[CPAP] AHI display observations.

[graeme]

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.

[justMongo]

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!

[PaytonA]

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.

[justMongo]

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.

[PaytonA]

How does 101 degrees F strike you. Way too darned hot and me with no air conditioning!! Oh well, sweat on.

Best Regards,

PaytonA