Tidal volume and Flow limitations

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dataq1
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Tidal volume and Flow limitations

Post by dataq1 » Wed Nov 03, 2021 12:56 pm

One might expect that there is a relationship between the severity of flow limitations and tidal volume, yes?
In the following capture, taken during a period of slowly falling pressure and no snoring, no change in leakage, the grading of flow limitation increases from 0% severity to 25% of most severe during a period that the tidal volume has remained fairly consistent (from time 05:07:00 to 05:10:12).
Flow limitations and Tidal volume_002.jpg
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palerider
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Re: Tidal volume and Flow limitations

Post by palerider » Wed Nov 03, 2021 2:46 pm

dataq1 wrote:
Wed Nov 03, 2021 12:56 pm
One might expect that there is a relationship between the severity of flow limitations and tidal volume, yes?
No, no relation

Please stop littering the forum with your random foolishness, keep them all in one thread, so they can be easier ignored by people that actually have issues.

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Re: Tidal volume and Flow limitations

Post by dataq1 » Wed Nov 03, 2021 4:19 pm

palerider wrote:
Wed Nov 03, 2021 2:46 pm
Please stop littering the forum with your random foolishness, keep them all in one thread, so they can be easier ignored by people that actually have issues.
Definitely high class, sir. Personal attack in response to honest question, trying to understand the implications and circumstances surrounding therapy.
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palerider
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Re: Tidal volume and Flow limitations

Post by palerider » Wed Nov 03, 2021 4:53 pm

dataq1 wrote:
Wed Nov 03, 2021 4:19 pm
palerider wrote:
Wed Nov 03, 2021 2:46 pm
Please stop littering the forum with your random foolishness, keep them all in one thread, so they can be easier ignored by people that actually have issues.
Definitely high class, sir. Personal attack in response to honest question, trying to understand the implications and circumstances surrounding therapy.
No, you're nitpicking meaningless things.

Keep them all one thread, please.

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Re: Tidal volume and Flow limitations

Post by Pugsy » Wed Nov 03, 2021 5:18 pm

If I had known a while back that you were going to go down this road with so many different questions about the data you see on the OSCAR software reports I would have encouraged you to keep all your questions in one thread.
Much easier read for one thing and the other (and main reason) is that it could have been used as an educational thread for newbies encountering the data in OSCAR and wondering what it all meant and maybe going down the same road you have gone down. With every little question scattered throughout the archives they are pretty much lost and most people won't get the benefit or education because they don't know about its existence.
dataq1 wrote:
Wed Nov 03, 2021 12:56 pm
One might expect that there is a relationship between the severity of flow limitations and tidal volume, yes?
No. Going down the wrong road here with your thinking.

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dataq1
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Re: Tidal volume and Flow limitations

Post by dataq1 » Wed Nov 03, 2021 5:38 pm

palerider wrote:
Wed Nov 03, 2021 4:53 pm
No, you're nitpicking meaningless things.
Keep them all one thread, please.
The thread started by MMcG "Flow Limitations" addresses the shape of Flow rate curves classed as flow limitations and his question if his machine is falsely flagging FL events. Tidal volume is never mentioned.
This thread asks about the relationship of flow limitation grading and changes in tidal volume.
Each is focused on two very different aspects.

Dismissing either question as meaningless is an insult to the readership.
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Re: Tidal volume and Flow limitations

Post by dataq1 » Wed Nov 03, 2021 5:57 pm

Pugsy wrote:
Wed Nov 03, 2021 5:18 pm
No. Going down the wrong road here with your thinking.
I assume you mean that there is no relationship between flow limitation (and it's grading) and tidal volume.

When your average "man-on-the street" hears that traffic on a street will be limited, they will naturally assume that the amount of traffic will be decreased (as compared to some non-limited condition).
When one is told there will be limited seating at an event, you expect that the total seating will be less than normal. etc...But you get the picture...

So, I just don't understand a "no" answer. Could you please expand on your answer, so that I can understand why the two should not be related.
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Re: Tidal volume and Flow limitations

Post by palerider » Wed Nov 03, 2021 8:56 pm

dataq1 wrote:
Wed Nov 03, 2021 5:57 pm
Pugsy wrote:
Wed Nov 03, 2021 5:18 pm
No. Going down the wrong road here with your thinking.
I assume you mean that there is no relationship between flow limitation (and it's grading) and tidal volume.

When your average "man-on-the street" hears that traffic on a street will be limited, they will naturally assume that the amount of traffic will be decreased (as compared to some non-limited condition).
When one is told there will be limited seating at an event, you expect that the total seating will be less than normal. etc...But you get the picture...

So, I just don't understand a "no" answer. Could you please expand on your answer, so that I can understand why the two should not be related.
Because *THEY ARE NOT RELATED*.

Why are pineapples and marble countertops not related? because they aren't, it's that simple.

These kind of comments from you are why you're trying the patience of people that know things.

