UARS, Flow Limit, and Flow Rate graphs

NotLazy, b/c you're using a Resmed machine you get in your data the degree of your Flow Limitation. The machine does it automatically by analyzing your respiration wave shape:

(It measaures the difference between a normal round wave and your flat top wave and gives it a level index between zero and one and that what you see in the Flow Limitation graph. Zero is good and one is bad)



So if your Flow Limitation is as bad as in this case:




Then I would look for a Sleep Clinic that could do UARS measurements with tools like these:

(as Dr Barry Krakow suggested in my above link)

http://journal.publications.chestnet.or ... sueno=2#f2

But, there is not much that you could do to cure UARS except using CPAP or AutoCPAP and hope that it will work and the side effects will away after several years.

blueh2o wrote:Of course, yesterday after reading your post I immediately went home to SleepyHead and starting studying my flow shapes. Regarding "Analysis of the Flow Shapes", I find it interesting that my shapes somewhat mirror those of the women (I'm OK with my masculinity) with my shapes being primarily composed of Class 6, secondarily of Class 2, and thirdly of Class 7. The authors assume that the women's flow shape has some correlation with postmenopausal levels of progesterone. I would argue and say this subset of women are most likely to be diagnosed with UARS and thus the similarities to my flow shapes.
Having said all that, it also occurs to me that you need to have some experience studying flow shapes to be able to come to any sort of reasonable conclusions and it appears this is a relatively new part of sleep medicine science. So, you can throw everything I just said out the door because I have no idea what I'm talking about.

I hear ya and feel the same way. Problem is, you would really need to look at a very large set of flows to come to any sort of conclusion, and probably need to do that over several nights data to get anything significant. Without software, like the pattern generator this study used, it would be a very tedious task. I sure hope we see more research in this area as I feel that will drive the CPAP manufacturers to develop algorithms specifically designed to eliminate more flow limit based arousals. But like you said, what do I know?

This may be heresy on this forum, but sometimes I almost feel sorry for sleep doctors (well, not the lazy, money grubbing ones ). The reason is that all these sleep issues we've touched upon are extremely amorphous and threshold challenging. Almost once a month someone posts a sleep doctor's new theory or paper in publication. And all the acronyms!!! Yikes, brain fatigue. Also, who do you believe? I mean, sample studies with nine people... they'd laugh that out of all the statistics classes I've taken.

When I first started reading this thread, my first thought was: Oh great, more sleep stuff to study and ultimately to worry about. Not to diminish the great contributions of people like SWS et al, none-the-less I'm feeling very small in a big sleepy universe. Frankly, I don't think most of the sleep doctors (those with any integrity anyway) or faithful techs feel much better Just my thoughts after a bad night.

NotLazy, b/c you're using a Resmed machine you can get in your data the degree of your Flow Limitation. The machine does it automatically by analyzing your respiration wave shape:

(It measaures the difference between a normal round wave and your flat top wave and gives it a level index between zero and one and that what you see in the Flow Limitation graph. Zero is good and one is bad)



So if your Flow Limitation is as bad as in this case:




Then I would look for a Sleep Clinic that could do UARS measurements with tools like these:

(as Dr Barry Krakow suggested in my above link)

http://journal.publications.chestnet.or ... sueno=2#f2

But, there is not much that you could do to cure UARS except using CPAP or AutoCPAP and hope that it will work and the side effects will go away after several years.

As a matter of fact, I doubt it if Medicare would pay the expenses if I asked a local sleep clinic to check my FL (including UARS, and RERAS):

http://www.bcbsnc.com/assets/services/p ... ndrome.pdf

Sir NoddinOff wrote:This may be heresy on this forum, but sometimes I almost feel sorry for sleep doctors (well, not the lazy, money grubbing ones ). The reason is that all these sleep issues we've touched upon are extremely amorphous and threshold challenging. Almost once a month someone posts a sleep doctor's new theory or paper in publication. And all the acronyms!!! Yikes, brain fatigue. Also, who do you believe? I mean, sample studies with nine people... they'd laugh that out of all the statistics classes I've taken.

When I first started reading this thread, my first thought was: Oh great, more sleep stuff to study and ultimately to worry about. Not to diminish the great contributions of people like SWS et al, none-the-less I'm feeling very small in a big sleepy universe. Frankly, I don't think most of the sleep doctors (those with any integrity anyway) or faithful techs feel much better Just my thoughts after a bad night.

I think I understand where you are coming from. You know in a perfect world, we the patients wouldn't have to know any of this stuff. We would just go to the doctor and he would say, "You have X. Here's a prescription for Y." and you would be cured. Unfortunately medical science hasn't advanced that far. But looking on the positive side, there is a whole lot more technology for us now than there was for OSA patients 20 years ago! Let's be thankful for that!

49er wrote: I do have a different take on what Krakow is doing. Just because no one else in sleep medicine is doing what he is doing doesn't mean it isn't legitimate.

I agree with that, 49er. I don't think we ever had a different take on that.

However, Krakow's work with higher-than-usual PS is experimental at this point. Last I checked there was no published empiricism, peer review, or replication to give the medical community a sense of patient outcome. I'm not harping on that since good research can take years. Because his PS work is unpublished, we have no sense of how well or poorly his techniques work across a target population. I do know those huge PS values are guaranteed to introduce aerophagia and central apneas to some of the patients.

That said, Krakow's experimental PS protocol is one that I would personally consider trying if I had residual FL and standard treatment protocols could not resolve my EDS.

-SWS wrote:

49er wrote: I do have a different take on what Krakow is doing. Just because no one else in sleep medicine is doing what he is doing doesn't mean it isn't legitimate.

