Series 6 Blood Oxygen / Pulse Ox Has Awful Accuracy

[Omenamies]

Even my Masimo MightySat has sometimes difficulties with accurate measurements, insanely low pulse 33 bpm (I am not Usain Bolt), low SpO2 but I just delete those readings from Health App.

It’s hospital-grade pulse oximeter with five parallel signal processors. I doubt $20 pulse oximeter from some supermarket is very accurate.


The next thing I’m waiting from Apple is blood pressure monitoring. Samsung already has it, it seems to be a joke. You need to constantly calibrate it with traditional blood pressure monitor.

 

[IamScotty]

https://www.reddit.com/r/AppleWatch/comments/j59dht

 

[michsu]

It's just like with everything else, you need to take multiple tests and take an average. A trendline is more important than a one time measurement. Also, just like with how your body changes every second, the measurement will be different. For example, if your pulse drops to 35, you know that's a faulty measurement. If it's like that for more than 5 minutes measuring, then something's wrong. Just use the average and the 95-100% thing for the blood oxygen, and you should be fine. If it's lower, you probably need more exercise I think. Your blood circulation isn't very good and there might be blockage. (I'm not sure if that's it or not).

 

[michsu]

Just found this..

(16) Why you MUST know your oxygen saturations / levels! - YouTube

 

[G5isAlive]

Check out the scientific literature. Try a PubMed search.

How dry. You don't actually say anything. But since you like to do searches, I recommend you check out the difference between reflective versus transmittance spectrometry. Hint: Transmittance, such as employed by finger tip pulse oximeters by virtue of this thing called physics, is inherently easier and more accurate which translates into cheaper. So I stand by my comment that to expect an Apple Watch to be better by virtue of price is a straw argument. Apple has little choice but to use reflective spectrometry give the geometry of the wrist. Is it a medical grade device? No. Is it useful? Yes.

 

[cdcastillo]

How dry. You don't actually say anything. But since you like to do searches, I recommend you check out the difference between reflective versus transmittance spectrometry. Hint: Transmittance, such as employed by finger tip pulse oximeters by virtue of this thing called physics, is inherently easier and more accurate which translates into cheaper. So I stand by my comment that to expect an Apple Watch to be better by virtue of price is a straw argument. Apple has little choice but to use reflective spectrometry give the geometry of the wrist. Is it a medical grade device? No. Is it useful? Yes.

I’m with you, but although it is soundly logical that light “trough” is not the same as light “reflected”, recently Davies Et al. in the imperial college London showed a proof of concept measuring the reflected light, but in the ear canal (same principle than in the wrist). They concluded non-inferiority to measuring in the finger tip.

One thing that caught my attention was that they used 1 cluster of green/red/infrared LEDs and 1 receptive photodiode, versus the watch’s 4 clusters.

Then again, they used wired sensors, instead of wireless and battery operated ones.
Ref: Davies HJ, Williams I, Peters NS, Mandic DP. In-Ear SpO2: A Tool for Wearable, Unobtrusive Monitoring of Core Blood Oxygen Saturation. Sensors 2020, 20(17), 4879

There’s also a few other papers comparing measurements on several body parts (forehead, shoulder, forearm, wrist, finger tip, etc) that showcase strengths and pitfalls of each location.

I’m currently working (meaning I’m designing and writing the protocol) on a national multi centric head to head comparison of the series 6 versus the gold standard in a clinical setting.

 

[jdb8167]

I’m currently working (meaning I’m designing and writing the protocol) on a national multi centric head to head comparison of the series 6 versus the gold standard in a clinical setting.

This is very cool. Please keep us apprised of what you find if you can.

 

[Neepman]

Why not? The oximeter from Amazon is single-purpose. The Apple Watch has many many many uses, even tells time. Does your $15 amazon oximeter do even that simple thing? No? Gosh I would expect anything with a screen and chip to tell time!

The oximeter from Amazon is much much much larger (sensor wise). So yep I would expect it to be better. The oximeter from Amazon also has much better placement for consistency (fingertip) without as much movement going around (respective to the fingertip) and also closer to blood (useful for measuring blood). I would expect it to be better.

Apple Watch: Multi-purpose, miniaturized, in a difficult place to measure for a variety of reasons.... yep, I would hope the oximeter from Amazon would be better

They are very accurate. I have compared them side to side with hospital grade sensors.

 

[cdcastillo]

This is very cool. Please keep us apprised of what you find if you can.

I will. I estimate that it will take us at least 3 months to get approval in all the different centers, 1 month to recruit the subjects and 1 month to analyze the results. I hope to be looking to publish around February-march 2021.

 

[jdb8167]

What I’ve noticed is that the Blood Oxygen sensor readings are very good when I take the measurement manually but like the heart rate monitor, it is sometimes much less accurate when the measurement is done automatically by the watch. Probably because I’m moving too much. They might need to tweak the algorithm that detects too much arm movement to be a little more sensitive.