Questions I asked at ASAA Lecture

What Rappaport described about BiLevel titration is precisely what I posted here a couple times: that EPAP must all too often be a CPAP-equivalent pressure to maintain a patent airway. I had gleaned those titration details from reading quite a few sleep tech posts on binarysleep.com. Yet, that contrasting BiLevel titration method that Titrator posted is also a real world method that obviously happens quite a bit.

Those two contrasting BiLevel titration methods just exemplify the state of sleep medicine in my opinion. Sleep medicine is still in its infancy. Among the world's best sleep practitioners and researchers there are still very many contrasting methods and opinions that have yet to achieve consensus opinion. Other examples: try researching the best way to titrate or otherwise treat central apneas or what the underlying failing airway mechanism for UARS happens to be. The varied professional opinions will make your head spin!

Just because Dr. Rappaport expressed his own personal view of BiLevel titration does not mean that there aren't plenty of well qualified practitioners and researchers out there with directly opposing views and methods. My own views of necessary BiLevel titration ran along the lines of what Rappaport expressed. However, I know for a fact that there are plenty out there doing it exactly the way Titrator was trained. The jury's still out in the sleep community regarding best standard medical practices in my opinion.

SWS,

I sure don't understand the highly technical stuff. But it was apparent to me that Rapoport also professed caution in drawing conclusions on much of the research and studies, saying there was so much to research and sleep apnea is complicated science. But Rapoport also has a vested interest, even though he's quite the expert in his field. His patents and treatment driven research may or may not resolve these riddles, and I suspect the technology will improve faster than the understanding of the science. But what do I know?

-SWS,

The question is, regardless of the expert opinions, WHAT WORKS?

Wouldn't we all like to know.

I believe (if I remember correctly) that Rapoport mentioned some up and coming technology or new type of machine (some new patent, no doubt). I wonder what he was referring to?

LDuyer wrote: But Rapoport also has a vested interest, even though he's quite the expert in his field. His patents and treatment driven research may or may not resolve these riddles...

Good point, Linda. I don't think any of his research and patent work is leveraged toward BiLevel therapy.

LDuyer wrote: ... I suspect the technology will improve faster than the understanding of the science.

Certainly faster than our understanding, Linda! I kind of suspect the bulk of technological sleep-science advancements will be driven by the understanding of the researchers, practitioners, scientists, and engineers working in the field of sleep medicine. My lay person's understanding of medicine in general is that sometimes extremely efficacious treatment(s) are derived before clinical etiology is fully understood.

Wader, your question nailed it in my opinion! My hunch is that there are some patients for whom the Rappaport method works best, and there are other patients for whom the method Titrator was taught works best. At what point through expiration or well into inspiration does any given patient's heavy apneas began to manifest?

You or Mike or somebody also raised the good point about sometimes achieving compliance at a slightly lower pressure is much better than a patient abandoning PAP therapy altogether. I think this kind of interpretive decision making is precisely what exemplifies the art of medicne versus the science.

Like I always say, Follow the money $$$$$$$$$$$$$$$$$

-SWS wrote: ..... Certainly faster than our understanding, Linda! I kind of suspect the bulk of technological sleep-science advancements will be driven by the understanding of the researchers, practitioners, scientists, and engineers working in the field of sleep medicine. My lay person's understanding of medicine in general is that sometimes extremely efficacious treatment(s) are derived before clinical etiology is fully understood.

Alright. That did it!
I'm pretty sure I understand what you said.
But gosh darn it, words like "efficacious" and "etiology" once again have me scurrying off to a dictionary. Dear god, before meeting you, I hadn't set foot near a dictionary in years. Now, every day, a new trip to my trusty dictionary. "Efficacious" I sort of understand. "Etiology," well........ I'm off to rifle through the "e's."


Linda

chrisp wrote:Like I always say, Follow the money $$$$$$$$$$$$$$$$$

Funny, Rapoport sort of said that too.
He said the only way to affect change is to work with the dreaded manufacturers. But then, he would say that, wouldn't he, having patents and all. Gosh, hope he's not watching!!
He was pretty charming, though.

Not trying to be argumentative here, but as I understand it, bi-level titration has to be thought of as two totally separate phases. If what some people and Dr. Rappoport call "titration" is aimed only at preventing obstructive apneas, and that is accomplished at a pressure of 10, then yes, that person's "titrated pressure is 10". However, just preventing full apneas and not bothering to prevent other things like hypopneas is not my idea of the definition of a titration for any kind of machine, bi-level, straight cpap, or autopap.

If the goal of titration is to also prevent other events - the hypopneas, flow limitations and snores - you can't stop titrating the bi-level at the 10 that keeps the throat open enough to prevent ONLY the obstructive apneas. You have to keep inching the pressure on upward until you accomplish the goal of keeping the throat clear of the other partially obstructive events also.

As I understand it, the "other events" (hypopneas, limited flows, and snores) require MORE pressure to prevent than it takes to prevent full obstructions - apneas.

Opening a closed throat a little bit puts a stop to it being an obstructive apnea. But it still leaves the throat partially closed...still leaves an hypopnea or limited flow situation which still needs to be addressed. Addressed with MORE pressure to clear the hypopnea event too by fully opening the throat.

