Flow limitations – how much is too much?

I've been on AutoCPAP now for a little over a month, and although some symptoms are better I'm definitely still fatigued and not getting more energy. After the wonderful help of many people on this site, I'm in the middle of slowly bringing my minimum pressure up, although it's now at 7.8 and the machine spends most of it's time at 8.5 a 9.5, so I'm not far from where it wants to be. After reading a lot of information here about arousals possibly caused by flow limitations, I have two questions:

1- Flow Limitations: how much is considered too much, or is that dependent on the person? Looking at my stats on sleepyhead, I see a lot of flow limitations throughout the night and they are usually from .25 -.50, although they can occasionally go up to .75.

2- When my machine was on auto CPAP for her, I have more flow limitations then when it was just on auto CPAP. I assume then that I should change it back to a regular AutoCPAP? I wasn't necessarily feeling better, but that was in the very beginning of treatment. Seems I should assume that if I have less flow limitations I am going to feel better?

Thanks as always for whatever help you can provide.

SleepCatz wrote:I've been on AutoCPAP now for a little over a month, and although some symptoms are better I'm definitely still fatigued and not getting more energy. After the wonderful help of many people on this site, I'm in the middle of slowly bringing my minimum pressure up, although it's now at 7.8 and the machine spends most of it's time at 8.5 a 9.5, so I'm not far from where it wants to be. After reading a lot of information here about arousals possibly caused by flow limitations, I have two questions:

1- Flow Limitations: how much is considered too much, or is that dependent on the person? Looking at my stats on sleepyhead, I see a lot of flow limitations throughout the night and they are usually from .25 -.50, although they can occasionally go up to .75.

2- When my machine was on auto CPAP for her, I have more flow limitations then when it was just on auto CPAP. I assume then that I should change it back to a regular AutoCPAP? I wasn't necessarily feeling better, but that was in the very beginning of treatment. Seems I should assume that if I have less flow limitations I am going to feel better?

Thanks as always for whatever help you can provide.

If you're getting lots of Flow Limitations (or even a few), they could be really messing with your sleep architecture by bumping you out of the needed sleep stages. When you enter deeper or REM stage sleep, your breathing may change and there may be more flow limitations (or snores). That triggers the machine to increase pressures which may bump you out of the needed sleep stages and into lighter ones. So, even if you have "good" numbers, you may be spending more time in lighter sleep stages and thus feeling less rested.
Even the pressure increases could possibly increase the number of flow limitations. It doesn't take much of a change in the breathing "curve" (shape) that APAP machines interpret as flow limitations. So, if the person's reflex reaction to a pressure increase triggers more of what the machine interprets as flow limitations, it could possibly lead to somewhat of a cycle that can only stop when the maximum pressure is reached.......or the users hits the button on the machine to take the pressure lower again.


Den

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Thanks for the info. So are you saying that there should be few, or almost no flow limitations? I thought flow limitations were natural in someone with SA and was what was telling machine how to work, but if Inunderstand you many people's graphs have few or no flow limitations?

And I should add- should I assume the correction for that is higher pressure? Or a constant pressure as opposed to a range of pressures in Auto mode.

SleepCatz wrote:Thanks for the info. So are you saying that there should be few, or almost no flow limitations? I thought flow limitations were natural in someone with SA and was what was telling machine how to work, but if Inunderstand you many people's graphs have few or no flow limitations?

It's very individual to each person's breathing characteristics. Some people have none, some have a few and some have lots. Someone with UARS would probably have many.

Mine are somewhat fewer but sporadic from night to night. And, for me personally, I don't want my machine chasing them so I choose to use a fixed pressure that will take care of almost all of my events (which are few anyway). I don't believe a few flow limitations are a big deal that need to be squelched by higher pressures, and they're not always a precursor to or predictor of apneas.

But, the bottom line is.......if someone is using an APAP in a range of pressures and it's chasing flow limitations and/or snores, AND........that user is feeling unrested, study the reports and see if it points to a problem in that regard.


Den

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I never have very much in the way of flow limitations.
Compare yours to mine. Yes, usually more pressure is what is needed to reduce the flow limitations as long as they aren't in the nose. If you have a lot of nasal congestion then it is possible that the FLs are from nasal congestion and more pressure is unlikely to help.

Wow, Pugsy, my graph looks like a blood bath in comparison. I am trying to post a screen shot and am not able to paste it into my reply, will keep trying. And no, I am almost never congested, so that is not the issue.

I use imgur to host my images as it is less annoying than Photobucket.
Here's how
https://sleep.tnet.com/reference/tips/imgur

If your FLs are really ugly then likely more minimum pressure is needed and you might need a little more beyond what normally gives you a nice low AHI. FLs may or may not be part of you're not feeling so great but if yours are real ugly...sure wouldn't hurt to try to kill some of them and see if it helps or not.

Okay, hopefully this works - http://i.imgur.com/BQYIv0V.png

SleepCatz wrote:And I should add- should I assume the correction for that is higher pressure? Or a constant pressure as opposed to a range of pressures in Auto mode.

Yes, no, maybe.......

If you have lots of them (sounds like it) and they (or the ensuing pressure increases) are disturbing your sleep (possibly), if increased pressure doesn't squash them, then straight pressure would be my recommendation.


