Thoughts on several items on various topics, mainly questions you have raised, dataq1:
1. First a clarification of one sentence in my previous post:
It read, "That out of place hypothesis has only a bit of support already posted in my first graphic at about 02:05-02:10 and 03:58-04:09." It should have read: "My only support for that hypothesis that has been posted in this forum and thread is in my first graphic at about 02:05-02:10 and 03:58-04:09." The hypothesis is that some FL flags do not and need not reflect any drop in Tidal Volume at all, though they mostly do that. At least two of three other FL generating breathing irregularities do not entail Tidal Volume drops.
2. After pondering and annotating the OP's recent graphic, as it is shown below. I belatedly ask anyone who knows, what are time lags and with what moving average windows do Resmed devices present data for Tidal Volume, Minute Volume, FL flags Inspiration and Expiration times, Mask Leak, and Leak? Is it simply and strictly a sample rate of 0.5 Hz (2 seconds) for all that data as I have assumed (and appears to be indicated in a signals list for PLD file data)? The device manifold pressure and flow rate data are sampled and presented at 25 Hz (.04 seconds).
3. The graphic below is my attempt to show answers and some relationships in partial answer to item no. 2 above and more.
4. @dataq1- post 03:02 pm 11/19: It is interesting (and to be remembered) that your FR dips show there had to be at least small drops in breath by breath TV, yet there was only a small increase in duty cycle as can be seen in divergence of the I and E time curves (I get longer, E shorter--not a lot) from about 050745 to 050852, well before pressure increased.
5. @dataq1-post 04:13 pm 11/19: I'm not quite sure what your "Julie wrote" quote referred to.
6.Re your two like graphics: You indicate all other wave forms are stable and I assume that means that all earlier flow-relevant curves (for, say, the past 30-60 earlier seconds {not shown]) and all those same curves concurrent with depicted curves were very close to and remain visibly invariant.
That being the case, then welcome to what I might call the world of Resmed (RM) phantom flow limits ("phFL"?), those FL's that arise from shape shifts without TV drops, probably without any increase in duty cycle. That is the reason I use "fL" to mean anything, short of apnea, to mean real flow limitation/constriction that reduces, by my definition, breath by breath tidal volume. That is the reason I don't know what a person means by the words "flow limit". Mostly they are referring to the Resmed FL flags. In my just-previous post here I referred you to two short periods of same in the graphic of my first post in this thread. But elsewhere I have seen and posted it multiple times. It's was to answer that conundrum that motivated my work to see breath by breath TV and TV drop from fL.
No one should get me wrong. Unrounded wave shapes tell us there is flow limitation in most if not all real flow limitation cases. Everyone can zoom them and check theirs out. As I understand, Dr. Barry Krakow is attentive to flow limitations and he tries to titrate OA, IFL and UARS sufferers best he can to attain/approach rounded inspiratory waves. BUT he deals with real flow limitation, not our device's warning of bad actor wave shapes that have not reduced our TV.
7. Your hoped for resolution for us here (by your numbering).
(7-1) I believe there would be some TV variations, yes, but (from the hip) I believe what you show is benign absent a duty cycle increase to corroborate the FL.
(7-2) My belief is those two terms refer to the same problem. But the question is, "what do normal sleepers" present among these kinds of wave forms, how much and at what range of seriousness? Normal sleepers and others have been tested to find controls and test subjects. The research finding was that it is normal for sleepers to have up to 30% of their sleep time flow limited to some extent. Dunno other answers. (Sao Paulo study, googleable).
(7-3) I doubt, but don't know if there are CNS connections to wave deformities.
(7-4) I know of scattered references that shed much light. There have long been shape and severity investigations. There are at least three papers, one a catalogue showing shapes. You might start with Tero Aitokallio, Ph.D, in Finland, PhD, (a medical statistician?) for the early 7 basic shapes. I think those images are in the AB Wiki somewhere. Then there is a study that dealt with 47 shapes as work was done to use a polynomial curve fit for analysis of shape effects; that study showed or relied three levels of severity. Then there is a huge shape catalogue behind a pay wall .
(7-5, 6) I dunno on either item but very much doubt what you show is reason for any concern. Such shapes and far worse haven't put me under. Such concerns as I have raised with my teaching pulmonologist sleep MD--recommended to me as best in our area by a known sleep tech--were minimized by this MD to my satisfaction. First thing he did as I started with him, after firing another "you are at 5 and treated" MD, was send me for a full pulmonary evaluation at a hospital where I did all kinds of huffing, puffing, blowing hard and some other exercises. No sleep study yet, given my AHI of down to 0.2 for about 2 years after about 58 at start. Simple OA with a sub-treatable few FL on my SD card, thanks to my out-of-pocket VAuto. FL remained bad after my Autoset made OA's rare.
A closing disclaimer: I only know the limited bit I have learned from my experience and help of others. I have no medical qualifications at all. Consult your MD before making any change you might consider after reading what I or any other forum member has posted.
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