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Why don't these flow rate curves count as flow-limited?
#41
RE: Why don't these flow rate curves count as flow-limited?
Those aren't flow limitations. Those are either a strange forceful cardiogenic oscillation or some other rhythmic effect being imposed on your flow rate chart. Cardiogenic oscillations are usually smaller amplitude and not visible during inspiration whereas whatever these are continue on into inspiration causing a single pointy peaked breath at times and at other times a double peak.

Maybe some sort of weird slow amplitude snore but seems far to consistent for that to be the case.

The easy way to think about this is to imagine that there are two things being combined in your chart. One is normal looking breaths and the other is little spikes every just under a second (which would correlate with a heart rate of roughly 80 BPM if cardiogenic oscillation related).
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#42
RE: Why don't these flow rate curves count as flow-limited?
New member, but I can't open your attachment.  Is this soft tissue vibration?  Again, I can't see the breathe.
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#43
RE: Why don't these flow rate curves count as flow-limited?
@cathyf: 'Late coming here but, WOW, what a dramatic change overall in your first night results with VAuto. Now the questions all note are whether and when your body will readjust itself and you enjoy more restful sleep with reduced breathing effort of shorter and easier duty cycles, fewer arousals, etc. Would you please consider posting a copy of embiggened OSCAR I and E curves for those 10 waves for which I worked up--er, roughly approximated--the  I-time/E-time qotient as well as duty cycles. I never did that before and want to cross check to see what agreement there is with I and E OSCAR curves.

@kappa: I believe your two graphics were specially chosen to contrast very similar waves that differ only in the flattening caused by a continuous FL and the rounded I-wave peaks without FL. The takeaway is, is it not, that good titration with PAP pressures will or should round out much of the deformities of flow limitations, flagged or not?

@TBMx: Oops It's past time for me to come clean with a mea culpa. Though writing this explanation here is only a partial excuse--if not a tu quoque (fallacy) argument. I did not check, as I should have, why you wrote "Around 6 minutes with a respiratory flow around 5 l/min....". I think you meant to say,  ". . . with a PEAK INSPIRATORY FLOW of 5 l/min ..." as was obvious in the graph when I revisited it after your rebuttal (above) and my remembering your humble reminders that you are not speaking to these matters in your Deutsch first language. ('Had two years of German in college, lost almost 100% of it from non-use. Did far better reading than speaking it. But "learned", as our Mark Twain jokingly said, you only need to read the last chapter of a book written in German because all the verbs are there. Anyway, no second language is well enough known to me to go much beyond a hello or thankyou, let alone say or write anything technical. English and its grammar? Hard enough for me.)

I didn't check the graph vs your wording because--wrong reason here--I saw you as continuing your quest along this line: it's another episode of TBMx poo pooing the meaning of Resmed's flow limitation (FL) flagging as just a marketing gimmick gullible people may fall for. Neither my thoughts about your 5 L/min and RM put downs nor your claims about RM, here and elsewhere, were or are accurate . A FL does convey in a simplified, imperfect way, the relative "TV losses" to us. Is the Resmed (RM) FL flag the ideal way to indicate drops that are smoothed over some in expanded views of TV and MV? Probably not, as sheepless has indicated. I see a FL flag as a likely byproduct of real-time feed back control to govern blower air output and make appropriate therapeutic pressure changes. Yes, you see, as I understand, the Resmed approach as wrong, too aggressive with pressure increases.

Nevertheless, the relationships shown among TV, MV, FR, L and RR during (click) that period you analyzed  were clearly inconsistent/incoherent as you indicated and, to your point: a simple (understating but close enough) 2 sec wide by 5 L/min "high" isosceles triangle, I-wave at a RR of 15 would yield TV much as you pointed out, only somewhat more than 1.25 L/min--if I am correct, which if continued for 6 minutes or less would likely, I think, be lethal. Except maybe for our perdurable cathyf?  On the other hand, credit to RM: the device is not, as you point out a research or good diagnostic tool, although it is used lightly for those efforts, even by some researchers if not care providers. IMO, cases like cathyf's push hard against at least one, maybe more design limits, including resolving power--a perfect analytical storm a la the movie. Too, we are talking about flow limitation scoring and values, off the therapeutic main road. But we try to utilize all bits and squiggles of information to best advantage even so because we want to sharpen our understanding.

