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AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
I believe members can collaborate in this thread to assess and deal more effectively with this subject's breathing disturbances now given that much of the necessary information is only two mouse drags away.  There is a ResMed patent signal (just below) that machine-algorithm help may be forthcoming within the next generation or two of their xPAP machines. 

This thread is not a call for my personal treatment help (though it will show my workups of OSCAR graphs, those crude things being all I have for illustrations and questions here). I will start or use a previous thread for my treatment related questions. 

Please contribute to here as our learning space if the thread subject applies to your sleep with low AHI. Contribute if you have questions, corrections, a different interpretation or have other information to share about feeling or being treated for unrestul sleep.

1. I've seen, as Pubmed indicates (2020),  our machines produce and do show untapped information though it is not machine flagged for OSCAR graphs that presently show that information (in the flow rate (FR) curve deformations). We can jointly try to devise a manual method  for seeing and using OSCAR's present display of that information now, while hoping next generation machines will exploit that information to help our sleep. See https://pubmed.ncbi.nlm.nih.gov/32289733/

Each of us must decide how important fixing our sleep is. "Improve your sleep hygiene" is the usual, good recommendation. But at advanced age, one's  remaining pleasures after treatment and reforms can be hard to drop.  Compelling focused evidence from a reasonable trial period of change would sell me. Such evidence would also scratch my continuing itch to learn more about this complex, interesting topic.

2. Dr Park explains detrimental effects of spontaneous and other arousals that cause sleep fragmentation:

3. Importance of measures and scoring of flow limits (FL) was the focus of a 2017 medical conference: https://www.atsjournals.org/doi/pdf/10.1...1704-318WS

4. Medical (and machine marketing?) importance of metrics, detections and flagging of flow-limit caused deformations of inspiratory flow rate peaks was recognized in the linked 2018 Resmed patent application: https://patentimages.storage.googleapis....2088A1.pdf

What is the problem and what gives rise to it? 

5.  Mainly, it is the Biomechanics of the upper airway. A floppy tube?

6.  UARS and  RERA definitions are clearly explained: 

7.  Nature of arousal in sleep, sleep disruptors:

8. Microarousals. More Sleep disruptors: 

9. How can we see our flow rate (FR) curve irregularities are causing or contributing to our arousals and micro arousals. Explained here there are 47 classes of normal or more deformed inspiratory FR peaks having 3 levels of severity: normal, moderate and severe:
https://www.hindawi.com/journals/cmmm/2017/2750701/ (Seven broad classes of shape were documented in 2001 by Tero Aittokallio, et al. in Finland, as noted below.)

How does  this and related information fit into information of the kind sensed and compiled in sleep laboratories' reports.

10. Here are two sets of curves. First, the "A" set which summarizes (in a set of 7 synchronized graphs) how the various PSG metrics (EEG, EMG, Pes, Flow, Ventilation and SpO2) all fit together and illustrates how the arousal threshold (ArTH) was "backed into" (with reverse-engineering calculations) to determine (estimate?) and graph the ArTH. OSA sufferers, as shown in "A" have a higher ArTH than UARS and FL affected patients. The patient's ventilatory drive has to reach a higher level to open the obstructed airway. Second, is the "B" set of curves for the low ArTH patient having UARS and FL who tends to awaken (arouse) more easily than the OSA sufferer. Note that the indicated gold standard for determining ArTH is the sleep lab's EMG (diaphragm muscle action measurement) and Pes (esophageal pressure). The A and B curves, showing ventilatory drive, necessarily used the gold standard EMG and Pes curves (standards) and data as baselines to back into the ArTH level. But the graphs include the corresponding EEG power.

11. Here is the research abstract of research underlying the A and B sets of graphs in the item above. 

Among other related and significant matters:

12. What level of FL is normal? Indications are that the "cut point" distinguishing Normal from troubled sleepers, is having an AHI<=5 with no more than 30% FL:

13. An indication the AutoSet (AirSense AutoSet?) can help identify arousals:

14. A survey reporting about literature on UARS topics:

15. Early research determining 7 flow rate shapes by Tero Aittokallia et al. of Finland, a bio-mathematician, I believe.

16. Some explanation of brain waves detected and measured in sleep and wakefulness: https://psych.athabascau.ca/html/Psych28...ness.shtml

17. Information about ArTH and related stimuli: https://pubmed.ncbi.nlm.nih.gov/9351134/

18. How low adherence or compliance can stem from low ArTH. PAP not or not seeming to help arousals and sleep fragmentation for UARS, etc.

19. Apparently there is a cognitive link between awake arousability and sleep-disturbing arousability.

I will post related matter from my OSCAR presentations in a later post.

