CPAPtalk.com

billbolton wrote: It seems to me it lies largely in your lack of understanding of what any xPAP machine is capable of scoring solely from air flow analysis, which is the only basic mechanism available for a flow generator (there is a huge amount of discussion about that topic here too). Newer models, like the S9, usually have much better ways of analysing air flow than older models.

A PSG scores AHI on the basis of a wide range of different and concurrent factors/approaches, so your lack of PSG data as your baseline for understanding what any xPAP does is definitely not going to help!

Well, when I was doing research years ago - we always said if it looks like BS, smells like BS, then it is BS. It really is that simple. The fact is that each manufacturer has developed its own unique "wheel", but in reality there is only one to be invented. Unless these companies talk about what their machines really do - we are buying the ultimate black boxes - and all this software mediated "self-empowerment" is a video game.

This is complicated by the fact that without a sleep lab or equivalent in equipment, you cannot even tell if your machine is performing as it says it is. Even then, with different definitions of what these things - i.e. - what events really are - we have no idea of how to determine what is right and what is wrong. And I still keep going back to the surveys here where a good percentage of people still don't fell better. That speaks volumes! It also makes me really wonder what we are doing sometimes when we look at our data.

For instance, why do I see my Respironics APAP to bring my AHI down close to 0? I find that hard to believe. Am I lucky, or is the machine making a fool of me?

jonquiljo wrote:The fact is that each manufacturer has developed its own unique "wheel", but in reality there is only one to be invented.

SInce there is no "one size fits all" wheel, and since antiquity there have been a wide range of wheels to fit many different needs, your analogy here is quite obscure.

jonquiljo wrote:....we have no idea of how to determine what is right and what is wrong.

There are lot of xPAP users here who basically have no real trouble figuring out what is works (i.e. right for them) and doesn't work (i.e., wrong for them) in their treatment based on the TREND information they download from their flow generators, so its evidently not anywhere near as difficult as you seem to want to make it out to be.

jonquiljo wrote:And I still keep going back to the surveys here where a good percentage of people still don't fell better.

xPAP treatment is not now, and is unlikely ever to be, any sort of silver bullet that will kill all Sleep Disordered Breathing problems, let alone all the other possible concurrent conditions which can disturb sleep.

Additionally, the flow generator is not the only componeent in an xPAP siolution, and it is abudently clear from even a cursory look a the message traffic here on CPAPtalk that new users have overwhelmingly more problems with masks than any aspect of flow generators.

jonquiljo wrote:That speaks volumes!

Only for the fact that a good percentage of people (whatever that really means) probably have issues that xPAP can never address in isolation.

jonquiljo wrote:It also makes me really wonder what we are doing sometimes when we look at our data.

I'm looking for trends and finding very useful information, but you seem to be looking for reference absolutes and so are bound to be disappointed.

Cheers,

Bill

billbolton wrote: I'm looking for trends and finding very useful information, but you seem to be looking for reference absolutes and so are bound to be disappointed.

You seem so quick to want to disagree.

Well, whether you agree with what I say or not, the bottom line is that each one of these XPAP machines or "flow generators" is quite likely feeding us information based on a totally differing set of criteria. Apneas, hypopneas, etc. - all have different definitions depending on the manufacturer. I'm not looking for "reference absolutes", but rather looking for some agreement among manufacturers as to what events they are trying to prevent. If not, then there is total chaos being reported to the end user and physician - and that is absolute nonsense, even for the medical world!

Looking for "trends" in phenomena means that the events being examined have some resemblance to each other. If you use a Resmed machine and see totally different information than what you see when using a Respironics machine then you are chasing "sleep fiction." Frankly, all you have to do is invent a XPAP machine that uses different criteria for sleep events and you can perhaps lower someone's AHI based on the definitions alone. I see no real meaning in that or trends. Now the medical community seems to have decided that an AHI over 5 defines sleep apnea. But that means you have to agree what an AI and an HI mean - or that definitions is meaningless.

