Clear Airway Apnea = Central Apnea?

[another_guest]

What have I wandered into?

Well where were you Oct 12, 1962? If you were in Seattle then, you will remember it well. This is about as strong of a wind storm here on your thread.

[GumbyCT]

What have I wandered into?

You, my friend, have brought out the ghosts of xmas past!!! or is that passed for some others here.

[barry15]

What have I wandered into?

Well where were you Oct 12, 1962? If you were in Seattle then, you will remember it well. This is about as strong of a wind storm here on your thread.

Ah, the Columbus Day Storm. I wasn't actually living here then, but I have heard of it. I was born in Seattle, though, and so I AM a native, although I actually grew up in Southern California. I was smart enough to return, though.

Yes, I can see that we had a little party here and I'm glad to be part of it.

[rested gal]

What have I wandered into?

You, my friend, have brought out the ghosts of xmas past!!!

I like that, Gumby! Good one!

[jnk]

What have I wandered into?

You have wondered into a forum where when someone has a particularly good original-post, it tends to get banter-bumped with scattered batter-matter/anti-batter-matter.

I believe that different masks often give different machine-estimated-data results for some of us. The numbers home machines give are estimates designed to be used as trending data and are not as reliable as the numbers from a PSG. The home machine data is very valuable as trending data, but changes in the variables, like the mask used, can, I believe, make it more difficult to see the trend.

The difference in your home-machine-estimated-data results between full-face and nasal masks could be because of mouth leak (or some form of lip-flutters) in the case of the nasal mask, or it may be because of mouthbreathing when using the full-face mask--which is OK, but may not be optimal. Your humidity needs may differ with full-face versus nasal masks. Breathing through the mouth tends to dry someone out more, even with a full-face mask, I have read.

It is also conceivable to me, though I have no idea if it is so, that when different masks have different resistance properties, an auto sensitive enough to attempt to judge the condition of the airway might be particularly helped with its data estimates if the resistance of the mask being used is known by the machine, as you mentioned.

Then again, I rarely have any idea what I'm talking about. I just wanted to join in the fun!

jeff

[Doze]

What have I wandered into?

I second that sentiment. I came back to this thread a short while ago intending to thank rested_gal for all those links yesterday, and got way confused. Thanks to those of you who cleared it up; I was really scratching my head on that for a bit.

Regarding those links (again, thanks RG), I have a bittersweet personal tale on that. Yesterday afternoon, I had got through one or two of those "centrals" links and was gonna click on a third when I realized I was barely comprehending things. That annoying 'foggy head' feeling had come back, and I was just going thru the motions of reading, without actually registering much of anything. Symptom of this beast that most of us share. Seems the previous day I had been posting and reading and cross-referenceing and... forgetting to watch the clock that evening. Didn't even think about getting to bed with enough hours left 'til morning to keep myself healthy. So somewhat abruptly yesterday I had to quit reading/posting/replying/anything and lie down (watched part of a movie) and then when I felt OK again, had to get back to other mandatory tasks so I could try to fall asleep at a reasonable hour yesterday evening. Feeling a bit better today, but my schedule's so messed up that I had 3 hours of sleep, 3 hours wakeful, 5 hours sleep. Not the best night, but at least enough total hours to be able to function today. Working my way through those confusing posts an hour or two ago definitely had me questioning my assumed mini-recovery though, hah!

[GumbyCT]

Enuff of the anti-batter-matter.

I believe Muffy had some sleeping issues herself this morning? What gives gf?

[-SWS]

Enuff of the anti-batter-matter.

Sir, I would very politely remind you that today is Friday. And that's a day traditionally reserved for fish fried with BATTER of all things!

I believe Muffy had some sleeping issues herself this morning? What gives gf?

That's pretty close to Muffy's usual "lark" rising time.

In a reply titled "Nope" sleepydave (RRT, RPSGT and manager of an accredited sleep center) responds to honda's question:

Oh, that guy thinks he's so smart.

