Cardiac oscillations Question

SWS, so good to see you posting. Thanks for the information!

Thanks, Rested Gal. I always take pleasure in reading your savvy posts here and elsewhere. I enjoy reading Nev's superb explanations too.

Titrator, I really appreciate that wonderfuul compliment, but just can't agree with you. I think you express yourself beautifully! I have read countless of your posts that are literally worth framing and hanging on the wall. While I'm not a teacher, I will take that confusion (or wise-crack ) as a compliment, too! I have only spent my career developing and otherwise working with hard-cold technology. By contrast teachers develope the young minds of society. Now THAT is a much nobler profession than mine!

On the topic of central apneas that Chris brought up, I think it's worth noting that positive pressure machines , by design, do not effectively treat either primary or significant occurences of central apneas. That statement includes AutoPAPs. In fact, you'll note that of the three AutoPAP manufacturer examples discussed above, all three of those design approaches are actually strategies of central apnea avoidance rather than central apnea treatment. That's a very key concept worth understanding.

Central apneas can occur for a variety of reasons, some of which are not fully understood by sleep science. It is known that some patients suffer primary cases of central apneas (irrespective of using PAP technology), however. Some central apnea patients unfortunately experience central apneas as a side effect of a chronic heart condition. Other patients seem to suffer central apneas that are of a primary nature because their respiratory drive and/or blood gasses somehow just don't function correctly. In these cases positive air pressure is not the machine that doctors will usually prescribe. Recall that AutoPAPs, CPAPs, and even very basic BiPAP machines all deliver positive air pressure---and nothing more. They do not attempt to properly ventillate the lungs in the case of "missing breaths" with an open airway (i.e. central apneas).

By contrast to the above cases, some patients do not seem to suffer central apneas unless they are using a PAP machine. These central apneas are thus not of primary nature, rather they are pressure induced. It is specifically this scenario that all AutoPAPs by design try to avoid or minimize when they factor central apneas into their design. It is important to realize when you see an AutoPAP discussion or even a marketing brochure discussing central apneas: central apnea avoidance is actually being discussed, and not central apnea treatment.

By contrast, sophisticated BiLevel machines that are specifically designed to address primary central apneas will actually detect more crucial ventillatory type parameters (tidal volume, timing, IPAP/EPAP transitions, etc), to properly ventillate the lungs if necessary. Simpler PAP machines cannot properly ventillate the lungs in cases of significant central apneas, where high-end BiLevel machines can do so by design.

SWS, that explanation you just gave should be in a textbook.

I'm in awe.



Laura

SWS,

Thanks for that detailed explaination of the issue of xpap and it's effect on central apneas.

To boil it down... simply put, in consideration of the subject of central apneas, one should look for an xpap that avoids causing secondary centrals and if the goal is to treat primary centrals, one should consider a bi-pap or phamaceutical avenues.

Thanks to all for a fantastic technical discussion. Many may think this level of technical understanding should be left to the sleep practitioners but I feel the little technical knowledge I've gained so far it only the tip of the iceburg, so I'll be absorbing all I can. A deeper understanding of the workings of xpap can only be beneficial for us "users"

Topping for Laverna

Please also note spec-correction to my previous post regarding the 420e's central apnea detction:

Specificity=100%
Sensitivity=62%

Meaning that all central apneas the 420e detects are, indeed, central versus non-central----if it happens to detect them at all. And that 62% of all central apneas passing through the 420e's sensors will actually be detected.

Thus the 420e's reliance on the command-on-apnea as an adjustable pressure "safety cap" to limit the risk of pressure-inducing "runaway" central apneas. This 420e functional feature is actually moot to most patients, however. For others it would be crucial.

I've just been through this topic again, and figured it might help many some new, and not so new member.

-SWS, I sure miss you....

Anyone curious to read more posts by -SWS is invited to the cpap faq "message board discussions with -SWS"

The info about the specificity and sensitivity comes fron a study published in: "Chest" vol.116, Sept. 1999.
O.

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CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP

I am home with strep throat... uhhgg... I was looking through old posts to find interesting reading.

Here is a thread that is masterfully written. It spotlights cpaptalker SWS and is vast area of knowledge.

Bringing this one back to life for everyone.

Ted the Titrator

Very interesting post. As far as the Central Sleep Apnea goes any type of CPAP or APAP will most likely actually make the Central component worse. The best thing out right now is the Adaptive Servo Ventilation VPAP just released by ResMed and Resperonics. I have not had an opportunity to use the Resperonics version but I am a PSG tech and we use the ResMed Adapt ASV in the lab to treat Complex Sleep Apnea and Central Sleep Apnea. The Adapt ASV is an amazing machine and when set properly has done a very impressive job of treating these difficult problems. If you are looking for a machine to treat Central Sleep Apnea either a VPAP ST, meaning it has a backup rate to stimulate a breath, or the VPAP Adapt ASV are the way to go. However, the downside is that they are both extremely expensive.