If so, we were better off in the days when there were no reporting capabilities at all. At least we weren't being led astray by one machine that scored events at its pleasure vs. another doing the same thing with different definitions for what it is to score. It's like someone telling their sex partner that they are "so good" in bed! Pretty subjective, huh? I wouldn't go looking for any trends because you won't find anything you can truly believe in. These are not "silver bullets", they are tools. And they are all calibrated differently if you want to even believe they are calibrated at all.

All kidding aside, its not like anyone can't feasibly come to some agreement with how these machines score events. They don't want to! As long as we are kept in the dark we will run around thinking we know what is going on while we sleep, but we really don't know a thing. They don't sell these machines saying they are incredibly subjective and need to be taken for trend data only - they sell them as reporting reality - and many people are believing them. Sorry but I am shocked by the simple yet elegant comparison reported by the original poster. It certainly gives one cause to think if we are all being led to believe in data a little too much.

jonquiljo wrote:You seem so quick to want to disagree.

Mea culpa for getting sucked into feeding the bears

billbolton wrote:

DHC wrote:it is not yet clear to me how ResMed calculates their published AHI. Do you know ?

The same way everyone else does AI+HI = AHI

DHC wrote:I find it curious, at least, that so few people have provided any definitive information about ResMed's algorithms.

There are numerous lengthy threads here that have discussed the various scoring algorithms from the various vendors in great detail... you need to do some work with the search facility.

DHC wrote:So where does the disparity lie?

It seems to me it lies largely in your lack of understanding of what any xPAP machine is capable of scoring solely from air flow analysis, which is the only basic mechanism available for a flow generator (there is a huge amount of discussion about that topic here too). Newer models, like the S9, usually have much better ways of analysing air flow than older models.

A PSG scores AHI on the basis of a wide range of different and concurrent factors/approaches, so your lack of PSG data as your baseline for understanding what any xPAP does is definitely not going to help!

Cheers,

Bill

Bill,

You must be right. I guess the reasons for the apparent disparity in the values of reported AHI between the S9 and the IntelliPAP are: (a) I did not have a "full Polysomnography" and am therefore "chasing shadows" and (b) my "lack of understanding of what any xPAP machine is capable of" and (c) I "need to do some more work with the search facility." Thank you for the insights.

Take care y'all.

billbolton wrote: Mea culpa for getting sucked into feeding the bears

I haven't the good grace that DHC has shown with you - so ... You aren't feeding the bears as much as you are slinging the shit.

I trained to get a PhD for 11 years, and worked as a molecular biologist for several more - and never once saw anyone who ever did anything notable that made such a big deal about insisting they were right all of the time. I had the privilege of working with many people who had become or were to become Nobel laureates. The one thing most of them had in common was that they were totally open to other's way of thinking. In short: they had humility and grace. You might have learned a few things even from having a few drinks with these people over dinner. Granted, I was never in that class of scientist - but I never pretended to be. I don't talk about this time in my life much - as it was more personally eye opening rather than anything to be proud of.

You obviously have a quick mind. Why not use it in a cooperative way? Or is is Bill's way or the highway? You remind me of our president. He slings the shit too! (sorry, no politics!) Sorry, I went over your last dozen posts or so - and it seems to me from the prevailing attitude that perhaps your XPAP hose is plugged into the wrong place.

If only we had an expert on this sort of thing.

All data has limited usefulness. Good scientists know that. (Even a few "Nobel laureates." ) That doesn't make the data useless to a good scientist aware of the data's limits. Being aware of the limits (the method of collection, how it compares to other data, what others have and have not been able to accomplish using it) makes the data more valuable, not less so. That is science 101.

So if I assume the data is something that it is not, that is MY fault, as I see it, not the fault of the providers of the data, who are mostly transparent when it comes to how the data is collected and why.