Your rebuttal also sent me back in my OSCAR to look for those instances, now extremely rare, when when there were sudden periods of LL with sharply and uniformly attenuated FR for a time. Unfortunately, records of those bad times are somewhere on an aged memory stick or SD card and I haven't taken time to dig info out. I suspect there may be attenuations with equations of the metrics that "won't balance" or reconcile. At the time I merely dismissed any perceived discontinuities as likely limitations of algorithm, sensitivity, etc. if they did not make complete sense...and they might  make sense if examined. After all, LL>25 (one or more places LL up to 35 is shown) was out of device bounds. 

Lastly, the piece you referenced and kappa linked to about the surprising lower survival rate and fitness of ASV users vs control non-users: It touched on (1) a question of mine about consequences if my air delivery volume from the VAuto (APAP mode) is excessive (CO2 cut) when I first lie down and then quickly fall asleep paying no more attention and (2) a paper on research ( ARMA and ALVEOLI research here) with ambiguous outcome, which seemed to show better survival of the intubated, lung injured ICU patients who got lower than usual ICU protocol for TV delivery.  And as in that research paper in one bit I understood: "There is a significant and growing body of literature focused ondrawing inference about dynamic treatment regimes from observational data with time-dependent confounders." What tortuous mathematical contortions there, a Bayesian what if approach they post-applied to selected "compliant" data: makes one wonder whether it can mean anything. RM or not, there are many confounders in sleep analysis and treatment and much to learn as well as lots of treatments inertia, ignorance, agendas and insurance barriers. 

Dad refused an "urgently needed" quadruple bypass in his early 70s, took chelation (good for heavy metals removal, pulls out some calcification) and lived another 8 years with new bounce in his farther more vigorous walks, with warmer feet and new tolerance for salad greens he could no longer could tolerate and had cut from his diet: "anecdotal evidence", true lots of it and physicians roll their eyes saying that after I apply this litmus test to a new-to-me MD after a while. I think the Loma Vista MD practitioner may have gone to jail in a related matter if it went that far. Anyway, like Hydroxychloriquine and Ivermectin, lack of large enough controlled (double blind) studies ostensibly--or is it too low of prospects for profitability to justify such study of a cheap old drug--stands in the way of getting past WHO (and NIH is it?) relaxing their stands against those drugs. NIH moderated a bit from being against Ivermectin to being neither for nor against it after its 20 or more years of use as a parasiticide to treat hundreds of millions of humans, if not billions. Google FLCCC (it is 3 Cs) critical care doctors organization.
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  

Of my 3 once-needed, helpful, and adjunctive devices I have listed, only the accelerometer remains operative (but now idle). My second CMS50I died, too, of old age and the so-so Dreem 2 needs head-positioning band repair--if, indeed, Dreem even supports use of it now.



 
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#44
RE: Why don't these flow rate curves count as flow-limited?
2SleepBetta, my friend, I think you are absolutely right. Well-done

Now we just have to curb our impatience and wait for Cathyf to tell us how she has fared with the new dream values and how great her newly regained new life feels. Grouphug3
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#45
RE: Why don't these flow rate curves count as flow-limited?
Ok, so how about WTF IDK for an answer to the question of whether the vauto makes things better?

As an aside, I think I now understand what a flow limit is. It's NOT about looking at the tippy-tops of those inspiratory flow rate waves like entrails of sacrificial goats. It's all about how the area is distributed under the curves.


Top is me on an AirCurve10, with PS set to 4:


Middle is me on an AirSense10, with EPR set to 3, 


Bottom is me on an AirSense10, with EPR set to 0, 

[attachment=33805]
Screen Shot 2021-07-15 at 11.37.00 PM.png

(You know how  the experts tell us that EPR is a "comfort" feature and we are all just whining wusses. Oh, and as the FDA told us all last month, fat alcoholic whining wusses!)

