is a pressure differential, pressure differential increases flow through a restricted airway. This is how PS treats flow limitations, it creates a more forceful inhale/exhale. 

Third capability is backup rate. Backup rate tries to force a breath if you don't take a breath spontaneously.

ASV uses a combination of varying PS and backup rate to treat both restrictive and central breathing issues. Backup rate is actually the most important part for treating central apnea because it tries to force you to take a breath when your body doesn't want to. The machine just varies the PS depending on how hard it believes it needs to try to force you to breath (tries less PS at first, sees it isn't enough so tries more PS, then if you start taking what it deems adequate breaths then it starts supplying lower PS again). 

So when you use a fixed PS with no backup rate you have absolutely no capability to treat central apnea nor does the machine attempt to treat restrictive breathing. The machine simply relies on your spontaneous breathing capability and supplies the same pressure support/ventilatory assistance each time you take a breath. If you use fixed PS with backup rate then the machine will do the same but during a central apnea the machine will supply a pressure increase and try to kick start your breathing, with a low fixed PS this may or may not be enough to actually force you to take a breath. 

I was actually wrong about PR ASV, it doesn't target TV but rather a peak flow rate (TV is the area under the flow rate curve rather than the peak value). Both act to treat flow limited breaths in UARS by increasing PS after you having smaller shallower flow limited breaths. 

If you use a fixed PS of 3.5 it might be good for the majority of the night but may not treat a period of restriction from you changing position or something like that. Using a PS range of 3.5 to a higher value allows the machine to increase PS at times where restriction occurs. If you use too high of a PSmin it can cause deep breaths that cause the machine to target a higher flow rate then you actually need which causes CO2 to wash out which then causes central apnea and/or respiratory depression. In that recent example you didn't have lots of central apnea but you were in a state of respiratory depression and would have been having central apnea if the backup rate wasn't forcing you to breath. Lowering PSmin reduces the chance of the machine targeting too high of a flow rate and leaving PSmax higher still allows the machine to increase PS to try and treat restrictive breaths when they occur.

You keep on talking about adjusting PSmin and PSmax at the same time but the two have very different effects and are used to treat different issues and there is never any reason to adjust both at the same time. PSmin is what determines the minimum level of ventilatory assistance provided to you. PSmax just affects how hard the machine will work if it feels it needs to. You increase PSmin if you believe you need more ventilatory assistance (have too much restricted breathing) and you decrease it if there are too many signs of over ventilation (central apnea, respiratory depression etc). You increase PSmax if you think the machine needs more ability to force you to breath when breathing is bad and you decrease it if too high of a PS is causing issues like aerophagia. If you want the machine to try to work for you and automatically adjust PS then you usually want PSmax as high as it is comfortable as that gives the machine the most power to try and correct issues when they occur. 

Feel free to keep trying the current settings to see if your body adapts. I don't know exactly why the machine targeted such high flow rate/ventilation so perhaps it is just a short term thing while your body adapts. If your body doesn't adapt and you keep having centrals or depressed respiratory drive then I would try a lower PSmin. One thing to note is that when using a range of PS and analyzing your nights data you have to look at the average PS not PSmin or PSmax when interpreting your data. For example the night you had super high central apnea was not because your PSmin was 3.5 or because your PSmax setting, it was because for some reason the machine targeted a high flow rate and supplied an average PS of 10 which over ventilated you and caused central apnea. The other night with mostly timed breaths was similar but because you had backup rate turned on it just lead to timed breaths occurring rather than central apnea. The key is trying to find the settings where the machine works for you but doesn't go overboard.  

Hopefully that helps you understand what you are doing/attempting to do with these changes rather than just taking our suggestions and blindly turning knobs.
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#88
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
(08-22-2021, 09:14 PM)ldinks Wrote: Oooh, I'm a bit slow today it seems! I think I get it now, the constant triggering could be because i just naturally have a lower BPM so a trigger of 10 is constantly triggered, but 8 might not be.

Actually if you look at nights where your breath rate was spontaneous it was in the 14-16 BPM range, the only night it was close to 8 was that night of ridiculously high central apnea and that is because your respiratory drive was non existent due to average high PS of 10. 

The reason BPM of 10 kept triggering that night is because the machine averaged a PS of 6 which washed out your CO2 and reduced your respiratory drive (slowed down breathing rate and would have done so to the point of central apnea occurring if it wasn't for the backup rate supplying breaths). 

Auto/10 works for now while you get the PS range dialed in.

I am hoping this post will make things click after you read my previous detailed post.
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#89
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
Wow. Thanks a lot for that, Geer1. 

I think I understand EPAP. For me, 6 is one or two some days, less is OA daily, 7 is free of OA. So I think that's the end of that for EPAP. 

I'll have a look tonight or tomorrow but I believe higher PS is helping my flow rate overall (4 is better than 3, just not completely curative), I get centrals even at 3 though and they increase at 3.5 and upwards. 

You've definitely made ASV and backup rate click for me! As well as how fixed PS (min and max) and backup rate on/off works. To be clear - ASV without backup rate wouldn't treat centrals then? It just dynamically alters PS to deal with restricted breathing based on the peak (using PR) flow rate?