And I appreciate others' pointing out to me the limits of the data my machine provides and how it is best used to optimize my therapy, as far as choosing a pressure, or range of pressures, for normalizing my breathing to the extent possible using airway pressure provided by a particular machine at a particular time in my life.

ps-Bill talks a little too rough for my tastes at times, too, but I find, in my experience, that he often makes very good points that are useful to me.

billbolton wrote: There are lot of xPAP users here who basically have no real trouble figuring out what is works (i.e. right for them) and doesn't work (i.e., wrong for them) in their treatment based on the TREND information they download from their flow generators, so its evidently not anywhere near as difficult as you seem to want to make it out to be.
Cheers,

Bill

Well said.
I still think that the Mseries set to auto w/software is the
best machine to use to self titrate.....but that may be because
it was the machine I had at my disposal at the time.
I was also in hyper-educational mode at the time.

If trend data is observed and some common sense added to it,
and a realization of how one is feeling,
any machine data could be used to optimize therapy.

It's not de lure of de machine,
that calls to me.....
it's not the glow of baubles and beads,
that beckon to me....

On the edge of the desperate, black inky night, it lurks,
it's the burning eyes of the beast....

it's de lure of sleep.

Having recently upgraded to the S9 AutoSet, this thread has peaked my interest.

The original hypothesis from DMC would be: "The S9 under-reports events"

DHC wrote:Using both the IntelliPAP AutoAdjust and the S9 AutoSet for a while now, and alternating usage to get an idea of the differences between machines and reports.....
....
A while back I watched the excellent DeVilbiss tutorials on their process for identifying and responding to events. It inspired confidence that DeVilbiss has it 'right' - which makes me concerned that ResScan is UNDER-reporting events.

Any thoughts on how to determine which of the two (or neither) are accurate?

There is lots of good info in the subsequent posts. IMO, the suggestion made by JDM2857 towards elimining one source of variability by setting the machines to CPAP mode is a key suggestion.

...To include a bit more info in this thread. Below is a link to a ResMed white paper on the S9 algorithm.

http://www.resmed.com/us/assets/documen ... -paper.pdf

"

jonquiljo wrote: Well, whether you agree with what I say or not, the bottom line is that each one of these XPAP machines or "flow generators" is quite likely feeding us information based on a totally differing set of criteria. Apneas, hypopneas, etc. - all have different definitions depending on the manufacturer.

They have differen operational definitions, because none of them can measure beathing the way it can be measured in the lab.

I'm not looking for "reference absolutes", but rather looking for some agreement among manufacturers as to what events they are trying to prevent. If not, then there is total chaos being reported to the end user and physician - and that is absolute nonsense, even for the medical world!

They are trying to prevent breathing disruptions, and have different way of concluding a breathing disruption ouccured.

Looking for "trends" in phenomena means that the events being examined have some resemblance to each other. If you use a Resmed machine and see totally different information than what you see when using a Respironics machine then you are chasing "sleep fiction."

The trends I use as an APAP user are between the nights of a single machine, as I am sure it true for Bill, and jnk, and the majority of people who use a machine's reported data to get that machine to give them the most effective therapy. Having experienced 4 different autos, I can tell you they work differenty. Of the 4 there were two I whose way of delivering air was intolerable to me. The two others give me informative trends about my breathing events, and I used each machine's trends to improve the therapy each machine gave me.

Frankly, all you have to do is invent a XPAP machine that uses different criteria for sleep events and you can perhaps lower someone's AHI based on the definitions alone. I see no real meaning in that or trends. Now the medical community seems to have decided that an AHI over 5 defines sleep apnea. But that means you have to agree what an AI and an HI mean - or that definitions is meaningless.

You seem to confuse the event definitions used by the medical community, and the operational definitions used by APAP makers. I pity you for being incapable of seeing meaning in the data you gather from your machine, since it means a. you wasted money on data capable machine b. you feel cheated c. you do not have the tools youi need help you improve your therapy should the need arise -- a very unhappy and frustrating state of affairs for a person to be in.

All kidding aside, its not like anyone can't feasibly come to some agreement with how these machines score events.

