What is ResMed's def of apnea?

[DrPepper00]

My new S9 has only flagged events on 5 days out of my 18 days of use. The events range from an AHI of 13.6 down to 3. Using SleepyHead User defined flags set at 20% for 10 sec. I get event/hr counts of 10.4 down to 1.45 on the nights that ResMed said 0 events. The User Defined flags pick up a few events that Resmed didn't flag on the nights that it worked. Does anyone know what criteria ResMed uses to define events? Pugsy?

[Pugsy]

Defninitions for APneas and Hypopneas are a little different from Respironics. % are slightly different.
Not huge difference though. Reductions in flow that don't meet their criteria will not be flagged as hypopnea or apnea.

These are ResMed's..

Apnea...When the respiratory flow decreases by more than 75% for at least 10 seconds.

Hypopnea....When the respiratory flow decreases to 50% for at least 10 seconds.

[DrPepper00]

Thanks. I will look at the data with those values in the User flags.

On one night that nothing was flagged, my oximeter had my O2 at 88 to 90 for 15 minutes twice during the night.

[derek70]

I've seen my S8 Autoset recording hypopneas with 20 minutes of use, while I'm awake.
It's odd because an event could last at least 10 sec to be regarded as event.
I'm focusing in AI (apnea index), S8 seem very sensitive in recording hypos.

[Pugsy]

I just tried turning the user flag thing on in my SH but I don't get any user flagged stuff at all on any of my reports. Perhaps this is just something ResMed users will see though I did look back in December when I used ResMed VPAP and I didn't have any then either.

[DrPepper00]

I think it only flags things that weren't already flagged.
I tried it with 75% restriction, 50% and 20%. Oddly enough there were more events flagged at 75% than 50 or 20.

75% restriction for 10sec 30 min window


20% restriction for 10 sec 30 min window


That isn't a good example. I need to find one that has more 75% flagged than 20%.

[Pugsy]

Hmm.. odd that I don't have one measly little reduction in something to flag. That goes against logic.
Oh well, lots of this OSA stuff defies logic.

What version of SleepyHead are you using? I have the latest Beta version.0.9.2 I think it is.

[DrPepper00]

I have 0.9.2 I think this part hasn't been debugged yet. Most people don't have a lot of data without flags. It would help to have a count of UF events on the flow rate as well as the count of AH. I am trying to get graphs of a section that has more events flagged at 75% than 20%

[Pugsy]

Okay, I got it to work.. I had to increase the % of reduction from 20% to get it to show any UF events.
Didn't try less than 50% to see where the cut off is but with it set to 50% I get 3 or 4 UFs along with my usual OA..hyponea..etc events.
So it added a few UFs but didn't change my other event flags.

[DrPepper00]

This is SH 75% for 10 sec.



Same time with SH 20% for 10 sec. Doesn't it seem that more events should be flagged at 20% than 75%?

[Pugsy]

Doesn't it seem that more events should be flagged at 20% than 75%?

One would assume so but maybe not enough difference in the flow at 20 % so the machine simply can't tell but at higher % reduction then it is more obvious. Perhaps if we were able to see 20% they would be all over the place and not able to define anything.

[Lizistired]

Not sure if I'm following you. Are you trying to determine what % of reduction in ventilation causes desats?
I have desats with no flagged events. When I zoom in I can see a reduction in flow. Usually an "apnea" that only lasts a few seconds.

[idamtnboy]

This is SH 75% for 10 sec.

Same time with SH 20% for 10 sec. Doesn't it seem that more events should be flagged at 20% than 75%?

Make sure you're looking at the % in the same direction. Resmed would be 75% reduction in flow below the baseline breathing rate. Are you sure SH isn't using 20% as the flow, in which case SH 25% would be the same as Resmed's 75%, providing SH calculation of baseline breathing agrees with Resmed's.

[DrPepper00]

This is SH 75% for 10 sec.

Same time with SH 20% for 10 sec. Doesn't it seem that more events should be flagged at 20% than 75%?

Make sure you're looking at the % in the same direction. Resmed would be 75% reduction in flow below the baseline breathing rate. Are you sure SH isn't using 20% as the flow, in which case SH 25% would be the same as Resmed's 75%, providing SH calculation of baseline breathing agrees with Resmed's.

SH definition is " % reduction in airflow from the median value. 20% works for flagging apneas."

That sounds the same to me. But if they are inverted that would explain the numbers.

[DrPepper00]

My DME just called. ResMed is sending them another machine for me to use while they check mine out. Does anyone know where a machine from Washington state would be sent for repair? I hope to get in at least one night of sleep with data before my Dr appt on Fri.