Thus the bi-level titration arrives first at the pressure of 10 to open the throat just enough to prevent fullblown apneas. 10 is set as the lower pressure - the Exhalation pressure. But another pressure to keep the throat even more fully open to prevent other events HAS to be set too. Those other events normally require higher pressures. Say it takes 17 to keep hypopneas, limited flows and snores at bay. That higher pressure of 17 then becomes the Inhalation pressure.

If that same patient were simply being titrated for straight CPAP instead of for bi-level treatment, that same patient's single CPAP pressure would be 17, because it takes 17 to keep the throat open enough to ward off ALL events - not just the obstructive apneas.

If that's so, then bi-levels are not having a few unnecessary points thrown on top for no reason. They are not having an arbitrary "higher pressure for inhaling" added on top just to give a contrast so the patient will "feel" like the exhalation pressure is less.

That higher inhalation pressure is there for an important treatment reason - to clear the hypopneas, limited flows, and snores. The lower exhalation pressure is also there for a treatment reason - to prevent total closure, as in an apnea.

Thus, the higher Inhalation pressure is indeed the "titrated" pressure (exactly the same as if the patient had gone in for straight CPAP titration.) The lower Exhalation pressure that clears only the pure obstructive apneas in a bi-level titration, would not be considered the full "titrated" pressure at all in a straight cpap titration.

Two more cents thrown in, even if it doesn't make "sense".

P.S. I do agree that if a lower "not-effective-enough-to-prevent-EVERYTHING" pressure is what it takes to keep a patient going who would otherwise simply quit - yes, use a lower pressure. Whatever it takes to keep them getting at least some treatment.

If what some people and Dr. Rappoport call "titration" is aimed only at preventing obstructive apneas, and that is accomplished at a pressure of 10, then yes, that person's "titrated pressure is 10". However, just preventing full apneas and not bothering to prevent other things like hypopneas is not my idea of the definition of a titration for any kind of machine, bi-level, straight cpap, or autopap.

As I understand it, the "other events" (hypopneas, limited flows, and snores) require MORE pressure to prevent than it takes to prevent full obstructions - apneas.

RG, I beg to differ on that one. In physics it does not take more pressure to eliminate lesser obstructions than total obstructions (unless we change names or labels on those complete obstructions at some midpoint during the correction process---calling any given "apnea" a "hypopnea" once it has reached only partial correction).

Rather, it takes more pressure to turn a completely closed apneic obstruction into a fully open and event free (thus fully corrected) airway than it does to either: a) turn a complete apneic obstruction into a partially corrected airway (thus leaving that event as a residual hypopnea and/or snore), or b) turn an inherent or primary hypopnea or snore into a fully open and event free airway. That is assuming like for like obstructive points in the airway with otherwise identical physical characteristics.

Can you picture many a sleep technician raising pressure on complete apneas until some of those are only partially corrected sleep events? They would see those partially corrected apneas as hypopneas and snores and thus erroneously generalize that it takes more pressure to correct obstructive hypopneas and snore than apneas. Given identical failing airway mechanics, in physics it will always take more pressure to correct a fully closed airway than a partially closed airway. It's the erroneous perception of any sleep tech who observes partially corrected apneas as hypopneas and states: "it takes more pressure to correct hypopneas and snore than it does apneas".

The less confusing statement in my opinion: "It takes more pressure to completely correct an obstructive apnea than it does to turn that same apnea into an obstructive hypopnea and/or snore."

I can go along with that statement, SWS. I like that one.

The less confusing statement in my opinion: "It takes more pressure to completely correct an obstructive apnea than it does to turn that same apnea into an obstructive hypopnea and/or snore."

I'll stop switching horses in midstream by re-labeling events. I know I said I wouldn't do that again, but I did, didn't I?

With your better statement in mind, are we still not saying that the highest pressure needed in a bi-level titration to "completely correct an obstructive apnea" (or in other words, to hold the throat completely, not just partially, open) is indeed the same high single pressure number, if it were a simple CPAP titration?

The higher pressure number for IPAP (Inhalation) in a bi-level titration is not just a few pressure points thrown on top for no other reason than to make the EPAP (exhalation pressure) fool the patient into thinking it "ah, that feels better", is it?

Ditto Linda


Donna in LA,who really understands the words,but had to read the post twice. Gets my brain to working.Thats a good thing!!!!

I guess I'm cpaptalk.com challenged.I still don't know how to enter a quote.
I've had help from very helpful people,but I still don't
"get it". I just gave up.

We've gotten caught up in this debate before. I think RG and -SWS are both right and here is why.

For this explanation let's just drop the definitions of "Apnea" and "Hypopnia"

The key question: Is the goal to open a closed airway only enough to begin the air flow (partially open), or open it to it's full capacity.

If the goal is to open just enough to begin the air flow, then during each "event" the patient is left in a state of hypopnia. In terms of "event" data collection this state of hypopnia is scored as part of an apnea event. In terms of the analysis of SBD, this state of hypopnia is just that, Hypopnia.

So, as I said you are both right.

Wader, I think you just jumped onto the horse that I got off of.

But yes, a lot of it is a matter of semantics and definitions. I got wet in midstream, but the drooling I'm doing is over SWS's perfect sentence:

"It takes more pressure to completely correct an obstructive apnea than it does to turn that same apnea into an obstructive hypopnea and/or snore."

Physics is physics. A = A. I think Aristotle was a distant ancestor of SWS. I mean that as a very big compliment.