"IMHO", PR SystemOne will perform no better that the ballistocardiography of PB420E (which, when you think about it, really isn't all that hot):

It's a 50-50 Shot

And I believe that neither ballistocardiography, pressure pulsation nor FOT will accurately identify central apneas because

The pathophysiology of obstructive sleep apnea and central sleep apnea overlap considerably. During normal inspiration, neuronal discharge to the diaphragm and dilator muscles of the pharynx increases. Failure to achieve pharyngeal dilatation in the presence of diaphragmatic contraction results in an obstructive apnea. If the diaphragmatic contractions are diminished, a central sleep apnea occurs. The hypopharynx may or may not be open during a central apnea. Studies have shown considerable narrowing of the hypopharynx during a central apneic event. If the hypopharynx is closed during central apnea and diaphragmatic activity resumes before pharyngeal dilator muscle tone is restored, a mixed apnea results.

Good A Reference As Any

Anyway, they call it a "Clear Airway" event because the airway is "Clear", it probably is, in fact, a central, but chances are there will be tons of 'em that will be missed.

Muffy

I agree with that assessment. If the airway happens to be "open" or "clear" during an apnea, then that apnea is obviously NOT obstructive. It must therefore be a central apnea according to xPAP machine algorithm. And that straightforward distinction allows for open-airway differentiation methods to enjoy near-perfect specificity of central-apnea measurement or detection.

But as Muffy points out, apneas lacking respiratory effort (thus "central apneas") sometimes entail a closed airway. Thus an open-airway differentiation method is going to miss all central apneas that occur with a closed airway. And that detection impediment undoubtedly accounts for the mediocre sensitivity rating that open-airway central-apnea detection methods typically suffer.

Alas... home-based central apnea measurement realities. Handy information none the less IMHO.

[Muffy]

Ya wanna see something REALLY funny?

Pharyngeal narrowing/occlusion during central sleep apnea
M. S. Badr, F. Toiber, J. B. Skatrud and J. Dempsey
Medical Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin 53705, USA.

We hypothesized that subatmospheric intraluminal pressure is not required for pharyngeal occlusion during sleep. Six normal subjects and six subjects with sleep apnea or hypopnea (SAH) were studied during non-rapid-eye-movement sleep. Pharyngeal patency was determined by using fiber-optic nasopharyngoscopy during spontaneous central sleep apnea (n = 4) and induced hypocapnic central apnea via nasal mechanical ventilation (n = 10). Complete pharyngeal occlusion occurred in 146 of 160 spontaneously occurring central apneas in patients with central sleep apnea syndrome. During induced hypocapnic central apnea, gradual progressive pharyngeal narrowing occurred. More pronounced narrowing was noted at the velopharynx relative to the oropharynx and in subjects with SAH relative to normals. Complete pharyngeal occlusion frequently occurred in subjects with SAH (31 of 44 apneas) but rarely occurred in normals (3 of 25 apneas). Resumption of inspiratory effort was associated with persistent narrowing or complete occlusion unless electroencephalogram signs of arousal were noted. Thus pharyngeal cross-sectional area is reduced during central apnea in the absence of inspiratory effort. Velopharyngeal narrowing consistently occurs during induced hypocapnic central apnea even in normal subjects. Complete pharyngeal occlusion occurs during spontaneous or induced central apnea in patients with SAH. We conclude that subatmospheric intraluminal pressure is not required for pharyngeal occlusion to occur. Pharyngeal narrowing or occlusion during central apnea may be due to passive collapse or active constriction.

http://jap.physiology.org/cgi/content/a ... /78/5/1806

So it would appear that new age central apnea identification will work great as long as you don't have sleep apnea.

Muffy

[-SWS]

Complete pharyngeal occlusion frequently occurred in subjects with SAH (31 of 44 apneas) but rarely occurred in normals (3 of 25 apneas).

