resmed, respironics, AHI and facts?

Well, one thing I am taking away from this thread is - yes, once again it seems a given that resmed scores hypopneas higher than other machine brands - so with a 7-10 ahi (1 ai) average I probably should not worry about the numbers. And look at the trends.

And reread this thread when I am more awake and see what I missed. A lot of good points that will take me a while to digest. Thanks

Guest wrote:Great post about the relavance of data jnk, I cringe everytime I hear somebody chasing that percieved nirvana of 0 AHI.

I also wish manufactures would quit using the term Hypopnea, a hypopnea is SO much more than what a PAP machine measures.


AKCPAPGUY

Thanks, AKCPAPGUY.

It is definitely a human tendency to see every problem as a nail when we have a hammer in our hands.

"Hypopnea" is a slippery word, for sure. It changes meaning according to context, and not just when it comes to machine discussions versus PSG discussions, either. There are broad uses and specific technical uses of the word, it seems to me. My definition for "apnea" is "I reckon that feller didn't breathe at all just then." My definition for "hypopnea" is "I reckon he breathed but he coulda done better." The technical PSG definition may be fairly clear in theory, but I don't think it is so clear in practice, and it is subject to change, just as it has in the past. (I think the insurance companies probably have as much say in that definition as anybody else.) So I don't fault the machine-dudes for using the word to mean "a breathing event that is less than an apnea." But I do agree it is confusing to patients how many different ways the word is used.

dkdc wrote:Seems some people think Resmed machines over report hypopneas and some people think Respironics machines under report hypopneas. I have seen Velbor's chart, and read some discussion - and I don't know what to think.

I would also call to your attention, if you have not reviewed it, my post at
viewtopic.php?f=1&t=42646
in which I present data from both ResMed and Respironics machines (same settings, same masks).
I will shortly be adding additional data to that posting.

Unfortunately, you may well still be left "not knowing what to think."
Careful comparisons are hard to come by, since even using both brands, you only have each brand's proprietary interpretation of outcome to compare. Without an "impartial" arbiter of breathing (such as the sensors employed in a PSG), information which is both meaningful and useful is hard to come by.

There are some published studies, which have been referenced in this forum (Ozij, can you help?), which, as I recall, show little relevant difference between the machines. That's to be expected, of course, across a diverse population. It seems reasonable to assume that there will be INDIVIDUALS who will do better on one (AutoPAP) machine than on another, but it's doubtful that there is any way to know or predict ahead of time which machine will do better for one person, and I think it quite unlikely that, for most people, one machine brand will perform CLINICALLY SIGNIFICANTLY better than another. For constant-pressure CPAP, there is NO efficacy difference by manufacturer (the AHI and other numbers will be different, but that is irrelevant), though there may be comfort-feature differences.

Good questions, good comments, little data and few facts on which to base practical choices.
Why should xPAP be any different than most of the rest of the real world? Velbor

Ah - the mythical Velbor appears! I thought you were like the tooth fairy - who never did show up. She just left quarters.

Thanks !

Great post, jnk!

When I was on CPAP/APAP, no matter what I did, my numbers (Resmed) were not great, and I didn't feel that much better than before CPAP. Once my doc switched me to auto BiPAP, I'm finding that tweaking my pressure does make a difference.

During both sleep studies, I had NO apneas, just hypopneas, but my AHI was enough to diagnose me with moderate OSA. Both by Resmed C/APAP & VPAP report a few apneas and a whole lot of hypopneas. The VPAP has shown that I have shallow/rapid breathing while asleep, so I'm assuming that accounts for the higher hypop count. Now that I'm on VPAP, I've been able to get my AI consistently below 1. HI is still high, but AHI is usually less than 10.

Because of my shallow/rapid breathing, I'll probably never get my HI very low on a Resmed machine, and my guess is it probably wouldn't be all that low on a Respironics either (though probably less than what Resmed reports).

I go mostly by how I feel and use the data and graphs to "see" what went on during not-so-good nights. It helps me to decide to change pressure (or not), to adjust my mask (or not), etc. That said, the couple nights I had an AHI less than 5, I felt VERY GOOD the next day. Last night was a rotten night (AHI a little over 12 and AI about 1.5), and I really feel it today. When I wake up, I assess how I feel before I look at my machine or download my data. My "guestimate" upon waking is always right, too.

