Visual exapmples of RERAS

-SWS wrote:The expiratory curves are too patterned/symmetrical to represent measurement artifact IMO: there are 15 consecutive and highly-symmetrical exhalations falling significantly short of volume compared to each prior inhalation.

You are so wrong, there. Heh. I have seen 15x15 of those, 225, because that pictured showed only one minute's worth, and I have seen that pattern go on without any interruption for 15 minutes.

-SWS wrote:The inescapable conclusion is that the exhale volumes are going somewhere else BESIDES past the pneumotach sensor inside the machine. Pick your favorite leak scenario.

Hold on. I think it might also be the case that the air is escaping my lungs too slowly (such as with the clogged nasal route that I experience on exhale only, described before) for the machine to pick it up. That would in fact be an artifact, I think. Please note: I do not inhale a lot of air, so it's not going to take long for the small amount I inhale the escape slowly. Think of this as an extended central hypopnea. Then you get the picture better.


How much pressure difference is required for the pheumotach sensor to pick it up, I wonder?

-SWS wrote:The big, burning question is WHERE are those missing exhale volumes going if not past the pneumotach sensor?

Sneaking past by going out so small it doesn't register? I really don't know. I'm sort of, at this moment, inclined to go with your leak theory.


Thanks again for your thoughts. My pulmonologist and RT had no thoughts on this.


Other than the flat tops, my picture really wasn't so different from the one in the journal, was it? I thought mine looked pretty severely flow-limited, yet my flow limitation graphs hardly ever show anything but halfway limited. I guess that might be because all of my breaths are flow-limited, so the FFL can't pick up on that?

-SWS wrote:there are 15 consecutive and highly-symmetrical exhalations falling significantly short of volume compared to each prior inhalation. Again, each inhale and exhale pair should be of equal volume.

Hmmm, now that I look at the picture again, it looks like the burst downward, while quite narrow, is twice as deep as the inhale. Not saying the volumes are equal (don't look equal to me), but perhaps the initial deep exhale, along with some small exhale sneaking and a tiny volume DOES explain it after all? I note that there is some stuff below the line throughout the entire exhale, so some pressure out is being registered, perhaps.

LoQ wrote:

-SWS wrote:The expiratory curves are too patterned/symmetrical to represent measurement artifact IMO: there are 15 consecutive and highly-symmetrical exhalations falling significantly short of volume compared to each prior inhalation.

You are so wrong, there. Heh. I have seen 15x15 of those, 225, because that pictured showed only one minute's worth, and I have seen that pattern go on without any interruption for 15 minutes.

Well, I think you might have misinterpreted my comment. I was referring to your above graph where there are exactly 15 breaths. That's enough to detract from a measurment-artifact hypothesis IMO... And that you can also cite 225-breath examples bolsters that comment about no measurement artifact being likely here IMHO... I think it's that sustained symmetry, rather than randomness, of your exhale graphs that seriously detract from any artifact hypothesis. So I think we're in agreement here, but I could be wrong about that...

LoQ wrote:

-SWS wrote:The inescapable conclusion is that the exhale volumes are going somewhere else BESIDES past the pneumotach sensor inside the machine. Pick your favorite leak scenario.

Hold on. I think it might also be the case that the air is escaping my lungs too slowly

Well, each inhale volume exchanged should equal each subsequent exhale volume. I think we can clearly see each of the above exhale volumes falls way short of each paired inhale volume. Again, since we are trying to compare volumes.... we are looking at the total area under each I-curve and comparing against each subsequent E-curve area.

Short of a graphing bug/error, the exhalations are simply not going past the pneumotach sensor. And breath rate is irrelevant since we are comparing total curve areas (pneumotach sensors can pick up delicate heart beat signals). Those exhalations are going somewhere else---meaning "leak" IMHO. And the exhale leaks are presenting as a fixed-function and thus do not seem reported on the leak graph line above---rather they are likely subtracted as fixed-function orifice leaks are subtracted.

-SWS wrote:I think you misinterpreted my comment. I was referring to your above graph: there are 15 breaths exactly in your graph above. That you can also cite 225 breath examples bolsters (rather than contradicts) my comment that we likely have no measurement artifact here...

Absolutely. I was kidding, trying to be funny that you claimed there were 15 breaths, when I know that there were several minutes of that, like 15 minutes. So it was a joke that went bad. (You would have thought I would have learned my lesson with the psuedo-French, pronounced swado-French, in case that joke is being missed as well, but some people just don't learn quickly, and I'm apparently one of them, making yet another poor attempt right here in this sentence.)

-SWS wrote:Each inhale volume exchanged should equal each subsequent exhale volume exchanged. I think we can see each of the above exhale volume graphed falls way short of paired inhale volume. Again, since we are trying to compare volumes.... we are comparing the total area under each inhale curve against the total area under each subsequent exhale curve (albeit a inverted E-curve).

