CPAPtalk.com

-SWS wrote:Theorists aren't so bad. You are one in this thread.

Busted ... yep, gotta agree with ya.

Now I have to admit that I am clueless as to why this thread is at an impasse.

It seems to me that many good points were raised, that many points were justifiably overturned, and that everybody even seemed to overturn some of their own points toward the learning process (myself certainly included).

Then, of course, in the end everyone is always left to maintain their own enhanced conclusions, and hopefully not resent the conclusions of others. At least that's the way I perceived it.

Wulfman wrote:

ozij wrote:Which brings up a further thought
Is the worst NR number on a Respironics just 1/8 of the total? How are the events in the preceding sequence counted? are they called apneas, or are they reported as NR retroactively?

O.

Ozij touched on some things I've been wondering about for a long time. And that is.....how do the "events" that are detected and recorded by the various machines (and the software) ACTUALLY compare to what would be seen in the sleep lab?

Since these machines are based on air flow, and have to read a "pattern" of events before it decides to act......how many of those events would be scored by the equipment in the sleep labs?

Did I actually have four or six hypopneas last night?......or was it just the two that showed up on the Encore report?

Also:
Do my machines when set in straight-pressure mode (CPAP) report the NON-APAP (snores, hypopneas and apneas) events the same as the APAP machine? (since it doesn't need to respond to those and more types of events)

"SAG" (Dave)......are you reading this thread?


Den

-SWS,

Thanks for taking a speculative crack......instead of a wise crack.

I think it would be interesting to do some "clinical trials" (I read that term in a previous post) on some of these machines in an actual sleep lab setting. (Interesting, but far too expensive ) One would hope that the manufacturers did some similar trials......but I doubt that we're ever going to see their documentation. (I'm not talking about the non-human simulators either.)

Some sleep doctors embrace this type of technology (reporting) and some definitely do not (like mine). Maybe I wasn't too far off when I told my sleep doctor that even if my AHI from the Encore reports was multiplied by 3 times, I would still be under the 5.0 mark.

Den

Clinical Evalutation of the Good Knight 420E Auto-cpap system for treatment of obstructive sleep apnea syndrome

Like most PB pdf files, this one can't be copied from, so I can't quote - and I'm terrible at copying - but it's an interesting read.

It compared a diagnostic PSG and the GK420E "treatment night" for 12 "newly diagnosed unselelcted patients".

O.

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): 420E, auto

NightHawkeye wrote:

rested gal wrote:For one thing, they've known all along that the throat is not a bottle and the tongue is neither a cork nor an egg.

And therein you illustrate with high precision the batteline in this discussion - an entrenched inability to move beyond points provided for illustrative purposes.

You may see a battle line -- perhaps of your own making. I see people discussing machines, what they may do, how they may do it, and learning from each other.

NightHawkeye wrote:Should I apologize for debunking your long-espoused theory about how Respironics APAP's zap apneas when they occur, with solid evidence from the manufacturer, I might add.

No apology needed at all, least of all from you, Bill. We're all here learning as best we can. With good humor, I'd hope. I thought the wink and the laugh would show you that was a good natured tweak about the cork and egg. My sincerest apologies if that bothered you.

By the way, my "long espoused theory" for at least the past four years has not been that APAPs "zap apneas as they occur." My longtime theory has been that APAPs can preemptively prevent most apneas for most people, IF:

The minimum pressure is set high enough to prevent most apneas in the first place.

I'll be the first to admit that I thought the pressure increments that can result in an NR flag on Encore data were dealing with one apnea. I was glad to see -SWS's and ozi's discussion clearing that up nicely.

We're all learning. And that's good!

I'm just glad the machine designers already knew quite a lot about apneas and how to design the machines we use.

ozij wrote:Clinical Evalutation of the Good Knight 420E Auto-cpap system for treatment of obstructive sleep apnea syndrome

Like most PB pdf files, this one can't be copied from, so I can't quote - and I'm terrible at copying - but it's an interesting read.

It compared a diagnostic PSG and the GK420E "treatment night" for 12 "newly diagnosed unselelcted patients".

O.

Thank you!
Just had time to skim through the highlights, but according to the report,it appears that there's a pretty high degree of accuracy in comparison to the PSGs.

Den

Well, I shoulda known better! I'm not sure what possessed me to share the epiphany, anyway. It was too much stuff all lumped and dumped together into a single post. (I have to relearn that lesson every now and again.)