It's not about those tops that look like the letter "M". It's about how the sides of the inspiratory curve become more vertical -- they are talking about flatter, but also wider.

But, anyway... I've done every night except one in my FFM. The one night that I tried the nasal mask was kind of, well, odd! While still awake, it felt like the air was just blasting into the back of my throat. And I kept having my cheeks inflate -- chipmunk cheeks -- which sometimes caused my lips to pop open and let out a puff of air. And the whole entire night was just a total train wreck of leakage -- median 7.2, 95th%tile 26.4 -- with what looked like significant flow limits during period where the leak rate was 35ish. So I'm back to the FFM.

How do I feel? Well I feel like someone who hasn't taken her arthritis meds for almost a month because there's a worldwide shortage. Someone whose vauto arrived the morning of her first day back at work after 16 months of unemployment. (Oh, I do want to say "thank you" to all you US taxpayers!) I don't think I feel worse, and the numbers are certainly dramatic.

You know almost seven years ago, a few weeks into this whole APAP fandango, I was already looking at my data, already trying to figure out what the heck are these flow limit things, and why is the machine raising the pressure in reaction to them, and if I set the max pressure very low the machine pegs the pressure there and reports even more flow limits, but other than that nothing bad or even interesting happens. I was already asking "where's the 'ignore flow limits box' because I want to check 'yes' for it!"

And here I am circled back there. With the vauto I don't have flow limits, the pressure stays low, if I fall asleep on my back without the cervical collar the vauto is just as helpless as the Air10 (because pressure does nothing for chin tucking). So except for the very impressive numbers, I dunno?

I've got two friends with dreamstations, one APAP, one biPAP. I'm wondering if I ought to give the one friend my Air10 and the other my vauto and just sleep in my cervical collar...
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#46
RE: Why don't these flow rate curves count as flow-limited?
(07-16-2021, 12:39 AM)cathyf Wrote: As an aside, I think I now understand what a flow limit is. It's NOT about looking at the tippy-tops of those inspiratory flow rate waves like entrails of sacrificial goats. It's all about how the area is distributed under the curves.
Well, not "really": A real, physical flow limitation is something that happens with your body, it's not about graphs.  A happening flow limitation is a non-linear response 
between your breathing efforts and the amount of air you're actually breathe.  That is: your belly is moving up and down but there's only few air reaching your lounges. It's not possible to detect a real FL with our machines for certain.
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#47
RE: Why don't these flow rate curves count as flow-limited?
I agree with multicast. The ResMed FL heuristic is primarily about breath flatness as a way to detect physical flow limitations (the patent says it's "based one or more shape indices"). Yes there is a correlation between lower TV/MV (= area under curves) and flatter breaths/FL as 2SB has shown elsewhere (effect / cause?) but changes in TV/MV are used to classify Hypopneas and Apneas.
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#48
RE: Why don't these flow rate curves count as flow-limited?
(07-16-2021, 12:39 AM)cathyf Wrote: (2SB's insertions are in colored, bold-faced font and much has been omitted without ellipses to show it.)

Ok, so how about WTF IDK for an answer to the question of whether the vauto makes things better? IMHO its a miracle you have survived intact with your long history of great struggle with SDB. No offense intended, to me you are an outlier, the el primo anecdotal case I have seen, in my--yes--limited experience. I think not only of the recent displays, but back to what you characterized as your fat girl days. Wow, all those classical sagging chair shaped waves when there was a lot more tissue to sag and ripple, I assume, down into air stream and cause such pronounced irregularities. Your sample, as always, seemed to display uniformity


It's not about those tops that look like the letter "M". True. Those are just signals, first clues, for those who have some or a lot of low level flow limitations, and they are far from the whole story for many and may become more serious and will remain when things become worse.

It's about how the sides of the inspiratory curve become more vertical -- they are talking about flatter, but also wider. Maybe more vertical, but most often flatter and wider with increased I/E time ratio. 

