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Why don't these flow rate curves count as flow-limited?
RE: Why don't these flow rate curves count as flow-limited?
I post again rather than further edit pargraph 4's--not explicitly stated  Hammer --hypothesizing or speculating (just above) about what I think I see is and have called "bridging". If it exists as I think then the trailing end of an ending FL instance extends "bridges over" and obscures an adjacent or abutting large drop among flaggable flow limitation, FL, or obscures an I-wave shape irregularity that is ordinarily flagged when alone. 

The bridged drop or shape defect  would not be shown with an appropriate flag level drop, not even a relatively deeper flow limitation drop. The FL curve would look continuous at an elevated level. Only small shape irregularities, deformed wave tip by wave tip, would continue uninterrupted causing 1 or 2 scaling-unit changes up or down in the continuously high FL curve. 

The idea comes from what I have seen as irregularities in how some series of misshapen and/or smaller inspiratory FR are or are not reported out, with or without FL flags when seeming applicable, and how they  are reported out with flags when stacked up or layered by tight  short series of near-neighbor wave shape change and/or FR drop(s) . In addition to the vagaries of the interacting roles of shape, flow rate and respiratory rate changes and their combined effects  there is the added factor of the 2-second FL resolution limitation, and probably other algorithm settings in fuzzy logic that sometimes present us with the slightly analogous camera concept of "the circle of confusion". Similarly, multiple conflicting FL conditions are not always in sharp focus--just one of those few limitations of our great machines and their algorithms--all the brands I expect, some better at one or more things than others.
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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RE: Why don't these flow rate curves count as flow-limited?
To me its pretty simple. These are either flow limitations or periods of declining respiratory effort, very small chance of a worn out machine giving inconsistent data readings.

I believe they are flow limitations, Cathy has positional apnea and there is inspiratory snore present in a number of these situations. The declining amplitude breathing often ends in arousal/recovery style breathing and it is more similar to obstruction then central. She has small amplitude breaths due to small size and once her breathing declines she loses pressure support from the machine making things worse and affecting data values.

Vauto is coming soon, and will allow all theories to be tested. Cathy I would try similar settings to what you currently use and increase PS to 4 as a starting point.

I believe that anyone that has concomitant nasal congestion, reflux and other digestive issues should investigate food intolerance issues. My theory is this falls more in line with people that have UARS more so than obvious apnea issues like Cathy has. I don't remember seeing Cathy comment on those symptoms to know if they are worth looking into. Although in my case it was dairy I think these issues can be caused by any food intolerance, dairy and wheat would be the two most common though.
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RE: Why don't these flow rate curves count as flow-limited?
(07-04-2021, 01:18 PM)TBMx Wrote: Around 6 minutes with a respiratory flow around 5 l/min and a respiratory rate around 11 per minute. If that would have been your breathing you wouldn't be alive to tell us (unless you are really(!) small / petite) - that is only slighty above deadspace ventilation.
What is fascinating is what your device makes out of that: The airflow was too small to get detected as breathing - your tidalvolume and your resp. rate actually go down to 0  Huhsign
But at the very same time there is absolutely no FOT-Signal and your flowlimitation actually increases ... and to my surprise not even a single hypopnea flagged. (as usual I am clearly with you - if THAT is no Hypopnea what does one have to do?  Oh-jeez  )

As one can (clearly) see in the SPO2 you were (in reality) breathing normally - reducing all that data to just random garbage.  Dont-know
(and that is actually important! - the data does not make any sense - no need to dissect that even further[Fullstop])

Obviously I have huge areas of ignorance here -- as I characterized the 6 minutes of 5 l/min as "peculiar" as opposed to the full bemusement appropriate to the machine reporting that I'm really dead and have been for the last 3 weeks since it happened! Dielaughing 

Ok, 5 l/min is just wrong.

What about 7-8-9 l/min? At what point do you believe the machine?

Back on the topic of my size :-)  Is it possible that I still have some of that fat girl's breathing capacity even after losing an entire person worth of weight?

I'm a musician. Everyone knows about the barrel chest that horn players -- and many opera singers -- develop in order to push more air through the instrument. COPD / emphasemia as well. Is it possible that people who have lots of overdeveloped breathing muscles might respond differently to apneas?

