Flow Limitations - Min Pressure Too Low?

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MMcG
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Flow Limitations - Min Pressure Too Low?

Post by MMcG » Fri Jan 14, 2022 2:02 am

I tried posting this as a comment on a previous thread, but got no replies. Hence, the new post.

Thankfully, things have improved hugely since my original post in October, but I still tend to wake every couple of hours, and sometimes more frequently later in the night. Below is a screen shot from a typical night. You can see that my events are mostly hypopneas and I understand that Devilbiss/Intellipap machines tend to over-report these. But I am concerned about flow limitations, which I believe are waking me, perhaps even more frequently than I recall. And because I get a lot of them, I suspect that they are lowering my O2 saturation somewhat - I still wake up occasionally with a dull headache.

I still have periods of exhale puffing too, but have held of on trying a chin strap or mouth taping, as it doesn't appear to be leading to apneas/hypopneas.

I have a review scheduled with my doctor/consultant next week and I am going to ask her opinion. My own inclination is that I need to increase my minimum pressure to at least 7, maybe 8 and increase the max to maybe 11-12. Would be helpful to get some guidance here first. I don't understand what the index for FL's in the table means either. Is it events per hour? Thanks in advance, Michael.
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MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Sat Jan 15, 2022 11:38 am

Looks like I'm talking to myself then!

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Pugsy
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Re: Flow Limitations - Min Pressure Too Low?

Post by Pugsy » Sat Jan 15, 2022 11:53 am

Sometimes you don't get answers to questions because no one knows an answer.
My main reason....I don't know much about how or why or what criteria the Devilbiss machines does anything especially with flow limitations.

You are using a machine that there are simply not many people using that same machine and we don't have any documentation or experience to drawn upon to answer your questions....and to be honest I don't have the time or desire to go looking for the documentation needed to figure out how DeVilbiss does the FLs. I wish I did but I just don't.

About all we can offer is the usual "more minimum pressure" thing that was already advised for you to try but you decided you wanted to wait until you had a chance to chat with your medical care team.

FWIW....I do think you are correct in that more minimum is needed...up to you when you decide to try it.
Will it fix the problem???? No way to know because that is the Million dollar question but if you don't at least try the most common place idea then you already know the answer and that answer is what you see in front of you right now.
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Miss Emerita
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Re: Flow Limitations - Min Pressure Too Low?

Post by Miss Emerita » Sat Jan 15, 2022 1:06 pm

I googled your machine, and at this site there's a link to a pdf of the manual:

https://www.drivedevilbiss-int.com/prod ... lbiss-blue

Apparently you can set your machine to provide "SmartFlex," which will lower your exhale pressure. I recommend that you try level 2 (of 3) to see how you like it. There are also settings for inhalation and exhalation "flow rounding" that you'd need to set. I don't know what to advise there; the options go from 1 to 5 so maybe 3?? You might try the various flow-rounding settings during the day to see how they feel.

The reason I go into this is that pressure relief can be of some help with flow limitations (and possibly hypopneas). It lowers pressure when you exhale, but by the same token, it increases pressure when you inhale, and that increase can help reduce your flow limitations if they are due to relaxation in the tissues lining your pharynx. Worth a try.

Because you have some obstructive events, I'd recommend increasing your minimum to offset the flex. So increase the minimum from 6 to 8. An additional increase may be warranted, but one thing at a time.

I would also recommend increasing your maximum pressure. You are stuck at the maximum from time to time, and it might be good to give the machine a little more leeway. Nothing dramatic; maybe just start by increasing it to 9.5 to see what happens.

Ideally you could try these settings before your appointment so you can report on the results.
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dataq1
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Re: Flow Limitations - Min Pressure Too Low?