So, having said that, I'll take a stab at one specific item.

-SWS wrote:So you and Bill were quite literally talking about "the vacuum-based airway occlusions from hell". None of us have a medical term for what you two are proposing. So we've been loosely using terms like "cork theory", "super cork theory", and even at times "vacuum-based occlusion" (with the ever-so-crucial "from hell" part simply omitted)

Now, I really, really don't understand why there is any contention about this. A "medical term" for it does exist, btw. The term is obstructive apnea. The tongue falls into the back of the throat, closing off the windpipe, and while the lungs expand trying to get air a vacuum is created. Now, vacuum is measured on a continuum and so far as I know nobody has yet figured out how to create a perfect vacuum on this earth. With air already in the lungs, the vacuum is certainly not perfect. Even with an imperfect occlusion though, the vacuum still occurs and as a result of that vacuum the pressure above the tongue would be greater than the pressure below the tongue in the windpipe. Result is that the tongue gets pulled tighter into windpipe. (Ever wonder why apneas run for several minutes sometimes?)

Any chance of agreement on this single point?

> Do my machines when set in straight-pressure mode (CPAP) report the NON-APAP (snores, hypopneas and apneas) events the same as the APAP machine?

An interesting question. When my Auto M bipap was set at _fixed_ bipap, Flow Limitation was zero -- precisely zero -- _every day_. When I set it to auto bipap, FL averaged 1.0. That's 8 events per 8 hours. Something is peculiar between those two very different averages.

At the same time, snore went from around avg 0.7 (fixed) to around avg 4 (auto), a factor of 5.7x.

Has anyone else observed this?

1. There could be some problem with the Auto M. Perhaps either the observation of events or, possibly, the reporting of events could be in error. There's so much "sloshing" of air _back and forth_ in a bipap -- more than a cpap, even more when in bipap auto mode -- that the degree of difficulty in determining that an event just took place -- and what kind of event was that? -- must border on voodoo.

2. Or ... the difference in events could be real. It happens. Occasionally.

Fixed cpap, auto cpap, fixed bipap, auto bipap. Some patients using correct pressures (the titration was accurate), some not. In auto mode, some using a "good" range, some not. Some using humidifiers, some not. (Think "sloshing water".) So very many variables.

Given the economic constraints that most corporations place on researchers, it's difficult to believe that "all the cases" have been a) adequately tested and b) properly addressed. As a, uh, technologist, I have seen too many mistakes in my lifetime to simply believe "the numbers".

Given the overall design of the Auto M (the humidifier you love to hate, the absolutely idiotic power cord bungle, the blue lights from hell, etc.), all that speaks to Respironics severely limiting design time and cost.

Clearly, "fixed cpap" is the trivial case in comparison to the other possibilities. I'll bet they tested that mode pretty well. :)

That said, isn't xpap great? We'd probably be dead without it. Well, our ancestors were. My auto M is light years more advanced than its predecessor. I think that what happens is that they've got it mostly right, but far from perfect.

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): auto cpap, respironics, bipap, humidifier, Titration, CPAP, Power, auto, APAP

ozij, thanks for the link to that PDF! As Den did, I skimmed it first and see that it's a very interesting read.

As best I could tell with a "first skim", the 420E APAP mode settings for that trial was the default range of 4 - 20. Very impressive correlation with the PSG recordings done while the 420E was being used.

Anecdote of one:

I had three consecutive nights of full PSG at SAG's sleep center in 2005. First night was baseline (no cpap), second night was manual titration with the lab's equipment, third night was monitored by the lab's PSG equipment while using my 420E.

If SAG sees this thread, he can fill you in on how the 420E's actions looked to him, compared to what the PSG showed.

Only thing (and I'm still kicking myself over this) was I forgot to take along the air hose with the PB's own sensor line. An essential thing to have if a person is gonna use that machine. So, we jury-rigged a sensor line from an argyle tube.

-SWS can tell you how that may have changed the flow the 420E would normally be sensing.

All I know is that on my Silverlining data from that night, there were a considerable number of Ca's marked, that I normally haven't had on my 420E data before or since. The PSG was showing no centrals at all, on any of the nights. And normally, using my 420E no "Ca"'s appear, of if a random one does, it's once in a blue moon.

So, since it was a substitute sensor tube shaped quite differently from the 420E's own sensor tube, I'm not sure how accurate the comparison really was. As I said, I'm still kicking myself over leaving the PB's own sensor line at home when there was such a wonderful opportunity to see what the PSG said the 420E was or wasn't doing "right."