Another question about the physics. I spent a lot of years sleeping with a full-face mask that was too damn big. One of my tricks was to inflate my cheeks chipmunk-like in order to seal all around the mask. My intent was to make it a habit so that I would do it while asleep. So in a nasal mask with my mouth closed, what's the effect of the air pushing up my nose, into the back of my throat and then into the "cavern" of my closed mouth? Imagine my airway is obstructed partially, with air pumping in and out of my lungs but also in and out of my closed mouth through my nose? (If you are familiar with how inflation and deflation of the aortic arch transfers pressure from the systolic to diastolic phase of your heartbeat, imagine the same thing happening with your mouth?) So does that make the data complete garbage?
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RE: Why don't these flow rate curves count as flow-limited?
Re your MV of 5 L/min:

Some linked items and/or snippets suggest the idea--if apneic matters were ignored--you may breathe more normally than most "normals": suggest that your breathing training, breathing muscle development and the aerobic benefits--even your flow liimited beathing?? Surely not!?---may be why your SpO2 does not fall significantly from normal (if at all--did it?). All of which is not to suggest your FLs do not harm your health and sleep and need to be treated more effectively--the obligatory disclaimer here, as if you needed it now (or ever?).

My work to correlate Resmeds' FLs with "breathed volume losses"----vs an assumed fixed-for-now, imaginary baseline volume, around  MV = 7----prompted me to look into your "shocking" 5 L/min MV and the charges against your Resmed device's reports.

As below and elsewhere, normal resting MV is variously reported as 4, 5, or 6 L/Min. most MV indications seen tonight have normal ranges bounded within 4-9 L/min. 

Buteyko's lower end is 4 L/min with 4-6 range. Elsewhere it's 5  (or 6?)  for a 154 lb. (70kg) male. A 135-140 lb female? Didn't see that. (Buteyko's treatment of asthma, at least with his breathing retraining methods, has been criticized.)

Scan selections from Table of Contents. The 4-6 range is there as well as a good discussion of that Bernoulli Principle I've tried to use to explain reductions of critical cross sectional areas of airways by slack tissue: the "wind slammed doors", air foil lift, etc. There it gets into velocity and pressure differentials at most pronounced narrowing. 

Here are more items in a disorganized mix of supportive, related links and a sample from my quick scans:

IMST training: "Originally developed in the 1980s for those who suffer from respiratory issues, High-Resistance Inspiratory Muscle Strength Training (IMST) requires you to inhale really hard on device that provides resistance. "Imagine sucking hard through a tube that sucks back," explain the authors from the CU Boulder, in the official release. The exercise is known to strengthen your breathing muscles ("inspiratory" muscles), as well as your diaphragm."


Novel 5-minute workout improves blood pressure, may boost your brain | CU Boulder Today | University of Colorado Boulder

5-minute breathing workout lowers blood pressure as much as exercise, drugs | CU Boulder Today | University of Colorado Boulder




Normal Respiratory Rate, Volume, and Chart (e-breathing.com) A snapshot of Buteyko's normal is quoted toward the end.

Other (I lost the source URL):
"Average minute ventilation for a person changes throughout the day depending on many factors.
Normal minute ventilation range at rest is 5-6 L/min. Average minute volumes numbers for modern people at rest are close to 12 L/min. This means presence of overbreathing and hypocapnia (low CO2) in contemporary population leading to chronic cell hypoxia (reduced O2 levels).

"What about minute ventilation in people with chronic diseases? 
For people with chronic health problems, respiratory volume is greater."
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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RE: Why don't these flow rate curves count as flow-limited?

So is it remarkable that my median minute vent over a whole night is in the 4.3 - 4.6 range -- over the entire going-on-seven years that I've been on CPAP?

(Overview minute vent statistics since I restarted cpap March 14, 2021 Screen Shot 2021-07-06 at 4.20.26 PM.png)

When they say "normal is 4-9" what exactly do they mean?

So this is a piece of a different night. No leaks at all the entire night I was asleep (a few little ones way back at the beginning of the night when I was talking with the nasal mask on before I went to sleep.)

(10-minute view June 17, 2021 ~5am Screen Shot 2021-07-06 at 4.34.34 PM.png)

I blew up the minute vent graph and adjusted the y-axis.
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RE: Why don't these flow rate curves count as flow-limited?
@2SleepBetta: Maybe I'm now totally lost - I'm actually having a really hard time with all the abbreviations. At least I was talking about the respiratory flow rate of 5 l/min - that is SPEED and not volume. (From the looks of it cathyf has not reached a minute ventilation of 5 l/min for quite some time - but that is not a problem with a little over 60kg^^)

OCD (used correctly) is not a Bug - that's a Feature  Cool

Well ... let's start with going a few steps back and look at what we actually have in the first place.