Agreement? It is either published or it is not. If it is published, you either trust it or you do not. Agreement does not come into it at all.

As long as we are kept in the dark we will run around thinking we know what is going on while we sleep, but we really don't know a thing.

There are no so blind as those who will not see. You and DHC have just been told by Bill Bolton that searching this forum will give you many links to how the machines collect their data and how they score it. You can also use google scholar, and google patents. Instead of searching and reading and learning you both perfer to remain in the dark caused by your psuedo scientific doubt casting. Casting doubts is a great way of giving youself a sense of superiority. Unlike learning new things -- which makes you face how little you understand and know.

They don't sell these machines saying they are incredibly subjective and need to be taken for trend data only - they sell them as reporting reality -

There are studies showing how the machines' reporting correlates with the analysis made of the same data, by experienced sleep techs in sleep labs. Look for them.
If you think a company can simply say "my machine get's lower AHI" to beat the market, think again: Their competitors will take the machines to a sleep lab, and show how valid the statements are. As a matter of fact, I'm sure they've all done that with each other's machines already.

Sorry but I am shocked by the simple yet elegant comparison reported by the original poster.

I am shocked at the way both you the, scientist (? did yoiu ever get that PhD you studied for?) and the original poster ignore the fact that the dependent variable (AHI) is one achieved by 2 different machines, at different pressure levels. The "simple and elegant comparison" you admire confounds 2 independent variables. A no no every budding scientist learns to avoid when he or she is in his or her educational diapers.

Speaking of Nobel Laureates -- may I recommend "Opening Pandora's Box: A Sociological Analysis of Scientists' Discourse "?

The book can be dowloaded in pdf's in this site: http://www.surrey.ac.uk/sociology/peopl ... as_box.htm (the HTML links dont' work).

Although in this book we aim to obtain general conclusions about scientific discourse, most of
the data we shall be drawing upon come from the interviews that we carried out with scientists
working on bioenergetics, and from their research papers and other literary products.

jnk wrote:All data has limited usefulness. Good scientists know that. (Even a few "Nobel laureates." ) That doesn't make the data useless to a good scientist aware of the data's limits. Being aware of the limits (the method of collection, how it compares to other data, what others have and have not been able to accomplish using it) makes the data more valuable, not less so. That is science 101.

So if I assume the data is something that it is not, that is MY fault, as I see it, not the fault of the providers of the data, who are mostly transparent when it comes to how the data is collected and why.

And I appreciate others' pointing out to me the limits of the data my machine provides and how it is best used to optimize my therapy, as far as choosing a pressure, or range of pressures, for normalizing my breathing to the extent possible using airway pressure provided by a particular machine at a particular time in my life.

ps-Bill talks a little too rough for my tastes at times, too, but I find, in my experience, that he often makes very good points that are useful to me.

>>Bill talks a little too rough for my tastes at times, too, but I find, in my experience, that he often makes very good points that are useful to me.<<

Actually, Bill talks out of his a$$ - in this case essentially accusing me of being both lazy and stupid. Notably, his posts - in this topic at least - demonstrate a dearth of substantive information. Whether he possesses substantive (helpful) information remains to be seen. It has not been evident in this topic.

ozij wrote:"

jonquiljo wrote: Well, whether you agree with what I say or not, the bottom line is that each one of these XPAP machines or "flow generators" is quite likely feeding us information based on a totally differing set of criteria. Apneas, hypopneas, etc. - all have different definitions depending on the manufacturer.

They have differen operational definitions, because none of them can measure beathing the way it can be measured in the lab.

I'm not looking for "reference absolutes", but rather looking for some agreement among manufacturers as to what events they are trying to prevent. If not, then there is total chaos being reported to the end user and physician - and that is absolute nonsense, even for the medical world!

They are trying to prevent breathing disruptions, and have different way of concluding a breathing disruption ouccured.

Looking for "trends" in phenomena means that the events being examined have some resemblance to each other. If you use a Resmed machine and see totally different information than what you see when using a Respironics machine then you are chasing "sleep fiction."

