On another forum I have seen a knowledgeable person declare that Resmed HI data is about twice what respironics is.  She gives a lot of caveats - she is not a doctor or a sleep practitioner of any sort, she is not saying that resmed measures things incorrectly - just different, etc, etc.

Google "Well, some of the following links contain my non-medical opinion, and I can sure be wrong. Velbor's chart is very interesting." to see a summary of links

Or even just "Velbor's chart is very interesting"

Anyone here support this idea or decry it?

It made me feel much better about my HI readings!


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

dkdc wrote:

On another forum I have seen a knowledgeable person declare that Resmed HI data is about twice what respironics is.

There is now some good evidence that the Respironics algorithm leads to underscoring of HIs.

If you want to halve the score of a Resmed xPAP to make it equivalent to what a Responics xPAP might score, that's up to you, but you may be fooling yourself in doing so.

Cheers,

Billl

I think the person you are talking about has had experience using, and getting data from, BOTH brands of machines.

Bill Bolton wrote:

There is now some good evidence that the Respironics algorithm leads to underscoring of HIs.

Do you know if this has been published in a peer reviewed article somewhere?  Sorry, my med device compliance background makes me want real data.


_________________
Marie
Newbie with Severe OSA
ResMed S8 Elite II CPAP with EPR and H4i humidifier
ResMed Mirage Quattro full face mask
Contec CMS 50-E Pulse Oximeter

mreewh wrote:

Do you know if this has been published in a peer reviewed article somewhere?

No...... and neither has the orginal contention.

There has, however, been robust discussion in other places regarding the way that the Respironics scoring algorithm handles variable breathing events.

There is good emperical evidence that it suspends the scoring of hypopneas while what it considers a variable breathing event is in progress, leading to "lower than PSG" HI scores.

mreewh wrote:

Sorry, my med device compliance background makes me want real data.

There's a good research topic for you then!

Cheers,

Bill

Thanks for the discussion.  PLEASE NOTE - I am not adopting any position on this - I am just asking.  And the person to whom I sort of linked made about five disclaimers as well.

It seems like someone somewhere in the production of these products and in government testing - would have to have compared each respironics and resmed model to what a sleep lab gets for data.  In fact almost every sleep lab USES one of these companies machines with their sophisticated measuring equipment to compare them to (or could compare them).

So, no tech here is willing to say?

I should add - maybe I am talking beyond my knowledge base.


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

It is an interesting question.  My AHI in the diagnostic study was 6, and 9.71 (w/ .5 AI) in the titration.  Low, but I had low oxygen and high heart rate.  On my Resmed auto-pap data capable machine, my AHI has gone as high as 15.7 - based on 12.2 HI and 3.5 AI.  On average, according to my machine, my HI is about 9 and my AI is about .5.   So the average is pretty consistent with my titration results, but can be quite higher than diagnostic all around.

My AHI usually comes in around 10 and my AI around 1 to 1.5

But over the weekend I have felt better - which is odd since this is the time of year my seasonal affective disorder kicks in.  (It is hard to use the lights on a busy weekend with an energetic 6 year old).

Anyway, the majority view seems to be that resmed machines score HI higher than other machines and higher than sleep study equipment. (Though no one can prove one brand is more accurate than another.  The resmed scientists certainly know what they are doing).

So, if I cut my 10.0 in half I get 5 and I am feeling better - so some objective and subjective evidence that I am on the right track.  

If indeed I am feeling better and this continues - it will have taken me almost 2 months of pretty solid use to get feeling better.

Thanks for everyone chiming in.


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

This is the huge problem with these results, IMO. The numbers generated by these machines, regardless of brand, are not representative of actual numbers. In fact, these numbers are best used for trending purposes only. This is important because there is never a need to double a number here or halve a number there.

Take your readings and begin to look at them biweekly. Throw out the outliars (best and worst day in the two week period), then calculate the average daily AHI.

If you do this the same way every week, then you will begin to see if your treatment is getting better, worse, or staying the same. The fact is that the actual numbers per day do not mean a whole lot.

Both companies AHI readings are inaccurate, so why bother messing with the values as if they mean something individually?

My reply is general and not directed at the OP (or anyone really).

Isn't looking at trends different than looking at biweekly numbers?  I can see looking at trends, but actual numbers for a 2 week period or month would lead resmed users to feel like their AHI is still too high, usually.