Our devices are NOT diagnostic devices - those are treatment / therapy devices!

The devices basically have 2 sensors - 1 for the flowrate and 1 for the pressure - just those 2 nothing more. And those sensors are actually both in the device and not in the mask - about 2 meters away from us.
From those 2 values they derive all the magic - including the repiratory flow which is just a small portion of the total flow measured.

Now let us take a look at the clinical guide and check what they say about the accuracy of the displayed values:
Quote:Mask pressure ±[0.5 cm H20 (0.5 hPa) + 4% of measured value]
Flow ±6 L/min or 10% of reading, whichever is greater, at 0 to 150 L/min positive flow
Leak ±12 L/min or 20% of reading, whichever is greater, 0 to 60 L/min
and for the measurement system uncertainties
Quote:For measures of flow ± 1.5 L/min or ± 2.7% of reading (whichever is greater)
For measures of volume (< 100 mL) ± 5 mL or 6% of reading (whichever is greater)
For measures of volume (≥ 100 mL) ± 20 mL or 3% of reading (whichever is greater)
For measures of pressure ± 0.15 cm H2O (0.15 hPa)
For measures of time ± 10 ms

Well ... quite the error-range  Huhsign

I spare you the details about the data resolution and accuracy in the edf files. (comes down to 2 ml/s or +/- 1 ml/s - that is ON TOP of the above)

So it is quite clear, that they simply CANNOT be diagnostic devices. (fun fact: in lab sleep studies are not that much better datawise and don't get me started on the simple difference between thermistors and nasal cannula - but: they do have much more channels)

The only task for an APAP-Device is: adjust the pressure between properly and carefully titrated pressure ranges. No need to worry much as both are safe.
(one could now make an excursus to the philosophical question of whether the only task of the APAP mode is to INCREASE the pressure as required (above the otherwise set CPAP pressure) or to LOWER the pressure as possible (below the otherwise set CPAP pressure) ... just semantics in the end^^)
They do log data but the manufacturers are not (willingly) giving us the software to look at or analyze that - that data is clearly meant for medical professionals.
I often enough say that the logged data should just be seen as something like an "evidence log" - all the machines do there is logging why they raised or lowered the pressure or kept it steady. (There! I saw that and that is why I did this.)

The data from the devices is nowadays not bad - actually quite good! BUT: only and only IF all goes well.

So the first thing I ALWAYS do if I look at data is: establishing a trust level (of that data)!
A very good indicator is of course the leak rate. No matter how high or low - if the leak rate is different from zero that means the dataquality takes a nosedive.
Then I look after things that simply make no sense - or are too far from the other data present.

If you have not done by now then let's make a simple test to get some feeling of what I'm talking about:
just take your DreamWear mask and attach it to the machine and start the machine and let it run for 2-3 minutes (well that should get to 4 cmH2O with your settings - but you should be able to do that even with EPR off^^) .... now block one side of the frame for 1-2 minutes ... maybe the other side as well and at the end let's repeat the start with both sides free.
(make sure you can import short sessions!)

What we did there is producing a major leakage - as a matter of fact as you were not wearing the mask the pressure in your airways was exactly 0  Too-funny  ... take a look at the data and check what pressure the machine saw. (actually I have not done that with a ResMed device - hopefully I do not embaress myself too much) - if all goes well even the leakrate should change when you block one side of the frame.

So that is the ERROR I am talking about during leakage - you simply do not know!  Thinking-about

Now to the june the 19th and that "thing" around 2:00 :
Your respiration diminishes to roughly half of your normal ventilation - so far that is not surprisingly for an APAP - but: that is steady for about 6 MINUTES.
So 6 Minutes with half the minute ventilation - respiratory rate remains quite the same and I would assume the breathing timing as well?
Well - we do not need to gues - you provided the PulseOximeter data as well - no Desaturation and no visible change in pulserate.

Does that make sense to you? To me it does NOT.

Now: at the beginning and the end was a short spike in the pulse rate and during that phase there was a little leakage. Now THAT is interesting. That part is missing - on that day and the other - but that part actually is revealing!
Would be interesting to see if the start was movement as well - at the end I would suspect movement or more a change in position. The start could also have been an obstruction and maybe the seal of the mask broke during the recovery breaths (that happens quite often if you look closely enough) or the mouth was opened to compensate.