Guest wrote:...I also wish manufactures would quit using the term Hypopnea, a hypopnea is SO much more than what a PAP machine measures.

Say what??? Explanation please.

This is an excellent thread and again JNK has provided a very lucid and well worded set of responses.

I agree with AKCPAPGUY that the way hypopneas are talked about by the manufacturers is confusing &
in my mind has led to much consternation among cpap users and led to some heated brand vs brand
exchanges here in the past that should never have taken place. Unfortunately, I believe it will remain
probably that way, but as long as we have people like JNK who can explain the complexity in simple
language, hopefully we here will be better informed than average.

When I 1st started out with cpap (2005) I thought that the measurements (AHI, HI & AI) were sort of
scientific medical monitoring and that because the FDA (as powerful as they are) regulate these machines,
there must have been some consistency to what was being measured & reported. Turned out I was very
wrong. That took me a couple of years to wake up to & that was when the realisation sank in that each
machine's data was *relative* by this I mean relative to that brand (& sometimes model). JNK's explanation
of 'trending' is an excellent way to understand it.

Again, an excellent & informative thread.

DSM

Ok, since i have received so many PM's and Muse has asked the question here, let me explain my position on my Hypopnea statement.


Yes I am willing to concede that Hypopnea literally means underbreathing, however in the context of diagnosis and treatment of sleep disorders, a hypopnea event is not considered to be clinically significant unless there is a 30% (or greater) reduction in flow and an associated 3% (or greater) desaturation in the person's O2 levels for 10 seconds or longer, or if it results in arousal or fragmentation of sleep. There currently is no PAP machine on the market that can correctly identify a Hypopnea under that definition, so IMHO the manufacturers should rename the measurement to Flow Reduction greater than 30% (FL30). After all, that is all they are measuring FLOW, they are not taking in to account the rest of the equation.

Do I think the measurements that the machines come up with are significant and useful, yes. If your HI average is elevated and subjectively you are feeling like your treatment is suffering, titrate. However if subjectively you feel great and that your treatment is working, don't titrate just because the HI average is elevated, it is possible to have Hypopneas that have no ill affect on the body or your sleep. Atleast that is the belief so far, we will never know forsure until someone is able to do realtime measurement of hormone levels in the body as we sleep.


AKCPAPGUY

Mr Guest sir, may I call you sir? My sleep study found like zero apneas and lots of hypnoapneas. I was diagnosed with mild OSA, but since I fell asleep while driving and got into a car accident both my doc and me thought it might be a good idea to do CPAP. And that's with essentially all hypnos and zero apneas in the study. My machine does record apneas now as well as hypnos. And obviously it measures events differently than the sleep study. But my point is just cos the sleep study shows no apneas doesn't mean that CPAP is not a good thing. So watch it with generalizations. Thank you and have a nice day.

Pugsy wrote: If a person had a majority of hypopneas on the sleep study then they likely will also tend to score more hypopneas on any machine. It is hard to compartmentalize the ResMed data because we see and hear that "magic" less than 5 AHI number and it seems like so many ResMed users tend to report a little higher HI. Especially if they also had a majority of hypopneas during their sleep study. There are ResMed users that have AHI less than 5 and even less than 2. So where do we draw the "line"??? What number does it take to validate what we perceive as optimal therapy? If Respironics users didn't "seem" to be reporting less HI, would that make it easier? How many of the hypopneas that any machine flags are really maybe simply turning over in bed and maybe briefly holding our breath? Remember the machine is stupid in that it doesn't know if you are awake or not or you maybe hold your breath for some other reason. It reports whatever it senses based on how it has been told to report.

Not sure I agree here with direct comparison to sleep results and machine results. My sleep study showed virtually all hypnoapneas and no apneas, yet my machine shows differently. And my doc told me that the sleep lab measures stuff different than the machines do and I shouldn't equate the sleep study to machine results. So I'm not convinced yet of the correlation. I just know I see a link between how I feel and my results from my CPAP therapy. And when the therapy is effective (low leakage, low apneas), I feel better. I haven't gotten the correlation yet on optimum pressure and I'm working on this, but I'm not sure its possible to directly correlate sleep study results and machine results quantitatively. I think of the machine as measuring "events" and if we get those numbers down we'll feel better. I'm not so focused on a specific number, but on low numbers. But then I'm a veteran of less than 3 months with CPAP. Pugsy, don't get mad, please. I greatly value your opinion. I'm just not convinced here.

