definition of flow limitation

[oak]

i didn't see anything in the CPAP Wiki...

could someone enlighten me. i don't really get it.

mine is still wild.

thanks in advance. Oak

[NeedHelp2]

Count me in as well. Mine is very wild and I don't really understand what this means, nor what to do about it.

[JDS74]

Flow limitation describes a condition in which the air flow into the lungs decreases by a certain percentage of the running average. I think for some reporting, the percentage is 10%.

An hypopnea is similar but the percentage is greater, I think 50% of the running average.

An apnea describes a cessation of air flow.

Depending on your particular machine, there is an minimum interval that the condition must meet before it is recorded. So a 5 second occurrence will not be recorded but a 15 second one will be (the nmber may be 10 seconds)

[kaiasgram]

i didn't see anything in the CPAP Wiki...

could someone enlighten me. i don't really get it.

mine is still wild.

thanks in advance. Oak

Are you asking for more info about what FL actually means, or are you trying to figure out how to interpret the FL graph in SleepyHead?

[oak]

so what could be the cause of a wild flow limitation if my numbers are under control? .50 AHI, almost no leaks.

i changed my pressure from constant 9cm to a range of 9-15 two nights ago. seems to be no change in flow limitation

kaiasgram--both what it means and how to interpret

[kaiasgram]

so what could be the cause of a wild flow limitation if my numbers are under control? .50 AHI, almost no leaks.

i changed my pressure from constant 9cm to a range of 9-15 two nights ago. seems to be no change in flow limitation

kaiasgram--both what it means and how to interpret

oak, I had the same issue, great AHI but significant flow limitation. Give me a minute to find an older thread from last fall about this. Meantime here's a pictorial of flow lines during normal breathing and breathing with flow limitation. In SleepyHead you would be looking at your Flow Rate line to compare to these images:

[NeedHelp2]

This is helpful information. Is there further information on steps to take to reduce flow limitation "events" or otherwise improve the Flow Limitation graph?

Or, alternatively, information on how/when to make the judgement call that a person's flow limitations are within acceptable ranges.

[kaiasgram]

We need some of the real pros to weigh in here, but I can say that assuming no big leak problems, pressure is the only way I know of to reduce FL. It's one of the reasons I keep my machine in Auto mode.

I'm posting SleepyHead screenshots below from a recent night -- on this night I had zero leaks and zero snores and my AHI was 0.0. So the only real influence on my pressure changes would have been my FLs. In the first screenshot below you see how my FL graph peaks correspond with pressure increases from my machine. My S9 VPAP seems to respond very quickly to those FL's. In the second screenshot I zoomed in on the highest peak from that same night so you can see the sensitivity of the machine to the FL.



Close-up screenshot:

[kaiasgram]

Here's the thread on FL I was trying to find. It might prove more confusing than helpful, so read at your own risk. It's never been totally clear to me how SleepyHead is coming up with those Flow Limitation numbers we see to the left of our Daily charts or how to interpret them so I've just looked at the waveform (the Flow Rate) graph to see how rounded the inspiratory peaks are.

viewtopic/t83692/Flow-limitation-questi ... toset.html

[Stormynights]

My Sleepy Head graphs don't show a separate flow limitation graph. It is checked under graphs in preferences.

[StuUnderPressure]

I also have some fairly ugly Flow Limitations (Graph in ResScan Software only).

I have gradually raised my lower Auto pressure withOUT any improvement.

My AHI is always less than 4 & very often less than 3 & some times less than 2 & sometimes even less than 1.

My AHI usually consists of Hypopneas only.

And I have virtually no leaks recorded.

[oak]

kaisgram-great chart. so if i understand this in a most basic way , these constant flow limitation spikes i have are sort of hypopnea wanna be's, but aren't severe enough to count as real "events." Right?

so back to needhelp2's question: are they really nothing to be concerned about as long as everything else looks good?

[SleepWellCPAP]

In my experience, flow limitation can be corrected by increasing the pressure, but also by increasing the humidity or controlling leakage.

With a nasal pillow mask, and I learned this here, I would highly recommend using Lansinoh to help keep the pillows from leaking. Even with a climate tube, little leaks can evacuate your circuit of moisture, you sinuses react by swelling up and viola! Flow limitation. Those F&P graphs by the way are awesome!

The worst thing about flow limitation in my opinion, is that it makes people feel like their equipment isn't doing them any good. They wake up in the morning and think, "Why am I using that thing again?"

Good luck!

Jim

[kaiasgram]

kaisgram-great chart. so if i understand this in a most basic way , these constant flow limitation spikes i have are sort of hypopnea wanna be's, but aren't severe enough to count as real "events." Right?

so back to needhelp2's question: are they really nothing to be concerned about as long as everything else looks good?

Yes, maybe even apnea wannabes if allowed to go unchecked long enough.
As for whether they're of concern I think it depends on whether they're interfering with your sleep quality, e.g. If your FLs are bad enough to be causing lots of RERAs.

[oak]

In my experience, flow limitation can be corrected by increasing the pressure, but also by increasing the humidity or controlling leakage.

Jim

I will try increasing the humidity some more. Its now at 3.5. My pressure range has been changed and running pressure is no longer bumping to the top. I dont have leak problems.

As for whether they're of concern I think it depends on whether they're interfering with your sleep quality, e.g. If your FLs are bad enough to be causing lots of RERAs.

my resmed s9 charts dont show any RERAs. I noticed that people who post here who show RERA's seem to have Respironics machines? Yes?