Flow Limitation?

DoriC wrote:I'll try to word my question without confusing you...does anyone know the average measurements of inhale/exhale that occurs with normal breathing at rest without cpap?

In normal spontaneous breathing, the inspiratory time is about 1.0 seconds, expiratory time is about 1.5 to 2.0 times as long as the inspiratory time. Thus, the I:E Ratio is 1:1.5 - 2.0.

jnk wrote:I am not against Docs K or G or researchers. I am only against what I consider to be Avi's posts that reflect his gross basic misunderstanding of statements by Docs K and G and researchers. K, G, and researchers are smart enough to use EEG and score their own flow tracings and would never dream of relying on our machines' flagging of precursors to diagnose or tweak for optimal sleep.

But hey, that's just my opinion. And what do I know.

And I defer to the pros on this board when it comes to questions in the realm of mechanical ventilation. I know a little about PAP for OSA but do not begin to grasp the intricacies of human ventilation beyond that.

I try to know my limitations. Maybe I do. Maybe I don't. But I welcome others' pointing out my limitations on such matters.

Reply,

Don't many of us, for years, have been checking our own residual data from our XPAPs, be it events, AHIs, leak, etc, without relying on EEGs, so why not do it for Flow Limitation? The data for FL is available so why not pay attention to it?

jnk wrote:

robysue wrote:

robysue wrote:It is a shame, however, that PR does not tell us what has to be going on for a FL to be scored as a tick mark. It is also a shame that PR's System One machines do NOT record FL when they are used in fixed pressure mode.

I admit that my thinking can be nonstandard, but to my way of thinking it would be silly to report a precursor in a non-auto mode, since the whole point of a treatment machine's keeping track of precursors is to use them to decide whether to raise pressure.

But snoring is also regarded as a precursor to events and snoring data is recorded when a PR machine is run in fixed pressure mode. Or rather, at least part of the snoring data is recorded in fixed pressure mode.

jnk wrote:I agree 100% that it is high time the big manufacturers came clean with what is going on in their APAPs. I think some docs don't prescribe them, and discourage their use, just out of spite for how secretive the manufacturers have been on the details of their algorithms. The manufacturers seem to print more disinformation than actual information on these important life-and-death matters.

I agree with you on this. And I think you're right, the secretiveness probably is a significant part of why many docs are so reluctant to prescribe APAPs. It also is probably related to why many docs also do not trust the data from any full efficacy machine and would just assume have their patients using bricks.

jnk wrote: I try to know my limitations. Maybe I do. Maybe I don't. But I welcome others' pointing out my limitations on such matters.

But the question still remains, do you know your Flow Limitations?? Sorry, it just typed itself!

Sludge wrote:

DoriC wrote:I'll try to word my question without confusing you...does anyone know the average measurements of inhale/exhale that occurs with normal breathing at rest without cpap?

In normal spontaneous breathing, the inspiratory time is about 1.0 seconds, expiratory time is about 1.5 to 2.0 times as long as the inspiratory time. Thus, the I:E Ratio is 1:1.5 - 2.0.

So if cpap therapy is optimal is that approximate ratio we should be seeing on the data?

DoriC wrote:

robysue wrote:

jnk wrote:My understanding of ResMed's point of view historically on FLs in the context of home treatment machines is that an FL is considered a possible precursor to upcoming snoring or OSA-related events, but an FL is not so much considered an event in and of itself. ResMed uses FLs as indicators of the need to increase pressure in an APAP in order to prevent actual events and snoring from happening.

I just want to point out that PR's System One machines record and respond to flow limitations by increasing the pressure when they are run in Auto mode. PR's Auto algorithm responds to FL for the same reason that ResMed's machine's do: PR regards FL as a possible precursor to obstructive events.

It is a shame, however, that PR does not tell us what has to be going on for a FL to be scored as a tick mark. It is also a shame that PR's System One machines do NOT record FL when they are used in fixed pressure mode.

If you set min/max to same pressure won't it give you FL? I seem to remember doing that on my Autoset.

Yes, if you're using a PR System One Auto CPAP you can set min pressure = max pressure in Auto mode and you've got a straight CPAP with A-Flex available that records FL and both VS and VS2 snore data in SleepyHead language.

It's a different problem when you're using a System One BiPAP Auto, however. On the older Series 50 BiPAPs like mine, there is no minimum PS setting; the min PS defaults to 2cm and there's no way to change it. So unless your desired EPAP and IPAP are two cm apart, you can't set the Series 50 BiPAPs to run in Auto mode with a de facto fixed pressure setting. On the new Series 60 BiPAP Autos, however, you can run the machine in Auto mode with a de facto fixed EPAP and IPAP pressure settings by setting both min PS and max PS to equal (max IPAP - min EPAP). That will force the machine to keep the EPAP at min EPAP all night and it will also force the machine to keep the IPAP at max IPAP all night.

DoriC wrote:

Sludge wrote:

DoriC wrote:I'll try to word my question without confusing you...does anyone know the average measurements of inhale/exhale that occurs with normal breathing at rest without cpap?

In normal spontaneous breathing, the inspiratory time is about 1.0 seconds, expiratory time is about 1.5 to 2.0 times as long as the inspiratory time. Thus, the I:E Ratio is 1:1.5 - 2.0.