I would write those phases off as "artefacts / insufficient data due to leakage" ... for the whole night those phases maybe sum up to 20 or a little more minutes - compared to 8 and a half hours. You obviously didn't wake up and can't remember - why even bother? (although around 5:45 you clearly stopped the machine - and that phase is basically the same)

I would 'trust' the other data for that night.  Okay

The flowrate might look distorted - pay attention to the scaling - how often does one look at such a scaling? Honestly: I can not make the distinction between signal noise and actual data - if that would be rescaled to a "normal" scale I would assume it looks quite normal. (considering the leak of course)
Nevertheless: snoring is nothing that has to be done by hand - the device actually does score that! And the device looks at the rawdata at a much, much higher sample rate - if there is nothing in the snore graph then there was no snoring. (I do not know what OSCAR is calling a "max" value - but that was 0.00 for the whole night)
And I am also not able to see those severe flowlimitations there - that was an honest Plea: please mark those for me. Well - the device was not able to tell the breaths apart ... maybe it just saw one very long breath? Would fit the definition of a flowlimitation. Very much like the doubling in the respiratory rate where very severe flowlimitations are seen as 2 (or in rare cases more) breaths - then of course "perfect" breaths - but in reality that was just one breath with very severe flowlimitations.  Huhsign

The question is also not so much what to trust - but more what NOT to trust. Sounds like semantics too but makes a little difference.
If I roughly calculate that through I would say that with your little over 60 kg your tidal volume is normal - your respiratory rate is astonishingly low which results in amazingly low flow rates. But honestly: not a medical professional - I actually do NOT know those things.

From the little I know (or more "imagine") with more weight one can NOT breath better - in fact the opposite should be true and breathing should be more efficient if you weigh less. (more room for your lung and your breathing muscles)
(I was actually amazed by your respiratory rate with the FFM and most likely mouth breathing (back in the 'other' days^^) - with that respiratory rate I would have been convinced that it was nasal breathing - also the difference still fits compared to now around 11 / minute^^ ... usually I consider resp. rates starting at 17 as a good indicator for mouth breathing)

---- let's make a cut here and come back to "my" issue with "flowlimitations"  Too-funny

First of all: there is no such thing (currently and that I personally know of) as THE device that is a perfect fit for everyone. We (as people) are different and so it is actually a good thing that we have different machines!
There are machines out there where I like this or that better than compared to others - but the others have different thinks I prefer more and so on.

If one now says, that "flowlimitations are a real issue for OSAS-Patients and need to be be taken care of", THEN this is exactly the same as saying "there is only one machine out there for OSAS and that is ResMed AND: patients with another machine are not or undertreated".

And that is - and please forgive me - BS!
There are millions of devices out there from different manufacturers that do there job very good. I suppose Philips you all know well enough - that would be Löwenstein: https://www.docdroid.net/LPC2YQl/prisma-...tx#page=22

Maybe my whole confusion with the usage of "flowlimitations" here is just a language-problem!? - for me Flowlimitation is a term with a precise meaning - and that is not simply a limitation in the flow as seen in apneas and hypopneas - those 2 are NOT Flowlimitations.
Flowlimitations in my book are increased breathing effort where the maximum flow speed(!) cannot be reached (because that is limited) - thus resulting in an increased breath-duty-cylce - thus the ventilation or air volume stays steady - thus it is NOT hypoxic (in contrast to hypopneas and apneas). .. if there is another definition out there please point me towards that!

Measuring "Flowlimitations" directly from the flow is just a simplification or surrogate because that is "easier" than measuring the breathing effort (gold standard would be esophageal pressure - respiratory inductance plethysmography (RIP) is also good enough) but there you have to be precise!

I have read a few articles and studies and such stuff - by far not all and I am always eager to learn.
I know of no article or study where they found that flowlimitations play a role in people with OSAS - in fact having an AHI over 5 is widely seen as an exclusion criteria for UARS ... and for those that have mostly apneas and nearly no hypopneas flowlimitations are very rare.

There has been extensive research in the past on the NON-hypoxic sleep related breathing disorders - mostly focused on flowlimitations and at first arousals and after that was not enough even CAPs (cyclic alternating patterns). But all those do NOT have OSAS!
And then there came the sao paolo cohort around the corner: IIRC 30% with flowlimitations is NORMAL! (and 5% of the healthy(!) population have even much more - IIRC ... maybe I should get my facts straight beforehand) ... and also IIRC they even raised the question if flowlimitations themself play a crucial role / are important!? (or maybe it was in one of the last articles from Guilleminault)

Back to ResMeds APAP-algorithm based purely on flowlimitations (and of course obstructive apneas):
the Benchmark Study
A and B are ResMed - pay attention to the blue line, that is the needed pressure for FULL breathing normalization.
ResMed overshoots not just a little bit, but by far! They actually do overtreat! (as in always!)

