Rules of Thumb for xPAP Tweaks

Recently, I posted a thread in which I inquired about how to "logically" go about tweaking my xPAP settings.

I've got this fancy machine, for which I am thrilled, but there obviously are so many variables that could be fiddled with, added, removed, etc, that I thought rather than just doing trial and error, I would approach the optimal settings by using my brain (or what's left of it).

After all, there is obviously far more to this than just saying: OA's go away if you turn up EPAP high enough, and Hypopneas will drop if you just keep increasing the IPAP.

For instance, what if you throw in the added variable of AbPAP versus AbFlex or BiPAP versus BiFLEX? Or fiddle with the rise time? Or the flex settings? Or even the PS?

How much does anatomy have to do with what will work? In particular, the base of tongue is my "problem area", not my uvula. It would seem like that should matter.

Who would do better with a oral appliance in place, in addition to the xPAP? (oops, wrong board?).?

I'm sure if you dig deep enough, there are some unreliable "scientific" algorithms standing on some shakey ground. And even though andecdotal evidence is so tempting and fraught with problems, it still can be a source for ideas that need to be explored.

Anyway, without further ado, I will say that I was pondering if some of you academically minded folks might consider the wisdom of an informal data base that would tap into these Rules of Thumb. I don't know anything about the Wikpedia concept, other than I love it, and the memories I have of going to the Encyclopedia Brittanica or the World Book Encylopedias as a child seem laughable by comparison.

But what if there were some way to incorporate the Wikipedia type approach to cataloguing the Rules of Thumb? Maybe even include a snippet that speculates about why a particular strategy seems to work.

Anyhoo, here are two response from an earlier thread that kind of struck me:

-SWS said:
Drbandage, these questions you pose have no clear empirical or probability-based answers among us. To my knowledge there are bits-and-pieces and little hints regarding this topic scattered about the medical literature and among thousands of patient message-board anecdotes. We know that purely obstructive etiology is believed to be more prevalent than purely central etiology. We also know that 8cm and 10 cm pressure barriers have been mentioned in patent-related medical literature regarding statistical relevance, by the way of pressure-induction of central events. We also know that patients and clinicians very often encounter what we like to refer to as an AHI "sweet spot" relative to a 4-to-20cm pressure spectrum. We thus might presume that "sweet spot" is the convergence of at least two etiologies or physiologic mechanisms that interact in a diametrically opposed manner, with respect to high and low pressures.

Drbandage, I would like to revisit this thread and speculate with you, when I return from vacation in a couple/few weeks.


Snoredog said:

But we as patients can only share our own experiences through trial and error. As a result, there is a general rule of thumb some of us patients use(ed. note: bold print is my emphasis); if the event is obstructive pressure should reduce the frequency of events seen. If the frequency of those events increase with pressure then the event is more likely central vs. being obstructive.

So, I am going to ask anyone, I mean anyone, if they have any Rules of Thumb that they use (and let's not require that the evidence be any more than "I have found") in tweaking the Black Box.

For that matter, feel free to mention anything that may even resemble a Rule of Thumb that applies to anything xPAP (e.g. masks, DME, sleep studies, etc.) Impossibly broad, I know, but I just would like to not have to think outside the box. Therefore, I am endeavoring to make the box walls very flimsy and full of holes. Could be fun and educative.

The biggest issue I see with rules of thumb is that there are just SO many variables.

For instance:
Central/Mixed events.
Which part of anatomy is causing the problem.
What machine they're using. (if any)
What mask they're using. (if any)
Weight/neck size

etc etc.

The rules of thumb are different for every individual based on those factors. While upping the pressure may decrease my AHI, it'll surely raise someone else's.

Perhaps if we had a questionaire of sorts that went though:

Are central events mentioned on your sleep study?
Yes
No
Not Sure.

At the end we could then display a somewhat tailored list of rules of thumb that could be helpful. Of course then we also have to keep the lawyers happy and make sure that nobody thinks we're telling people to change their pressures, etc.

I'd be happy to donate a wiki (I just set one up last night). Perhaps cpap.com would like to integrate the final product into the almighty light bulb?

I agree with blarg,

There are to many verialbles AND it is an individual thing.

I like the idea of a data base of what has worked in the pass. My fear would be someone who reads the advice, keep increasing your pressure until you get no more events. Will with Centrals, the more you increase the pressure the more centrals you will get, in some individuals.

Why this caustion of increasing the pressure like you said, may just start the centrals, because it happened to me.

Since bi-level machines have so many variables, A place with information on how the different settings effect the outcome would be an intresting thing to see.

I also agree, increasing the pressure like you said, may just start the centrals.

Blarg, Congrats on submitting a piece.

blarg wrote:The biggest issue I see with rules of thumb is that there are just SO many variables.

For instance:
Central/Mixed events.
Which part of anatomy is causing the problem.
What machine they're using. (if any)
What mask they're using. (if any)
Weight/neck size

etc etc.

The rules of thumb are different for every individual based on those factors. While upping the pressure may decrease my AHI, it'll surely raise someone else's.

Perhaps if we had a questionaire of sorts that went though:

Are central events mentioned on your sleep study?
Yes
No
Not Sure.

At the end we could then display a somewhat tailored list of rules of thumb that could be helpful. Of course then we also have to keep the lawyers happy and make sure that nobody thinks we're telling people to change their pressures, etc.

I'd be happy to donate a wiki (I just set one up last night). Perhaps cpap.com would like to integrate the final product into the almighty light bulb?

SelfSeeker wrote:I agree with blarg,

I like the idea of a data base of what has worked in the pass.

Yes, that's what I have in mind.

My fear would be someone who reads the advice, keep increasing your pressure until you get no more events.

Without question, all the usual disclaimers and cautions would have to accompany this.

Will with Centrals, the more you increase the pressure the more centrals you will get, in some individuals.

I think we just have our first Rule of Thumb!!
Thanks, SelfSeeker.

Since bi-level machines have so many variables, A place with information on how the different settings effect the outcome would be an intresting thing to see.

Yep.

I also agree, increasing the pressure like you said, may just start the centrals.

Yep, there's a ROT, but it is pretty similar to your first one.

Thanks for the contributions, Blarg and SelfSeeker.