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spO2 measurement
#1
spO2 measurement
Hi all,

I've completed an oximetry study and will soon take the next step sleep study to determine whether I have OSA. I have my own SleepU device and would like to get a better idea of how to interpret my data in advance of my Dr reviewing my sleep study results. He tends to take a passive treatment philosophy, so I fear he may categorize my OSA as merely "mild", thus no treatment warranted. It may in fact be on the mild side by clinical criteria, but it does wake me up throughout most nights, so I hope some type of treatment is recommended. Also, even though my number of events may be in the mild category, some of the drops seem kind of low to me, with the recent lowest at 77%, if my device is accurate.

Anyway, the O2 Insight Pro software that goes with my SleepU device indicates around 4 events of ODI 3% per hour, and only maybe 2.6 events of ODI 4%. On the other hand, when I import that same data into OSCAR, it shows an SpO2 drop index of 7.31 - which I believe indicates 7.31 events per hour. But it's not clear to me what % drop benchmark that is using. 

So my questions are: 

1) What is the standard % benchmark for tallying OSA events per hour? It seems surprisingly difficult to find that detail online. 
2) What % drop does the OSCAR software use to calculate its SpO2 drop index? I can't find an explanation of this with the documentation.
3) Do doctors take into account only the AHI when determining whether treatment is warranted? Or is the % drop also taken into account?

Thanks much!

jwoodz
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#2
RE: spO2 measurement
Welcome to the forum

1. I assume that you are talking about % of O2 desat, to my knowledge there are two standards, 3% and 4%, both are used and I certainly do not know which your doctor uses.
2. OSCAR reports data from the Oximeter, it doesn't calculate them.
3. Most doctors only use the AHI, or maybe the RDI to determine if treatment is warranted. Since a CPAP will improve oxygen sats only in extreme cases will supplemental oxygen be prescribed with the CPAP. If you have significant desats it is recommended that you get a compatible pulse oximeter to validate that your sats are good.

Extended time at and below 88% needs to be managed. Note that this is with CPAP treatment and this is rarely checked. See 3 above.

Be sure to get a copy, an electronic copy is fine, of all sleep studies, and this means full copies with the charts and tables, not just the summary. Also a copy of any prescription that is issued.

Post a copy of your studies here, with your personal info redacted.
Fred Bonjour - Project Manager and Lead Tester for OSCAR - Open Source CPAP Analysis Reporter 
OSCAR

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#3
RE: spO2 measurement
Thanks, bonjour, for the info! 

Regarding my question about the OSCAR report, I guess what I mean is why would the same data that shows 4  drops/events of 3% ODI on the SleepU software show a "SpO2 drop index" of 7.31 in OSCAR? What specifically does that metric represent in OSCAR?
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#4
RE: spO2 measurement
an Index is events per hour
Fred Bonjour - Project Manager and Lead Tester for OSCAR - Open Source CPAP Analysis Reporter 
OSCAR

Download OSCAR
New to Apnea? Helpful tips to ensure success
Soft Cervical Collar
Mask Primer
Dealing with a DME
Organize Charts
Attaching Charts

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.
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#5
RE: spO2 measurement
Interesting. I guess it must be either a discrepancy between the SleepU software and Oscar or a different percentage threshold. Do you know what is the specific criteria (i.e., a drop of what %) for OSCAR to count an "SpO2 drop index" event? It's not clear by the name of the metric.
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#6
RE: spO2 measurement
I haven't compared the thresholds between OSCAR and O2 Insight Pro. Have you tried changing the oximetry parameters in OSCAR?
Crimson Nape
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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.
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#7
RE: spO2 measurement
I have not. I didn't know you can change the parameters. I just imported the data and viewed the report
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#8
RE: spO2 measurement
Look in, File → Preferences → Oximetry.
Crimson Nape
Apnea Board Moderator
www.ApneaBoard.com
___________________________________
Useful Links -or- When All Else Fails:
OSCAR Chart Organization
Attaching Images and Files on Apnea Board
Beginner's Guide to Sleepyhead and OSCAR
Apnea Helpful Tips

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.
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#9
RE: spO2 measurement
Got it. Thanks much! I hadn't seen those preferences. This helps clarify things for me.

So I believe the answer to my question is that OSCAR allows you to configure the "SpO2 drop index" metric to your own criteria - with the initial/default setting set to count drops of at least 3% for 8 seconds.

For my changes to the preferences to take effect, it looks like I need to "purge" the oximetry data I imported, then re-import it. I don't see a way to refresh the report after the data is already imported.

I don't see any especially useful explanation of this on the wiki (http://www.apneaboard.com/wiki/index.php...OSCAR_Help), but perhaps I missed it.

Anyway, what I've found is that to get my OSCAR results to match my SleepU results I had to set the oximetry preference in OSCAR to 4% for 13 seconds. After I do that my OSCAR report numbers match up with my SleepU report. For example, for last night:

My SleepU software shows I had 21 "Drops over 4%" and shows "Drops per Hour" of 2.6. 
My OSCAR software now shows I had 21 "SpO2 Desaturations" and a "SpO2 Drop Index" of 2.65. To get the report to reflect those numbers, matching those from SleepU, I had to first change the oximetry preferences in OSCAR to, as noted, 4% for 13 seconds.

Thanks all!

jwoodz
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