Once again: 1 Step back!
What was the task of an APAP again? Adjust the pressure BEFORE an obstruction happens.
Flowlimitations or variations in the shape of the inspiratory flow seem to be not a bad sign for that. And once again: those devices are NOT diagnostic devices. What is a good sign to raise the pressure does not need to be a problem on itself.

Well ... one step to the side:
It is called syndrome and not dissease - and that for a reason! Even nowadays noone really understands it completely! Noone!
Current studies come to the conclusion that 1 of 4 women and nearly 1 of 2 men have a sleep related breathing disorder  Huhsign  OK - that actually is a problem! Not enough devices out there - not enough capacity to actually test those (properly) - if the insuracenes opt out the profits per device are dropping - bad thingy.
Now they come up with different stereotypes of OSAS and also symptomatic and asymptomatic OSAS ... and as knowledge progresses they even consider the possibility that an elderly is not the same as a younger / middle-age one.

And that is one thing, that I am actually interested in regarding overtreatment. If we are honest we do not really know what healthy sleep is - what is a healthy AHI?  Thinking-about  is below 5 good? is 0 good or maybe better or even worse? We do not KNOW!

As noone knows it gives room for the layman approach (what else is there then?). That is a good thing - I'm all in myself  like
But: we replace evidence based knowledge / medicine with anecdotal 'knowledge'.

Happens to best of us  Too-funny  - You all know the SERVE-HF Study! You could have asked every doctor in that topic out there - everyone would have told you: ASV is the best for central apnea syndrom and CSR with heart failure.
Well ... the study ended with: NO! (and that study was done after the even bigger CPAP-study showed no advantage for those)
evidence vs. anecdotal!

The study sparked my interest a while back again - an ASV is by definition the best device there is out there. Breath by breath normalisation - what more can you get? So basically that device is the definition of overtreatment.
In that study where ONLY(!!!) people with an LVEF <= 45% - it ended early because they where dying earlier than the control group - it ended denying those an ASV treatment. Shocker!

Now that does simply not say anything about other people or patients ... but it makes me think! Why would people with a serious heart condition not profit from a nearly complete elimation of their central apneas? Does that mean, that somehow those apneas have a protective function?
Are heart conditions not one of the reasons we strap on a mask each night?

Reminded me of this: https://doi.org/10.1111/j.1365-2869.2009.00754.x

But somehow younger perople tend to profit more from a very low AHI - if they actually are getting older? Well - I do not know^^ ... maybe it would be not that bad if at a "certain" age one makes a shift (or stops to adjust^^) towards a higher / more normal AHI!?

Evidence vs. anecdotal!?

Back to the flowlimitations:
If one chases flowlimitations hypoxic events are (or should be) no longer an issue. The very definition of OVERtreatment^^

I have to admit I am really biased! I have not seen enough clear(!) cases where the elimination of the flowlimitations actually helped that much. And to be completely honest I have my doubts that EPR is doing any good on flowlimitations at all. I do however not doubt that Bi-Level is working there!
The thing with EPR simply is the data! We do not have raw data we cannot control or retrace / comprehend if that actually works. I get on a theoretical level that it should work to a certain degree - I also get that even if it does NOT work in reality the data looks better because only the introduction of a varying pressure smoothes the respiratory flow.

My bias comes from my personal experience back when I noticed a very slight / sublte difference in my .. well resilience / productivity / what I could do - but NOT so much on how I subjectively felt on 2 different devices.
I ended up spending nearly half a year in total and doing a couple of tests and taking notes to objectify that. The funny thing is: the 1 device actually made me around 5% more productive AND I slept in average about 20-30 minutes SHORTER with that device. (which is quite funny because the manufacturers advertise it as a good thing if you sleep LONGER with their devices^^)
BUT: the other device won in the end and all in all because I LIKED the humidification more  Oh-jeez

And that was one of those "hit me with a rock" moments - I had the data that one device was actually and to best of my possibilities making me more(!) productive and giving me more effective sleep (as in: sleep less but be equally or even more rested) BUT I preferred nevertheless the other device because as a mouth breather sleeping on my stomach humidification is kind of crucial to me  Dielaughing

I notice in others quite often that there there is a tendancy towards the data - I cannot shake the impression that many (personal feeling: most!) people wake up and look at there data and after they ckecked that they feel accordingly - not the other way around: wake up and check how you are feeling and AFTER that maybe take a look at the data (and do not alter how you feel!)
So in my opinion there is bias in the data! - I tried to explain that in the flowlimitation-index thread with "if you create a meaningless new value and put a shiny name on it people start to put meaning into that! (and feel accordingly)"

Nowadays there are more than 200 sleep disorders - OSAS beeing just 1 of that - but a quite prominent one (compared to the others). (once again: I am from germany - here maybe 1 out of 80 or maybe 70 people is diagnosed with OSAS - the prevalence is much, much higher!)

