Significance of flow limitations

[puglover333]

I'm curious about the significance of flow limitations. I'm new to CPAP (almost a month now). My machine is set to APAP 5-20 (I know from reading on here that that's not the best setting, but I figured I give it some time and collect some data before tampering with it). My AHI has been great, almost from the first night. I feel marginally better, but still am significantly fatigued during the day. I'm using sleepyhead and notice that I seem to have a lot of flow limitations. I've tried searching through some threads, but it is very confusing.

[Pugsy]

Your flow limitation graph is a bit what I call "active" but it isn't horribly horrible. I have seen much worse. I have seen better...my own FL graphs are extremely boring. Pretty much textbook "no flow limitation" examples.

Flow limitations are something the machine will try to fight because they are generally thought of as an early warning sign that the airway is trying to collapse. The air flow has reduced but either isn't reduced enough to earn an apnea even flag of some sort or it doesn't last long enough. Depending on the brand the reduction has to be either at least 40 or 50 % and with both brands it has to last at least 10 seconds to get some sort of apnea flag. In your case with your low AHI it isn't progressing enough to earn an apnea event flag.

Now sometimes the flow limitations aren't necessarily related to the airway trying to collapse but the machine may not know that. All it does is measure air flow...it doesn't always figure out the reason for the reduced flow.
Do you experience very much nasal congestion? If you do then some of the flow limitations you see on the FL graph could be related to nasal congestion which isn't sleep apnea reduction in air flow.
OSA is from the airway down from the nose collapsing...OSA is not the reduce flow that occurs because the nasal mucosa is swollen and causing congestion and the congestion is causing the reduced air flow.

Unfortunately all the machine knows is reduced air flow and records and responds accordingly.

Sometimes the flow limitations need to be dealt with and sometimes they don't and sometimes even if they need to be dealt with the dealing with them causes more problems than the flow limitations cause.

If you aren't feeling the good numbers in the manner you want you get my first usual speech and questions in this situation.
1. The nasal congestion question
2. Do you wake up frequently during the night for any reason and if you do any idea why?
3. Do you take any medications and if you do what are they?
4. Do you have any other health condition that might impact how you feel or your sleep quality? Pain/arthritis/or whatever?
5. Do you notice the pressure changes during the night for any reason?
We start there and do a little detective work with maybe more questions depending on the answers to these questions.

Now your pressure settings are fine in terms of keeping the AHI low...they may or may not be fine for more subtle reasons.
We don't know if your flow limitations are causing poor sleep quality or are even remotely related to your not feeling the good numbers.
It may be that you just need more time to feel the good numbers. It took me months to sleep better and feel better in general despite getting my therapy optimized fairly quickly. I had 2 main symptoms of sleep apnea pretty much go away immediately (nocturia and killer morning headaches) but the other usual symptoms were a lot slower in reducing.

So while it may be just that you need more time...there's no reason you can't at least try to see if you can do anything to make things better while giving it time. You gotta use the machine anyway but that doesn't stop you from seeing what you could maybe do to speed up things.

Flow limitations are usually dealt with by increasing the pressure...in your situation increasing the minimum.
If the changing pressures aren't causing wake ups...leave the maximum alone...doesn't hurt a thing and doesn't change the way the machine responds. It won't go anywhere it doesn't think it needs to go.
If the changing pressures seem to bug you then we have a little different discussion about that maximum.

I don't know how much more pressure you might need to deal with the FLs. We never know..sometimes it's a little, sometimes it's a lot and sometimes the little buggers simply won't respond at all.
About all we can do is try and see what happens.
If you aren't comfortable with changing things on your own then get your medical care team involved but I guarantee you that they will say nothing needs to be changed because they will look at AHI and maybe leak and that's it.

Depending on your answers to the above I will likely have some additional thoughts.

[puglover333]

If you aren't feeling the good numbers in the manner you want you get my first usual speech and questions in this situation.
1. The nasal congestion question
Yes, I always seem to have some degree of nasal congestion. Almost never enough that I it occludes breathing to the point I have to resort to mouth breathing though.
2. Do you wake up frequently during the night for any reason and if you do any idea why?
Before starting therapy, I rarely woke up at night. I occasionally make a restroom trip, but that's it. Since starting, I do have more wake ups. They are related to mask leak or getting tangled in the hose.
3. Do you take any medications and if you do what are they?
I only take a couple. I take synthroid for my thyroid and Nexium for reflux.
4. Do you have any other health condition that might impact how you feel or your sleep quality? Pain/arthritis/or whatever?
I do sometimes get lower back pain if I end up on my back for too long of a time, but that's been for ages - nothing new.
5. Do you notice the pressure changes during the night for any reason?
Other than the first couple of nights, no I haven't noticed the pressure changes.
We start there and do a little detective work with maybe more questions depending on the answers to these questions.

[Pugsy]

Have your bathroom breaks reduced or ceased with cpap therapy?
Pre cpap were the bathroom breaks...oh well I am awake I might as well go pee or was it ...OMG my bladder is going to burst I gotta go pee right now?

[avi123]

I only take a couple. I take synthroid for my thyroid and Nexium for reflux.

If you take Synthroid it means that you suffer from Hypothyroid Hashimoto's disease. This is an underlying medical ailment that a CPAP does not treat. It could be behind your flow limitations.

Google: Hashimoto's and Sleep Apnea syndrome.
BTW, I would seek to be checked by a Thyroid Endocrinologist MD. Google this line for your local. They are located every where. I was treated by one.

If you treat your Hashimoto optimally then those FL should reduce.

