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Yes, you are correct..... I got the inhalations switched.
why would the shorter inhalation-period=breath, be considered superior

robysue1 wrote: ↑

Fri Dec 02, 2022 10:33 am

And then, there's the stuff about "divide by zero" nonsense. Once again my heart is going pitter-patter because I have a chance to talk about Calculus in a public forum full of non mathematicians. Today's topic is the derivative.

Oh god woman, what have you done to me... I find myself watching THIS youtube today:

https://www.youtube.com/watch?v=rCfPQLVzus4

I mean, I clicked back to that tab and was faced with this:



WHAT HAVE YOU DONE???

(no, I don't pretend to be following all the math, but I'm happy enough with the broad concepts.

dataq1 wrote: ↑

Fri Dec 02, 2022 4:53 pm

Yes, you are correct..... I got the inhalations switched.
why would the shorter inhalation-period=breath, be considered superior

As I said in my previous post: It wouldn't.

And the decreased in the amplitude of the flow curve from a series of breaths with inhalation length = 1.4 seconds and TV = 500 mL to a series of breaths with inhalation length = 1.7 sec and TV = 500 mL would not be enough to be flagged as a hypopnea under ordinary circumstances: The decrease in amplitude of the peaks of the flow curve would be in the neighborhood of 17%, which is nowhere near big enough to qualify for being flagged as a hypopnea.

robysue1 wrote: ↑

Fri Dec 02, 2022 6:18 pm

dataq1 wrote: ↑

Fri Dec 02, 2022 4:53 pm

Yes, you are correct..... I got the inhalations switched.
why would the shorter inhalation-period=breath, be considered superior

As I said in my previous post: It wouldn't.

And the decreased in the amplitude of the flow curve from a series of breaths with inhalation length = 1.4 seconds and TV = 500 mL to a series of breaths with inhalation length = 1.7 sec and TV = 500 mL would not be enough to be flagged as a hypopnea under ordinary circumstances: The decrease in amplitude of the peaks of the flow curve would be in the neighborhood of 17%, which is nowhere near big enough to qualify for being flagged as a hypopnea.

Need the hammer?

Rubicon wrote: ↑

Fri Dec 02, 2022 8:36 pm

Need the hammer?

That the big one or the little one?

Wish I could give 'em a pop quiz. They'd both fail miserably.

robysue1 wrote: ↑

Fri Dec 02, 2022 6:18 pm

The decrease in amplitude of the peaks of the flow curve would be in the neighborhood of 17%, which is nowhere near big enough to qualify for being flagged as a hypopnea.

And that's my point (and i suspect wonder's); you are focused on the decrease in amplitude of the flow rate curve, at the exclusion of the tidal volume.



Your contention (as well as other on this board) is that despite of the volume or duration of the inhalation, the "A" curve is superior to the "B" curve simply because of the very quick, but unsustained rush of air.

And I'm saying that that rush of air at the beginning of A's curve, is not the only basis for evaluating breaths that may be the beginning of a hypopnea.

robysue1 wrote: ↑

Fri Dec 02, 2022 9:14 pm

Rubicon wrote: ↑

Fri Dec 02, 2022 8:36 pm

Need the hammer?

That the big one or the little one?

Wish I could give 'em a pop quiz. They'd both fail miserably.

And even a hammer won't help....

https://bengtwendel.com/your-teacup-is- ... -your-cup/

old zen story wrote:Nan-in, a Japanese master during the Meiji era, received a university professor who came to inquire about Zen.

Nan-in served tea. He poured his visitor’s cup full, and then kept on pouring. The professor watched the overflow until he no longer could restrain himself. “It is overfull. No more will go in!”

Like this cup, Nan-in said, you are full of your own opinions and speculations. How can I show you Zen unless you first empty your cup?

dataq1 wrote: ↑

Fri Dec 02, 2022 10:42 pm

robysue1 wrote: ↑

Fri Dec 02, 2022 6:18 pm

The decrease in amplitude of the peaks of the flow curve would be in the neighborhood of 17%, which is nowhere near big enough to qualify for being flagged as a hypopnea.

And that's my point (and i suspect wonder's); you are focused on the decrease in amplitude of the flow rate curve, at the exclusion of the tidal volume.

That's because when the sleep medicine community officially defined hypopneas and apneas in the context of sleep disordered breathing events, they defined them in terms of the decrease in amplitude of the flow rate curve. And for some reason you just will not concede that the whole of the sleep medicine community does not use tidal volume when it comes to defining sleep disordered breathing events.

Your contention (as well as other on this board) is that despite of the volume or duration of the inhalation, the "A" curve is superior to the "B" curve simply because of the very quick, but unsustained rush of air.

Given the scale that you've drawn those graphs, "A" most likely has more tidal volume than "B". So I'm not sure what your point is. There's nothing particularly wrong with a significant sharp inhalation that then slows down. The problem with sleep disordered breathing is that normal inhalations do not happen when the airway is compromised and starting to collapse. Flow limitations (i.e. distorted inhalation shapes) often occur before the airway actually collapses, and when the airway collapses, the flow of air into the lungs is compromised. And that means the amplitude of the inhalations in the flow curve decrease significantly as compared to the normal sleep breathing pattern before the airway collapsed.

Here's a homework assignment for you:

Read or skim throughThe role of flow limitation as an important diagnostic tool and clinical finding in mild sleep-disordered breathing,
which is a scientific paper about the subtleties and problems of diagnosing sleep disordered breathing.

