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07-04-2024, 04:27 PM (This post was last modified: 07-04-2024, 04:29 PM by MargaretS.)
Wellue O2 data vs Oscar
Because I have sleep apnea with correction by a professional oral device, I’ve had a Wellue CheckMe O2 sensor for years. During those years I’ve used the reports generated by the CheckMe to judge my “bad” and “good” nights. Recently I’ve been reading the apnea forum, and decided to try using Oscar to evaluate my apnea. Obviously, because the data is not coming from a C-pap device, there is more limited data, but I have some questions. With the Wellue, I’ve based “good” and “bad” on the O2 score and the drops over 3% and drops over 4%. Now with Oscar I find that I might not have my apnea under control as much as I thought. For instance. Last night with Wellue my O2 score was 9.6 (<90% time: 1 m 22s); drops over 3%: 12 times 1.3/h; and drops over 4%: 0.7/h). I just learned to calculate AHI from your forum, and AHI would be 19.2. With Oscar, my SpO2 desaturations: 166 (24.97%) 18.48/h. Am I correct in assuming that the Welllue calculated AHI of 19.2 and the 18.48/h desats would be generally equivalent? If so, having apnea that, with those scores, is rated as moderate does not make me happy. Using the O2 scores and 3-4% drops previously, I thought I’d been rocking it, keeping my apnea controlled. This could explain why I’m usually drowsy. My sleep neurologist said I have multiple arousals according to my original and repeat sleep studies. Have I interpreted the data correctly? I have the mandible advancement as far as possilbe on my oral device (I've recently received a new device). I was unable to use a c-pap because it completely clogged my sinuses. And BTW, this is not a criticism of Wellue. Their device has worked well, but I apparently needed to go further with my interpretation.
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.
My apologies for not replying sooner. I thought I would be notified if my post had received a reply, but I received no notification. It's only when I returned to this tab and refreshed the page that I saw the replies. Here is the formula that I used for calculating the AHI :
"Multiply the total number of hours of sleep by 60 to yield the number of minutes. For example, if the study was conducted over 6 hours, multiply 6 by 60 to yield 360 minutes. Divide the total number of events calculated in Step 1 by the total number of minutes calculated in Step 2. In this example, 250 events divided by 360 minutes yields 0.694 events per minute. Multiply the result from Step 3 by 60 to yield the AHI number. In this example, 0.694 multiplied by 60 yields 41.62. This patient would be categorized as having severe sleep apnea."
I interpreted "events" as the number of drops below 90% O2, and the number of drops below both 3 and 4% (as interpreted by the Viatom Wellue device).
Attached is the latest summary from my Oscar downloads. If you need the graphs, I'll have to do a screen grab, which may not be helpful to you. My Oscar download to my desktop apparently doesn't allow me to print the summary and graphs together. Sorry, I feel kind of stupid with this. Am I correct that the Oscar data that shows 34.92/hr the same as the AHI score?
To take a screenshot in OSCAR, use the F12 key for a Windows computer and Fn+F12 on a Mac. Please see the links in my signature for instructions on OSCAR and posting images here.
- Red
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.
I'm afraid your calculation method begs many questions and corrections (such as why would you multiply by 60 and then immediately divide by 60?!), but the bottom line remains the same: you cannot calculate AHI from the results of an oximeter test.
Some people do believe that poor results from an overnight oximeter study suggest a possibility of sleep apnea, and thus a full PSG might be a good idea, but my detailed daily studies of my own data from CPAP and oximetry do not suggest a strong correlation between CPAP-flagged events and significant blood oxygen drops.
In your calculation, you say "Divide the total number of events calculated in Step 1", but you do not quote whatever Step 1 is. What "events" is it referring to? If this is a formula for calculating AHI, it probably means apneas and hypopneas, not SPO2 drops. Where did you quote this from?