Post by dataq1 » Sat Jan 15, 2022 11:03 pm

While not a direct answer to your question, are you aware of this document from Devilbiss? If it is applicable to your machine, it may provide some insight into the algorithms used by DeVilbiss.
[http://www.devilbisshealthcare.com/file ... T-2089.pdf][/url]

A couple of things caught my eye:
"The DeVilbiss AutoAdjust algorithm uses snore as precursor to apneas and hypopneas. As
mentioned earlier, no clinical studies have found a superior proactive event to preventing obstructive
events.
Page 7
and
"Some manufacturers and many bench-top studies tout the speed with which some devices respond
to events. However, this may not be a viable advantage...There are two reasons for responding less quickly to breathing events: fast response times wake
patients or bring them to partial arousal; and fast response times have a greater percentage of false responses
.." Page 7
and
The definition (and graphic representation) of "snores" Page 8
Regards,

MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Sun Jan 16, 2022 1:56 am

Pugsy wrote:
Sat Jan 15, 2022 11:53 am
Sometimes you don't get answers to questions because no one knows an answer.
My main reason....I don't know much about how or why or what criteria the Devilbiss machines does anything especially with flow limitations.

You are using a machine that there are simply not many people using that same machine and we don't have any documentation or experience to drawn upon to answer your questions....and to be honest I don't have the time or desire to go looking for the documentation needed to figure out how DeVilbiss does the FLs. I wish I did but I just don't.

About all we can offer is the usual "more minimum pressure" thing that was already advised for you to try but you decided you wanted to wait until you had a chance to chat with your medical care team.

FWIW....I do think you are correct in that more minimum is needed...up to you when you decide to try it.
Will it fix the problem???? No way to know because that is the Million dollar question but if you don't at least try the most common place idea then you already know the answer and that answer is what you see in front of you right now.
Thanks Pugsy. Unfortunately, I'm stuck with the Devilbiss machine for another seven months, because it's rented and I signed a 12 month contract. After that, I'm going to get a Resmed by hook or by crook! I re-read all the replies (including yours) to my original post (six weeks into CPAP usage) and I've certainly learnt a lot since then! I didn't even know how to get into the "clinician's menu". Since then I've experimented a bit. I tried Smartflex (EPR) but found it strangely noisy and uncomfortable. I even tried it on ramp only and found it difficult to fall asleep, so I reckon it's just not right for me. I'm fairly sure that I need to get my min pressure up some more, but the problem I have is noise. It's mask noise rather than machine noise in the sense that the machine noise seems to transmit through my head at higher pressures (I wear a Phillips Resperonics Dreamwear mask with nasal pillow - so the air tube comes in at the top of the head). I've narrowed the problem down further over the last couple of nights and am now sure that what happens is that when I turn on my side (I spend more than half the night on one side or other), the tubing on one side compresses, making the noise louder on the other side. Looks like the answer is to either find a similar mask that's a bit more rigid or look at a nasal pillow mask where the tube comes in at the nose. I may need to do this before raising my minimum settings. Anyway, thanks for the feedback. Much appreciated.

MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Sun Jan 16, 2022 2:20 am

Miss Emerita wrote:
Sat Jan 15, 2022 1:06 pm
I googled your machine, and at this site there's a link to a pdf of the manual:

https://www.drivedevilbiss-int.com/prod ... lbiss-blue

Apparently you can set your machine to provide "SmartFlex," which will lower your exhale pressure. I recommend that you try level 2 (of 3) to see how you like it. There are also settings for inhalation and exhalation "flow rounding" that you'd need to set. I don't know what to advise there; the options go from 1 to 5 so maybe 3?? You might try the various flow-rounding settings during the day to see how they feel.

The reason I go into this is that pressure relief can be of some help with flow limitations (and possibly hypopneas). It lowers pressure when you exhale, but by the same token, it increases pressure when you inhale, and that increase can help reduce your flow limitations if they are due to relaxation in the tissues lining your pharynx. Worth a try.

Because you have some obstructive events, I'd recommend increasing your minimum to offset the flex. So increase the minimum from 6 to 8. An additional increase may be warranted, but one thing at a time.

I would also recommend increasing your maximum pressure. You are stuck at the maximum from time to time, and it might be good to give the machine a little more leeway. Nothing dramatic; maybe just start by increasing it to 9.5 to see what happens.

