Flow Limitation - can you explain?

[stanleydean]

Thanks Sleeprider and robysue for your very helpful responses. For now I think it will be more productive for me to just let the FLI data continue flying under my radar and focus my efforts on reducing my leakage.

[Sleeprider]

Stanley, I agree with Robysue to the extent that I have never been an advocate of chasing FL when no other problems are present; however I'll stick with my suggestion that if you want to try a solution, that would be an increase in minimum PS. Actually I think both Robysue and I are in agreement on that.

[stanleydean]

I increased the minimum PS from 2.0 to 2.5 and will watch FLI for a few days and post.

Thanks, Stan

[Sleepster]

can somebody explain what "flow limits" or "flow limitation" means in Sleepyhead?

Flow limitation is something the machine manufacturers use to determine an impending obstructive apnea or hypopnea. It's based on anomalies in the flow rate graph. In other words, when the flow rate graph starts looking hinky your machine will raise the pressure in an attempt to prevent an impending obstructive apnea or hypopnea. Put a stop to it before it happens!

There is a value from 0 to 1?

Zero means no flow limitation, meaning you're breathing normally. A higher value means there's something weird in the pattern, for example the positive part of the flow rate graph will have a chair shape instead of the nice hump shape it should have.

Look at RobySue's guide to SleepyHead, I believe she shows pictures of these shapes in the section on flow limitation.

[Walla Walla]

There was a good write up on this board by Dr Barry Krakow about Flow limitation. The link is:   "http://www.apneaboard.com/forums/Thread-Flow-Limitation-UARS-and-BiPAP?highlight=barry+krakow".  If the link doesn't work try search and look for Dr Barry Krakow.

[Sleepster]

There was a good write up on this board by Dr Barry Krakow about Flow limitation. The link is:   "http://www.apneaboard.com/forums/Thread-Flow-Limitation-UARS-and-BiPAP?highlight=barry+krakow".  If the link doesn't work try search and look for Dr Barry Krakow.

That article is an example of what I meant when I said that the medical community refers to flow limitation as something possibly different from what CPAP manufacturers refer to when they use the term. To the medical community it's UARS. Like obstructive apneas and hypopneas, it's a form of sleep disordered breathing. To CPAP manufacturers it's a signal that an apnea is about to occur.

[Dugy40]

The Airsense 10 does not change pressure on a breath by breath basis, but the fastest algorithm for flow limitation, (meaning the one that increases pressure the most following detection of FL) is reported to be the STANDARD algorithm, followed by the FOR HER setting and finally the SOFT.  I have not personally made any comparisons and this is simply based on Resmed claims.  The quote below from http://www.resmed.com/us/en/commercial-p...r-her.html also shows what flow limitation looks like on a flow graph.  I also have not seen a comparison between For Her and Soft.  In the figure below the For Her response first to FL while standard Autoset remains flat, however when subsequent FL events are detected the Autoset Standard rises much faster than For Her.  So cumulative increase in pressure is fastest in standard Autoset, but For Her will rise on a single event.

The pioneering new algorithm used in the AirSense 10 AutoSet for Her works by increasing sensitivity to flow limitation and optimizing the response to these events. By responding to each flow-limited breath, the algorithm helps provide comfortable therapy for women.

Hello sleeprider. Been reading a lot of threads.  Do you think increasing my min by 1 might be helpful.  I seem to have a lot of flow limitations.  I can post last nights screenshot on my therapy thread if needed.  My ahi’s have rarely been getting below 1.   But.  The main thing is I am still sleepy in the day.