DreamStation AHI Higher than System One

[Petie]

I’ve been using a PR System One for 13 years and averaging an AHI of .5 to .6.  I just started using a PR DreamStation machine one week ago, and I’m now averaging 1.5, or almost 3x my old AHI.  Can anyone please help explain the difference in outcomes between the two machines?  I had been like clockwork for 13 years before starting with the DreamStation machine.
Thank you!

[OpalRose]

I really can’t explain it.  I’m not certain, and I’m not aware of major changes in Respironics algorithm from the 60 series to the DreamStation.

There are a couple possible reasons to see a change like that.  

1.  Maybe the 60 series wasn’t working up to par.  Thirteen years is a bit past the machines life span.
2.  You are unknowingly using different settings?  Even a change in the Flex setting could affect AHI.
3.  Are you using the same mask?  

Whatever the reasoning, you are welcome to download the free OSCAR software, post a screenshot from the daily page of the 60 series and a screenshot from the new DreamStation for comparison.

The links in my signature line below explain how.  We might be able to spot a reason for the difference.

[Fedman]

When I switched from a System 1 to a Dreamstation, I found the exact same thing in terms of AHI.  With System 1, I was averaging an AHI of around 0.6.  After my switch to Dreamstation using the same pressure range (7-12) I was averaging around 1.5 or more.  I increased my minimum pressure from 7 to 8 and then 8.5.  My AHI is now averaging less than 0.5 per night.  (That 0.5 increase worked very well for me.)

Your profile shows your low at 5cm.  I'm wondering if that's too low for you.  OSCAR would help you see what is going on.

[Petie]

OpalRose,
Thanks for your helpful considerations.  
I’ve actually owned 3 separate 60 series machines over the 13 year period, and my average.5 to .6 AHI has been like clockwork throughout this period. 
My machine settings, which I verified within the provider screen portal, are identical to those from my 60 series machine.
Lastly, I continue to use my trusty Resmed Airfit 20 mask; so I’ve changed nothing except the machine.
I assume the DreamStation somehow reads apneas and hypopneas more aggressively, but I suppose I should rule out that something is t wrong with this particular machine.  Thanks again for your help.
Peter

[Petie]

Fedman,
Your email is quite helpful.  In fact I increased my minimum to 6 last night, which didn’t help, but I’ll try an additional increase tonight.  It sounds like you had an identical experience to me, and so I assume my remedy might be close to yours as well.  I’ll try a minimum 6.5 tonight, and I’ll keep bumping until it works.
Thanks so much for sharing your similar experience and solution!
Cheers,
Peter