Ideally you could try these settings before your appointment so you can report on the results.
Thanks for the feedback. I have that PDF saved on my computer and am familiar with all the machine settings at this stage. See my reply to Pugsy about Smartflex (EPR). It just doesn't work for me. But I think I definitely need to raise my pressure settings (both min and max). It probably leads into a different topic, but the underlying problem is machine noise being transmitted through the mask. That's why I reduced my max settings. Anytime the pressure went up to more than 9, it kept waking me. And while I managed to get used to a min of 6 (started at 5), that can still cause problems when I lie on my side. I've figured out (just over the last couple of days) that when I lie on my side (I tend to roll over on my right to fall asleep), the mask tubing gets compressed on one side, making the noise louder on the other (it's a Philips Respironics Dreamwear nasal pillow mask - the one with the tube coming in at the top of the head). Maybe I need to try a different style of mask - one where the tube comes in at the nose?

MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Sun Jan 16, 2022 2:33 am

dataq1 wrote:
Sat Jan 15, 2022 11:03 pm
While not a direct answer to your question, are you aware of this document from Devilbiss? If it is applicable to your machine, it may provide some insight into the algorithms used by DeVilbiss.
[http://www.devilbisshealthcare.com/file ... T-2089.pdf][/url]

A couple of things caught my eye:
"The DeVilbiss AutoAdjust algorithm uses snore as precursor to apneas and hypopneas. As
mentioned earlier, no clinical studies have found a superior proactive event to preventing obstructive
events.
Page 7
and
"Some manufacturers and many bench-top studies tout the speed with which some devices respond
to events. However, this may not be a viable advantage...There are two reasons for responding less quickly to breathing events: fast response times wake
patients or bring them to partial arousal; and fast response times have a greater percentage of false responses
.." Page 7
and
The definition (and graphic representation) of "snores" Page 8
Regards,
Thanks Bob. I have that PDF file saved on my computer. I've managed to educate myself a lot over the last 4-5 months and perhaps got a little too pre-occupied with the technical stuff (you know I have an engineering background), because the funny thing is I think I've just sort of stumbled upon the underlying problem and probable solution. I've always considered my machine (Devilbiss) to be noisy (even though my wife barely hears it), even though they are considered to be among the quietest, and that has restrained me from increasing my pressure settings. Looks like it's really a mask problem. I wear a Respironics Dreamwear nasal pillow mask; the one where the tube comes in at the top of the head. The problem with it is that when I lie on my side, the mask tubing gets compressed between my face and the pillow (it's very soft/flexible) diverting all the air flow one side, and that creates the noise. It's not air escape, more the sound of the air flowing through the tubing. So I'm considering purchasing a different mask style, where the tube comes in at the nose. Going to discuss it with my consultant next Thursday, before proceeding. Cheers, Michael

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Miss Emerita
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Re: Flow Limitations - Min Pressure Too Low?

Post by Miss Emerita » Sun Jan 16, 2022 12:28 pm

Michael, like you, I couldn't stand that mask because of the noise of the air moving through the tubes that crossed my face. A couple of ideas.

You could use an "at-the-nose" mask along with a hose lift (aka hose stand). The Hose Buddy is very sturdy; the Houdini is not so sturdy but swivels beautifully and tucks behind a pillow sham during the day.

Using a fleecy hose cover can cut down on noise somewhat and makes the hose more comfortable if you're routing it across your body.

The Aloha mask -- which I used before switching to the Bleep -- routes the short hose up through a loop on the strap that goes across the top of your head. I benefited from using Pad-A-Cheek strap covers for the Aloha, just for comfort and fewer marks on my face in the morning.
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Pugsy
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Re: Flow Limitations - Min Pressure Too Low?

Post by Pugsy » Sun Jan 16, 2022 12:46 pm

MMcG wrote:
Sun Jan 16, 2022 2:20 am
Anytime the pressure went up to more than 9, it kept waking me
I see this statement all the time. People blame the pressure increase for the wake up and they never consider that the reason the pressure went up (airway flow reduction from some sort of apnea event) might actually be the cause of the wake up and not necessarily the pressure increase itself. Pressure changes themselves are extremely slow but what happens in the airway with the apnea event doesn't happen so slow. It's much more abrupt.
So what do people do...they limit the pressure from going up and trying to prevent the next airway issue instead of increasing the minimum pressure in an effort to better prevent the airway issue from ever happening in the first place.
They set themselves up for not getting effective therapy and not solving the wake up problem.