Well, that somewhat common central-apnea airway closure is said to occur most often at a central apnea's nadir. So theoretically differentiation in the time domain can occur based on the non-closure segments for those nadir-closed central apneas.

But speaking of FOT, I originally thought Weinmann formerly employed a method entailing time-domain reflectometry based on return measurement of their pulse wave. The reflectometry method I thought Weinmann and others were employing would entail looking for wave reflection along with time measurement.

That's not at all what Respironics and Resmed are doing. They're simply launching a pulse wave, and performing a coarse measurement of whether mass airflow happens to be moving or not. That's altogether different than time-domain reflectometry based on reflected energy waves. They simply perform a very coarse detection of flow admittance or lack thereof. Undoubtedly that's much easier for patients to sleep through as well.

Upon "reflection"... silly me!

[Muffy]

That's not at all what Respironics and Resmed are doing. They're simply launching a pulse wave, and performing a coarse measurement of whether mass airflow happens to be moving or not.

ResMed's gonna use FOT.

Muffy

[-SWS]

That's not at all what Respironics and Resmed are doing. They're simply launching a pulse wave, and performing a coarse measurement of whether mass airflow happens to be moving or not.

ResMed's gonna use FOT.

Muffy

That's what I heard... maybe in one of your posts. Their FOT and Respironics' version both entail coarse detection of mass airflow---upon launching a low-amplitude pressure pulse.

I'll have to eventually take a look at Sherman and Mr. Peabody's Way Back Machine to see if Weinmann ever used more accurate time-domain reflectometry. I thought they employed a pulse-wave reflectometry method but discontinued using it. If so, that would have been more difficult to sleep through compared to what Resmed and Respironics employ by the way of FOT...

[dsm]

On FOT
We discussed previously how Resmed had an AutoSet Spirt II machine (S7 shaped) that employed FOT but they never came to market with it.

Also if any cpap manufacturer used reflective wave technology, you would need a doppler radar speed-gun to accurately measure the speed of their apnea

DSM

PS Weinmann appeard to use conventional fot bursts.

[dsm]

PPS

Am sure the new Bipap AutoSV Advanced is using FOT as well for its CA sensing (Auto Epap adjustement) - am sure I read it in the patent. Will take another peek later to see if I can extract any wording.

Also SWS, Re the comment about 'mesuring mass air movement' after a FOT burst - isn't the issue that there is no air movement & that is what triggered the FOT burst. I am just trying to picture how the xPAP detects the difference between the air circuit ending at the throat (an apnea) vs ending at the bottom of the lungs (airway open). How would say a 5000 cycles p/s FOT burst of one frequency signal back the difference ? (has me really thinking as to just how FOT etc: might actually work).

DSM

[FeistyWifey]

I like it because I have nose issues (long, long story), and breathing through my mouth when awake in the night gives my nose a chance to settle down a little. I can't tell if I am actually doing any mouth breathing when I am asleep or not. I breathed exclusively through my mouth for most of my life, until I had to learn to breathe through my nose when asleep, so I could use CPAP, and now I think I have forgotten how to breathe through my mouth when I am asleep. I'm not sure I want to relearn to do that, either, as it is a problem with the nasal mask or nose pillows.

I put some additional leak information in a post above, and at this point, I see no difference in the data for the nasal mask or full face mask, so I don't think that leaks are the reason for the increase in CA's, but it is early days yet, and I will keep it in mind.

Well, I should have done my homework re your prior post. I'm sorry! I wish I could have been of help, but instead have just helped my husband. He uses a nasal mask but has nose issues too a lot of the time. A FF may be the ticket for him and he is thrilled that your beard causes no leaking with that mask. His beard length varies, too, mostly long w/some soft curling. As for your discipline and weight loss, you deserve a Commendation. What an inspiration. I didn't really think leaking could cause a Central, but thought it might cause a false report of a Central. I'm a newbie (he's been on CPAP for ten years now but everything has changed since he received that machine and then my abandoned one.) So, from a re-newbie, best wishes for the most favorable outcome for you!