"Using a PS range of 3.5 to a higher value allows the machine to increase PS at times where restriction occurs. If you use too high of a PSmin it can cause deep breaths that cause the machine to target a higher flow rate then you actually need which causes CO2 to wash out which then causes central apnea and/or respiratory depression. "

If I understand correctly then, given I get more centrals with a PS of 3.5 or higher, I'd set a backup rate to treat the centrals if I did this?

Regarding PS min and max. You're suggesting to lower the PS min back to 3 (if not lower), to trigger less centrals, as the ASV should handle the UARS anyway if the PS range I set allows. And if that triggers centrals, the backup rate should be able to kick in and force a breathe. Is that correct?

To be clear, as I'm a little unsure if this isn't the case: PSmax being too high can cause issues like aerophagia, so the machine doesn't necessarily stop at the appropriate PS and can overdo it, which mine did. And you can limit this by lowering PSmax until it is high enough to handle centrals, and no higher?

Completely understand taking an average for PS.

Three more questions:

What does depressed respiratory drive look like on the graphs? 

If PS can't treat the UARS, do I have other options? 

If the UARS is still there when using ASV, what does that mean? Night before last I noticed flow rate issues in an hour with no timed breaths. 

What if the ASV algorithm doesn't seem to treat the UARS? Night before last, I still saw flow rate issues when I had an hour or so of no timed breaths.

Again I really appreciate the explanation. I'm going to reread it a few times throughout the day and really try to take it all in.


(08-22-2021, 09:56 PM)Geer1 Wrote: Actually if you look at nights where your breath rate was spontaneous it was in the 14-16 BPM range, the only night it was close to 8 was that night of ridiculously high central apnea and that is because your respiratory drive was non existent due to average high PS of 10. 

The reason BPM of 10 kept triggering that night is because the machine averaged a PS of 6 which washed out your CO2 and reduced your respiratory drive (slowed down breathing rate and would have done so to the point of central apnea occurring if it wasn't for the backup rate supplying breaths). 

Auto/10 works for now while you get the PS range dialed in.

I am hoping this post will make things click after you read my previous detailed post.

Absolutely, and I'm so glad you've cleared all of this up for me. While I'm not sure I'll change settings right away, I imagine by dialling in PS, I should start with minimally decrementing PSmin to 3.0?
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#90
RE: Seemingly little correlation between EPAP (or PS) and AHI or flow rate. [UARS]
Yes ASV without backup rate cannot treat centrals unless it is able to do so before the central apnea starts. In fact ASV without backup rate is likely counterproductive because just before the central apnea starts it would raise PS causing more CO2 to be washed out then once the central apnea starts the machine will do nothing (just like the day you had lots of CAs).

Yes as long as you use a range of PS the ASV will adjust PS to try and treat restricted breaths. Then when you have CA the machine will use backup rate to try and force you to breath.

The higher PSmax is the more powerful the machines attempts to correct central apnea, restrictions etc can be. The lower PSmax is the more handcuffed the machine is. If you want to be able to treat centrals the best you want PSmax to be high. Sometimes it might only take a PS of 3 to kick start a breath but other times it might take 6 or 10 etc. If PSmax is set high enough the machine will try higher PS as it believes is necessary. If you limit PSmax to say 3 or 6 then the machine may not be powerful enough to force you to breath (whether due to central, restriction etc).

UARS is a tricky beast and a lot of the symptoms are not specific to breathing issues although many people that get diagnosed with UARS then blame all their symptoms on it. It is possible that your UARS is treated and that you have lingering fatigue etc due to other health issues. Since you can't easily monitor UARS the best you can do is try the different settings available and see what seems to work best and then stick with it. In theory if your symptoms are due to UARS then higher PS creates higher flow rate and should provide enough ventilatory assistance for your body to overcome restricted airway, this is why Gideon was trying higher PS and hoping your body would adapt to it. My only interjection is that perhaps you should try a lower PSmin and see if letting the machine try to treat restrictions when they occur is more effective then just setting a higher PSmin which seems to cause more central related issues.

Flow rate issues do not always mean UARS. Flow rate issues can be present for a number of reasons. If they occur in a periodic nature throughout the night they could be related to REM sleep which always has worse flow rate graphs because part of bodies partial paralysis in REM sleep. Flow rate also gets affected by other things such as periodic limb twitches etc. Interpreting the cause of flow rate change is often very difficult and knowing if that is an issue or treatable is even more difficult.

Reduced respiratory drive is like the beginning of an apnea. You start taking slower/paused shallower breaths because your body doesn't think it needs to breath (due to low CO2 levels which is what drives spontaneous breathing effort). When you have backup rate on then this will mostly be seen as timed breaths. The machine is only forcing you to breath because your respiratory drive has decreased to the point where the machine thinks you need to breath more often. This is the reason that on that night you had lots of timed breaths and during many of them the machine was using higher PS because it was trying to not only force you to breath more often but to breath more deeply as well. This can be due to incorrect settings (if BPM was set too high) but in your case an auto BPM of 10 is low enough compared to your spontaneous BPM of 14-16 indicating it was a sign of reduced respiratory drive (due to average PS over 6).
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