A Doctor's Take On Apple's 'Blood Oxygen' Sensor

As a physician who is infatuated with tech, I often live at the intersection of medicine and technology. Naturally, wearable biosensors have piqued my interest over the last several years. In this video, I discuss Apple Watch Series 6's "blood oxygen" sensor (essentially a reflectance pulse oximeter), what this biosensor is ACTUALLY measuring, and why the semantics can matter.

Subscribe to the channel, and drop me a comment with questions or suggestions!

-----

[ICUAdvantage]

Great discussion. You have a knack for explaining things. Keep up the great work!

[georgeadleman]

I had my Apple watch report LOW blood oxygen. Due to this my PCP referred to a Pulmonologist who did an overnight SpO2 which resulted in up to 10 minutes of SpO2 below 86%. Then he ordered a Sleep Lab study and we'll figure what to do after that. So, I feel the Apple watch alerted me to a problem (even though I am on cPAP with low AHI). Thank you Apple.

[cshull]

Huge fan man. I’m currently doing my anesthesia critical care fellowship and read your stuff all the time. I also shared your critical care reference sheet with my medical students and residents. They loved it!

[vadimpolishchuk]

This is very important for people to know! Very well said Rishi!

[BigPiePublishing]

Apple does have several disclaimers about the oxygen sensors being for exercise and well being, not medical purposes.

[tiffanylane]

I love apple and this review was so well said. I was born with a vsd, epilepsy, and hemophilia as well as ehlers danlos. I really lost out on the genetic lottery and obviously have a lot of specialty doctors who work as a team. I love technology and the advances that we are making in medicine, I have a VNS device for my epilepsy and chest ports.. So I can not wait for the day that wearable devices become common household items for healthcare, but after this video and chatting with my cardiologist trying to decide if paying to upgrade my watch was worth it, our technology isn't there yet in my opinion, but normal apple users using their watch regularly will help them home in and perfect the devices over time.

[fpat]

You raised an important point about O2 SAT’s limitation by only measuring the percentage of oxygenated hemoglobin molecules while not reflecting the blood oxygen content because it does not take into consideration of the serum hemoglobin concentration. But the same limitation also applies to the finger tip oximeter used in physician offices. The important take-home lesson should be for both Apple Watch and finger tip oximeters users to not rely only on the O2 SAT reading from the watch, but always consult a physician for evaluation of symptoms of anemia or general health concerns.

[joshuahowitt]

Thank you! This was very informative. I was evaluating if the O2 sensor was worth it for an older parent to upgrade their watch for. This was the only attribute that presented a useful upgrade. She already uses a pulse oximeter that works fine. I thought that the watch might be useful for an on-the-go, or just while hanging around, option. It still might be. But the specific caveat you identified was enlightening because I never knew there was a specificity in the way oxygenation is measured. Thanks! It might be just as well to have a few extra pulse oxymeters around that measure reliably in real time. I subscribed!

[tweetiebird]

I'm glad to see a Dr to take the time to put out a youtube video to inform people of the pit falls of relying on readings for Oxegen blood levels. I was excited to find out apple had a watch that could monitor this anytime by just a click of the watch. I have COPD and need to keep an eye on my levels. Thank you for clarifying the accuracy issues and excellent presentation.

[mds]

Great job explaining the limitations with the current Apple technology. Very fair and balanced.

[UApro_]

Thank you very much I was close to buy 6 series just to use that oxygen level feature but now I'll decide about SE or 5 series watches

[egg]

While I didn’t actually catch it as I haven’t had my series 7 very long, it could have told me I was going to be sick up to 2 days before I had any symptoms.

My usual resting heart rate is around 50, on Sunday it spiked up to and then held at around 80, Wednesday I lost my voice, Thursday I went home feeling like crap, and now Friday I’m really bad.

Will be making sure to check my resting heart rate from now.
As for my blood oxygen reading, it dipped a little, but not enough to actually notice anything strange.

[saravucic-sneperger]

duuude sir your voice is so soothing
and thanks a lot for the info!

[joeygan]

Thanks for the explanation. Would love to also hear your explanation on these smartwatches on measuring SPo2 in the context of acclimatisation when climbing. what should we keep in mind on its methods, accuracy?

[paulineanne]

During my last infusion for my RA treatment; my blood oxygen was 90 then 91 my nurse was concerned with low number; I started retaking my asthma inhaler (was having issue of being tried and sleeping all the time) thinking about getting Apple watch or the blood oxygen senor

[robertlongoria]

I know" a difference" now.
However is there a sensor that can measure hemoglobin density in the blood so we can have a more complete picture of respiratory health?

[georgehny]

I was looking at how to explain O2 saturation etc to a friend that has a 94 O2 sat but is having major problems. Went to his cardiologist and is repeating tests that showed red blood cell. I use both the same Oximeter you showed and do wear Apple watch though not the series with Oximeter yet. They are great tools but as you point out only one piece of a huge puzzle called health. I have forwarded a link to this for my friend to watch. Thank you for taking the time to explain this so understandably.

[Maillady]

Ty for this detailed explanation! I was A little leery about the blood oxygen w/my apple 7 series watch level compared to my pulse oximeter on my finger because there are many points difference. I love all of my Apple devices however I will stick with my doctors recommended devices for more serious issues.

[davidbratchersr]

Great Video, thanks Doc!! It was an awesome explanation ! Facts, and figures without bashing a great product and feature. Wonderful explanation!

[CT-umzq]

So, if you are suffocating due to low hemoglobin, an 02 sensor won't detect it?😨