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This is a request for clarification on breath flow patterns that was raised earlier in this thread.
It was suggested that a sinusoidal flow rate pattern is characteristic of "awake " breathing, but not of "asleep" breathing.( see viewtopic/t184231/Respiratory-Rate-of-7 ... l#p1410330 and surrounding discussion.
However, Resmed's videos that are trying to discuss (for example) flow limitations appears to begin with a flow-rate pattern (during sleep) that looks like this: This screen grab seems to show a unobstructed "asleep" flow morphology that is sinusoidal.

So what I'm trying to understand is this ideal (and untreated) flow pattern during sleep sinusoidal nor not .

I don't have an answer for data, but it's an interesting question.
Particularly because the resmed algorithm uses the relative deformation of flow rate curve as a principle in a determination of flow limitations.

Palerider seemed to be confident that the balanced (sinusoidal) flow rate breaths is only characteristic of breathing while awake, and not expected while sleeping. Maybe that's not what he meant, but he seemed to be asserting that, and no one disputed it.

Another question might be: what is the limiting factor (tongue muscles relaxing, uvula flapping, mucus plugs etc) that shows up only on the inspiration side of the breath cycle ? In other words, why wouldn't the expiration flowrate be a mirror image of the inspiration flowrate?

Tec5 wrote: ↑

Fri May 27, 2022 10:06 pm

Another question might be: what is the limiting factor (tongue muscles relaxing, uvula flapping, mucus plugs etc) that shows up only on the inspiration side of the breath cycle ? In other words, why wouldn't the expiration flowrate be a mirror image of the inspiration flowrate?

Ever tried sucking air through a tubular balloon?

Try it, get one of those balloons that they make balloon animals with, cut the end off, try sucking air through it, report back.

Compare and contrast that with blowing through the same one.

Report your findings.

Tec5 wrote: ↑

Fri May 27, 2022 10:06 pm

In other words, why wouldn't the expiration flowrate be a mirror image of the inspiration flowrate?

Because normally, inspiration is active while expiration is passive, resulting in an Inspiratory: Expiratory (I:E) Ratio of ~1.0 : 2.0.

Rubicon wrote: ↑

Sat May 28, 2022 2:39 am

Because normally, inspiration is active while expiration is passive, resulting in an Inspiratory: Expiratory (I:E) Ratio of ~1.0 : 2.0.

Ummm ....

I:E Ratio of what measure? Flowrate? and if so, I'd be grateful for an explanation of what is "flow" and what is "rate" in that measure.

ozij wrote: ↑

Sat May 28, 2022 3:33 am

I:E Ratio of what measure? Flowrate?

Time.

Consequently, as volume is constant, flow rate becomes variable.

Thanks.

Ignore this if I'm wrong. I hear some bells ringing.
Do you cross the Rubicon every 1000 posts?

No one has an answer to data’s question? Is the representation in the Resmed video incorrect, sinusoidal pattern is not characteristic of normal ( non-limited) sleep ?

Tec5 wrote: ↑

Sat May 28, 2022 5:53 am

No one has an answer to data’s question? Is the representation in the Resmed video incorrect, sinusoidal pattern is not characteristic of normal ( non-limited) sleep ?

Rubicon did indeed reply.

1. Inspiration and expiration are not identical
2. Inspiration (let me add: in humans) requires effort expiration does not, its passive
3. "resulting in an Inspiratory: Expiratory (I:E) time Ratio of ~1.0 : 2.0."

Rubicon wrote: ↑

Sat May 28, 2022 3:40 am

ozij wrote: ↑

Sat May 28, 2022 3:33 am

I:E Ratio of what measure? Flowrate?

Time.

Consequently, as volume is constant, flow rate becomes variable.

My emphasis.
It takes twice as along to let the air out as it take to pull it in. So the flow can't be perfectly sinusoidal.

There is no reason to assume Resmed's explanatory video is showing real time flowrate graphs, any more that there is reason to assume it's showing a real person.
Both are graphic simplifications for the sake of explaining an issue.

The idealized flow trace inside the O in the Oscar emblem is much closer to reality than the trace in the video.

@ozij,
I could be mistaken, but I "think" that data1 was questioning the difference between "asleep" and "awake' breathing patterns. Previously the suggestion was made that a sinusoidal pattern was more characteristic of an "awake" breathing pattern.

But that can be clarified when he or she returns.

On the other area that Rubicon brought up, the matter of the expiration time being twice as long as the inspiration time, but maintaining the same volume. That would suggest that Resmed's stylized plot ought to look more like this: (half the amplitude but twice the duration)

Tec5 wrote: ↑

Sat May 28, 2022 12:54 pm

@ozij,
I could be mistaken, but I "think" that data1 was questioning the difference between "asleep" and "awake' breathing patterns. Previously the suggestion was made that a sinusoidal pattern was more characteristic of an "awake" breathing pattern.

Teck5 is correct, my question (above) stated: " It was suggested that a sinusoidal flow rate pattern is characteristic of "awake " breathing, but not of "asleep" breathing.( see viewtopic/t184231/Respiratory-Rate-of-7 ... l#p1410330 and surrounding discussion."

Is the "sinusoidal" flow pattern representative of awake or asleep breathing or not (or neither) ?

BTW, it would be very odd indeed that non-limited breathing pattern be a perfect sine wave. So Teck5's example, where the inspiration phase is a half-sine, and the expiration phase is a different half sine (reduced amplitude and longer time duration (thereby maintaining the volume), while still a stylized representation is a sine shaped pattern.

Miss Emerita wrote: ↑

Sat May 28, 2022 11:58 am

The idealized flow trace inside the O in the Oscar emblem is much closer to reality than the trace in the video.

This is typical of my asleep pattern with no flow limitations, @5 cm pressure, 1 cm EPR, no snore, no leaks. Doesn't seem at all like the OSCAR logo.

I think I would be looking at something like this for "normal" waveform (from a post by JayHC);



As that little blip on the expiratory limb appears in the same spot every breath, I don't think that's CB artifact, more like a palatal something.

Expiration starts out strong and tapers off.