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AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
#31
RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
cathyf, a bit of follow up.

In re the top and bottom of your third graphic in your most recent post: 

I see your point about similarity of FR curves vs difference in FL. Unless expanded views of one to two minutes showed sufficient explanatory small FR and FL variations  (and there are some indications of small FL changes), it almost seems, given the stickiness of your FL values, that the FL scale-# holding register could  require a substantial drop in the sliding window-area value from the earlier stored scale #. Then the register would be reset to enable a fresh look at changes in (sliding window) air volume delivery. That delivery (biorn indicated, as I understand him ) is based on a 2-second-wide look back window for determining the FL flag value (if any). I do believe zoomed views of 1 - 2 minutes of FR and corresponding FL would clear away our questions--if enlarged so that an enclosing rectangle for a single breath would  require a 1/2" wide x 1" box, or (better) a larger box, on screen.

I don't know what to make of your "FR falls from the top of stairs" vs indicated FL:

Similar to my comment above, I think--confirmation bias flag flying here-- that expanded views of the inspiratory curves would show reasons for most all the FL's displayed--there being at least one main exception from about 05:44:00 to 5:45:45--it's those first two FR drops to the bottoms of the stairways, particularly, those along with the drop after the peak at about 5:45:10. The upstairs moves would be mostly ignored (until flow was above the axis), as I understand, but it seems greater FL's would show for the drops.

As a beginner fiddling with this unfamiliar topic, I have come to believe my visual assessments are not at all dependable; one has to (I must) measure variables and their accumulations. My slow developing understanding has come to realize that the signal represented by the FL flag is dependent not only on the variations in the inspiratory FR amplitudes and shapes (the most obvious things) but also on the more subtle accompanying relative durations of inflow and outflow.  It's a matter of all those variables and the critical differences in fill levels of successive sliding window-boxes which the Resmed algorithm uses. 

I did paste a couple of 1 min. to 2 min. views into MS publisher and stretched them way out to get a better feel for your variations in FR form and size at large variations in FL, but those checks were not enough to conclude what I've written, not more. 

A late-in-PAP-life learning example from working on assessing a FL after an OSCARed sigh in a FR currve last night:

It always puzzled me  why (amid clean breathing) a small FL so often occurred during exhalation immediately after one of those "Norwegian" sighs--those two stage inhalations that together with their exhalation afterward create huge repeating spikes in many of our FR curves. The drop, I concluded, from measurements, is because of the prolonged exhalation which more than offsets the two stage (two step) inhalation. The sigh's sliding window, however wide, had sufficiently less fill than the predecessor sliding window. Therefore, a FL flag.



Musing, yes, but no help here Oh-jeez . I do hope you will use the c-collar, get a VAuto, get an oximeter and get a device (a camera or accelerometer) to show your sleeping positions. My Autoset FL were bad but nowhere equal to yours. The VAuto cut them waaay down--with pressure support of just 4cm--vs my 3 cm EPR with the Autoset--to the point FL are few above about 0.20 and FL are mostly sparse along the nightly time line.


A later relevant research addendum for cathyf's consderation:

A research paper applicable to patients with low AHI but inspiratory flow limitation: Quantifying the magnitude of pharyngeal obstruction during sleep using airflow shape.
shape

https://erj.ersjournals.com/content/erj/...2.full.pdf
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  (Disclaimer use permitted by sheepless)

 
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#32
RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
So is there actually any way to eliminate RERAs lol. i might speed up my jaw surgery if not
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#33
RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
(05-19-2021, 04:03 AM)KingKongBingBong Wrote: So is there actually any way to eliminate RERAs lol. i might speed up my jaw surgery if not

Please see your other thread http://www.apneaboard.com/forums/Thread-...ting-RERAs
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#34
RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Parts of the report linked below are covered in the ApneaBoard's Wiki, but the compreshensive treatment of CPAP type machines and their differences justifies posting the link and a few comments, here, now, and later. In my limited understanding, it treats at a fairly deep level almost all brands and types of machines most regularly discussed here at AB, including a lot of detail about algorithms.

