S9 - Unknown Apneas???

[KatieW]

I'm posting this because it's new, and curious to me. On ResMed's Data Management Guide, Unknown Apneas (yellow) are: "an apnea during which a leak higher than 30 l/m occurs, precluding accurate determination of whether the apnea is obstructive or central."

Well, my leaks were zero. So what is it--just a hiccup?

Here's a close-up:



Any guesses?

Here's some 30 second views. I don't know why the times are out of sync, but #1 is the 1st one, and #2 is the 2nd one.





I'm wondering if they even are apneas.

[Nord]

There doesn't seem to be any apneas happened according to your breathing, ventilation or leak.

Have you had unknown apneas before w/o the high flow leaks???

Someone else (may have been DreamDiver) on this forum had some apnea events that were recorded that occurred at the wrong times... he did a thread on it. The readings were skewed several times in one session. Is it possible that these were skewed in time as well???

Other than that I have no explanation... everything looks good.

Nord

[dave21]

Hi Katie, to me they don't look like Apneas to me. What if you check your Summary screen, do the Apneas show up there too? I'm wondering if the detailed view is counting something it shouldn't just like my last nights graphs where the detailed graph view is actually counting less Hypopneas than it should.

Thanks
Dave

[dave21]

Someone else (may have been DreamDiver) on this forum had some apnea events that were recorded that occurred at the wrong times... he did a thread on it. The readings were skewed several times in one session. Is it possible that these were skewed in time as well???

That's actually a good point Nord, yes believe it was DreamDiver that had this problem. Looking at Katies graph again it does look like you might have some skewed graphs here. I've put arrows on your graph below so you can see the skew.



Thanks
Dave

[DreamOn]

Here's DreamDiver's recent thread about the time-skewed data: viewtopic.php?f=1&t=50578&p=464957. It looks like that's happening with Katie's data too.

Dave21 and Nord, you had reported in the other thread that this hasn't happened to you. I'm just wondering if DreamDiver and Katie are doing something different than you two. Would the way the SD card is handled or the data downloading technique make any difference? It'd be interesting to figure out why this is occurring to some, but not others.

[dave21]

I wouldn't think the data download process is making any difference, but I always close the first dialog that opens and then manually open the patient record and then click download data then discard.

[DreamOn]

I wouldn't think the data download process is making any difference, but I always close the first dialog that opens and then manually open the patient record and then click download data then discard.

Not that this is particularly relevant to the immediate discussion, but I just thought I'd mention that the initial dialog box that pops up by default when the ResScan program is opened can be turned off in ResScan 3.7 by going to Tools | Options | Download and then uncheck "Show the Quick Start dialog every time a device is attached." I assume that option is also in version 3.10.

[Nord]

Katie

Can you check your data screen again for that date and see if those 2 apneas have "corrected" themselves by coordinating with the Flow position. My original thought with DreamDiver was that it could be a temporary memory thing that it was "out of position".

If it has not corrected... then I really don't understand. Seems to me that all AHI reporting by the machine comes from the Flow data and simply "scores" the data it finds - not changes it in any way.

I have checked all my data carefully every day for 16 days and it hasn't happened to me.

One other thought... since the SD card holds 8 days of info... has it given you any more difficulty with missing flow info???

Nord

[KatieW]

Here's the 5 minute screen shot of Unknown Apnea #1. To the left of the Apnea, there is a decrease in Flow, and a tiny drop in Flow Limitation. No change in zero leak though.

This doesn't meet ResMed's definition of Unknown Apnea, which is Unknown because there is a high leak.

Thanks for your replies. To answer your questions:

Nord--No, haven't had Unknown Apneas before these ones, on the night of March 26. This morning, they have not corrected themselves. No, I haven't had any problems with Flow information, once I corrected the initial problem of not checking the box.

Dave21--Yes, the Unknown Apneas are on the Summary Screen. Thanks for the graph with the arrows, very helpful.

DreamOn--Yes, I download my data the same way as Dave. Thanks for the link to DreamDivers' thread. I'll study it, and try and unskew my data.

I find this so interesting. Thanks everyone, for your input.

Oh, by the way, no Unknown Apneas this morning. Just a few Obstructive and 1 Central.

[DreamDiver]

So I'm not crazy... Hmmm... I'm sorry it happened to you KatieW, but I'm glad it's reproducible. I hope someone is Resmed picks this up.
(I have not seen any unknown apneas as of yet.)

[dave21]

Thankfully the Unknown Apneas have stayed off my graphs too

[Rebecca R]

Katie, I have absolutely no qualifications to take a guess but: Is it possible that the apnea just barely crossed the ten second threshold, but ended before the S9 had time to test whether it was obstructive or central?

Just a very wild guess.

r

[coreyg]

I get on average about 1 unknown apneas every day (my average AHI is about 6 right now). About half of them are from massive mask leaks (I think the mask may have actually been taken off in a couple of the cases). I've noticed on a couple of the unknowns (without the massive mask leak), the flow curve looked a bit odd at the start and end of the apnea.

I have not seen any data time shift yet (15 or 16 days so far) and I have been doing close up looks of at least 2 apneas every day so I would have seen them. My standard process on an XP system:

Put SD card in and wait for directory volume to pop up.
Close the volume.
Launch ResScan
Wait for the start up load window to open and close it. (I just clicked on the "don't open this window on startup" so it shouldn't happen again).
Open Patient and click on me.
Download data (leave everything at default)
Discard data (First 6 days was overwrite) and close the download window.
Click on Review data.
When done, close ResScan, click yes on save data
Go to remove USB device and stop it.
Remove SD card (and unplug card reader).

The last 2 steps, I haven't done all of the time, I just started them when DreamDiver showed the data skew error. I used to remove the card after the download data and before ResScan finishes. I have never bothered with write locking the SD card. I have used the same SD card the whole time and never formated it or erased it.

Could it be on the S9 side? I usually turn the S9 on before I put the SD card in so it can say "reading card" when I put it in and then I shut it back off.

I hope we figure this out soon, I don't want my data messed up.

-Corey

[jmelby]

I had a bunch of unknown apneas when I wore a full face mask for a few days last week when I had a cold, but otherwise haven't seen them.