Those paired curve areas don't come close to matching. Short of a graphing bug/error, the exhalations are not going past the pneumotach sensor. Breath rate is irrelevant since we are comparing total curve areas. The exhalations are going somewhere else---meaning "leak" IMHO. And the exhale leaks are presenting as a fixed-function and thus do not seem reported on the leak graph line above---rather they are likely subtracted as fixed-function orifice leaks are subtracted.

Well, I obviously agree that in theory, the area under the two parts of the curve must be equal. I also agree that subjectively, the areas are NOT equal in that graph.

Where I'm coming from is intuition about equipment, having been around a lot of equipment for a lot of years. Lots of devices have the property that they perform (measure in this case) accurately in a certain range, but sometimes not so accurately at the extremes. Zero is probably an extreme to this machine, though it is not clear since it measures both positive and negative pressure differentials. I simply do not know the details for that device. I also do not know if we know where zero really is on the graph. I bet ResMed has to guess at that, too. I think it is a theory that has to be considered, in spite of the fact that I do tend to view your leak theory as having a higher probability.

Oui! ...Time to get out the tub-and-tile caulk for a one-night anti-mask-leak experiment...

-SWS wrote:And the exhale leaks are presenting as a fixed-function and thus do not seem reported on the leak graph line above---rather they are likely subtracted as fixed-function orifice leaks are subtracted.

I'm not entirely sure what that means. I understand the words, but I'm having trouble picturing how it connects to the graph. The bursts of leaking is subtracted only during exhale from the leak graph? Is that what you mean?


Otherwise, there is a constant leak all the time that is being substracted? That can't be right. The flow graph doesn't support a constant leak, does it?

Heh. I actually found an example of breath-stacking in my folder that I had saved because it was odd, and I didn't know what it was. Thank you for clarifying that for me, -SWS. I also have had periodic breathing quite a bit.

My respiratory system is outta whack!

LoQ wrote:

-SWS wrote:And the exhale leaks are presenting as a fixed-function and thus do not seem reported on the leak graph line above---rather they are likely subtracted as fixed-function orifice leaks are subtracted.

The flow graph doesn't support a constant leak, does it?

Indirectly the flow graphs portray fixed-function leaks as missing volume... hence the missing curve-area/exhale-volumes on the flow graphs in the original white paper or your graphs. But your leak graph (not your flow graph) is where the fixed-function leaks get subtracted off...

BTW, you're right about outstanding flow limitations. You have them. The question is whether they disturb your sleep. I understand that you are inclined toward central apneas with higher pressures. You just might be a case where an ASV trial makes sense: high pressure to address the outstanding FL and obstructive H, but the ASV algorithm to address machine-induced central apneas.

LoQ wrote:Heh. I actually found an example of breath-stacking in my folder that I had saved because it was odd, and I didn't know what it was. Thank you for clarifying that for me, -SWS. I also have had periodic breathing quite a bit.

My respiratory system is outta whack!

Okay, if I were you, I think I'd very seriously consider a trial with ASV. I think NotMuffy recently commented along those lines as well. Unlike me, he's a sleep professional. He's a good one to listen to IMO...

While you two are arguing the minutiae of this, a first class issue of real moment goes nearly unattended....

Didn't you hear me call out "Superheroes, Assemble!"??

Be so good as to hie thee over to the Citalopram vs. Zoloft thread and save our bacon. M.D.Hosehead's reputation is at stake.

I haven't even read that thread yet ...only a quick skim! But all the big guns in that thread are the kind folks I'd come to with my pharmaceutical questions!

I am curious how abnormal LoQ's flow graph is for representing home-machine-measured flow-limited inhalations followed by quick exhalations from the mouth into a full-face mask. Cheeks expand, mask seals with give allow mask movement, etc. So is that a really rare look for a flow sine from an S9 or a common one? Do we have mouth-breathers using S9 and ffm who can post graphs for comparison?

-SWS wrote:

I haven't even read that thread yet ...only a quick skim! But all the big guns in that thread are the kind folks I'd come to with my pharmaceutical questions!

I'm telling you, it's a real head scratcher. jnk's last ditch attempt to lure you back into this big snoozer notwithstanding.

brain_cloud wrote:jnk's last ditch attempt to lure you back

Here: Neato graphs.

There: Drug wars.

You decide.

I like your puffed-cheeks idea, Jeff.

I'm thinking the pneumotach-remiss volumes in that scenario should occur during the beginning of each exhalation---as the expanding cheek pockets are filled with early-phase expiratory volume. Once the expanded cheeks fill, then mid- and late-phase exhalation should begin to register more magnitude across the pneumotach sensor. But LoQ's mid- and late-phase exhalations are where is flat lines occur. His seem an opposite time-based flow pattern for that hypothesis...

I'm just wondering if exhalation happens so fast with some mouth-breathers during sleep that between EPR and and the slow dissipation after the initial puff that the graph for home-machine-measured flow and time isn't going to reflect volume very well.

But hey, I've always been spatially and mathematically challenged, so graphs ain't my thing.