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S8 vs S9 AHI Event readings
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Tom Offline

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Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Full face mask
Mask Make & Model:
Humidifier: H5i
CPAP Pressure: 12cm H20
CPAP Software: ResScan SleepyHead

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Sex: Male
Location:

Post: #1
S8 vs S9 AHI Event readings
I just got my new S9 Autoset yesterday.

I been running an S8 Autoset for the past few years with AHI Events between 4 and 5.

First night on the S9 I got a 1.32 AHI.

I wonder if it was just an extra good night (although I never had a number below 3.0 AHI with the S8).

Setup is the same. Both machines running in plain CPAP mode at 12cm H20. Same mask, same bed, same pillow, same wife.

I wonder if anyone else experience lower AHI numbers with the S9 over the S8???
04-18-2012 02:19 PM
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CHanlon Offline

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Posts: 292
Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Nasal mask
Mask Make & Model: ResMed Activa LT
Humidifier: ResMed Hi5
CPAP Pressure: 12 -20
CPAP Software: ResScan SleepyHead

Other Comments: Mirage Activa LT nasal mask

Sex: Male
Location: Ontario, Canada

Post: #2
RE: S8 vs S9 AHI Event readings
I've only ever had an S9, but I do notice different numbers when I swap wives. :-p
04-18-2012 02:23 PM
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Dreamcatcher Offline

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Posts: 899
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Machine: Resmed Autoset Spirit II with Quattro F/F & FX Masks
Mask Type: Full face mask
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Humidifier: H4i
CPAP Pressure: 10 - 18 cmH20 (auto range)
CPAP Software: ResScan SleepyHead Other Software

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Sex: Male
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Post: #3
RE: S8 vs S9 AHI Event readings
(04-18-2012 02:23 PM)CHanlon Wrote:  I've only ever had an S9, but I do notice different numbers when I swap wives. :-p

Laugh-a-lot Too-funny Bigwink

Its been said over the years that the S8 is more agressive when it comes to registering apneas and again you have seemed to add more weight to the argument. The only real way of getting proof is to wear two machines at once but this cant be done. It does seem to be though that the information is true but thats only my opinion.
04-18-2012 02:28 PM
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SuperSleeper Offline

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Posts: 9,967
Joined: Feb 2012

Machine: PR System One REMstar Auto (DS560)
Mask Type: Nasal pillows
Mask Make & Model: ResMed Mirage Swift II
Humidifier: none
CPAP Pressure: 12.5 - 18.5 cmH20 (auto range)
CPAP Software: SleepyHead

Other Comments: Have diabetes Type II

Sex: Male
Location: Illinois, USA

Post: #4
RE: S8 vs S9 AHI Event readings
Each machine having a different algorithm is going to record AHI differently, (such as the variations between the S8s and S9s which have differing algorithms). Probably more variation between two separate brands of machine as well (ResMed S9 vs. PR System One Auto).

What's important is not so much what the recorded AHI is, but rather your trend data. Most of these modern machines will accurately record the trends for you, which is what you will use to determine the most effective pressure(s) over time.

In other words, it would be inaccurate to say "since the S9 is recording my AHI at 2.0 and the S8 records it at 2.3, the S9 is doing a better job of lowering my AHI levels".

Now, some of that decrease in AHI may in fact be due to a more refined and updated algorithm and better equipment in the S9 units over the S8 units. So some of the lowering of your AHI is for real... but you can't determine that for certain unless you use two machines simultaneously (which as Dreamcatcher pointed out, is impossible).

One thing I will say, is that with a 1.32 AHI on your first night, that is AWESOME. I wouldn't change a thing at this point in your therapy. I can only wish that I could get AHI numbers at that level on a consistent basis.

SuperSleeper
Apnea Board Administrator
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.

04-18-2012 03:13 PM
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Tom Offline

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Posts: 14
Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Full face mask
Mask Make & Model:
Humidifier: H5i
CPAP Pressure: 12cm H20
CPAP Software: ResScan SleepyHead

Other Comments:

Sex: Male
Location:

Post: #5
RE: S8 vs S9 AHI Event readings
All good points.

I agree the AHI Events reading is more of a relative thing. As long as the trend in numbers stays the same or goes down I am happy.