But, anyway... I've done every night except one in my FFM. The one night that I tried the nasal mask was kind of, well, odd! While still awake, it felt like the air was just blasting into the back of my throat. And I kept having my cheeks inflate -- chipmunk cheeks -- which sometimes caused my lips to pop open and let out a puff of air. . . . That, I had too, but found it can be prevented. See recent posts on mouthbreathing as I shamelessly indulge in what I have seen others say is pimping to get clicks of their posts or comments.

How do I feel? Well I feel like someone who hasn't taken her arthritis meds for almost a month because there's a worldwide shortage. . . . I don't think I feel worse...Great, it's a start.

With the vauto I don't have flow limits, the pressure stays low, if I fall asleep on my back without the cervical collar the vauto is just as helpless as the Air10 (because pressure does nothing for chin tucking).  I'm about to test your theory by taking off the collar and now, having put aside my supinity block, remove the collar as  test to see what happens. I have not tried that. at all with the VAuto and I have reverted to a  lot of supine sleep without noticing adverse consequences.

(07-16-2021, 02:33 AM)multicast Wrote: Well, not "really": A real, physical flow limitation is something that happens with your body, it's not about graphs.  A happening flow limitation is a non-linear response 
between your breathing efforts and the amount of air you're actually breathe.  That is: your belly is moving up and down but there's only few air reaching your lounges. It's not possible to detect a real FL with our machines for certain.
Yes, yes, yes and yes. And yes in a manner of speaking, because we cannot detect flow limitations because they are a something that is not there, the continuation of preceding TV, the then missing continuation of the areas under the preceding inspiratory wave curves..

(07-16-2021, 03:19 AM)kappa Wrote: I agree with multicast. The ResMed FL heuristic is primarily about breath flatness as a way to detect physical flow limitations (the patent says it's "based one or more shape indices"). Yes there is a correlation between lower TV/MV (= area under curves) and flatter breaths/FL as 2SB has shown elsewhere (effect / cause?) but changes in TV/MV are used to classify Hypopneas and Apneas.
Yes to all.

Slow in drafting the following, I wanted to respond to what was posted, as just above, while I wrote my  usual book. It follows now, unmodified.

I've long seen you case as a headscratcher with you here to get help and teach many of us something new. You are teaching  me for sure with your few or small drops in SpO2, if any, your high and quite uniform levels of FL and with both accompanied by your amazingly uniform FR wave forms. I've not seen OSCAR charts like yours.


My first reactions to what you now display:

--Small matters to note: Recognition that by my counts and arithmetic the RRs are 13, 11 and 11 bpm, and these curves, uniform as they are, are selections, as they necessarily must be, from different bodily and sleep states; they are not  identical triplets, if there are any human identical triplets.

--The displayed, slightly higher RR and  higher FR, IMO, account for a slightly greater steepness of FR--a higher rate of FR change, for the PS4 case.                                                      
--The I/E and duty cycle seem significantly lower in the PS4 case than the others, suggesting relatively less work is being done in sleep. Hopefully that will carry through to improve sleep. Question: what if any difference do you see regarding mini and other arousals? It may be too early to see full effects of the change.

--What do the the sharper/faster transitions from little to no FL up to your .45 and .55 levels look like in one or  two minute views? It seems only changes at those transitions, as required by the algorithm, can account for a rise where FL  becomes perched, lacking sufficient flow limiting(+) changes to break out downward. (I have speculated on this resolution related idea elsewhere, as you know.) Likewise, that same question for sharper deeper FL drops. Uniformity maintains your FL level closely until there is/are enough change among FR, RR,  and wave shape and flatness indices to trigger the algorithm to issue a pressure-change order.

