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[Treatment] Shouldn't the goal of PAP treatment be to minimize Obstructive Apnea?
#21
(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. Smile

You're welcome.

You also wrote elsewhere, in the Clear Airway Definition thread, that
Quote:
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. like i said, its splitting hairs because they go up and down together. 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. all of the programs and all of the doctors are not wrong. 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.
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#22
(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. Smile

You're welcome.

You also wrote elsewhere, in the Clear Airway Definition thread, that
Quote:
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.

My age is none of my mind's business. --- Netskier
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#23
I agree with your point on AHI, at least when interpreting data from a home PAP machine. With the additional data available during a sleep study such as the EEG and pulse oximetry, things may differ, but I don't know enough specifics of all the sleep study data as a whole to form that opinion entirely yet.

I did come to a similar conclusion about not relying on the full AHI readings after reviewing the first six weeks of my own data. I only look at the hypopnea and obstructive counts when judging the efficacy of my own treatment. If I saw a large increase in CA events compared to what I believe my baseline to be, which is fairly low in total even though it's about half my AHI, then I would investigate further.

My AHI tends to be about 2.5 at my current PAP settings, and about half are CAs. I do believe the CA events increase with higher pressures as the article stated, because in going from a pressure of 9 to my current 12, my CA events at least doubled while my OA events went down to nearly zero.
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#24
(03-23-2012, 06:15 PM)shanzlik Wrote: I agree with your point on AHI, at least when interpreting data from a home PAP machine. With the additional data available during a sleep study such as the EEG and pulse oximetry, things may differ, but I don't know enough specifics of all the sleep study data as a whole to form that opinion entirely yet.

I did come to a similar conclusion about not relying on the full AHI readings after reviewing the first six weeks of my own data. I only look at the hypopnea and obstructive counts when judging the efficacy of my own treatment. If I saw a large increase in CA events compared to what I believe my baseline to be, which is fairly low in total even though it's about half my AHI, then I would investigate further.

Thanks. I am glad someone agrees with me.

Quote:My AHI tends to be about 2.5 at my current PAP settings, and about half are CAs. I do believe the CA events increase with higher pressures as the article stated, because in going from a pressure of 9 to my current 12, my CA events at least doubled while my OA events went down to nearly zero.

Thanks for the corroboration. You confirmed my prediction.
My age is none of my mind's business. --- Netskier
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#25
(03-22-2012, 02:44 PM)Netskier Wrote:
(03-22-2012, 08:23 AM)TheDreamer Wrote: I've tried a regular pulse oximeter a couple of times....gets really annoying when the alarm goes off because I momentarily dropped below 80%.

The Dreamer.

Did the alarm ever go off from either hypopneas or clear airway events, or just from Obstructive Events?

Well, can't say for certain....because I eyeballing between the cpap graph and the pulse oximeter graph...but.

In the first time, there was a drop below 80% that seems to coincide with an OA event recorded by my CPAP.

And, in the second time...there is a drop below 80%...that falls in the vincinity of several H events.

Back when I was doing this experiment...I was on a Respironics M-Series Pro for CPAP, and using a Contec CMS-50F.

I haven't decided if I'll seek out a pulse oximeter that'll connect to my new autocpap....

The Dreamer
You may be a dreamer, but I'm The Dreamer, the definite article you might say!
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