The machine increases the pressure (or tries to) for a reason. When you stop it from doing its job by limiting the max...you aren't going to fix the very reason the machine wanted to go up in pressure in the first place.
The best solution is an increase in minimum pressure to better try to prevent the collapse of the airway from ever happening in the first place. Often when people will do this the machine ends up not needing or wanting to go to that higher pressure anyway.

These machines can't/won't increase the pressure to what might be needed in the blink of an eye. They just can't.
So sometimes we just have to give them a better head start to holding the airway open better and preventing the collapse from ever happening or at least limiting the number of collapses.
Mask: Bleep no headgear mask.. https://bleepsleep.com/
Machine: AirCurve 10 VAuto

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MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Mon Jan 17, 2022 5:50 am

Miss Emerita wrote:
Sun Jan 16, 2022 12:28 pm
Michael, like you, I couldn't stand that mask because of the noise of the air moving through the tubes that crossed my face. A couple of ideas.

You could use an "at-the-nose" mask along with a hose lift (aka hose stand). The Hose Buddy is very sturdy; the Houdini is not so sturdy but swivels beautifully and tucks behind a pillow sham during the day.

Using a fleecy hose cover can cut down on noise somewhat and makes the hose more comfortable if you're routing it across your body.

The Aloha mask -- which I used before switching to the Bleep -- routes the short hose up through a loop on the strap that goes across the top of your head. I benefited from using Pad-A-Cheek strap covers for the Aloha, just for comfort and fewer marks on my face in the morning.
I looked up both of those masks just now. I like the idea of the Bleep, except that I expect the prongs would irritate my nostrils (very sensitive). So what I'm giving serious consideration to is an AirFit N30 Nasal Cradle mask. The tube also attaches at the nose and there is just a very minimal strap around the back of the head. I've seen mixed reviews though - people either love it or hate it. But I think it's worth a try.

MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Mon Jan 17, 2022 6:04 am

Pugsy wrote:
Sun Jan 16, 2022 12:46 pm
MMcG wrote:
Sun Jan 16, 2022 2:20 am
Anytime the pressure went up to more than 9, it kept waking me
I see this statement all the time. People blame the pressure increase for the wake up and they never consider that the reason the pressure went up (airway flow reduction from some sort of apnea event) might actually be the cause of the wake up and not necessarily the pressure increase itself. Pressure changes themselves are extremely slow but what happens in the airway with the apnea event doesn't happen so slow. It's much more abrupt.
So what do people do...they limit the pressure from going up and trying to prevent the next airway issue instead of increasing the minimum pressure in an effort to better prevent the airway issue from ever happening in the first place.
They set themselves up for not getting effective therapy and not solving the wake up problem.

The machine increases the pressure (or tries to) for a reason. When you stop it from doing its job by limiting the max...you aren't going to fix the very reason the machine wanted to go up in pressure in the first place.
The best solution is an increase in minimum pressure to better try to prevent the collapse of the airway from ever happening in the first place. Often when people will do this the machine ends up not needing or wanting to go to that higher pressure anyway.

These machines can't/won't increase the pressure to what might be needed in the blink of an eye. They just can't.
So sometimes we just have to give them a better head start to holding the airway open better and preventing the collapse from ever happening or at least limiting the number of collapses.
I hear you, Pugsy. But I just don't trust my Devilbiss machine and I guess I'm stuck with it unless I can get out of the 12 month contract I signed some five months ago. Why don't I trust it? Well for one thing the pressure can rise pretty quickly and for no apparent reason. I woke yesterday morning at 5-40 am and struggled to get back to sleep. I had it on twenty minutes ramp and, when it ended at 6-00 am, the machine went from 6 to 8.5 in six minutes while I was awake. Oscar showed that my machine recorded two hypopneas (both false flags anyway) and responded to those, even though I think it's not supposed to respond to hypopneas and apneas. I'm planning to try a Resmed AirFit N30 Nasal Cradle mask to reduce noise - it's compatible with my Devilbiss machine - and I'll still be able to use it when I eventually switch to Resmed which I plan to do sooner or later. When I resolve the noise issue, I think I can make some pressure changes without affecting my sleep.

