(03-23-2012 04:47 PM)greatunclebill Wrote:
(03-23-2012 04:25 PM)Netskier Wrote:
(03-23-2012 03:49 PM)SuperSleeper Wrote: Thanks Netskier... good thought-provoking info.. I'll have to digest this when I get more time.. might have some more questions for you too, if that's okay.
You also wrote elsewhere, in the Clear Airway Definition thread, that
But in CPAP therapy, for better or worse, sleep apnea severity and effectiveness is generally measured in AHI, and increasing pressures to combat obstructive events, even though it may slightly raise clear airway events, still can cause a net decrease in the overall AHI. For each individual, (on constant-pressure CPAP) there is a "sweet spot", or best range of pressures (for autos) that will result in the lowest AHI levels, while still maintaining clear airway events within an "acceptable" range.
My point is that it is worse, not better, to measure efficacy of PAP therapy with the AHI, and that it would be better to measure PAP efficacy with an "Obstructive Index" which would simply sum OSA and Hypopneas. Ideally one would want to combine this Obstructive Index with both blood pressure and blood oxygenation. It would be better to minimize the Obstructive Index than the AHI, up to the point where central events begin to decrease the partial pressure of oxygen.
Quote: That is why making small, incremental adjustments to pressure over time, noting the effects on AHI (and looking at obstructive and 'central' events also) can result in lowering AHI levels. It's basic scientific analysis.
This approach is ok, but could be improved by using the Obstructive Index instead of the AHI.
so if the goal is get the oa to zero and don't worry about ahi so much i don't buy it and most professionals don't or we wouldn't even have an ahi index in all of the programs we use and the sleep labs use.
I am a professional with a Ph.D. in Physiological Psychology, and I don't buy it. Professionals disagree with each other all of the time. In fact, we consider it our duty to speak out when we think we see an error, or an unclear conceptualization. We call it work.
The fact that we have an AHI now, and that we use it, simply means that this is the current state of the medical art. I believe that we can improve it, and that is one point of my post.
Quote:like i said, its splitting hairs because they go up and down together.
No, it is not splitting hairs, because they do not go up and down together. Increasing pressure will decrease the Obstructive Index and the AHI, until the pressure increase begins to either increase central apneas, or increase artifactual apneas by increasing leakage, at which either
point the AHI begins increasing while the Obstructive Index does not increase. Here, the two curves diverge. So the PAP-pressure-to-AHI relationship is not linear, nor even monotonic, but rather is a U-shaped function.
Quote:nobody has shown me yet how you target oa and not affect ahi. ahi will always be my goal and the oa will follow with it until the industry changes and it comes out of the programs or downplays it.
I have just shown you how increasing pressure first decreases both the Obstructive Index and AHI, and then begins to increase the AHI but not the Obstructive Index.
Quote:all of the programs and all of the doctors are not wrong.
I have just shown you that they appear to be wrong.
Quote: this debate is like distilled vs tap. it will never end so you concentrate on oa and i'll concentrate on ahi and we'll all meet at the bottom of the scale.
Good health to us all.