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

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.

Apple Watch Series 6 Does Not Measure “Blood Oxygen”: https://rk.md/2020/apple-watch-6-does-not-measure-blood-oxygen/
What Does A Pulse Oximeter Tell Us?: https://rk.md/2016/pulse-oximeter-tell-us/

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50 Comments

  1. @NicksStuff on January 4, 2025 at 6:18 pm

    The point of these measurements isn’t to know your hemoglobin concentration but to detect sleep apnea and similar disease

  2. @MullenMindfulness on January 4, 2025 at 6:19 pm

    Hi, great video. I have sleep apnea and use a CPAP nightly and I also live at altitude (7500 ft). Do you have an opinion about the pending Masimo Freedom watch as it relates to its tech, accuracy, and providing more reliable data vs. other watch brands? Thanks!

  3. @gerardoesquivel9919 on January 4, 2025 at 6:19 pm

    Then what would be the most accurate and best way to measure real oxygen levels?

  4. @lephotographinc on January 4, 2025 at 6:20 pm

    Thank you Doctor. Greatly appreciate this video.

  5. @arieisenberg2266 on January 4, 2025 at 6:24 pm

    Treat the pt, not the monitor. SPO2 is one little piece of information, it like many things is overused and dangerous in the hands of the uneducated. In short, it is not very sensitive for overall oxygenation, but very specific for not having oxygen saturation.

  6. @OkiDingo on January 4, 2025 at 6:24 pm

    The Apple Watch is so inaccurate. My Apple Watch 7 will say 91 – 93%, and a finger pulse oximeter will say 98%

  7. @dave1ahc on January 4, 2025 at 6:24 pm

    That was a great explanation I hope that everybody got the idea that if you’re so low on hemoglobin you could be having tissue hypoxia and still show up as 98 or 100% saturated because everything that you have a saturated but there’s nothing there to carry the oxygen! Nice back to basics for this respiratory therapist as well thank you so much!

  8. @DigitalAndInnovation on January 4, 2025 at 6:24 pm

    So its a pulse oximeter- and other than using reflected light- it comes with the same exact disclaimer as a SpO2/PLETH sensor in the hospital- pretty darn straight forward…

  9. @watchthis90 on January 4, 2025 at 6:25 pm

    Hi! My watch says I’m between 80% and 100% today. Am I need to worry about that? The everyday average is 92%.

  10. @sensnowy on January 4, 2025 at 6:26 pm

    Thank you for this. What about the oura ring or device that transmit light from a to b? Could a watch band help these o2 level readings when it takes 2 point readings ?

  11. @donnalee574 on January 4, 2025 at 6:27 pm

    Thank you for the explanation! ❤

  12. @jacquesmertens3369 on January 4, 2025 at 6:28 pm

    You’ll never convince the brainwashed followers of the Apple Cult that anything could be wrong with any Apple product.
    Their former cult leader died because he only ate fruit and ignored his doctors.
    Apple Cult members don’t see a doctor as long as their watch tells them they’re doing OK. And then they die, just like their guru.

  13. @vidonivision on January 4, 2025 at 6:28 pm

    The problem of a well saturated anaemic person is not isolated to Apple’s reflectance oxymetry. I think this should’ve been made clearer in the video because some may think that they can rely on an oximeter more than an Apple Watch, even though the watch is always on their wrist and just as valid as an occasionally used finger tip oximeter.

  14. @t.bailey5043 on January 4, 2025 at 6:29 pm

    Why must I not wear a fitness tracker when I’m getting blood work done? Would fitness tracker effects your results?

  15. @Jeeksters on January 4, 2025 at 6:30 pm

    I have a question
    Can you say all this in English please hahaha
    Naw I’m kidding. Great video doctor!

  16. @MargisonGODBEY on January 4, 2025 at 6:31 pm

    Apple Watch is saying resting heart rates of 57 and I’m not an athlete and o2 of 93 should I call the dr

  17. @thethoughtessencepath on January 4, 2025 at 6:32 pm

    Oh well, I guess that’s another one the adage creators got wrong. An Apple a day may not keep the doctor away, make sure your Apples are ripe! Thanks, Doc. This one is for you🍎!