Separate PSG reports (as well as some screenshots from Silverlining) of each night of that three night study are here:

http://www.tnlc.com/Lara/laura/osa/study-Oct2005/

I had set the 420E's range at 8 - 14
Starting pressure set at 8. No ramp.
IFL1 turned off.

xyz,

You only see those events (NR & FL and a few different charts/reports) from a machine that's capable of being set to Auto mode and when it IS set to Auto mode.

Den

-SWS wrote:
<snip>

Kind regards, Doug! Because we are friends we can playfully rib each other. Please don't take any of mine to heart!

<snip>

SWS,

So you didn't see the smile on my face when I posted 'Now SWS'

What I was trying to say is I don't and never id subscribe to a cork in the bottle mouth as a cpap theory, it was a visual illustration of a principle.

So I merely painted a picture of an obstruction at one end and a vacuum at the other. I intended to use that to lead into what Sullivan discovered.

What I see in some of your posts is you positioning me as the inventor of a cork in the bottle theory when from my perspective I joined in the discussion about occlusions and humorously introduced the egg in the bottle mouth, then you introduced a tongue wedged tightly in the throat scenario.

To get around this changing of the argument I would like to come back to this point I raised ... what other types of occlusions are there that are not vacuum based and on which Sullivan founded his work ?. A Central isn't an occlusion, a flow-lim isn't & neither is a hypop - so what is

Also I don't believe we have any firm conclusion that caution about centrals is the only reason the Apap designers only ever cautiously raise pressure. RG hasd claimed an end to that theme prematurely - the matter of the goodbad effects of raising pressure against an existing block has not been resolved it has been skirted thus far.

DSM

PS I am sure you have enjoyed the repartee as much as I have

NightHawkeye wrote:Well, I shoulda known better! I'm not sure what possessed me to share the epiphany, anyway. It was too much stuff all lumped and dumped together into a single post. (I have to relearn that lesson every now and again.)

Bill, it only took me a few hours to understand the human factors that went into that single post. By contrast it would have taken someone with better social acumen but a few seconds. Absolutely no need for you to apologize, but I will for delivering humor that just didn't come across right. Den very succinctly underscores that point above. I ain't never going to learn to dance right, Bill.

NightHawkeye wrote:So, having said that, I'll take a stab at one specific item.

-SWS wrote:So you and Bill were quite literally talking about "the vacuum-based airway occlusions from hell". None of us have a medical term for what you two are proposing. So we've been loosely using terms like "cork theory", "super cork theory", and even at times "vacuum-based occlusion" (with the ever-so-crucial "from hell" part simply omitted)

Now, I really, really don't understand why there is any contention about this. A "medical term" for it does exist, btw. The term is obstructive apnea. The tongue falls into the back of the throat, closing off the windpipe, and while the lungs expand trying to get air a vacuum is created. Now, vacuum is measured on a continuum and so far as I know nobody has yet figured out how to create a perfect vacuum on this earth. With air already in the lungs, the vacuum is certainly not perfect. Even with an imperfect occlusion though, the vacuum still occurs and as a result of that vacuum the pressure above the tongue would be greater than the pressure below the tongue in the windpipe. Result is that the tongue gets pulled tighter into windpipe. (Ever wonder why apneas run for several minutes sometimes?)

Any chance of agreement on this single point?

Bill, we absolutely agree on mechanics and terms. The gist of what I have going in that part you have quoted directly above is that off-the-mark humor I had to sincerely apologize for.

That's clearly an obstructive apnea that you describe. I think the gist of your theoretical inquiry may have to do with suspecting that very severe residual obstructive apneas while on PAP are numerically problematic across the patient population---but more specifically residual apneas at the high end of the vacuum spectrum.

Don't confuse my own poor humor as if I am flat out rejecting your theory. Absolutely not. I never have! Rather, I thoroughly enjoy your proposed line of exploration! Just don't get thrown off by my very quirky humor, please.

Doug, I immensely enjoyed it!

Cheers, friend!!!


P.S. Wife's impatiently calling me to dinner now....

dsm wrote:RG hasd claimed an end to that theme prematurely - the matter of the goodbad effects of raising pressure against an existing block has not been resolved it has been skirted thus far.

LOL!! Pray, don't stop on my account. No claims here. I hope this thread never ends. It's been very illuminating as well as entertaining. I enjoy learning. And laughing.