So if cpap therapy is optimal is that approximate ratio we should be seeing on the data?

Yep!

However, TTBOMK the only way you could figure that out would be to blow up the waveform and manually calculate it.

penuel wrote:Reply,

Don't many of us, for years, have been checking our own residual data from our XPAPs, be it events, AHIs, leak, etc, without relying on EEGs, so why not do it for Flow Limitation? The data for FL is available so why not pay attention to it?

Because home-treatment-machine data are for trending only, and not for diagnosis or to be held equivalent to PSG data. It is very valuable and extremely useful data as long as not misused.

A home-treatment-machine-scored apnea is likely a real apnea and can at least be assumed to be a true 10-second pause in many cases. But it may be a pause that would be ignored and thus not scored in a PSG. And even more significant, what home machines call "hypopneas" and "FLs" are just estimated based on proprietary definitions that vary from manufacturer to manufacturer.

But my only point is that my opinion is that it is often better to judge by overall feel than to read too much into machine data when it comes to choosing successfully a tweaking pressure for oneself. If the changes in the airway are causing arousals, that should show up in feel.

I just consider it misleading to post info from reseaechers about REAL FLs and then tell people that the info applies directly to the maybe-maybe-not "FL" info from their machines. The FLs Docs K and G discuss are very different beasts from the precursor guesstimates on so-called "FLs" that, although possibly useful for long-term trending when choosing a pressure, are not flagged and collected for diagnosing RERAs or FL troubles clinically.

I've made the point multiple times, so I'll shut up now. You have the floor and the thread now, Avi, sir. Knock yourself out.

penuel wrote:

Jay Aitchsee wrote:

penuel wrote:About JNK post, imo, a lot of water came down to Jordan river since Jeff's reference to 1981 report...

As to Jnk's posts I find him often to be a "shmearer" = a smudger, and of course he has buddies.

http://www.urbandictionary.com/define.php?term=schmear

Is Katz's Deli on the lower east side in NY still around? Yummy!

A home-treatment-machine-scored apnea is likely a real apnea and can at least be assumed to be a true 10-second pause in many cases. But it may be a pause that would be ignored and thus not scored in a PSG. And even more significant, what home machines call "hypopneas" and "FLs" are just estimated based on proprietary definitions that vary from manufacturer to manufacturer.

And as a sleep professional pointed out in a email to me, home machines may be missing apneas that would be scored in a PSG. This person who is definitely not against folks being as informed as possible at the same time feels that people take home data as gospel when they shouldn't.

Dr. Krakow has said the home data should not be trusted when people aren't doing well.

49er

In my situation I have been helped a lot by checking my own home XPAP data during the 3.5 years since I started CPAPING. Judge for your self:

The followings are my first sleep study results, done in 2010. Notice the pressure of 6 cm to be set on a CPAP:



However, the ResScan data from the S9 Elite looked lousy.

Here are a couple of examples:





My treatment was really bad in 2011:





I immediately tried to titrate myself and see if a higher pressure would give me a better treatment, and I came up with this log:




The log that continued to pressures up to 12 cm indicated to me that I could have lower AHI with a pressure of 10 cm to 12 cm.

Talking to my sleep doc about it he suggested doing another sleep study b/c he does not trust data from my own home CPAP. OK, but we needed Medicare’s agreement to pay for a sleep study before a year was over since the last one. It took a few months.

The sleep study indicated a therapeutic pressure for me of 13 cm on CPAP.

At this point my sleep doc agreed to give me an Rx for S9 Autoset, for which I had to pay cash from my pocket.

Since then (beginning of 2012) I been changing the setting on the S9 to improve my treatment and run it in the APAP mode.

Examples of my data:









No, I don't want to converse with Jeff who never shows his data. Just words, words, words.

penuel wrote:In my situation I have been helped a lot by checking my own home XPAP data during the 3.5 years since I started CPAPING. Judge for your self:

Good job, Avi! Do you suffer residual daytime sleepiness?

Jay Aitchsee wrote:

penuel wrote:In my situation I have been helped a lot by checking my own home XPAP data during the 3.5 years since I started CPAPING. Judge for your self:

Good job, Avi! Do you suffer residual daytime sleepiness?

Reply,

Not anymore. I did during the first 6 months after I started. Since then I get about 7 hours of sleep which is enough for me, and I have no RESes ((Residual Excessive Sleepiness) during daytimes.

The more I think about the above thread it seems to me that it has been a waste of time. This is b/c all the Auto CPAPS on the market are using built-in methods of dealing with Flow Limitations by calculating the shape factor of the respiration waves flatness, and then those XPAPs are taking automatic actions to deal with it. So Resmed auto cpap machines have their own calculations of proprietaries procedures dealing with the corrective action to be taken b/c of the flatness (shape factor) of the respiration waves, causing the Flow Limitations, while other makers might deal with it differently. So essentially, we the users, can't do anything about it, by for example, changing the pressure. So when Dr Barry Krakow stumbled on a BiLevel machine which best treated his UARs and regarded it as puzzle, it probably was due to the methodology in that machine.

penuel wrote:The more I think about the above thread it seems to me that it has been a waste of time.

Nah, somebody probably learned something.

See also informal poll (new) at viewtopic.php?f=1&t=98168