Now answer these questions for me:

1) How many times is tidal volume mentioned in the entire article? What's the context of when tidal volume is mentioned?

2) Click on the link for Figure 4. What are the names of the three graphs in the figure? And what are the units for each graph in the figure?

3) In light of your answers to Question 2, what units do you think the authors of the paper use to measure what they call "flow" throughout the paper? Do the authors of the paper use the word "flow" in a way that is consistent with thinking of "flow" as a volume function or as a rate function?


And here's a Google assignment for you: Find me a scientific paper on sleep disordered breathing that makes the argument that tidal volume should be used as a criteria for scoring hypopneas on a PSG. Give me the full citation or a web link to the article.

robysue1 wrote: ↑

Fri Dec 02, 2022 9:14 pm

Wish I could give 'em a pop quiz. They'd both fail miserably.

IMO they're doing that now w/o the quiz.

robysue1 wrote: ↑

Fri Dec 02, 2022 10:33 am

If you really think I should do it, let me know that and I'll reconsider registering over there under a new (robysue1) name since I can't recover my old robysue account over there.

No need, looks like they got everything solved:

Wondering2 wrote:OK, lets try it this way, does the EDF file containing what OSCAR plots on the flow rate graphic have a heading and dimensions?
Like "flow rate, ml/sec "?

pholynyk wrote:Of course it does... read up on the edf file format: https://www.edfplus.info/

From the header:
Code:
Label >Flow.40ms <
Transducer > <
Units >L/s <
Min >-2.000000<
Max >3.000000<
Dmin >-1000<
Dmax >1500<
PreFilter > <
Smp/Rec >1500<
Reserved >
<
OSCAR scales the values to ml/sec for convenience

Wondering2 wrote:Thanks much...that is helpful

Prepare to be bombarded!

Rubicon wrote: ↑

Sat Dec 03, 2022 3:58 am

robysue1 wrote: ↑

Fri Dec 02, 2022 10:33 am

If you really think I should do it, let me know that and I'll reconsider registering over there under a new (robysue1) name since I can't recover my old robysue account over there.

No need, looks like they got everything solved:

Wondering2 wrote:OK, lets try it this way, does the EDF file containing what OSCAR plots on the flow rate graphic have a heading and dimensions?
Like "flow rate, ml/sec "?

pholynyk wrote:Of course it does... read up on the edf file format: https://www.edfplus.info/

From the header:
Code:
Label >Flow.40ms <
Transducer > <
Units >L/s <
Min >-2.000000<
Max >3.000000<
Dmin >-1000<
Dmax >1500<
PreFilter > <
Smp/Rec >1500<
Reserved >
<
OSCAR scales the values to ml/sec for convenience

Wondering2 wrote:Thanks much...that is helpful

Prepare to be bombarded!

So they're still resisting the idea of actually, you know, looking at the units that Oscar actually writes as the units for the graphs it displays. Or maybe the whole lot of them haven't discovered the floating tool tips in Oscar.

And it still sounds like none of them have bothered to look at the exact same data in ResScan. I kind of wish I had a working PC write now so I could just it up, launch ResScan and give 'em a bunch of fresh ResScan shots of the same data presented in both Oscar and ResScan and ask them to tell me why the official software is incorrectly labeling both graphs and units on the graphs. I'll have to ask hubby if he's got a working PC in his large stack of various computers used for various things ...

Or maybe since they're so sure of themselves, they honestly believe that the engineers at Resmed and the programmers who wrote the software for the Resmed xPAPs and the ResScan software itself don't know what they're doing because they label the first curve in question Flow and put the L/min units right there on the curve itself in the lower part of the panel.

Or maybe they're still trying to convince themselves that TV is measured in mL/sec?

I think I should have put a due date on that homework assignment I gave them.

robysue1 wrote: ↑

Sat Dec 03, 2022 8:04 am

Or maybe since they're so sure of themselves, they honestly believe that the engineers at Resmed and the programmers who wrote the software for the Resmed xPAPs and the ResScan software itself don't know what they're doing because they label the first curve in question Flow and put the L/min units right there on the curve itself in the lower part of the panel.

Or maybe they're still trying to convince themselves that TV is measured in mL/sec?

I think I should have put a due date on that homework assignment I gave them.

I'm sure that you've come across especially dense students that refused to believe you, and the Dunning-Kruger effect.

We've got several sterling examples here.

robysue1 wrote: ↑

Sat Dec 03, 2022 8:04 am

Whew, back after several grueling days at hospital, worked like a rented mule!

Data is pretty much spot on in assuming that my thought is that tidal volume plays a significant role in detecting a hypopnea.

Take a look at the OSCAR chart that I posted way-back:

viewtopic/t185583/Baseline-for-Desatura ... rates.html


There doesn't appear to be much change in the peak amplitude of the inhalations before the big breath and after, at not so as to be immediately discernable.

However, looking at the TV chart, a significant change is clear (before big breath and after).

That's why I suggested, and continue to suggest that TV data should be considered when looking at these incidents.

Frankly, I don't know if the Resmed engineers only look at the peak height of an inhalation and use that as the yardstick to evaluate subsequent breaths for possible hypopneas.
But it would appear that the TV of subsequent breaths is a clearer indication that the patient has "diminished" ventilation.

robysue1 wrote: ↑

Fri Dec 02, 2022 9:14 pm

That the big one or the little one?

The little one.

Clearly gonna need the big one:

Wondering1 wrote: ↑

Sat Dec 03, 2022 11:31 am

mule!

(headed)

Finally, something accurate.