--My long shot guesses next, my what-iffing to show the greater fool, while trying to account for what you show now and most always  show: It seems that both a most rigid and a less rigid upstream tissue structure partial closure has to account for chronic flow limitation after start of the ordinary relaxations accompanying sleep. The VAuto pressure creates enough opening of your less rigid (trained? unusually firm? genetically endowed?)  tissue at the pinch point which continues downstream with few irregular or slack zones to cause more usual high turbulence. But it seems there must be thin layer of surface tissue and/or mucus lining that ripples in the air stream causing irregular peaks in the higher FR PS4 case (vs very little deformation in the other two cases where flow is much more restricted upstream reducing flow and peak flow and boundary layer turbulence. (Here's hoping this speculation might help trigger someone's breakthrough to explain and better treat your and others' flow limitation cases--at least to cause some welcome laughter.) 

I have to admit that when I first switched from Autoset with high FL count and large FL"wave areas" to the VAuto with vastly reduced FL, I wondered if the device just covered up a lot of the bad FL news like our hear-see-and-speak-evil-selectively opinion and knowledge molders and  purveyors do now. How can you account for that change in FL?. Just 1 cm more PS?.  In my case the Autoset gets the most credit in that it whipped/treated  terrible and damaging OSA and cut bladder calls. There was a big jump in restfulness,  but I had never felt down before, just found it very easy to doze off at rest when my mind was idle. The cut in FL by the VAuto reduced arousals and improved restfulness, but less dramatically. Not troubled much with FL now, it still greatly challenges and interests me.
 
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  

Of my 3 once-needed, helpful, and adjunctive devices I have listed, only the accelerometer remains operative (but now idle). My second CMS50I died, too, of old age and the so-so Dreem 2 needs head-positioning band repair--if, indeed, Dreem even supports use of it now.



 
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#49
RE: Why don't these flow rate curves count as flow-limited?
The change in flow rate in those examples is substantial and obvious. With the EPR examples your flow rate maxes at 12-13 and inspirations are extended to intake large enough breaths, with the vauto example flow rate maxes at 17-20 each breath and you are taking more natural breaths. Your body is not working as hard with the vauto.

2SleepBeta regarding the vauto PS vs autoset EPR the one difference that may be present other than increased PS is if the vauto pressure waveform occurs slightly earlier to give more inspiratory assistance whereas EPR usually peaks just as exhalation is ready to start. In the examples I have looked at I figured they were pretty close to each other at normal trigger/cycle sensitivities but with the vauto you definitely have the ability to change that by increasing trigger sensitivity.
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#50
RE: Why don't these flow rate curves count as flow-limited?
I'm going to replace that comparison picture by this one --

   
https://www.dropbox.com/s/19i1c5nsfs60ta...M.jpg?dl=0

It has more information in it than the previous version. I added segment on the vauto from last week which shows a very brief high flow limit that looks very different from the FLs I see on the autoset.

Last night I fell asleep at 9:45 without cervical collar -- it was all I could do to get my shoes off and mask on! I was trying to sleep on my side, but had a little chin-tucking hot mess after 2 hours.

   
https://www.dropbox.com/s/lgkqf4hmhodpqc...M.png?dl=0


Here's a closeup:
   
https://www.dropbox.com/s/mrz0fvjlav0rey...M.png?dl=0

I can certainly confirm (again!) that no amount of anything that a cpap machine can do has any effect against positional apnea!

One thing I'm starting to wonder about... The machine always shows leaks during these crapfests. I had concluded before that you can't trust the flow rate numbers during leaks. Now I'm getting a lot more suspicious in the other direction -- wondering if it's the leak numbers that are garbage. Is leak being calculated by integrating over the inspiratory and expiratory segments and if what goes back to the machine is missing compared to what went in, then the machine measures that as leak? Because sometimes what I'm feeling is that when I have my mouth closed the air is coming up my nose, hitting the back of my throat, and splitting between down my windpipe and inflating my cheeks chipmunk style. If my closed mouth is functioning as a backwater capturing air and then releasing it at unexpected intervals, I can imagine that would look like some kind of leak down at the machine? And also, when the flow rate is jumping around repeatedly and wildly crossing zero in a totally chaotic way, how can the machine even properly pair inspiration with expiration?
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