Flow limitation

[SleepyHenry2]

Danem;
Thank you for posting your charts and comments on Flow Limitations.
Similar to you, I have questions such as:
          1) how many Flow Limitations are normal and abnormal per night?
          2) how do I measure Flow Limitations to try to intervene in a way to improve the Quality of my Sleep and decrease my EDS and “Brain Fog”?
I have not been able to find the answer to Question #1 in the literature. An example is the Study from Brazil that you quoted before. It uses a different measure than the one provided by ResMed. In fact, until there is a universal definition for measuring Flow Limitations, no study can provide us the answer.

For question#2 I have the ResMed "Index". It is an engineering answer that doesn't take into consideration yours and mine suffering. I understand it to measure the shape of respiratory flow during ventilation &\or breathing cycle..... That is actually fine, but I have trouble how it is reported as a 95\99.5% tile!.  It only covers one night, and what we need is how much better we are getting every week.
You reported the Flow Limitation Index from WORKPLACE Testing.com. What they suggest is the same mathematics used in the AHI. That would be an improvement, but we all know that the AHI is a flawed historical measure that is being improved.

[Brazen]

@SleepyHenry2

Through the experience of the experts here the aim is to have the 95% flow limit under 0.1, ideally under 0.03, by sleep session and overall but you're right that there doesn't seem to be a set "normal" and "abnormal" number in the same measurement given by the machines.
There needs to be more studies on flow limits - as they relate to normal/disordered and to sleep quality. 

Without this forum I would have gone on thinking that low AHI means my treatment is resolving my sleep quality issue and all is well.  Very thankful for this place.

Re: flow limit trends...
On the Statistics tab of OSCAR you can get your stats for 95% flow limit in different time ranges, at the bottom of the page you can even pick custom date ranges.

[Crimson Nape]

Danem -  This post is an answer you asked me back in your post #60 - (shortcut here) "Where to get real time data".   You will not be able to easily obtian this information from OSCAR, but you will find the Flow Limit channel in your Resmed "_PLD.edf "file.  It is signal #10 - FlowLim .2 sec data.

Sorry for the delayed response.
- Red

[DanEm]

SleepyHenry2
how many Flow Limitations are normal and abnormal per night?

Hello SleepyHenry2.  The only figure I got with definitive relation to FL is 0.1 or less is the goal.  That number was given to me in this forum.
Is the figure the result of a study, a poll of forum members or something else, I do not know.

One place where there is a lot of technical info is in the ATS Journals.
Link: https://www.atsjournals.org/doi/10.1164/....3.9708056

But you will not find something related to a unique figure
.

I have trouble how it is reported as a 95\99.5% tile!.  It only covers one night

Don't you use OSCAR? 
It reports on FL for each session and you get data for all the nights of your treatment.
Or maybe I am not reading you the right way. 

I am still searching even though I sometimes get frustrated and want to throw everything out the window.

[DanEm]

Thank you for the info _Red

I once tried to look into edf files and just quit.  To complicated to get the proper view.

Can you just describe what is the "actual point in time" and what are the units involved (cm3, litre, gallon, ....).
I would surmise that "actual point in time" is the measure of air flow or speed in a given volume or through a specific orifice at a set frequency.

How or to what OSCAR transforms that data (formula involved).

On the same topic, I read this:

The flow limitation index (FLI) is calculated by dividing the total number of flow limitation events  (NFLE) which occur by the number of hours (HRS) over which events were recorded.

So, FLI = NFLE / HRS

How does FLI fit into OSCAR if it so do?

Also, what are the differences in the following values exported by OSCAR:

• 99.5% Flow Limit.
  
• 95% Flow Limit.
  
• Median Flow Limit.
  
• FL Count (the name is quite close to the above NFLE description which is just a count number)
  

I know what is the difference between 95 and 99.5% but to what is each applied?

If the Flow Limit. in OSCAR is the FLI, then the 95 and 99.5% do not make sense for me.

I hope you can shed some light on my dark ignorance, I would greatly appreciate.

-Frenchy  (DanEm) 

[DanEm]

From Brazen
Through the experience of the experts here the aim is to have the 95% flow limit under 0.1, ideally under 0.03

Does someone know if those values were obtained by a poll or survey through this forum?

If so, are the results of such available?

If no, would it be a value added to do such survey?

[Brazen]

@DanEm

I don't know where those values were obtained but someone might.  
It would be good to know.

I kind of feel like flow limitations are one of those things that no one knows why they matter, they just do?
Why is it considered normal breathing to have flow limitations up to 29% of your sleep time? And what causes them - only obstruction or other factors?
What is the effect? If flow limitations always affected sleep quality I would think the threshold for normal would be much lower.

Can I ask, what is your work background? Just curious. 
Not everyone digs into data like you seem to.

[DanEm]

Brasen 

My search on internet gives me the same impression although I am far from having visited all the related sites.

My background is with large hydro projects generators manufacturing, sales and marketing then I went to Hydro-Quebec and managed large powerhouse refurbishing and construction projects.

I am curious by nature and I have an electrical engineer degree.


When confronted with a problem, I like to get to the bottom of it, especially if it concerns my health.

Plus I had bad experiences with Sleep Clinics (2) that could not answer simple questions.
I don't live near a large city and here specialists are scarce and sometimes not too knowledgeable specifically about sleep problems.

[Brazen]

Sounds like interesting work, thanks for sharing.
I suspected engineering of some sort.
Curiosity is one thing, having the background/knowledge to absorb info and understand data is another and you seem to have both.

I'm an informatics nurse so I deal with big chunks of data on a regular basis.

I am finding a similar situation with sleep clinics and specialists. We have to keep advocating for ourselves.

[SleepyHenry2]

DanEm;
The recommendation to try to get your 95% Flow limitation to below 0.1 is “Good”!!!......and everyone should follow their advice to see if it works for them..... If it doesn't work, then BiPAP therapy is needed.
The picture of the Flow Limitation graph provided by OSCAR is even better... I copied a bunch of them and took them to my Sleep Doc, who had been doing his best to improve my EDS.
First we had to shift his thinking from OSA TO UARS where flow limitations rather than Apnea\Hypopnea is the main culprit… Second, he saw I had a very low residual AHI and that my RDI was larger than my AHI. Thirdly, I showed him all my efforts (under the directions of the OSCAR team) to get “better” to no avail….and lastly, I showed him all my Flow Limitations Graphs....Finally, he looks at me and says, “You need BiPAP”.

Now Bilevel Machines are more expensive and harder to get, and I will report back when I am able to get one. I know I will need help setting my correct PS.