  18. @kandymich4861 on January 4, 2025 at 6:35 pm

    I get it the other way around. My watch gives a 94 and my finger monitor gives me 98.
    So, what’s up with that?

  19. @dmaifred on January 4, 2025 at 6:36 pm

    So the concern is for Apple watch AND finger devices?

  20. @ICUAdvantage on January 4, 2025 at 6:38 pm

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

  21. @maryannwilks7689 on January 4, 2025 at 6:39 pm

    So as someone with PAH and on oxygen 24/7 what device do you suggest I purchase to alert me of low oxygen levels? Id like to wear something all the time.

  22. @noahman27 on January 4, 2025 at 6:40 pm

    Thank you so much for sharing this useful information about the usefulness and uselessness of some of these bio-feedback data from smart watches. I was interested in getting a device to help track my sleep and 02 levels as i might possibly have sleep apnea. Are there any devices that are any good at detecting whether or not you might have sleep apnea that you can use on your own and share the resulting reports with your doctor? Will an Apple watch be a waste of money for that?

  23. @schwalleyf on January 4, 2025 at 6:41 pm

    One other thing I am a pulmonary physician. If you have 5gm of HGB or less you will not observe cyanosis. I agree but the apple watch is great for many pulmonary conditions.

  24. @CT-um7zq on January 4, 2025 at 6:42 pm

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

  25. @marksargent2440 on January 4, 2025 at 6:42 pm

    Your eyes lit up once you spoke about what technology can do but also that we need not to put all our faith in the flashy apple waches but check into a drs now and again😊

  26. @trevormason3825 on January 4, 2025 at 6:42 pm

    Really great explanation. Thank you

  27. @LakitaGaleDuton-br8zf on January 4, 2025 at 6:43 pm

    Your content was excellent. You presented it well, and I wish you well in all your endeavors. I’m sure I speak for many people when I say, "It was helpful. Thank you.

  28. @GerryJ08 on January 4, 2025 at 6:44 pm

    Great explanation. Well presented. What would you recommend for an in home pulse ox reader?

  29. @MrMitchjos000 on January 4, 2025 at 6:48 pm

    I am considering a apple watch with a pulse ox to monitor oxygen saturation levels for asthma related issues. Do you think it would still be reliable for that?

  30. @tylert2514 on January 4, 2025 at 6:48 pm

    Great job

  31. @peterfslife on January 4, 2025 at 6:48 pm

    PLEASE DO NOT trust the medical monitoring functions in the Apple Watch! ESPECIALLY THE EKG, AND O2 Sat! The O2 sat monitor is not placed in a way to APPROPRIATELY monitor Oxygen Saturation! The EKG is not accurate! It can’t tell you if you’re in A-Fib, SVT, or any other rhythms! It can’t accurately trust that! GO SEE A PHYSICIAN!

  32. @nigel900 on January 4, 2025 at 6:50 pm

    I understand and appreciate the critique and explanation between a clinical O2 reading vs a store bought device, but unless I’m bed ridden in an ICU, I’ll have to use what’s best available. I’m a recovering COVID patient suffering from COVID fibrosis. My pulmonologist recommends I cary a (store bought) pulse ox unit to monitor as I use supplemental oxygen. The Apple Watch, though considerably more expensive), would make monitoring my O2 levels much easier.

  33. @jeanneeber on January 4, 2025 at 6:50 pm

    Wonderful info. Thanks! I wonder why Apple lost their lawsuit to Masimo for theft of their patent on the "light emitting technology" that was invented & patented by Masimo? Maybe Masimo also invented the reflectance technology you’re speaking about as well?

  34. @manuelmorales946 on January 4, 2025 at 6:52 pm

    I was told this will maybe help dectect a seizure coming is this true or maybe give some type of alert that one is coming on

  35. @laurelctlady4557 on January 4, 2025 at 6:54 pm

    My Apple Watch shows an 84-88% oxygen level during 3am-7:00 am. Not sure it’s accurate.