But - after reading how she had managed her "diet" - I am quite confident that cathyf can make the distinction between actual feeling and data induced bias or feeling^^ So I repeat: I am really interested if a VAuto makes any difference at all for her!

--- so let's cut back on cathyf^^

If I put it all together I do not trust that you have those seemingly severe flowlimitations! You have very shallow breathing - which is not by itself a bad sign as most likely pointed out by 2SleepBetta (I have not read the links - but I know what should be behind them) ... so basically you are operating at the end of the specification of your device.
We already found out that EPR is not always triggering with your breaths (and leaks) ... well if 4 cmH2O are enough for you is debatable - I would ask if there is a real reason for EPR in the first place  Cool  - no EPR no problem on that front^^

From what I understood, remember and have read of yours you have enough on your plate to be in the position to just pick one for the reason of a bad or not that good-nights-sleep! So it is debatable as well if your SRBD really is the cause for that^^

I would not care too much about whether one or the other data is correct or relevant and focus more on the subjetive feeling and maybe objectifiable things (like: irritability / productivity and so on)
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RE: Why don't these flow rate curves count as flow-limited?
Minute vent is a large range because it is largely dependent on size and muscle etc that requires oxygen.

A quick google shows 70-100 ml/kg which would be 4.3-6.6 L/min for your weight.

You are small and have restrictive breathing. Low TV and MV is to be expected and not out of normal range
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RE: Why don't these flow rate curves count as flow-limited?
I wanted to respond with a long post to TBMx, but I have a new VAUTO to program, and need to get to sleep for my third day of my new job tomorrow, so it will have to wait.

One thing I will add to my original response to flow limitations. As I said before, within a short time of starting therapy with my new Resmed machine back in 2014, I was on another apnea board asking where to find the "ignore flow limitations" setting on my machine. Because it was obvious to me from my data that raising pressure didn't fix the flow limitations, but unfixed flow limitations were not causing events. But there is one other piece of data maybe interesting.

Back in 2014 before the in-lab test I had an ApneaLink screening (ApneaLink is also a Resmed product.). It's the only place other than my Resmed machine that ever mentioned flow limits. 63% of my breaths were flow limited in the ApneaLink (60% without snore, 3% with).

Another oddity is that according to my Airsense10, I probably have 10 apneas for every hypopnea. But according to the screening and the 3 sleep studies, apneas were rare, most events hypopneas.

5/12/2014 -- 1 apnea, 65 hypopnea
7/29/2014 -- 14 OA, 0 centrals, 77 hypopnea
11/11/2020 -- 2 OA, 1 central, 9 hypopnea
4/1/2021 -- 0 apnea, 106 hypopnea

Not sure what that means -- is the machine using 80% and the sleep lab equipment using 90% as the cutoff between hypopnea and apnea?

Another note, I think that I have two somewhat independent phenomenae going on. First is the every-so-often total-hot-mess of positional apnea. (which has dozens and dozens of apneas and only the occasional hypopnea). However between the attacks of positional apnea, Then there is the continuous flow limits while asleep problem, and that's pretty constant.

So when you say something like "AHI above 5 excludes a diagnosis of UARS" -- what about the patient with an AHI of 70-80-90 during positional apnea, but under one in the in-betweens? If I spend 45 minutes a month with apnea after apnea crashing in one atop the other, and 11,000 minutes a month with high flow limits and AHIs under 1, does the 45 minutes exclude UARS? I can't imagine that's how that works!

...more tomorrow...
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RE: Why don't these flow rate curves count as flow-limited?

Simply amazing.


In nearly 7 years of using a ResMed machine, the only time I've ever seen a flow limit graph that looked like that was when I was awake the entire time.

Off to work!
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RE: Why don't these flow rate curves count as flow-limited?
Nice! Now, the BIG question... How do you feel?


- Red
Crimson Nape
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