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OSCAR Problems with times since BST?
#1
OSCAR Problems with times since BST?
Hi all...

So, I've had some issues since the clocks went forward, and I'm wondering if I'm missing something. 

Then the clocks originally went forward, I ended up with a single file from my Viatom CheckMe O2 ending up with a time an hour earlier than the related results from the Resmed 10. This was because the device doesn't automatically switch to  DST, it only updates when connected to the phone (or manually via the computer). This was on Sunday (post time change) but with data still being stored on Saturday because it splits the days at midday. On Sunday, which had the data from overnight Sunday-Monday, the data matched up just fine, and I thought, okay, everything is working, I guess that somehow OSCAR is compensating for the lack of automatic time change on the Resmed. However YESTARDAY, when I uploaded my data, I found that everything was now an hour out of sync, with my Resmed data starting an hour before my Viatom data - and this was the case for ALL of my data, not just the recent ones. So now I am super confused. I've fixed it as a whole (apart from that single recording before my Viatom device updated its time - that's STILL an hour before the CPAP data) by using the option to correct the time by an hour in preferences (even though it's not MEANT to be used for DST corrections) but I don't know how else to fix it. I've ensured that my time zone is correct in both the profile and my Win10 PC, I've tried reloading the data both with and without the DST box checked in the profile... but nothing seems to make any differences. 

So - any hints, other than leaving the correction in place until BST is over (as I read that its best not to alter the internal clock, plus it would probably p*** off my sleep clinic no end)? Also, is there any way I can manually fix the one Viatom sessions with the mismatched time?

Any help gratefully received.
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#2
RE: OSCAR Problems with times since BST?
The preferences setting for CPAP drift is applied when (CPAP) data is displayed and doesn't change what's in OSCARs database. So if you have a single day (or DST months) that is out of sync it will fix it for that period and break every other day, past and future. Other data types don't apply the drift setting.

I don't see an issue with changing the CPAP clock - your sleep clinic probably doesn't care if you sleep at 10pm or 11pm. The only challenge is with changing the clock backwards after DST ends. Just do this after 1pm on the day DST ends and it will be fine.
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#3
RE: OSCAR Problems with times since BST?
Hello, the timezone and dst change nothing about your data time reports. It just play a role in the today summary.

So to answer the question, yes you could purge the day and use the clock drift offset in Preferences/CPAP and import the day again.
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#4
RE: OSCAR Problems with times since BST?
Changing clock drift doesn't impact data import... it just changes the display of CPAP data. I assume Ratchick wants her Oximetry data to align with the CPAP data, which can be done by changing the drift setting apporpriate for that day... at the expense of breaking the view of every other day that requires a different drift setting.
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#5
RE: OSCAR Problems with times since BST?
I use a cms 50f. What I do is import using (I’m paraphrasing) I started the Cpap and O2 at the same time. It is an option on Oscar. Then the O2 just uses the Cpap clock.
Apnea (80-100%) 10 seconds, Hypopnea (50-80%) 10 seconds, Flow Limits (0-50%) not timed  Cervical Collar - Dealing w DME - Chart Organizing
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#6
RE: OSCAR Problems with times since BST?
Stacey - The CMS-50 series has a different set of import options.  One of them is the option to have the start time of the CMS-50 match that of the CPAP's start time.  Unfortunately, the Viatom/Wellue device import doesn't have that feature.  The start time is written into the O2's data file header.  So far the only way I know to adjust this is to edit the O2 data file with a hex editor, modifying its start time.    I did this for another member that had only one day's data with a different time offset.  It would get rather tedious for more than a few days of edits.
Crimson Nape
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#7
RE: OSCAR Problems with times since BST?
(04-06-2021, 07:14 AM)kappa Wrote: Changing clock drift doesn't impact data import... it just changes the display of CPAP data. I assume Ratchick wants her Oximetry data to align with the CPAP data, which can be done by changing the drift setting apporpriate for that day... at the expense of breaking the view of every other day that requires a different drift setting.

ho ok, I din't understand that, so the only way is to edit the starttime of the machine datareport and import.
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#8
RE: OSCAR Problems with times since BST?
Thank you all for your feedback.

As Crimson stated, that was exactly the issue - I don't have a problem using the drift to compensate at all, that's fine. The main problem outside of that is the single session that is one out-of-sync. I will take a look at the session file with a hex editor and see if I can fix it up.

I do have an unrelated question that I guess I will just ask here instead of a new thread: I was wondering how the machine tells the difference between an obstructive and a central apnea? I've tried looking at everything and the tricks for interpreting the data, but occasionally it'll decide to throw up a few obstructive events despite there being nothing on flow limit, snore, etc. and the shape of the waveform not looking substantially different (to my non-expert eyes) from the central apneas. So I guess I would ask: is it likely that they're actually mislabeled centrals? I would imagine that the Resmed APAP is probably more likely to expect OAs. Most of the time otherwise, OAs seem to be clustered around when I'm awake, so I suspect they're probably just artefacts. but it seems strange to have what seems like a whole string of centrals with a random obstructive event in the middle.
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#9
RE: OSCAR Problems with times since BST?
It's hard too see the difference without sternum information. and the CPAP have lots of error about that.

In general with OA you have a hight breathing peak after the apnea and not with central. With CA you could have the amplitude of airflow reduced before the apnea or the apnea start after inhalation. OA are always after exhalation.

And you could have mixed apnea xd
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#10
RE: OSCAR Problems with times since BST?
The algorithms vary between machine manufacturers. You can look at some details in table 2 of this article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4629962/

ResMed seems to do a better job of detecting CA using FOT (forced oscillation technique) compared to Respironics which uses pressure pulses.
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