Leaks and OA's?

Nope.....no coincidence. Leaks mean a pressure drop....pressure drop means collapse of tissues.....and that collapse means restrictions. Restrictions mean apnea.

Connect the dots......

Gerald

Show me a drop in pressure caused by a leak

Also, what about those leaks that aren't associated with apneas?

The evidence is all there....if you want to see it. It's just Physics. Any good mechanic who understands seals can see how it works.

Connect the dots......

Gerald

Gerald wrote:The evidence is all there....if you want to see it. It's just Physics. Any good mechanic who understands seals can see how it works.

Connect the dots......

In order for your chain of logic to work all the dots have to connect, to use your terms. It collapses at the leaks cause a pressure drop assumption. Show me anywhere that a moderate leak causes a drop in the pressure delivered by any xPAP machine. Otherwise those dots you want to connect may simply be spots before your eyes.

Speaking of physics... leaks and apneas are known to concur for a reason not yet discussed in this thread: an obstructive apnea causes a rather sudden pressure peak in the upper airway and at the interface seal as well.

That instantaneous pressure burst tends to blow out the mask seal in some cases.

End result: apneas and mask leaks can very nicely line up on the reports because of those sudden pressure bursts.

SWS.....

Interesting point. I wonder if what you're talking about could be suppressed somewhat by running a little higher pressure?

Gerald

Gerald wrote:SWS.....

Interesting point. I wonder if what you're talking about could be suppressed somewhat by running a little higher pressure?

Gerald

Right. More pressure to stent the airway... as long as you can control mask leaks at that higher CPAP pressure. Almost a Catch-22...

As another interesting side note, that little pressure burst or peak that occurs at the onset of an obstructive apnea: That's the same little pressure peak that Weinmann looks for (signal processes) in order differentiate an obstructive apnea from a central apnea. Weinmann refers to that differentiation method of theirs as Obstructive Peak Pressure (OPP) technology.

Also Berthon-Jones, "THE" CPAP industry icon and chief science officer at Resmed, has at least one published white paper in which he mentions that little obstructive-apnea pressure burst sometimes breaching mask seals.

So in that scenario, first comes the OA and then comes the resulting leak...

Gerald wrote:So if he has apneas when he has leaks....and the machine is supposed to be compensating for the leaks....what's causing the apneas?

Gerald

Gerald,

Don't be put out by the opposing views. Your point re high leak affecting respiration is not at all invalid.
Some of our regulars though are saying that they don't think the leak shown would cause that big a drop
in pressure and that the machines do compensate. I once would have agreed but not any more..

I have charts I can show, where I had a massive leak (LL) all night & I argued at the time that my wizbang
machine appeared to compensate for massive leaks & what a great sleep I had because the machine had
adjusted pressure to compensate. After 3 such nights I was so sleepy in the daytime I had to revise my
opinion (plus desperately get the leaks fixed) & at that point came to the realization that the leaks were
killing my therapy but the machine data was saying everything was fine.

Here are 3 nights of massive leaks - LOW AHI scores - BUT therapy went downhill rapidly. I regard this
data as being supportive of Gerald's point.

http://www.internetage.ws/cpapdata/dsm- ... d_leak.pdf
http://www.internetage.ws/cpapdata/dsm- ... d_leak.pdf
http://www.internetage.ws/cpapdata/dsm- ... d_leak.pdf

The third chart is the clincher - almost no HI or AI events but massive LL - and by that day I was like
the walking dead.

DSM

-SWS wrote:

Gerald wrote:SWS.....

Interesting point. I wonder if what you're talking about could be suppressed somewhat by running a little higher pressure?

Gerald

Right. More pressure to stent the airway... as long as you can control mask leaks at that higher CPAP pressure. Almost a Catch-22...

As another interesting side note, that little pressure burst or peak that occurs at the onset of an obstructive apnea: That's the same little pressure peak that Weinmann looks for (signal processes) in order differentiate an obstructive apnea from a central apnea. Weinmann refers to that differentiation method of theirs as Obstructive Peak Pressure (OPP) technology.

Also Berthon-Jones, "THE" CPAP industry icon and chief science officer at Resmed, has at least one published white paper in which he mentions that little obstructive-apnea pressure burst sometimes breaching mask seals.

So in that scenario, first comes the OA and then comes the resulting leak...

SWS

Interesting point alright. & thanks for clarifying that OPP explanation - have been working over & your simple wording suddenly made it clear & here is why I think it happens.