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Pugsy
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Re: Flow Limitations - Min Pressure Too Low?

Post by Pugsy » Mon Jan 17, 2022 7:46 am

MMcG wrote:
Mon Jan 17, 2022 6:04 am
6 to 8.5 in six minutes
I guess speed is relative...2 1/2 cm in 6 minutes isn't fast at all.
There are machines that will go up 10 cm within ONE breath. Now that is fast.
MMcG wrote:
Mon Jan 17, 2022 5:50 am
I like the idea of the Bleep, except that I expect the prongs would irritate my nostrils (very sensitive)
Nothing goes inside your nostrils with the Bleep. There are no prongs. Those little plastic thingies hang down outside the nostrils.

But you might like the N30. I am giving it a try now just for the fun of it and it's a nice little mask. Sure wouldn't replace the Bleep or the P10 but it's a nice little mask.
For my experience with it....it's not as stable as I would like at the tension I prefer but it's pretty forgiving if someone wants to crank it down in terms of tension and doesn't hurt the nose. Will be doing a review on it shortly.
Mask: Bleep no headgear mask.. https://bleepsleep.com/
Machine: AirCurve 10 VAuto

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MMcG
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Re: Flow Limitations - Min Pressure Too Low?

Post by MMcG » Mon Jan 17, 2022 10:52 am

Pugsy wrote:
Mon Jan 17, 2022 7:46 am
MMcG wrote:
Mon Jan 17, 2022 6:04 am
6 to 8.5 in six minutes
I guess speed is relative...2 1/2 cm in 6 minutes isn't fast at all.
There are machines that will go up 10 cm within ONE breath. Now that is fast.
MMcG wrote:
Mon Jan 17, 2022 5:50 am
I like the idea of the Bleep, except that I expect the prongs would irritate my nostrils (very sensitive)
Nothing goes inside your nostrils with the Bleep. There are no prongs. Those little plastic thingies hang down outside the nostrils.

But you might like the N30. I am giving it a try now just for the fun of it and it's a nice little mask. Sure wouldn't replace the Bleep or the P10 but it's a nice little mask.
For my experience with it....it's not as stable as I would like at the tension I prefer but it's pretty forgiving if someone wants to crank it down in terms of tension and doesn't hurt the nose. Will be doing a review on it shortly.
It doesn't usually respond that fast though and while 8.5 wouldn't usually wake me, it most certainly would stop me getting to sleep right now, because of mask noise, especially if sleeping on my side. I think what happens is that the tubing (the mask frame) compresses under the weight of my head on one side, thus diverting nearly all the air to the other side. Then the machine responds immediately by nearly doubling the fan speed (to maintain the delivered pressure). That's what it sounds like anyway. It might just be that my Respironics Dreamwear nasal pillow mask is especially soft and pliable compared to other brands that might be more rigid. But I don't want to waste money finding out. So that's why I'm leaning towards something like the N30. But maybe the P10 would work too, now that I know those prongs don't go up the nose! It looks more sturdy than the N30 anyway.

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Pugsy
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Re: Flow Limitations - Min Pressure Too Low?

Post by Pugsy » Mon Jan 17, 2022 11:03 am

See my newly posted review of the N30...I talk a little bit about the P10.

The Bleep doesn't have prongs. Nothing at all goes inside the nostril

The P10 has little soft inner cones that barely go inside the nostril BUT THEY SHOULDN'T be touching anything inside the nostrils at all. If they do...wrong size or improperly fitted.
The bulk of the P10 nasal pillow is supposed to rest GENTLY on the nostril and the tiny tip of the cone sits barely inside the nostril not touching a thing.

Now there is a real "prong" mask...there's a difference between pillows and prongs so make sure you use correct terms. :lol:

https://www.cpap.com/productpage/innome ... l-size-kit

This sucker does go way up in the nostril and touches all the insides of the nostril.
prongs.PNG
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Mask: Bleep no headgear mask.. https://bleepsleep.com/
Machine: AirCurve 10 VAuto

I may have to RISE but I refuse to SHINE.