big breaths, THEN the OA happens-NotMuffy could you comment?

[robysue]

I've spent a lot of time looking at my wave forms over the last 10 months.

I was under the impression---maybe false?---that a typical apnea or hypopnea is likely to END with some recovery breaths---breaths that are larger (and quicker?) than the running baseline, but that the breathing before the apnea would either look normal or look like flow limitation breathing---i.e. breaths becoming more ragged and more shallow. And I do see those kinds of OAs, CAs, and Hs in my data.

But I also see a lot of the following kinds of OAs and CAs (and sometimes Hs) that follow several larger than normal breaths such as these, which are taken from five different nights' data during the period between July 15 and Aug. 1 :












In all of these cases, I don't remember waking up right before or after the apnea: When I wake up, I routinely turn Kaa off and then on so the conscious wakes are visible in the wave forms. An example of a wake that I remembered is shown in the break in the wave form at the end of the first example. Notice the similarity between the breathing right before I turn Kaa off and the breathing right before the apnea.

So what are those big breaths preceding the apneas? Any speculation?

And for what it's worth, I do sometimes have these random "big breaths" without having an apnea occur or the following breaths being labeled as a hyponea.

[dsm]

Robysue

Tks for such clear images - I have some questions re the data - I don't have a PR1 & haven't really looked at the charts off this machine in detail but am wondering if those red squares represent 'Pressure Pulses' ? (am sure they are).

In the one at the bottom chart with the CA you appear to be going through a sleep arousal - deeper breathing - have a natural central (benign one) then resume normal sleep. Not sure I can see evidence of rolling over (as steps in the wave form just prior to the CA)

Just my impressions

DSM

[robysue]

Robysue

Tks for such clear images - I have some questions re the data - I don't have a PR1 & haven't really looked at the charts off this machine in detail but am wondering if those red squares represent 'Pressure Pulses' ? (am sure they are).

Yes, the red boxes are indeed the Pressure Pulses that the PR S1 uses to determine the patency of the airway.

In the one at the bottom chart with the CA you appear to be going through a sleep arousal - deeper breathing - have a natural central (benign one) then resume normal sleep. Not sure I can see evidence of rolling over (as steps in the wave form just prior to the CA)

Just my impressions

DSM

Yes, I think I know what you are talking about. These are ambiguous though. Usually when I see those steps you are talking about as possibly indicating turning over---the steps are more pronounced and I don't get anything scored in the aftermath or I get a H scored occasionally.

[NotMuffy]

But I also see a lot of the following kinds of OAs and CAs (and sometimes Hs) that follow several larger than normal breaths such as...

"IMHO" (and of course, if there were EEG channels, it wouldn't have to be an "O"), I believe the succession of events would be:

• A spontaneous arousal or awakening;
• Recovery breaths related to the arousal or awakening; and
• Compensatory central apnea (all of them) because

• (existing technology for all the) central identification algorithm(s) is (are) flawlessly specific but horrid in it's (their) sensitivity...

[robysue]

NotMuffy,

First, thanks for answering my question. That's what I'd been beginning to suspect about these events following a few big breaths.

Next question which comes even further from the realm of supposition: Let's suppose there was EEG evidence that showed an initial spontaneous arousal before these events. Would the compensatory central apnea immediately following the event even be scored as sleep disordered breathing? Or would it just appear as a spontaneous arousal?

Again, thanks for taking a look and answering my question. Because I see a lot of these: Some nights they make up the vast majority of the events scored by my machine. And on the nights where they're not as common, the AHI is usually less than 1.5; where they are exceptionally common, it's often above 2.5.

[milw]

Interesting... I can find similar events in my flow data, but I wonder about jaggedness of the data recorded right before the apneas- could it be bigger breaths to overcome nasal congestion followed by one or two mouth breaths that are not recorded by the machine? (I might try that tonight before falling asleep, to see if I can reproduce that waveform).

Another idea- in reading suggested by dsm and others, when breathing is under chemical feedback control, bigger breaths would lower blood pCO2 below the apneic threshold, so an apnea could follow deep breathing (I don't have the reference(s) to hand at the moment).

[robysue]

Interesting... I can find similar events in my flow data, but I wonder about jaggedness of the data recorded right before the apneas- could it be bigger breaths to overcome nasal congestion followed by one or two mouth breaths that are not recorded by the machine? (I might try that tonight before falling asleep, to see if I can reproduce that waveform).

Do let me know the results of your experiment if you do it. Although in my case, I don't think this is the likely candidate because between the daily zyrtex, sinus rinse, and flonase, I've got zeror nasal congestion this summer---for the first time since I can remember. Pre-CPAP I simply didn't do the whole nasal hygiene routine that I'm doing now.

Another idea- in reading suggested by dsm and others, when breathing is under chemical feedback control, bigger breaths would lower blood pCO2 below the apneic threshold, so an apnea could follow deep breathing (I don't have the reference(s) to hand at the moment).

Yes, that's actually why NotMuffy is saying that in his opinion all those examples of mine are likely "compensatory central apneas" regardless of what the machine scored; my question then becomes: Are they sleep disordered breathing? In the sense of: Would they have been scored on a sleep study? And the answer to that, alas, really depends on the EEG data which is lacking.

[dsm]

<snip>

Another idea- in reading suggested by dsm and others, when breathing is under chemical feedback control, bigger breaths would lower blood pCO2 below the apneic threshold, so an apnea could follow deep breathing (I don't have the reference(s) to hand at the moment).

Yes, that's actually why NotMuffy is saying that in his opinion all those examples of mine are likely "compensatory central apneas" regardless of what the machine scored; my question then becomes: Are they sleep disordered breathing? In the sense of: Would they have been scored on a sleep study? And the answer to that, alas, really depends on the EEG data which is lacking.

What NotMuffy is highlighting is that the current state-of-the-art cpap machines are now super sensitive at detecting events - even the *many* benign ones. They don't differentiate (yet) and will score them on your nightly data. That tends to send us plebs into anxiety attacks over the 'centrals' & other events that we are seeing in our nightly data when in a sleep lab many would be discounted. That anxiety further convinces us we must have something worse than vanilla OSA (for those that fit that category). It is very human to react this way - been there done that

As a simple answer, I believe that in a lab, benign events that get discounted, are not considered SDB. Outside the lab & at home it depends on how we choose to see the events or if we can get an expert to give an opinion on them, which is a tad harder to do than when scoring events whilst in a sleep clinic because in the clinic the scorer usually has a wide array of feedback channels to aid in determination of an event.

DSM

[milw]

So regarding EEG, is the Zeo about the only game in town for consumer grade monitors? Has anyone on the board thought of making their own EEG? (homebuilt, like on http://openeeg.sourceforge.net/doc/ )? There are a few other Google hits for homebuilt EEG...

[jnk]

Sometimes, as I understand it, it's the pause in breathing (so-called "central") that allows the airway to close. And it isn't the pause in breathing that is the problem (that's natural after deep breaths)--it is the fact that the airway closed and turned a natural pause in breathing into an obstructive event, a mixed apnea.

Said another way, it is possible for the machine to be putting out the perfect pressure for keeping your airway open during breathing, but for that pressure not to be enough to prevent the airway's closing during the natural pause in breathing. A person with that problem may find it better to run a constant pressure slightly higher than what an auto would settle into, in my opinion.

My comment mostly applies to the events you showed us in which there are recovery breaths--not the events where breathing starts up normally after the apnea. I would assume those without recovery breaths are pure centrals, as has been stated.

Then again, I'm just an opinionated patient, not a pro.