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Why don't these flow rate curves count as flow-limited?
RE: Why don't these flow rate curves count as flow-limited?
Last night as I headed into bed I realized that the night before I had slept with a cervical collar, but also two pillows. (Yeah, I know, dumb!) Last night I did much better -- one reasonable pillow (a MyPillow), cervical collar on, FFM, and it was all pretty uneventful.


Here's a closeup of those two little periods of flow limits which drove a zoom in pressure:


I'm really getting a much better feel for how the vauto works so much better for me. It's like with the Autoset it reacts too little too late and it ends up spending most of the night at higher pressures. With the vauto, the pressure support and fast trigger keep the FLs mostly away, and when something starts the machine zooms in and smacks it down hard.

Lots of waking up, though... Although maybe not -- it averages out to 3-5 times per hour, and I don't see anything in my breathing before the arousals that would indicate that the breathing is what's waking me up.

Here are two closeups of the "Tale of Two Pillows" night.


In both cases there's an arousal leading into the OAs. It's tempting to discount that as sleep-wake junk, but there's a 61-second OA with a substantial desat in there. I can't imagine that I could have done that if already awake.
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RE: Why don't these flow rate curves count as flow-limited?
A number of arousals/micro arousals is normal, no one sleeps 100% of the night and there are a multitude of things that can cause arousal. The key is trying to minimize the number of arousals and if you are at only 3-5 per hour are doing good.

The large OA with desat may or may not have been real. One thing to remember is that our spontaneous respiration is not driven by oxygen levels but rather by carbon dioxide levels. In that instance you had an arousal, followed by an "obstructive apnea" followed by some large amplitude recovery breaths followed by the long apnea. The large recovery breaths would have washed out CO2 and it is possible they played a role but there probably was some sort of obstructive nature included.
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RE: Why don't these flow rate curves count as flow-limited?
And this:


ladies and gentlemen, is how a bipap stops a flow limit, in its tracks, without waking me up. According to my fitbit, I slid from light to deep sleep right at 23:18.

BOOya!!!!   like
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RE: Why don't these flow rate curves count as flow-limited?
Now, after a little over a full month with the AirCurve, can you give a summary judgment? - after all the "FL"s are gone now.

Do you sleep better or feel more rested / refreshed or are you more resilient - compared to the AirSense 10 before? ... or maybe other health problems / diseases have improved or have disappeared completely?
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RE: Why don't these flow rate curves count as flow-limited?
Another possibility which would be pretty sweet if true.

The last couple of nights I've felt like I got the collar on a little too tight -- was feeling like it was pressing on my throat. Last night I think I loosened it a little too far, and I think I had positional apnea. But I think that the bipap might actually help that by turning what would have been a cluster of 20 events into a cluster of 3,4,5 events? Which would be completely unexpected!



And, yeah, I actually feel pretty good -- to answer your question, TBMx, this is certainly not double-blind, and I know myself well enough to know that I am powerfully influenced by the data that I see.

But I think I feel better... I certainly am not napping as much as before, even though I'm not getting enough sleep. (unemployment was so much more leisurely, LOL. But seriously, I started my new job after 16 months of unemployment the day that I got the vauto. So, yeah, I am working harder, more stressed, etc.)

I did finally get my arthritis medicine today after not being able to get it for seven weeks. Hopefully that will tone down the tendonitis, although I'm afraid the joint damage I've accumulated is probably permanent. (It usually is...)

If the vauto can tone down the positional apnea that would be a big win. I'm trying to balance too tight on the collar and it's choking me, and too loose and it doesn't keep my chin up. 

And the positional apnea is the only reason that I have a prescription for APAP anyway. Without it I'm the flow limit queen, but not much in the way of apneas...
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RE: Why don't these flow rate curves count as flow-limited?
If you are starved for air (too much flow limitation) a natural response is to mouth breathe which causes mouth to open/chin to drop which is often what causes positional apnea and also leaks in some patients. If vauto is helping positional apnea it is by helping overcome flow limitation so you mouth breath less.
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RE: Why don't these flow rate curves count as flow-limited?
Ah, yes, that makes sense...

You know something that I don't think I've mentioned that may be relevant to more than me, too -- I have a tendency to positional vertigo. If I throw my head back, the room starts spinning and my stomach starts churning. It kind of sucks because it's the position that you take to get your teeth cleaned at the dentist, or to get a thyroid ultrasound. I can get my head far enough back for those things, but I've learned to go just far enough and no more or I am in serious trouble.

A couple of times I have been on my back and asleep and hyperextended my neck all the way back and woken up with vertigo. Once I got out of bed and fell and slammed my hand against the nightstand. Ended up in excruciating pain, half asleep, trying to figure out what WTF happened! Another time I ended up puking in the wastebasket. After one thryroid ultrasound I jumped off the table and went sideways and collapsed.

So I am VERY paranoid about this, and I think that's one reason that I chin tuck -- that paranoia extends to when I'm asleep!

The cervical collar on me is important both ways in keeping my neck straight. That's why I have to shorten it so that the ends don't overlap in the back and have a lump pushing my neck up and head back. And I'm starting to worry that the feeling in the front of my neck is the collar pressing my enlarged thyroid into my airway...

There's definitely a Goldilocks problem here. (Or maybe it's a princess and the pea problem, LOL.)
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RE: Why don't these flow rate curves count as flow-limited?
Now looking at last night:


That pair of flow limits at 3:02 and 3:13 started and the vauto made short work of both without waking me up. Here's a 3-minute zoom of the first one:


And the second one which is more ambiguous:


There is definitely a lot less going on here than with the Autoset -- the vauto is just better at it!
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RE: Why don't these flow rate curves count as flow-limited?
All it is doing is raising pressure, same as autoset. Either it raises pressure faster (should be able to compare to autoset data) or your body responds to the higher pressure differently with higher PS.

I found what looks like a good deal on a used vauto (hopefully it is in good working condition) so bought one to try out myself. After I use it for a while going to try looking at the data closely to see if there are any noticeable differences in programming (waveform shape, pressure responsiveness, flow limitation reporting etc) as to my knowledge there is no mechanical difference in these machines.
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RE: Why don't these flow rate curves count as flow-limited?
Well I think that maybe the key is not raising the pressure but lowering it. The pressure goes from IPAP to EPAP before I finish the inhale -- I think that it is noticeably faster than the EPR drop.

And when I do get a burst of flow limit, it zooms the pressure, the flow limit ends, pressure falls back.

I'm assuming that is controlled by some of those other settings which I just left at default.

(08-15-2021, 09:01 AM)Geer1 Wrote: ... as to my knowledge there is no mechanical difference in these machines.

Yeah, it's really a travesty if true. The already spent all of the money on the software once they produced the first bipap. It wouldn't cost them any different to just put the bipap software on every autoset, and then just sell it for the autoset price. That would put a nail in PR's coffin -- "If you buy the ResMed autoset and later your sleep doctor decides you need bipap, the DME can just reprogram it as a bipap, no extra cost."

Of course maybe we're wrong and there is some extra hardware in there to support the bipap functionality.
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