  36. @ashleighnichole8197 on January 4, 2025 at 6:55 pm

    As a respiratory therapist,I love this video

  37. @discovertogether294 on January 4, 2025 at 6:57 pm

    so get the cheaper watch and the finger test device?

  38. @DanielRamos-tq7cz on January 4, 2025 at 7:01 pm

    I just stick to a good picketer over any watch

  39. @R2jjj on January 4, 2025 at 7:02 pm

    Rightnow its showing 89% is it good ?

  40. @roady1710 on January 4, 2025 at 7:04 pm

    Well, I just got my Apple series watch nine and Apple has discontinued blood oxygen. Do you no longer have that I have an Apple series 7 that does have it on there but what do you suggest let’s say from Amazon or manufacture for the fingertip is a good O2 sensor.???

  41. @jacquelinebrunner899 on January 4, 2025 at 7:05 pm

    I never understood why by finger measurements were about 2-5 points lower than my Apple 8. Thank you

  42. @anand.b6883 on January 4, 2025 at 7:09 pm

    Fun-Fact : The sensor apple uses in their watches were stolen from a Medical company, Masimo laboratories.😂 But got Caught Red-Handed now

  43. @zaftra on January 4, 2025 at 7:10 pm

    that was interesting

  44. @nicoladalbenzio9712 on January 4, 2025 at 7:10 pm

    Apple needs a disclaimer. If you’re tired, faint, dizzy, bleeding, disoriented, bruising easily, call your Dr no matter what your watch says.

  45. @CeeJayKay on January 4, 2025 at 7:12 pm

    I have a question. I am 73 and have a lot of shortness of breath. In 2015 I had a triple bypass, and presently I have apnea but cannot use the cpap machines because it makes my stuffy sinuses even more stuffy and basically I can’t sleep with the machine on. I’ve started gargling warm salt water before bed which has improved the sinuses greatly so I’m glad that’s helping. My question to you is why don’t either my general physician or cardiologist seem to be concerned at all about my shortness of breath? I have stress in my job so I usually blame the shortness of breath on that but that’s not the only time I get it. Thank you for your thoughts on this.

  46. @albertdonnay8295 on January 4, 2025 at 7:12 pm

    Toxicologist here to say Dr. Kumar is WRONG about what SpO2 measures. The SpO2 in pulse oximeters is NOT a measure of the oxygen bound to Hb.

    SpO2 is actually a measure of the sum of oxygen and carbon monoxide bound to Hb, because pulse oximeters with 2 wavelengths cannot tell them apart (COHb also peaks at 660nm).

    This is not a big error if you are healthy with normal COHb around 1%. But arterial COHb may be 5%, 10%, 20% or more from either exogenous (inhaled) and/or endogenous (internal) sources of CO exposure (as in COVID) — in which case your actual oxygen level would be that much lower. Only pulse CO oximeters with more wavelengths, such as Masimo’s RAD57, can distinguish COHb and O2Hb, but they cost $5000 to $10000. (I have no affiliation)

    The correct way to describe any pulse ox SpO2 display is as a measure of the total O2 and CO bound to arterial Hb. If normally low methemoglobin is >1%, it also may be misread as SpO2. Since the SpO2 value is always closer to the saturation pressure of all bound Hb than to the pressure of O2Hb alone, it is more accurate to think (and speak) of SpO2 as SpHb.

  47. @BltchErica on January 4, 2025 at 7:13 pm

    I guess it’s good that you’re explaining this, but as an Apple Watch owner without knowledge on the topic I’ve never assumed this blood oxygen feature tells you how much actual blood you have, I think it’s only a few people who stupidly assume that’s the case.

  48. @neovincibeats on January 4, 2025 at 7:14 pm

    When I go to the doctors they say my blood oxygen is great but I always feel short of breath since COVID 4 months ago is the finger test enough to tell me that I don’t have enough oxygen in my blood

  49. @Oneonone2020 on January 4, 2025 at 7:14 pm

    just go see a doctor 🥃

  50. @sofnaji on January 4, 2025 at 7:17 pm

    How come you’re wearing medical scrubs at home

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