Den

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SleepCatz wrote:I've been on AutoCPAP now for a little over a month, and although some symptoms are better I'm definitely still fatigued and not getting more energy. After the wonderful help of many people on this site, I'm in the middle of slowly bringing my minimum pressure up, although it's now at 7.8 and the machine spends most of it's time at 8.5 a 9.5, so I'm not far from where it wants to be. After reading a lot of information here about arousals possibly caused by flow limitations, I have two questions:

1- Flow Limitations: how much is considered too much, or is that dependent on the person? Looking at my stats on sleepyhead, I see a lot of flow limitations throughout the night and they are usually from .25 -.50, although they can occasionally go up to .75.

2- When my machine was on auto CPAP for her, I have more flow limitations then when it was just on auto CPAP. I assume then that I should change it back to a regular AutoCPAP? I wasn't necessarily feeling better, but that was in the very beginning of treatment. Seems I should assume that if I have less flow limitations I am going to feel better?

Thanks as always for whatever help you can provide.

I've asked this question a lot. Like most things xPap, it seems the answer is an individual matter. Members have posted they didn't feel better until hammering them out as much as possible. Others sleep and feel fine with some pretty heavy numbers. The following post discusses it a bit with some points to research on the subject.

viewtopic.php?f=1&t=100447&st=0&sk=t&sd ... n&start=15

I found it interesting in some of that research that flow limitations are present in folks without sleep disordered breathing. If you look at the charts, all limitation shapes are present in the subjects. It's just the frequency of type that varies. The sleep field recognizes a "Rera" by a pretty defined criteria. As mentioned, the machines can only make a guess on what needs to be addressed. Thus, they respond to most everything to my understanding. This doesn't mean much to us if either a benign limitation or the resulting pressure response disturbs sleep as Den mentions . We are left to just our best guesses and experimenting unless we have a really good sleep study with a really good interactive review by the right person. You may as much success in finding the right person here to look at your data as finding that really good professional in the field. I've always thought that the designers of the algorithms could really dig into our data constructively. In a perfect world, they could probably design a custom algorithm for a specific user's unique condition. There's a post by Mollette in the stickies that links titration guidelines. I think it's really a great read when on this subject.

I kind of go by logic and deductive reasoning. In my case, I know I don't feel as good as I should even though my numbers, including flow limitations (95%<.01), look good. I also know that I felt half decent before OSA got a quick grip on me. Now, with therapy and the help of those here, I know that I have reduced events by well over 90%, eliminated snoring, incredibly reduced flow limitations from my pre-therapy snoring/apnea monster, and just by deduction should also have reduced Rera's by a close percentage to the event number. Thus, I kind of figure that it may well be something else that is at play and causing me to react (arouse/awaken) to rather benign things in sleep and therapy. Of course, this is just today's theory, and I'm still trying different things related to therapy just in case I have the revelation.

I certainly welcome discussion on this subject and the technical aspects of treatment. I applaud you for digging deeply and hope it serves you well.

Best,

Mike

SleepCatz wrote:Okay, hopefully this works - http://i.imgur.com/BQYIv0V.png

It's difficult to say, but those may be a "self-feeding" situation.........some FLs lead to more pressure which leads to more FLs.

My suggestion would be straight pressure at around 9 cm. and see what things look like. You apparently aren't having many/any "events" that they may be preceding and so there's no use in chasing them. SOME FLs may be slightly detrimental to sufficient oxygen quantity, but one of the things I was looking at is where your pressure line is in relationship to where your FLs are fewer or non-existent. When the pressures are climbing, the FLs are more abundant.


Den

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I've never understood what "rera" is or means. any help?

Oh that's not horribly horrible...I have seen much worse.

If you look at your pressure graph and the flow limitation graph you can see where the machine wanted to try to do something with that particularly dense cluster early in the night and then things sort of back off and aren't quite so ugly.

Do you sleep much on your back?

Your AHI is nice and low.
Flow limitations are something the machine will respond to in an effort to make them not happen.
It's part of the machine's job and algorithm when in APAP mode.

Couple of things to remember...it could be the pressure changes maybe disrupting sleep when the machine is trying to get a better handle on the FLs ....and it could also be that the FLs themselves are disturbing your sleep. We don't have anyway to know for sure so about all we can do is maybe try to reduce the FLs and see if you start feeling better...if those FLs are responsible for not feeling the otherwise good numbers.
You may be like Den is and find that variations in pressure are themselves a disturbing factor in terms of sleep quality. He does better with fixed pressures. Me...I sleep through some massive changes and doesn't seem to bother me and I prefer that option to using a fixed higher pressure because it would have to fixed really high and I only need higher pressures in REM stage sleep.

Your first ugly cluster looks to be too soon in in the night for REM sleep but it wouldn't be impossible.
My first suspect would be sleeping on your back maybe making things worse and the need for more pressure.

My personal opinion about FLs...there's a reason that they are part of any apap algorithm so I don't ignore them.

Good food for thought, lots of information to take into consideration. I generally DON'T sleep on my back, but I have been known to roll on my back in a deep sleep. I doubt that would happen in the beginning of the night though. There are some nights that I wake up in the exact same position on my side as I've gone to sleep, so I don't think back sleeping is a big factor here. I can certainly try to prevent back sleeping with a pillow or something. I changed my auto Pap for her to a regular auto Pap tonight, since I seem to have fewer flow limitations when I had the original AutoCPAP machine that did have the For Her, although I Had a wider hose with that one too, but will definitely be adjusting the pressure in subsequent nights ( I hate to change more than one thing at a time because then you never know what actually worked) to try to address this. Any other suggestions are always welcome!