Strange AHI data

I'd appreciate some insight to my AHI readings.
In April I switched from a S9 to a Dreamstation. (yes, i know about the recall)
The dream station shows my hypopneas much higher that the S9. That drives my AHI higher by 3 to 4 times. See the attached image. There isn't much difference the the OA and CA data.
I'm not sure how to interpret this. They both can't be right. Has anyone else seen this? Which one do you think is correct?

Thanks,
Larry

Different algorithms and different criteria for flagging.
Are you using the same pressure on both machines and exactly same exhale relief (if using exhale relief).
Most of the time people need more baseline pressure when using Respironics machines than with ResMed machines to get essentially the same results.

Larryfff wrote: ↑

Sat Jun 19, 2021 1:13 pm

hey both can't be right. Has anyone else seen this? Which one do you think is correct?

Yes they both can be correct.

The S9 (or the settings on the S9) might be treating your events, much better than your DreamStation.

Pugsy wrote: ↑

Sat Jun 19, 2021 2:22 pm

Different algorithms and different criteria for flagging.
Are you using the same pressure on both machines and exactly same exhale relief (if using exhale relief).
Most of the time people need more baseline pressure when using Respironics machines than with ResMed machines to get essentially the same results.

and, as you know, this DRIVES ME UP THE @%#$ING WALL!!!

particularly in this time of the philips recall. i went back to my resmed and, of course, the same thing happened as the last time. much higher ahi THAN on the philips.

<sigh> back to the philips i go.

i really need to get off my lazy hinder and look for my devilbiss intellipap just to see what happens with THAT.

zonker wrote: ↑

Sat Jun 19, 2021 3:52 pm

much higher ahi on the philips.

I thought your Phillips had the lower AHI and that is why you were using it????

And people need to qualify what "much" higher is....I remember yours...I don't even blink with such a small AHI with either machine.
It's not like one machine gives you 1 AHI and the other gives you 10 AHI.

Now the OP in this thread....there is a consistent difference but there is so much information we don't know that we really can't make much of a judgement about the results.

Hell...when I used the Respironics years ago with minimum at 10...my AHI was 2 to 3....at 8 cm it was around 8 AHI.
I mention the 8 cm because when I went to ResMed APAP I was able to get by with 7 cm minimum and AHI was still around 2ish.
I have come to realize that there is a good chance that even back then I had a chunk of SWJ being flagged but didn't know it.

Numbers don't mean squat to me....sleep is what is important to me....but each to their own.

The question from the OP here was why or what could cause the difference.
The different algorithm is one reason and a very probable reason....different pressures might be another and different flagging criteria another.

Given past experience with people and Respironics machines.....and the OP's main increase seems to be in OAs....I suspect the minimum needs to be a bit higher with the Respironics machine.

We cannot logically expect different brands to give the same results when they use different algorithms or criteria flagging.
Yet people seem to expect it. It's like comparing apples and oranges...both are fruits but that's as far as it goes..
both are apap/cpap machines and that's as far as it goes.

Pugsy wrote: ↑

Sat Jun 19, 2021 4:11 pm

zonker wrote: ↑

Sat Jun 19, 2021 3:52 pm

much higher ahi on the philips.

I thought your Phillips had the lower AHI and that is why you were using it????

grrrr....i left out the word "than". "much higher ahi than on the philips". hey, if i edit it, will your quote change?

Pugsy wrote: ↑

Sat Jun 19, 2021 4:11 pm

And people need to qualify what "much" higher is....I remember yours...I don't even blink with such a small AHI with either machine.
It's not like one machine gives you 1 AHI and the other gives you 10 AHI.

po-TAY-toes, po-TOT-toes. i just say taters.

Pugsy wrote: ↑

Sat Jun 19, 2021 4:11 pm

We cannot logically expect different brands to give the same results when they use different algorithms or criteria flagging.
Yet people seem to expect it. It's like comparing apples and oranges...both are fruits but that's as far as it goes..
both are apap/cpap machines and that's as far as it goes.

i've never claimed to be logical <sniff!!>


yeah the resmed wants to show obstructive events and philips don't.

They were both on auto although the S9 ran at higher pressures for some reason. I'll look up the pressures and post tomorrow. I seem to sleep fine with both so maybe it doesn't matter it just seemed odd to me.

The S9 responds faster and more aggressively when it senses a problem happening in the airway to the point that it will work very hard to try to prevent it from happening again.
It won't do anything during the actual apnea event but it will go higher and stay higher based on what he senses is going on.
I can't see the flow limitation graph details but I have a strong suspicion it is fairly active and the machine runs a little higher because of the FLs and FLs are early warning signs the airway is trying to collapse. We see this often.
So by fighting the FLs more aggressively it prevents full grown OAs and hyponeas from happening.

With Respironics machines the algorithm isn't as responsive or as quick to decide what to do .....so the Fls grow up to be OAs or hyponeas.
You will likely need more minimum baseline pressure to give the Respironics a head start.
You can still get decent results but will just need a higher minimum ..most likely. Without seeing the actual daily detailed report...hard to say how much.

Hi Pugsy,
Can you clarify what data you would need see to evaluate? I have OSCAR but I'm a novice.
Thanks,

Larryfff wrote: ↑

Sun Jun 20, 2021 1:37 pm

Hi Pugsy,
Can you clarify what data you would need see to evaluate? I have OSCAR but I'm a novice.
Thanks,

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