Guest wrote:...a hypopnea event is not considered to be clinically significant unless there is a 30% (or greater) reduction in flow and an associated 3% (or greater) desaturation in the person's O2 levels for 10 seconds or longer, or if it results in arousal or fragmentation of sleep. There currently is no PAP machine on the market that can correctly identify a Hypopnea under that definition, so IMHO the manufacturers should rename the measurement to Flow Reduction greater than 30% (FL30). After all, that is all they are measuring FLOW, they are not taking in to account the rest of the equation...

Thanks! Succinctly, precisely phrased...nice . I am one of those whose PSG showed no apneas and many, many hypops with significant desats (enough that the resulting periodic hypertension was causing 8-10 pee trips a night and I know I'm still recovering from the brain damage), so I am hyper-vigilant to statements that de-value the seriousness of hypops...now that said, I fully understand what you are saying, that a hypop detected in a PSG might be quite different than the flow limitation reported in our xPAPs. While it might be the same as the one detected during a PSG, because there is no way to detect desats (unless you have a recording oximeter & use it faithfully to determine if each xPAP reported hypop corresponds to a significant desat) and are wired to detect brain wave patterns (and relate each xPAP detected hypop to an arousal or move to a lighter sleep stage). Somehow I can't see too many people sleeping with a recording oximeter and a Zeo (well, not perfect but the best we have to assess our sleep stages) every night and then spending who knows how many hrs the next day trying to figure out if they really had 'real' hypopneas the night before or just flow limitations!

Thanks again for this explanation. In that sense, the flow limitation reported by our machines as a 'hypop' may or may not meet the stringent definition of a hypop in a PSG. Objection to the use of the term hypop by manufacturers duly noted...think I agree, calling the xPAP detected flow limitation a hypop just confuses us hose-heads...not sure what a better term might be, maybe categorizing them by degree of limitation L30-40, L50-60, L60PLUS if they last more than 10 secs or something. Seems to me the value of data is to observe trends over time. One day, more sophisticated technology will allow us to do something more like a PSG in our homes so we can assess the effectiveness of our therapy...blue sky right now

GaryG wrote:Pugsy, don't get mad, please. I greatly value your opinion. I'm just not convinced here.

Gary there really wasn't any effort to convince you of anything here. I just told a story that really has no answer.
I have read lots, lots, and more lots of stories and medical things about personal sleep study results and see some comments with reports after they have been on the machine. No, we aren't going to expect match exact data from the sleep study to home cpap reports. But we can probably do a bit correlaton...

On another forum I see people post their sleep studies and not have hardly any apenas but they have ton of hypopnea. So the get started on cpap machine of choice and while they have a reduction of Hypopneas, they still have more than one would want. They don't seem to be as easy to blast away as apneas are...could be from any number of reasons and likely will take considerable detective work to sort through it. They Hypopneas are important. Just how important has to be determined on an individual basis.

About every 3 months we have this same old discussion about ResMed HI numbers and the mixed feelings it causes.
It has been hashed out many times with some comments getting to be less than polite at times. No real definitive answers come about that can be written in stone...There are as many opinions as grass.

Gary,

I'm not really sure how to respond to your post, other than to say, you obviously either didn't read the whole thread or you completely missed the point i was arguing. I never once said or implied that someone with only hypopneas on a sleep study shouldn't be on CPAP. Please go back to the beginning of the thread and reread it from the beginning.


AKCPAPGUY

I personally agree with Pugsy that there often is a very recognizable relationship between the data from a sleep study and the data we get from our machines.

And I personally read akcpapguy's comments as agreeing with what had already been said in this thread and adding in the important point that sleep studies collect data that can show the effects the changes in our breathing have. I also agree that these discussions would be much less confusing to many patients if home machines used terms that differed from the terms used in a PSG.

A hypopnea scored in a sleep study is something that likely should be treated. A "hypopnea" estimated by a home machine, particularly a ResMed, is something that may, or may not, need to be treated. Thus the importance of factoring in how we feel. But it is useful to have the numbers from the estimated "hypopneas" scored by the home machine as useful trending information when we tweak pressures in our attempts to work out our pressure needs over time.

jeff