A look here disabused me of the notion that Resmed Autosets, maybe their AirCurve VAuto, might reflect in flow rate (FR), tidal volume (TV), and minute volume (MV) a reduction for breathing deadspace. If I read the study correctly that deduction is only made by devices that are designed to deliver fixed MV or TV. Pictured, below, from the long paper is the heading from Table 2 comparing Auto CPAP device attributes for Resmed, Respironics and DeVilbiss devices. 

Table 2 coverage of flow limitation handling, and more, are likely to be of interest to flow limit sufferers who are digging deep in dealing with that mostly foster or forgotten child of sleep medicine and insurance. Table 2 mentions four elements involved in the Resmed detection and scoring of flow limitations with FL flags. I believe the AB Wiki includes much of that.

   
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  (Disclaimer use permitted by sheepless)

 
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#35
RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Part 1
     Recommended: Scan the research paper on nasal airflow restrictions and measurement  at [url= https://www.atsjournals.org/doi/full/10....1005-034RNhttps://www.atsjournals.org/doi/full/10....1005-034RN[/url]. This part of this post presents a few snippets and a couple of images  from that linked paper. I offer a few words attempting  to highlight what struck me most.

There are a couple of do-it-yourself tests. Most sufferers I am aware of would want to make a judgment about whether their sleep MD or advisor is giving them the guidance they need. The paper will help upper airway sufferer-readers do that. The ApneaBoard Forum has lay experts--not me--who can provide informed guidance and suggest possible answer to most all questions after they see the set of graphics they will call for. This ApneaBoard Forum, in my  opinion, would never have been needed if sleep medicine deficiencies and medical insurance had met needs dramatically better than is common. 

The text image, the first below, has these section headings:

-Nasal airway resistance is about half of total airway resistance (for normal breathing 2SB asks?)
-The nasal cycle usually lasts 4 to 6 hours
-To assess airflow one needs to understand the nasal valve (see second graphic picture and the related Cottle maneuver). The nasal cavity from the nostril to the nasal valve is the area of greatest flow resistance.
-It has been postulated that objective assessment of the nasal airway patency ("adequacy"?) can never predict the actual subjective sensation of nasal patency
-The Cottle maneuver is one anyone can do to check their nasal valve. Further, one can check whether or not a decongestant opens the congested airway. If it does not open the airway it is a sign of structural obstruction rather than nasal congestion.

Part 2
     More on the topic of upper airway resistance

Below there is a sampling from among recent threads that have dealt with, or are currently dealing with, difficult upper airway restrictions, flow limitations, and unrestful sleep as well as with the meaning of the Resmed devices' flagging and not flagging of flow limitations. There is an emerging success story and a continuing difficult case of airway restriction. These linkages are here instead of others only because I have spent more time and thought on them recently as I was preoccupied with matters related to this thread in the posts at the bottom most URL.

In some instances graphics have been deactivated as members ran out of their ApneaBoard storage space. Nevertheless, scanning the posts will yield better understanding of this little-treated subject of flow limitations--as distinct from apneas-- in sleep medicine. I either link to the first post in the threads or where posts seemed to become focused more directly on flow limitations.

The fourth link is focused currently on the extent to which a Resmed FL flag indicates drops in essential air flow, that is, drops in Tidal Volume. Some flags are believed  to reflect the machines' sensitivity--as part of its pressure regulation up and down--to certain wave shapes, inspiratory wave flatness and respiratory rate changes more than the flag reflects a local loss of TV.

http://www.apneaboard.com/forums/Thread-...#pid389057  - deals with nature of FL and how scoring it can be  summarized better

http://www.apneaboard.com/forums/Thread-...ow-limited - deals with a difficult case that appears to be a success story (after using the Resmed AirCurve10 VAuto to treat flow limitations

http://www.apneaboard.com/forums/Thread-...#pid400219 - deals with a difficult case of upper airway resistance and is motivation for sharing, at the top section of this post, the link to and the images and text snippets from the site https://www.atsjournals.org/doi/full/10....1005-034RN
 
http://www.apneaboard.com/forums/Thread-...#pid394885  - deals with trying to discover  the extent to which flow limitation flags, FL,  are determined by drops in tidal volume, TV, or by inspiratory wave shape, wave flatness or respiratory rate changes, RR changes.

         
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  (Disclaimer use permitted by sheepless)

 
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