I agree with that, 49er. I don't think we ever had a different take on that.

However, Krakow's work with higher-than-usual PS is experimental at this point. Last I checked there was no published empiricism, peer review, or replication to give the medical community a sense of patient outcome. I'm not harping on that since good research can take years. Because his PS work is unpublished, we have no sense of how well or poorly his techniques work across a target population. I do know those huge PS values are guaranteed to introduce aerophagia and central apneas to some of the patients.

That said, Krakow's experimental PS protocol is one that I would personally consider trying if I had residual FL and standard treatment protocols could not resolve my EDS.

That is logical. One of the reasons I started this thread is that I continued to find mounting evidence that "standard treatment protocols" (as you so eloquently put it) seem as though they should work for me. I can definitely visualize a negative correlation between flow limitation and pressure. I am almost tempted to dig into the raw data and see if I can't find an empirical relationship, but I don't think I have that kind of energy.

Not to belabor the point, but here is a text book Flow Limit based arousal I experienced yesterday evening while napping. The arousal was so intense it woke me up. You can clearly see the flattening of the inspiratory flow shapes leading up to the arousal. Then the huge gasp of air (the one with the large inspiratory amplitude) and then nice rounded curves (which should be expected as I was awake by then). I've also included the Flow Limit graph for illustration. The ResMed algorithm is detecting the flow limitation, but is coding it as very minor. As a result, you can see that not only is pressure not increased, it is actually decreasing just before the arousal. I have probably looked at over 1000 breaths in the last two weeks. I can see repeated patterns like this, but usually there is no large gasp of air, just nice rounded inspiratory curves flowing a period of flow limitation. I suspect, but cannot prove without EEG, that these are RERAs and continue to disturb my sleep architecture. The Responics devices actually detect these scenarios and flag them as potential RERA events.

I post this to further point out that the ResMed algorithm is not aggressively attacking flow limitation. As I've said before, not everyone will experience arousals from flow limitation, so it may just be a case of ResMed coding for the greatest common denominator. The workaround seems to be to increase the minimum pressure in APAP mode. I am getting more comfortable with the therapy and will consider trying this for myself very soon...

NotLazyJustTired wrote:Not to belabor the point, but here is a text book Flow Limit based arousal I experienced yesterday evening while napping.

I'm not seeing what you're seeing with that spike. I'm thinking machine anomaly, a hitch in breathing, a software misread, mask fart or whatever. But hey, I'm not a sleep doctor.

Hey I'm no doctor either! This was definitely an arousal. It woke me up and I noted the time on the clock. I know I am having arousals per the sleep study, but they are hard to see in the data without EEG to correlate. This one was obvious. The ugly flow rate graph preceding is what has led me to believe that this is the cause. But I will humbly admit, I am speculating. If my speculation leads to better and more timely treatment, I will take it!

I know one data point does not a trend make, but here goes. I bumped my minimum pressure up from 5 to 7 last night. Here is the graph. I have also include a graph from last week. To my eye flow limitation has been reduced! I also zoomed in and took a look at the flow curves. While I do see some inspiratory curves that are not as round as I like, they are much reduced. I'd estimate less than 50% show the patterns I was seeing at 5cm. I am encouraged. I'll keep this setting for a week or two and see how I feel. Thanks for giving me a place to blab on about this. It is helping me, and hopefully will help others as well.

Last night:



Typical previous night:

NotLazyJustTired wrote:Hey I'm no doctor either! This was definitely an arousal. It woke me up and I noted the time on the clock. I know I am having arousals per the sleep study, but they are hard to see in the data without EEG to correlate. This one was obvious. The ugly flow rate graph preceding is what has led me to believe that this is the cause. But I will humbly admit, I am speculating. If my speculation leads to better and more timely treatment, I will take it!

I agree that it's difficult to pinpoint stimulus/response sequelae in breaths without EEG. Yours seems like a reasonable guess in light of having noted time of awakening. Arousals often entail brief shifts in EEG frequency if not sustained shifts in sleep stage, often deteriorating sleep architecture----with or without awakenings. And I'm no doctor or medical professional either.

May your experiments in CPAP bring improved flow curves and restorative sleep... Again, good luck!

NotLazyJustTired wrote: ↑

Fri Mar 29, 2013 9:39 am

I know one data point does not a trend make, but here goes. I bumped my minimum pressure up from 5 to 7 last night. Here is the graph. I have also include a graph from last week. To my eye flow limitation has been reduced! I also zoomed in and took a look at the flow curves. While I do see some inspiratory curves that are not as round as I like, they are much reduced. I'd estimate less than 50% show the patterns I was seeing at 5cm. I am encouraged. I'll keep this setting for a week or two and see how I feel.

Guess it's been a few years, but just wondering: whatever happened with this experiment?

slowriter wrote: ↑

Wed Jul 24, 2019 8:00 am

NotLazyJustTired wrote: ↑

Fri Mar 29, 2013 9:39 am

I know one data point does not a trend make, but here goes. I bumped my minimum pressure up from 5 to 7 last night. Here is the graph. I have also include a graph from last week. To my eye flow limitation has been reduced! I also zoomed in and took a look at the flow curves. While I do see some inspiratory curves that are not as round as I like, they are much reduced. I'd estimate less than 50% show the patterns I was seeing at 5cm. I am encouraged. I'll keep this setting for a week or two and see how I feel.

Guess it's been a few years, but just wondering: whatever happened with this experiment?

you are unlikely to get a reply as he hasn't logged on here since 2013.

it's possible that invoking his name may make him appear, i suppose.

how are you at pentagrams?