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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
2SB, you've clearly put some time into this. I am very interested in the topic but will admit I'm not likely to immerse myself to a similar degree. consequently, I appreciate the broad brush introduction / summary you've presented and encourage you to continue to give us crib note level summaries, your analyses, hypotheses & conclusions (in addition to the citations for those that want to dig in). I don't know that I'll be able to contribute much to the discussion but I will surely be following along.
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Physiological consequences of prolonged periods of flow limitation in patients with sleep apnea hypopnea syndrome - Respiratory Medicine

I found this interesting from resmed
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Good article with explanations of flow limitation and its impacts. I is surprising to me that they were able to optimize using CPAP alone without bilevel pressure. Article is a little short on details for therapy inputs.
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Thanks 2SleepBetta, very informative, I will continue to read this.

And thank you Zackio! a most timely post and highly relevant to my own experience here.

I hesitated to post this much detail and such a long post, but you have inspired me to share this.
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
I found this interview very interesting in light of UARS https://doctorstevenpark.com/expert-inte...lt-on-uars

Sleeprider, I thought that too. Problem is even if you could, the pressures required may be very uncomfortable and create it's own problems.
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Zackio and SevereSleepApnea,

Great on target and solid contributions to "the cause" from both of you. Lots to digest, re-read, think about, act on and share where appropriate. I read or listened to  it all, learning a lot but needing to spend more thinking time. Thank you for posting and commenting here.

Dr. Guillenmenault clearly explained the progression that begins with mild, untreated (flow limited) SDB and snoring which destroys critical sensors, burns our "recovery bridges" behind us. We eventually reach endpoints/waypoints in Sleep Apnea and various well known and serious comorbidities. My sense is most of us come to treatment and awareness of need along a tortuous, even circular path, often one of denial, with severe irreversible damage done along the way. We complete our circle (with our treated low AHI if OSA was our problem as mine was and is) and still need to  deal with our now lifelong, underlying flow limits of one kind or another (UARS like symptoms at some level); further, we have lost/destroyed/squandered much of the neuromuscular capacity we once had to deal with it. I took that path anyway (multiple heart implants, a level of CAD now) and I would bet SSA would concur--thinking of the hellish medical event he survived during a visit to Italy and is still addressing. 

There's a lot to go back and review from those good UARS-focused sources, but here is one more tidbit from that pioneer sleep researcher, Dr G. that rang a bell for me. He spoke of how early childhood mouth breathing interfered with development of adequate nasal airways. I was a sickly preschool brat that fortunately became a healthy kid and adult--asthma, allergies, seasonal respiratory problems, rheumatic fever--I'd bet all that contributed to becoming a mouth breather then that continues to now--some level of structural nasal airflow restrictions as a consequence of a plugged nose. 

Literally, I thank God, and a good doctor (with SDB) who started me with a home test, after complaints about nocturia (which puzzled me then), and an Rx for and delivery to me of an Autoset. But he then left me to sink or swim. Again, thank God, I soon found, lurked at and called for help at ApneaBoard; soon OSA was well controlled and it is now full circle, "back to dealing now with far fewer FL and lots of unflagged "fl".
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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Yes, the "progressive destruction" part caught my attention as well. Also what he was saying about the research not making the jump to clinical practice. The sleep techs not being fully trained or given time to fully analyse sleep studies.

There is a progressive nature to uncontrolled asthma too with "airway remodelling". I have read some papers about "overlap syndrome" Creating a worse condition than each alone, they suggested a unique pathophysiology in the paper. For some of us with nasal congestion or other airway problem, it's adding to the puzzle.

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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
As stated in the original post (OP), this thread is not about my therapy, though helpful comments are always welcome. The purpose is to see what of value can be learned from close reading (primarily) from our zoomed flow rate curves (FRc). In a few words, its all about irregularities in our FRc's and what those mean in our pursuit of better sleep. How should or can we respond to what they signal ? This post reviews some matters up-thread and reflects some later thoughts.

This long-time after my OP, I've put a lot of thought and effort into finding a way to "read" my FRc for all they may have to tell me/us. Soon after the OP, which promised more follow-up, I bought a Dreem 2 to see what light it could throw on how we (I, anyway) might be able to discern micro- and macro-arousals. Those often account for members' and sufferers' unrestful sleep and fatigue, though their AHI's are very low--say, no more than 1.0 or 2.0. 

The decision to buy the Dreem was made while knowing that its weakest point is in discriminating between WAKE and LIGHT SLEEP stages. Nevertheless, I hoped and came to believe, and still do believe, it likely that flow rate (FR) disturbance patterns (FRd)--all or any of those occurring just prior to  changes from REM or DEEP to LIGHT or WAKE stage sleep--would give some indication of, at least, the Dreem's objective criteria. All of Dreem's detection and sleep stage criteria, as I understand, are merged in its algorithms' interpretations of data signals from EEG, SpO2, heart rate (possibly HR variability too) and accelerometer devices in its headband.  