Main reason for upgrading to the S9 was for the CA detection. The older S8 would not do that.
04-18-2012 04:15 PM
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SlightlySleepy Offline

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Posts: 49
Joined: Apr 2012

Machine: Resmed AutoSet S9
Mask Type: Nasal pillows
Mask Make & Model: Puritan Breeze
Humidifier: Resmed H5
CPAP Pressure: 6-10
CPAP Software: ResScan SleepyHead

Other Comments: EPR off, humidifier 80 deg, heated hose, chin strap to reduce mouth breathing. BMI 21-22

Sex: Male
Location: an undisclosed location

Post: #6
RE: S8 vs S9 AHI Event readings
Can any more experienced user comment on how the S9 reports CA (presumably central apnea)? In other words, could it be inferred from the marked reduction in AHI on the S9 that many of the 'AHI' recorded by the S8 were actually CA and no longer treated by the algorithm or recorded? Or are they recorded in some way but just not treated (by escalating pressure)?

I am considering the purchase of an S9 so this is not just a rhetorical question for me. The answer might have some clinical significance for Tom also.

(04-18-2012 04:15 PM)Tom Wrote:  All good points.

I agree the AHI Events reading is more of a relative thing. As long as the trend in numbers stays the same or goes down I am happy.

Main reason for upgrading to the S9 was for the CA detection. The older S8 would not do that.
04-19-2012 12:43 AM
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zonk Offline

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Machine: A10 AutoSet
Mask Type: Nasal mask
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CPAP Pressure: 9/13
CPAP Software: ResScan

Other Comments: CPAP since Nov 2010

Sex: Male
Location: Australia

Post: #7
RE: S8 vs S9 AHI Event readings
CSA detection
It uses the Forced Oscillation Technique (FOT) to determine whether the airway is open or closed during an apnoea. Small oscillations in pressure are added to the current device pressure.
The CSA algorithm uses the resulting flow and pressures to measure whether the airway is open or closed.
http://www.s9morecomfort.com/s9morecomfo...toset.html

Central Sleep Apnea Detection and the Enhanced AutoSet Algorithm
http://www.resmed.com/au/assets/document...-paper.pdf
04-19-2012 01:13 AM
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CHanlon Offline

Advisory Members

Posts: 292
Joined: Mar 2012

Machine: ResMed S9 Autoset
Mask Type: Nasal mask
Mask Make & Model: ResMed Activa LT
Humidifier: ResMed Hi5
CPAP Pressure: 12 -20
CPAP Software: ResScan SleepyHead

Other Comments: Mirage Activa LT nasal mask

Sex: Male
Location: Ontario, Canada

Post: #8
RE: S8 vs S9 AHI Event readings
(04-19-2012 12:43 AM)SlightlySleepy Wrote:  Can any more experienced user comment on how the S9 reports CA (presumably central apnea)? In other words, could it be inferred from the marked reduction in AHI on the S9 that many of the 'AHI' recorded by the S8 were actually CA and no longer treated by the algorithm or recorded? Or are they recorded in some way but just not treated (by escalating pressure)?

I am considering the purchase of an S9 so this is not just a rhetorical question for me. The answer might have some clinical significance for Tom also.

(04-18-2012 04:15 PM)Tom Wrote:  All good points.

I agree the AHI Events reading is more of a relative thing. As long as the trend in numbers stays the same or goes down I am happy.

Main reason for upgrading to the S9 was for the CA detection. The older S8 would not do that.

(04-19-2012 01:13 AM)zonk Wrote:  CSA detection
It uses the Forced Oscillation Technique (FOT) to determine whether the airway is open or closed during an apnoea. Small oscillations in pressure are added to the current device pressure.
The CSA algorithm uses the resulting flow and pressures to measure whether the airway is open or closed.
http://www.s9morecomfort.com/s9morecomfo...toset.html

Central Sleep Apnea Detection and the Enhanced AutoSet Algorithm
http://www.resmed.com/au/assets/document...-paper.pdf

It still records them as events, and they still add to your AHI - so that doesn't explain the AHI reduction. That could be a change in the algorithm that detects them, or a "policy change" on what constitutes an event. Or even a higher success rate at preventing them. Don't think I've seen any definitive answer.
04-19-2012 08:54 AM
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