CAs will happen with a slowing of the airflow. No abrupt flow cessation. An obstructive apnea (even when flow drops 75% in 10 secs) is going to slow that 6 foot column of air in a recognizable way (pressure transducer will see a signature). If the apnea is a complete block the 6 ft column of air effectively 'bangs' into the blocked airway & a pressure spike will occur at the mask as the flowing air bunches up at the site of the blockage. Because air is so compressible, the signatures are going to be very easy to recognize (as a back pressure wave reflecting off the obstruction).

DSM

SWS & DSM......

You guys are cool.....and you've read much more about "this business" that I ever will. I look at things from a mechanic's standpoint....applying common sense.

DSM....on your last point about the 6' colum stacking up.....what you're talking about is sort of like "water hammer" in our household pipes. As I "looked" at what you are saying (in my head), I wondered about the velocity of the air in that 6' column.

When we're breathing while asleep, I suspect that the velocity is very low....especially if a person registers a few FL's (flow limitations) like I do. So where I'm going with this is a question about the possibility of your "air stackup" not being quite as pronounced as you might think it is.

Thanks again guys for your input......you help make this whole thing interesting. It's fun being out pretty close to the "leading edge".....and learning about ways to make CPAP therapy more effective. What we're learning is very valuable.

Gerald

Gerald wrote:SWS & DSM......

You guys are cool.....and you've read much more about "this business" that I ever will. I look at things from a mechanic's standpoint....applying common sense.

DSM....on your last point about the 6' colum stacking up.....what you're talking about is sort of like "water hammer" in our household pipes. As I "looked" at what you are saying (in my head), I wondered about the velocity of the air in that 6' column.

When we're breathing while asleep, I suspect that the velocity is very low....especially if a person registers a few FL's (flow limitations) like I do. So where I'm going with this is a question about the possibility of your "air stackup" not being quite as pronounced as you might think it is.

Thanks again guys for your input......you help make this whole thing interesting. It's fun being out pretty close to the "leading edge".....and learning about ways to make CPAP therapy more effective. What we're learning is very valuable.

Gerald

Gerald,

I too thought of the water hammer effect as a way of explaining the signature pressure wave. But as SWS explained, Weinmann call this effect OPP & use it to differentiate between an obstruction & a central. On their web site they show examples of the detected wave form.

And yes, this is a great place for exploring what happens & trying to visualize it.

DSM

#2 The Weinmann claim
http://www.weinmann.de/fileadmin/weinma ... neu_EN.pdf

DSM, Wow, and I get upset when hubby's report is showing 18 & 32mins LL these last 2 nights when he's wearing his new mask (same UMFF). I'm starting to wonder if he does better with his old broken in one? I'll be watching that. Do you know why you were having those massive leaks, any changes at that time and how did you correct them? If I'm understanding correctly, the reason your AHIs were so low was that with the LL you weren't getting any real pressure and your machine wasn't recording any of your apneas. Poorly worded but you get the idea. Thanks.

The first chart does not present massive leaks. Those are leaks within the machine's ability to compensate.
A mechanic's point of view assumes mechanical reason for everything. Now, while a breathing obstruction (sagging tissues) is no doubt a mechanical occurrence, the reason it happens is not necessarily mechanical. We don't know what causes an apnea in to happen at a certain point of time in the airway of a breathing, living human being. Setting higher pressures will not bring occurrence of obstructive apneas down to zero for all -- though it certainly does for some.

O.

dsm wrote:The third chart is the clincher - almost no HI or AI events but massive LL - and by that day I was like
the walking dead.

Well, the machines are very good at scoring apneas. They can't differentiate central from obstructive.

If you're saying that almost no recorded AI events supports any airway collapse theory---let alone as a clincher piece of evidence---then I'll have to politely disagree. If the airway collapses because of a miniscule 50 LPM leak versus a 30 LPM mask-orifice leak, then we have highly improbable airway collapse physics right there. A sudden 20 LPM leak increase causing airway collapse?

How about leaks cause so much awful tactile and auditory sensory input that your sleep was repeatedly disturbed by all the noise and tactile flutter? I can see that, in turn, causing sensory-stimulus/response central apneas---but they would be recorded.

Anyway, the white paper comment made by Berthon-Jones was that obstructive apneas sometimes bring on sudden mask seal breaches because of that little pressure burst in airway fluid dynamics. Also to comment that the CPAP chart by the original poster is not capable of displaying any precursor flow limitations that might have occurred. That's because the machine is being run in CPAP mode instead of APAP mode.

But yes, I do believe that a sudden stepped resistance in airflow ("obstructive apnea") will cause a sufficient instantaneous pressure burst, while using CPAP, that can and does occasionally breach mask seals. I agree with ozij here: the graphic evidence on page one is entirely inconclusive for any kind of firm scientific conclusion. It's apparently plenty of evidence for us message board posters to foster opinions, however.