The trends I use as an APAP user are between the nights of a single machine, as I am sure it true for Bill, and jnk, and the majority of people who use a machine's reported data to get that machine to give them the most effective therapy. Having experienced 4 different autos, I can tell you they work differenty. Of the 4 there were two I whose way of delivering air was intolerable to me. The two others give me informative trends about my breathing events, and I used each machine's trends to improve the therapy each machine gave me.

Frankly, all you have to do is invent a XPAP machine that uses different criteria for sleep events and you can perhaps lower someone's AHI based on the definitions alone. I see no real meaning in that or trends. Now the medical community seems to have decided that an AHI over 5 defines sleep apnea. But that means you have to agree what an AI and an HI mean - or that definitions is meaningless.

You seem to confuse the event definitions used by the medical community, and the operational definitions used by APAP makers. I pity you for being incapable of seeing meaning in the data you gather from your machine, since it means a. you wasted money on data capable machine b. you feel cheated c. you do not have the tools youi need help you improve your therapy should the need arise -- a very unhappy and frustrating state of affairs for a person to be in.

All kidding aside, its not like anyone can't feasibly come to some agreement with how these machines score events.

Agreement? It is either published or it is not. If it is published, you either trust it or you do not. Agreement does not come into it at all.

As long as we are kept in the dark we will run around thinking we know what is going on while we sleep, but we really don't know a thing.

There are no so blind as those who will not see. You and DHC have just been told by Bill Bolton that searching this forum will give you many links to how the machines collect their data and how they score it. You can also use google scholar, and google patents. Instead of searching and reading and learning you both perfer to remain in the dark caused by your psuedo scientific doubt casting. Casting doubts is a great way of giving youself a sense of superiority. Unlike learning new things -- which makes you face how little you understand and know.

They don't sell these machines saying they are incredibly subjective and need to be taken for trend data only - they sell them as reporting reality -

There are studies showing how the machines' reporting correlates with the analysis made of the same data, by experienced sleep techs in sleep labs. Look for them.
If you think a company can simply say "my machine get's lower AHI" to beat the market, think again: Their competitors will take the machines to a sleep lab, and show how valid the statements are. As a matter of fact, I'm sure they've all done that with each other's machines already.

Sorry but I am shocked by the simple yet elegant comparison reported by the original poster.

I am shocked at the way both you the, scientist (? did yoiu ever get that PhD you studied for?) and the original poster ignore the fact that the dependent variable (AHI) is one achieved by 2 different machines, at different pressure levels. The "simple and elegant comparison" you admire confounds 2 independent variables. A no no every budding scientist learns to avoid when he or she is in his or her educational diapers.

Speaking of Nobel Laureates -- may I recommend "Opening Pandora's Box: A Sociological Analysis of Scientists' Discourse "?

The book can be dowloaded in pdf's in this site: http://www.surrey.ac.uk/sociology/peopl ... as_box.htm (the HTML links dont' work).

Although in this book we aim to obtain general conclusions about scientific discourse, most of
the data we shall be drawing upon come from the interviews that we carried out with scientists
working on bioenergetics, and from their research papers and other literary products.

>> You and DHC have just been told by Bill Bolton that searching this forum will give you many links to how the machines collect their data and how they score it. You can also use google scholar, and google patents. Instead of searching and reading and learning you both perfer to remain in the dark caused by your psuedo scientific doubt casting. Casting doubts is a great way of giving youself a sense of superiority. Unlike learning new things -- which makes you face how little you understand and know.<<

And yet another allegation of laziness. Ignorance I will accept - and was the reason for posting this topic originally - to relieve the condition. In fact, I have managed to relieve at least some of it - though not enough. The allegation of laziness is clearly incorrect and is made in ignorance by the author (ozij, in this case). HOWEVER - now there is a new allegation - this one assigning the motive of "giving yourself [myself] a sense of superiority."