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Re: Tidal volume and Flow limitations

Post by dataq1 » Wed Nov 03, 2021 9:06 pm

palerider wrote:
Wed Nov 03, 2021 8:56 pm
These kind of comments from you are why you're trying the patience of people that know things.
Then you are free to ignore the question, just move on. Thank you, Your choice.
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Re: Tidal volume and Flow limitations

Post by palerider » Wed Nov 03, 2021 11:49 pm

dataq1 wrote:
Wed Nov 03, 2021 9:06 pm
palerider wrote:
Wed Nov 03, 2021 8:56 pm
These kind of comments from you are why you're trying the patience of people that know things.
Then you are free to ignore the question, just move on. Thank you, Your choice.
Since trying to get through to you seems to be a lost cause, maybe you'd do better if YOU moved on? You might find people that are more tolerant of your refusing to accept that your theories are groundless if you proposed them elsewhere?

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Re: Tidal volume and Flow limitations

Post by AmSleepnBetta » Sat Nov 13, 2021 4:42 am

dataq1 wrote:
Wed Nov 03, 2021 12:56 pm
One might expect that there is a relationship between the severity of flow limitations and tidal volume, yes?
I agree how we sleep is the important matter. But looking at "the numbers" can often help us make changes to benefit our sleep.

Graphics with a real example sometimes help. An insert or attachment below suggests there is some degree of relationship:

--There is visible correlation of Resmed FL flagging and tidal volume reductions to support "yes" or "no" answers to the question whether some flow limitation is present on the time line.
--There is a visible suggestion, if not correlation, that Resmed FL flagging and tidal volume reductions rise and fall together, presumably because of airflow limitations.
--There is no real correlation of the Resmed severity index number with tidal volume reductions.

Notes:

--The vertical axis to the right applies to the upper axis and the one to the left to the lower axis.
--The lighter green traces show tidal volume rises from the lower zero-axis.
--The curves represent 25 hz data sampling from Resmed generated BRP and PLD data files.
--There are edits that could be made to improve the graphic. Among those make clearer which axis applies where and paint out confusing parts of the vertical axes.
--Constructive criticism and suggestions would be appreciated.
ReducedTVdisplayOfsimilarity&differenceFL-TVd.GIF
ReducedTVdisplayOfsimilarity&differenceFL-TVd.GIF (96.17 KiB) Viewed 15200 times

What makes the Resmed FL flag vary (widely sometimes) from tidal volume reductions is the fact the FL flag, so far as I know, may indicate detection of any one to four different air flow concerns: wave shape other than flatness, wave flatness, ventilation (TV) change and breath timing matters.

Resmed-FL-detect&act.GIF
Resmed-FL-detect&act.GIF (18.17 KiB) Viewed 15200 times
This detail is from Table 2 when expanded to full size at this site https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4629962/

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Re: Tidal volume and Flow limitations

Post by dataq1 » Sat Nov 13, 2021 12:14 pm

Very useful citation in the in the Johnson and Johnson article.
The foundation of the original question was intended to be relative to the detection of Flow Limitations rather than the reaction to FL flags.
Perhaps the term "flow limitation" is a bit misleading. As I suggested earlier the intuitive ("man-in-the-street) sense of "flow limitation" is some sort of mechanism that depresses the normal or expected flow. The expectation might be that the validity of a flow limitation detection would be a subsequent observation of an actual reduction of flow.

What is really helpful in that article is the discussion of algorithms used by various manufacturers. There is a lot to study and learn in that article.
Thanks for finding it
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Re: Tidal volume and Flow limitations

Post by AmSleepnBetta » Sat Nov 13, 2021 6:12 pm

dataq1 wrote:
Sat Nov 13, 2021 12:14 pm
Very useful citation in the in the Johnson and Johnson article.
The foundation of the original question was intended to be relative to the detection of Flow Limitations rather than the reaction to FL flags.
Perhaps the term "flow limitation" is a bit misleading. As I suggested earlier the intuitive ("man-in-the-street) sense of "flow limitation" is some sort of mechanism that depresses the normal or expected flow. The expectation might be that the validity of a flow limitation detection would be a subsequent observation of an actual reduction of flow.

What is really helpful in that article is the discussion of algorithms used by various manufacturers. There is a lot to study and learn in that article.
Thanks for finding it
Your OP focused on the disparity between an OSCAR-portrayal of a series of flow limitations of various severities vs actual, concurrent tidal volume drops. My response was on target.

I failed to point out that I understand the Resmed-logged FL data is sampled at two second intervals and is logged accordingly in the PLD file. The flags must represent averages over 2-second periods, or some multiple of such periods. I don't think I ever saw a FL flag duration shorter than 4 seconds. The FL flags in the graphic are as they were logged.

The mere mention, in the small graphic, of how the machine responds to detected FL was simply to give some rough idea of what Resemed-severity level, obscure and flow-situational as that is, is considered by the Resmed 10 to be worthy of a "FL" flag.

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Re: Tidal volume and Flow limitations

Post by AmSleepnBetta » Tue Nov 16, 2021 3:17 am

A PM indicated some clarification of the graphic I posted above would be helpful for readers. I'm not sure if this will help or confuse more.