[palerider]

Flow limitations are bad for two reasons, one, as pugsy says, they're a sign of a narrowed airway, and are seen as precursors of apnea/hypopneas.

But, just as important, they also increase the effort of breathing, and that increased effort can tire you out, try breathing through a straw for a while, you can do it, but it takes more effort to get the air into your lungs, you're still getting a lungful of air (so no hypopnea, but it takes more work) now imagine doing it all night long. raised pressure opens up the straw and makes it easier to breath.

you need to get off the near default settings and raise your minimum.

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

[puglover333]

Have your bathroom breaks reduced or ceased with cpap therapy?
Pre cpap were the bathroom breaks...oh well I am awake I might as well go pee or was it ...OMG my bladder is going to burst I gotta go pee right now?

They have reduced. I think it was a combo of I'm kinda awake and kinda gotta go. Don't remember waking up thinking OMG I gotta go!!

[puglover333]

I only take a couple. I take synthroid for my thyroid and Nexium for reflux.

If you take Synthroid it means that you suffer from Hypothyroid Hashimoto disease. This is an underlying medical ailment that a CPAP does not treat. It could be behind your flow limitations.

Google: Hashimoto's and Sleep Apnea syndrome.

If you treat your Hashimoto optimally then those FL should reduce.

I have not had the workup to decipher if my hypothyroidism is in fact Hashimoto disease. My number were very mild and responded quite well to low dose synthroid.

[Pugsy]

I have only seen one person that I know had documented flow limitation problems secondary to thyroid disease.
Doesn't mean there aren't more out there that I haven't seem but it sure isn't very common at all. From what I have read it usually involves a very much enlarged thyroid.

Frequent urination is a common symptom of OSA...if you think yours has reduced then that's a sign that probably the OSA is being well treated at least in terms of reducing the cause of the nocturia (which is related to some stress hormones that are no longer flooding through your body). So that's good news.

Anytime our sleep is interrupted for any reason it messes with sleep architecture so that the necessary sleep stages don't progress like they need to and we don't get the right proportion in each stage that is needed for the restorative powers of sleep to work their magic.
So your fragmented sleep is probably a factor in not feeling so great yet. With time and experience the issues with the mask and leaks should diminish and at this that potential sleep disturbing factor will not be such a problem.

Now about the flow limitations...they could also be playing a factor in less than optimal sleep quality which might in turn affect how you feel during the day.
So since there is potentially some room for improvement showing up on the FL graph it's worth looking at trying to reduce the FLs to see if it helps or not with how you are feeling in general.

I can't promise that they will reduce with more pressure and if they do I can't promise that you will feel better but you never know till you try and it's sure worth trying.

[avi123]

I had some flow limitation indication for years. Here is an example from 2014:
All are ResScan charts.


My Auto CPAP is set at a min of 7 and max of 12.
EPR is 3.
Looking at the pressure graph it did not try to raise the pressure above 10 at any time. I don't think that changing pressures would reduce the FL values.

But there were other members of this website who had FL values twice as high as my. Let me see if I have their charts on Photobucket.
This one could have been me:


I don't have any mouth or nose malformation. But I wear upper and lower removable dentures. The FL graph seems to differ if I sleep without any of these dentures.

[Pugsy]

Avi...sometimes it's not the raising of the pressure by the machine in auto mode that is the trick to dealing with Flow limitations...sometimes it's raising the minimum which is the key...more minimum holds the airway open better and thus can hopefully prevent the FLs in the first place.
So..sometimes it's easier to prevent them from happening in the first place than it is to fix after the fact.
Finally..some FLs won't respond to more pressure in any form...we don't know why. It just happens.

[palerider]

Finally..some FLs won't respond to more pressure in any form...we don't know why. It just happens.

depends on whether they're caused by soft tissue issues or something else, like nasal structure problems, would be my guess.

[puglover333]

How quickly would you recommend upping the lower pressure?

[Pugsy]

How quickly would you recommend upping the lower pressure?

As in right now or later to make a change?
Are you comfortable with doing it yourself and understand what you are trying to accomplish?
Do do it just because so so on the internet said you should.
Do it because you understand the "why" behind the recommendation behind the suggestion and are comfortable doing it.
I prefer you make a well educated choice and not be blindly following suggestions without a clue what you are trying to do. That's why I tend to write some novels and ask a lot of questions...get you to thinking and learning while I get a bit of history which helps me come up with my ideas.

If it were me...and I understood what I was trying to accomplish then I would do it tonight.
You've given it a month (wasn't it?) and things likely aren't going to change much after this length of time.

[puglover333]

How quickly would you recommend upping the lower pressure?

As in right now or later to make a change?
Are you comfortable with doing it yourself and understand what you are trying to accomplish?
Do do it just because so so on the internet said you should.
Do it because you understand the "why" behind the recommendation behind the suggestion and are comfortable doing it.
I prefer you make a well educated choice and not be blindly following suggestions without a clue what you are trying to do. That's why I tend to write some novels and ask a lot of questions...get you to thinking and learning while I get a bit of history which helps me come up with my ideas.

If it were me...and I understood what I was trying to accomplish then I would do it tonight.
You've given it a month (wasn't it?) and things likely aren't going to change much after this length of time.

My understanding - Its possible that the flow limitations are causing me to rouse and disturbing my sleep. Its possible that by raising the pressures, I could lower the flow limitations. Its also possible that the higher pressures will disturb my sleep as well - replacing one disturbance for another. Its also possible that I haven't given it enough time, and it takes a while for the body to fully recover from so many years of bad sleep.

Sound about right?

I've got my follow up with the pulmonologist next week. I was going to talk to him and get his opinion as well before I started monkeying with the pressures.