My goal has been to find a way and reason for affected sleepers to scan their OSCAR presentations and rely on their examination and self-scoring of disturbances in the shapes of their FR and motion curves (possibly with aid from respiration rate, tidal volume and pulse rate curves).  In my case, and my guess is that this may be common, there is a most frequent FRd which is accompanied by the larger and/or longer duration bodily motions (bodily rotations, jerks, twitches, flinches, throat catches, whatever). How many are real arousals? Even  trained sleep techs differ in how they score them, though they often (always?) have the benefit of costly EEG equipment and training. Lacking all their equipment, can we just add an accelerometer or other consumer level device to come up with some means of meaningfully scoring and using FRd? Though far from the gold standard, an objective method would enable us to evaluate sleep benefits of, say, a 2-4 week change of a single life style element (e.g., habit or Rx).  

I have read  in sleep forums a knowledgeable lay analyst who explained certain sleep disturbances displayed in a member's OSCAR 2-minute views were arousals, but I have never been confident of making that call. One such interpreter of FRd indicated it was important to distinguish as arousals those FRd's that begin fractional-second/seconds before or after--which was it?--motion begins; that so as not to misinterpret as an arousal the commonly present benign gasp (or breath holding) before, say a comfort shift. I saw and still see lots of FRd which may or may not rise to the level of sleep disturbing arousals. In this case, very close synchronization of FRc and accelerometer data, within less than 0.5 second error, from those two devices is crucial; it even may not be attainable with two or more devices' clocks. I find that most sigh-movement traces yield the best defined (shortest duration) time markers. I assume, as shown in a graphic below, the middle of the similar, sharply defined motion trace must align with the time when an inhale slows and stops at the zero axis and an exhale begins.  

With Dreem, one can frequently see a large FRd (almost always accompanied by significant motions) just prior to a "drop" in sleep stage (REM to LIght, Deep to Light, REM or Deep to WAKE); but then, er, "confoundingly", I often see a similar disturbance earlier in the same sleep  stage segment (there was no change of stage then). On the other hand, the impact of and bodily response to a particular FRd profile or to an arousal cannot be expected (given our idiopathic system variations) to be uniform in the course of a sleep session, maybe not even through a sleep stage. 

Anyway, as a takeoff point now, here is a view "from 30,000 feet" of all three short "WAKE" or arousal "blips" from the Dreem-2's expanded hypnogram view last night. Those, I was slow to learn, will only show up, if any (whatever the resolution is), in the expanded view. (It can be seen by dragging the red colored button across the bottom of the hypnogram.)

It's interesting to see the three selections of WAKE (or arousal) by Dreem, with so many other (overlooked?) candidates for same in the session. My guess is that at least one or two of the Dreem's 30 second windows had to be scored before recording "arousal" or "Wake". (I'd appreciate being informed of what Dreem's resolution of detail is.) However, there is no WAKE indicated for the three WAKE or arousal blips in the overall hypnograms shown by Dreem software or OSCAR's view.

Notes about the images:

1. The note about motion intensity had an understating error. The corrected acceleration excursion over the period of 11 seconds was .16g, g being the acceleration of gravity, 32 ft/sec per second. The "zero" imposed-motion acceleration axis should be at 1.0g, not 0.95g as shown. The offset, irrelevant here, is from anisotropic measurements of g and bodily accelerations on the three (x, y, z) axes of the accelerometer sensor.

2. The Dreem 2 indication of supine sleep is indicated in bright red, roughly correct. I stand by the trace drawn from my data by Oscar'S Somnopose.

3. The three highlighted arousals or awakenings are enlarged below.

4. There is an example showing what I believe is the best way for me to synchronize graphs derived by two different clocks. It entails doing a trial import via Somnopose and then a more accurate one when the time discrepancy has been measured.

My intent is to dive deeper, in another post, into the same graphic and, there, compare and contrast the three highlighted points vs. other seeming candidates for the term "arousal", if that term is apt. Dreem found 3 out of what look to me to be 12 candidates for the more obvious arousals during the session, not to mention less conspicuous instances.

Please call attention to any errors you see, raise questions, and add any contributions that come to mind.

In short, the topics of inspiratory flow limits (IFL), UARS and arousals are most interesting as I hope to elicit others' contributions and come up with helps. A bit of one or all three sleep breathing irregularities show up in my OSCAR displays--maybe more arousals than I think.

Great sleep of my youth long ago left no memory trace for comparison now and my sleep is, as my bio shows, worlds better than when I started PAP: it's good--many thanks to AB , its advisors and the good Lord who keeps me a-hosing with unmerited favor. 

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RE: AHI < 1.0 now, but still tired? Is it UARS, RERA, arousals or FL in your FR peaks?
Where did you buy the dreem 2 and how much did it cost?
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