MY OPINION: I see one value of these nerdy TV-TVd-FL exercises, as above and explained (?) below, as helping me/us understand when there is need to look at lengthening Inspiratory times, unusually large and persistent I/E ratios, or better than I/E ratios, higher duty cycle ratios (Ti/(Ti+Te). Look at those indicators when sleep is unrestful with a low AHI. Look at them when the zoomed FL have high severity values or are of long duration; those FL flags may arise more from wave shape or breath timing than from drops in tidal volume. Shape and timing are important, but far overshadowed by TV need (as that ventilator crisis in ICUs and the EMTs' ABC rule-Airways first rule confirm).

Getting sufficiently regular tidal volume to support health and restful sleep is our goal. As others have pointed out, lengthening inspiratory time relative to expiratory time indicates more work is being done to get needed TV and there can be some or all the more usual negative consequences of apnea, maybe worse because sleep medicine often overlooks insidious flow limitations.

Redmed devices show your whole night's I/E ratio 1/1.8 = 0.56, for example. Better than that, with OSCAR you can put the Inspiratory time curve above the Expiratory time curve and look at FL where curves diverge widest. Note the higher ratios, and how persistent they are and how they vary night to night. This is one of the ways to help decide if a certain food, Rx or activity is helping or hurting your sleep.

ONWARD: The graphic below was on hand from my own sleep file, easy to grab. It had been stripped down to its barest essentials to show in a close-up concepts presented--squeezed together--in the zoomed-out graphic above. Comment here is about the lower graphic and how it explains the graphic above.

It was assumed in my stock graphic below that normal tidal volumes (TV) vary around, say, 0.5 L. This means that a single normal/ideal area between the green axis and the inspiratory curve would, when calculated, amount to a 0.5 L TV. Green vertical bar lengths indicate actual measured TV of the wave to the left as determined from data on a Resmed data card file. Below, we see some flow limitation effects, "fL", in tips of the waves but no FL flag. The green colored bar lengths correspond to the lighter green traces in the graphic above where the light green traces also rise above the flow rate traces.

Breathing in the upper graph showed TV varying up and down relative to 0.4 L. All red descending bars represent tidal volume (TV) drops, (TVd), below 0.5 L below, and below 0.4 L above. The leftmost inspiratory wave below has a TVd = 0.5L - 0.4L = 0.1L as one can see from differences in values at left. The upper graph, a different layout scheme, would (correctly) show a TVd of -0.1L. Nevertheless, the method is the same in the graphics above and below; main point: Tidal volume drop (TVd) is equal to the difference between the assumed baseline TV (="TVb", say) of 0.5 L, and the measured/calculated tidal volume TV. (In the graphic above breaths with TV larger than 0.4 "pushed" the red bars above the zero-TVd axis--that red "fuzz" or "negative TVd drops" that project above the axis). One note about TV, we tend to breathe deeper or longer or faster (faster and shallower being less efficient) to maintain a fairly steady TV if we are physically able to, apneas aside.

The graphic above shows some TVd-FL flag "agreement" (a) where red bars are overlaid by yellow to make rust color ("disagreeing" yellow color may extend beyond rust color) and (b) where the red bars are smallest without yellow or rust colors. Accordingly, the rust color blend and small red bars indicate some kind of concordance of FL flags and TVd bars. The yellow color extending beyond the rust color suggests, but does not mean FL severity, as scaled, is more serious than is indicated by TVd red bars. A Resmed FL flag, best I can determine, can simply signal the device algorithm has detected a wave shape or wave timing value it is "wary" of in this sleep context but there is no significant TVd to report.

A second graphic illustrates how TV values were determined by using Excel to add up all strip areas making up each TV. Each single-strip volume = .04 (second) X flow rate (L/sec) as both are logged in the Resmed BRP data file.

The attachment FR-TV-TVd-Concept.png is no longer available
FR-TV-TVd-Concept.png
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Re: Tidal volume and Flow limitations

Post by JLROhio » Tue Nov 16, 2021 4:19 pm

palerider wrote:
Wed Nov 03, 2021 11:49 pm
Since trying to get through to you seems to be a lost cause, maybe you'd do better if YOU moved on? You might find people that are more tolerant of your refusing to accept that your theories are groundless if you proposed them elsewhere?
One thing I've noted since being here is that you, are more often, the TOXIC poster around this website.

Your posts often come across as that somehow your opinion is supreme and the only one that matters.

Opinions are like assholes and everyone has one! What makes you think your asshole smells like roses and everyone else's stinks! :roll:

And why are you allowed to publicly have in your signature, a posting that disparages other users of this website and that their opinion does not matter? Oh yea, I forgot, you believe that your opinions smell like roses!

You and your posts are a perfect example of internet bullying - You believe you know everything and have an opinion about everything that you feel is more supreme than all others! I feel for those you live with, as I'm sure their lives must be rosy (no pun intended) being stuck around you and your opinions! At least some of us have the option of putting YOU on IGNORE!

I'm sure this is going to tick off Pugsy...but you need to be called out for your toxic posting, as you seem to LOVE to put down others!
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