Addressing this new allegation - I am not the least bit interested in representing myself as "superior" - to anyone, but especially to a forum with participants whom I have never met and have only recently begun to interact with. The allegation is non sequitor - except in the psychological context of projection by the author. As already stated, my question was a sincere one and there was no ulterior motive (such as wishing to be seen as "superior" - where in the heck does THAT come from ).

>>I am shocked at the way both you the, scientist (? did yoiu ever get that PhD you studied for?) and the original poster ignore the fact that the dependent variable (AHI) is one achieved by 2 different machines, at different pressure levels. The "simple and elegant comparison" you admire confounds 2 independent variables.<<

Maybe you missed my comment upthread (here -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd=a#p528340) in which I acknowledged the suggestion to remove the pressure differential from the equation by using both machines in straight CPAP mode at a given pressure. It is at least a misrepresentation that I ignored the input provided - but then again, as I am coming to discover, misrepresentation and/or ad hominem disparagement seem to be the stock-in-trade of at least of few of the forum denizens while engaging in a game of sport to NOT answer the questions posed.

Interestingly, in this topic billbolton addressed the question (it is not yet clear to me how ResMed calculates their published AHI. Do you know ?) with this answer: The same way everyone else does AI+HI = AHI (ref -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528746).

Yet, in the post immediately preceeding that (found here -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528731), ozij wrote:

"Resmed does not change pressure in response to hypopneas. But is scores them. The S8 reports hypopneas prolifically, the S9 seems to report less." and concurred with the conclusion that reported AHI by ResMed is different than reported AHI by DeVilbiss.

Those two answers appear contradictory (and note the word "seems" ozij used in her answer with emphasis - added). The resolution to the contradiction likely lies in the specifics of detecting and scoring AI and HI. Unfortunately, those who MIGHT be able to provide some answers or insights would rather engage in a game of 'sport' to NOT provide it. Anyone want to venture a guess as to why?

Back on topic (and in the context of ignoring inputs) - I'd like to return to the question raised (and ignored) upthread (viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528727) and has to do with USAGE of AHI. Does AHI hold any value to the insurance companies? Does anyone know?

Since the question of trends versus absolutes (in this case, better termed 'standards') arose - my bet is that everyone can appreciate the value in having data so that a person can see, and hopefully improve, their therapeutic benefit using that data over time. In that context, it would be mostly (though not entirely) true that using a machine producing consistent metrics is needed and the absolute values produced for the metric is far less important.

That does NOT abrogate the value of having a standard of reference that ALL manufacturers would apply in their algorithm. And PLEASE do not insinuate (yet again) that I am missing the issues of detection, scoring, analysis and response. I *do* have some level of both understanding and appreciation of the differences - just as I understand there is a difference between results from home use (with only air flow for analysis) versus a lab study. In point of fact, I chose to NOT bring those into the discussion earlier, as I did not want to appear condescending (though that does not seem to bother some others). I merely wanted (and still want) to find answers to what seems a simple question.

Is it not correct there exists an organization with the mission to establish clinical standards for sleep medicine? Does that, or any, professional organization publish any standards for the metrics such as AHI?

Is there really ANY valid argument that a standard for AHI used by all vendors would NOT be valuable?

DHC wrote: Bill talks out of his . . .

Yeah, sometimes. But then again, I don't always talk out of the proper part of my anatomy, either. Sometimes Mr. Grumpy-pants speaks in the old-school forum style of the computer geeks of days gone by. But he still says stuff I find useful on a regular basis.

DHC wrote: . . . another allegation of laziness.

I must have missed that. I assumed ozij was fussing at the other guy, not you, but happened to mention you as one being addressed by Bill.

DHC wrote: . . . Interestingly, in this topic billbolton addressed the question (it is not yet clear to me how ResMed calculates their published AHI. Do you know ?) with this answer: The same way everyone else does AI+HI = AHI (ref -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528746).

