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[CPAP] AHI display observations.
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graeme Offline

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Posts: 31
Joined: May 2013

Machine: Philips Respironics Remstar Pro C-Flex+
Mask Type: Nasal mask
Mask Make & Model: Fisher & Paykel ESON
Humidifier: Respironics System One Heated Humidifier with Heated Tube
CPAP Pressure: 14 cm
CPAP Software: SleepyHead EncoreBasic

Other Comments: Intermittently use CMS50D+ Oximeter

Sex: Male
Location: Liverpool, NSW Australia

Post: #1
Cool AHI display observations.
Recently my AHI has dropped to 0..zero..zilch..zippo on many occasions. Too good to believe! so I decided to make a table of readings from the CPAP Machine, SleepyHead and EncoreBasic 2.2.2.0.
The results are interesting...
1. There appears to be a DATE OFFSET of one day. I understand why.
2. If the AHI indicated on the machine LSD Info Screen is Zero, then SleepyHead and EncoreBasic show readings form 0.00 to 0.99.
3. Once the AHI is above 1.0 as indicated, there is acceptable correlation of the readings.
4. The readings from the software vary only due to rounding.
5. This tends to indicate that there is a threshold below which the machine does not indicate AHI whilst the Data is in the Machine and on the SD. I have kept a "Sleep Log" of indicated AHI and %PB for over twelve months and all entries showing zero AHI appear to satisfy this observation.
This may be of interest to others who have reported 0 AHI.
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05-14-2014 05:48 PM
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justMongo Offline

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Posts: 3,853
Joined: Sep 2013

Machine: ResMed VPAP Auto (S9)
Mask Type: Full face mask
Mask Make & Model: ResMed Mirage Quattro
Humidifier: ResMed H5i
CPAP Pressure: 18 IPAPmax - 11 EPAPmin, PS=5
CPAP Software: Other Software

Other Comments: μολὼν λαβέ

Sex: Male
Location: Калифорния

Post: #2
RE: AHI display observations.
your point #2 seems to indicate truncation, not rounding.
Rounding would give 1 for AHI greater than or equal to 0.50
Truncation takes even 0.99 and says Zero!

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.
05-14-2014 06:40 PM
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PaytonA Online
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Posts: 3,013
Joined: Dec 2013

Machine: ResMed S9 VPAP Auto
Mask Type: Full face mask
Mask Make & Model: Resmed Mirage Quattro
Humidifier: H5i(distilled-top up)
CPAP Pressure: VAuto MinE14.0 MaxI 20.6 PS4.0
CPAP Software: ResScan SleepyHead

Other Comments:

Sex: Male
Location: Orange County,California

Post: #3
RE: AHI display observations.
Actually if one truncated 0.99 to a whole number it would be 0. If one rounded it to the nearest whole number it would be 1.
05-14-2014 07:54 PM
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justMongo Offline

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Posts: 3,853
Joined: Sep 2013

Machine: ResMed VPAP Auto (S9)
Mask Type: Full face mask
Mask Make & Model: ResMed Mirage Quattro
Humidifier: ResMed H5i
CPAP Pressure: 18 IPAPmax - 11 EPAPmin, PS=5
CPAP Software: Other Software

Other Comments: μολὼν λαβέ

Sex: Male
Location: Калифорния

Post: #4
RE: AHI display observations.
(05-14-2014 07:54 PM)PaytonA Wrote:  Actually if one truncated 0.99 to a whole number it would be 0. If one rounded it to the nearest whole number it would be 1.

That's what I was trying to say... I wrote FORTRAN for early IBM 360's and truncation was always something I had to be aware of.
(Before that I wrote FORTRAN for the IBM 1620 which used BCD arithmetic without a fixed word length.)

From what I gather from the OP, his Phillips machine truncates to integers for the machine display. I think ResMed truncates to tenths. (i.e. -- 0.99 would display as 0.9 on a ResMed.)

Wow, it's hot here, what's it like in the OC?

edited for typos -- my fingers are not coordinated today.

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.
(This post was last modified: 05-14-2014 08:03 PM by justMongo.)
05-14-2014 08:01 PM
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PaytonA Online
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Posts: 3,013
Joined: Dec 2013

Machine: ResMed S9 VPAP Auto
Mask Type: Full face mask
Mask Make & Model: Resmed Mirage Quattro
Humidifier: H5i(distilled-top up)
CPAP Pressure: VAuto MinE14.0 MaxI 20.6 PS4.0
CPAP Software: ResScan SleepyHead

Other Comments:

Sex: Male
Location: Orange County,California

Post: #5
RE: AHI display observations.
How does 101 degrees F strike you. Way too darned hot and me with no air conditioning!! Oh well, sweat on.

Best Regards,

PaytonA
05-14-2014 08:24 PM
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