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

dkdc wrote:

Isn't looking at trends different than looking at biweekly numbers?  I can see looking at trends, but actual numbers for a 2 week period or month would lead resmed users to feel like their AHI is still too high, usually.

What is the difference? Essentially, you would want to throw out the nights that you have gigantic leaks, but ultimately looking at the data every 2 weeks is going to be as beneficial as looking nightly. If Resmed machines score high, then sure the actual numbers are going to appear the same, high, however a patient is going to have to factor in a few things... fatigue level, average drops offf of blodo pressure, etc. If you come home from the titration (which indicated X AHI for pressure Y) and you do not get those numbers with your equipment, then you dont have a whole lot of options. You can get retitated because you expect an error, you can wrestle with your equipment setup to try and get those numbers, or you can bank on your technician scoring your study appropriately and your numbers at home are "in normal range". If you make that assumption, then you can begin to trend without having to worry whether or not the RESMED elevated AHI is "real". Does that make any sense?

Lets just have an example, so that I make sure that I am thinking about this correctly:

Day 1 - Ahi - 4.7
2 - Ahi - 28.5  [throw out, the leak rate was terrible]
3 - Ahi - 7.6
4 - Ahi - 2.1
5 - Ahi - 0.1 [thrown out ... too low]
6 - Ahi - 8.5
7 - Ahi - 4.1
Daily Avg =  - Ahi - 5.4

Day 1 - Ahi - 9.6
2 - Ahi - 29.9 [thrown out as leak rate correlates]
3 - Ahi - 2.6
4 - Ahi - 7.6
5 - Ahi - 7.9
6 - Ahi - 9.2
7 - Ahi - 10.2
Daily Avg = - Ahi -  7.85

Day 1 - Ahi - 4.5
2 - Ahi - 13.3
3 - Ahi - 9.5
4 - Ahi - 9.5
5 - Ahi - 3.4
6 - Ahi - 10.1
7 - Ahi - 8.4
Daily Avg = - Ahi -  8.39

---

And so on... maybe this upwards trending AHI is occurring at the same time you are gaining weight...or maybe its coinciding with a new medication that you were given. Who knows.

You could probably come up with a better equation that factors in the average leak rate (to better get a grip on your numbers), but this was just a plain example. I would never pay much attention to the numbers daily except to see if maybe I had an uncontrolled leak that night before.

So you aren't really looking at the weekly averages of 5.4, 7.85 and 8.39 as important in themselves - but rather as useful data points to see a trend?

In other words - if this were a resmed machine your numbers are good but the trend is worrisome - which is really all that can be accurately said.  If this is a respironics machine your numbers are not as good but again it is only a trend we are looking for - the actual numbers are somewhat imprecise and not to be taken as important or trustworthy data.


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

dkdc wrote:

So you aren't really looking at the weekly averages of 5.4, 7.85 and 8.39 as important in themselves - but rather as useful data points to see a trend?

In other words - if this were a resmed machine your numbers are good but the trend is worrisome - which is really all that can be accurately said.  If this is a respironics machine your numbers are not as good but again it is only a trend we are looking for - the actual numbers are somewhat imprecise and not to be taken as important or trustworthy data.

That is exactly what I am saying. An AHI given from a machine is worthless as an actual value, IMO.

Sorry if I wasnt too clear. I just got home from work and my eyelids are staying shut a bit longer than normal.

Although if you know that resmed machines usually read the ahi high - and that people with an AHI of 10 on a resmed machine usually feel like the therapy is working - then you can be somewhat comfortable with the imprecise resmed 10 ahi figure.

At least I am at the moment.  And more importantly my trend is slightly lower - but the ahi of 10 is meaningful and reassuring to me, though maybe it shouldn't be.  I think it should be, though.


_________________
Resmed S8 Elite II with FitLife total face mask.
DISCLAIMER - I am sometimes corrected by those that actually do know what they are talking about.

dkdc wrote:

Although if you know that resmed machines usually read the ahi high - and that people with an AHI of 10 on a resmed machine usually feel like the therapy is working - then you can be somewhat comfortable with the imprecise resmed 10 ahi figure.

At least I am at the moment.  And more importantly my trend is slightly lower - but the ahi of 10 is meaningful and reassuring to me, though maybe it shouldn't be.  I think it should be, though.

Has your AHI (with that machine) always been 10? If it has been, then it SEEMS safe to feel reassured.

I hate to make too many comments or the moderators are going to say that noone here is authorized to make such comments. While I technically agree, ill say that its a safe assumption in my opinion only.