Yet, in the post immediately preceeding that (found here -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528731), ozij wrote:

"Resmed does not change pressure in response to hypopneas. But is scores them. The S8 reports hypopneas prolifically, the S9 seems to report less." and concurred with the conclusion that reported AHI by ResMed is different than reported AHI by DeVilbiss.

Those two answers appear contradictory (and note the word "seems" ozij used in her answer with emphasis - added). The resolution to the contradiction likely lies in the specifics of detecting and scoring AI and HI. Unfortunately, those who MIGHT be able to provide some answers or insights would rather engage in a game of 'sport' to NOT provide it. Anyone want to venture a guess as to why?

Velbor's chart was based on info the manufacturers released. Ozij said "seems," I believe, because the criteria for how the S9 scores hypopneas, as far as how a baseline is calculated, haven't, to the best of my knowledge, been so released.

DHC wrote:Back on topic (and in the context of ignoring inputs) - I'd like to return to the question raised (and ignored) upthread (viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528727) and has to do with USAGE of AHI. Does AHI hold any value to the insurance companies? Does anyone know?

Insurance wants proof someone is likely to benefit from treatment. AHI has been chosen as the yardstick. It is an imperfect yardstick, but it prevents the embarrassing circumstance occurring of everyone on the planet getting diagnosed OSA.

DHC wrote: . . . Is it not correct there exists an organization with the mission to establish clinical standards for sleep medicine? Does that, or any, professional organization publish any standards for the metrics such as AHI?

Sleep medicine is relatively new, so there are still questions being settled on how best to define the conditions and the measurements. Not long ago, "hypopnea" had multiple definitions in sleep labs (still true to some extent), and then there is the matter of human interpretation of the squiggly lines. Not every human scorer scores exactly the same way. Thus the need for educating ourselves on the subtleties of such matters. That will take you some time. I am NOT accusing you of being lazy. I AM lazy, though, and it took me a while to "get" some of this stuff. It might not take you as long as it did me, but the answers aren't as simple as many expect them to be.

DHC wrote:Is there really ANY valid argument that a standard for AHI used by all vendors would NOT be valuable?

Yes, that would be valuable. But right now, in the history of sleep medicine, we are at a point where allowing companies and doctors to make money treating sleep is taking a high priority in order to get the subspecialty and the treatments solidly founded. That makes things complicated. But if companies couldn't get patents and make bucks doing what they do, it wouldn't get done, so things have to be a little sloppy right now. Hopefully, it will get cleaned up in a few decades. Meantime, we all do the best we can with how the sleep-related industries go about things.

The above is only my opinion, based mostly on guesswork, and I have no way of proving anything I said. But it was fun to write. Hopefully a line or two may be useful to you. If not, I apologize.

DHC wrote:
Yet, in the post immediately preceeding that (found here -- viewtopic.php?f=1&t=56345&st=0&sk=t&sd= ... 15#p528731), ozij wrote:

"Resmed does not change pressure in response to hypopneas. But is scores them. The S8 reports hypopneas prolifically, the S9 seems to report less." and concurred with the conclusion that reported AHI by ResMed is different than reported AHI by DeVilbiss.

Those two answers appear contradictory (and note the word "seems" ozij used in her answer with emphasis - added). The resolution to the contradiction likely lies in the specifics of detecting and scoring AI and HI. Unfortunately, those who MIGHT be able to provide some answers or insights would rather engage in a game of 'sport' to NOT provide it. Anyone want to venture a guess as to why?

Tilting at this windmill has been fair sport on the forum for along time.

I will wager a SWAG that the difference in the S8 and S9 is pure marketing.
The much discussed "problem" w/the S8's was the prolific scoring of hypopneas.
It has been common practice here to take an S8 HI and divide by 2.
My guess is Resmed changed their algorithum so AHI's would come down.......
along w/the cosmetic changes so small children, family members and visitors
would not run in fear if they were exposed to your cpap machine.....
add to that the bassackward ergonomic design, and
you have a complete, customer oriented product.
Don't worry, be happy!

Flame on!

Carbonman likes being naughty.

I'm glad I'm not like that.