Software patents are a scourge.

> The iPhone will now calculate the ratio of absorbed red to infrared light, then apply calibration constants from experimental data to estimate blood oxygen saturation.

Sorry, maybe I missed it - but source for this?

Crazy that this is a 'patent'. We did this experiment in high school 30 years ago.

Phenomenal that the patent is only violated by doing it with the watch cpu but not by funneling the data to a separate cpu. The surest sign that it's a bullshit patent.

That is interesting, had not understood this previously.

Masimo only refined pulse oximetry in the 90s, as pulse oximetry was invented in the 1970s (prior oximeters did not resemble the devices seen today). Everything after that has been tweaks/improvements to the base method, but I wouldn't call them the inventors of the technology.

The only IP that companies can own now are specific methods/improvements, not the base idea of measuring SpO2 with light. All Apple has to do is avoid the specific improvements that Masimo owns and they are fine.

https://en.wikipedia.org/wiki/Pulse_oximetry#History

I'm out of the loop, can this be done without drawing blood now?

i'm not a smartwatch fan for the most part but i'd get one for CGM use if it meant no more knocking my sensors off walking through doors (because i'm apparently incapable of walking without moving like a wacky inflatable tube man) or nasty adhesive residue stuck on my arms.

Apple says:

> This update was enabled by a recent U.S. Customs ruling.

I can't find the ruling in question, though, so I'm not sure what they mean.

That's the capillary refill test which tests circulation and perfusion. Doesn't really tell you anything about oxygen levels.

In contrast my Garmin and finger pulseox match exactly.

Indeed, just generally this is a silly feature that was used to sell updated devices, but has almost no value to end users. There is shockingly little diagnostic value of the reading unless you are in such a critical state that you likely want something better than an incredibly unreliable and inaccurate smartwatch feature cram.

For anyone remotely healthy, 100% of the time your real value will be between 95% and 99%, and there is almost no diagnostic value to it. Heart rate is actually interesting and is something you can learn from and work towards. SpO2 is just "eh...neat".

Wouldn't you already be super dead with a true reading of 80? Or at least unable to cognitively interpret the reading?

That caused me nightmares when I was first diagnosed with sleep apnea. I would check my oxygen levels during the sleep to see if my treatment is effective. Even though the CPAP machine would show a few short events Apple Watch would show levels as low as 75%. Thankfully in my next sleep study I learned that my oxygen levels were consistently above 95% and the watch is indeed very unreliable (how snug it is, which direction it is facing etc highly affect the results).

The FDA standard for blood oxygen sensing is within 6% absolute, 95% of the time.

So variability in the sensing is pretty normal, and you want to look at long-term trends rather than individual measurements.

On their best days, they're accurate to within 2-4%. But so many things can trip up the reading, like melanin:

  As a result, for darker-skinned patients, oxygen saturation readings can read as normal when they are, in fact, dangerously low.

https://publichealth.jhu.edu/2024/pulse-oximeters-racial-bia...

When everyone starting looking at every percentage point of their SpO2 during COVID as if it were life or death, the FDA had to remind people of this:

https://www.fda.gov/news-events/fda-brief/fda-brief-fda-warn...

You would be unable to read an accurate pulse oximeter at 80% because you would have lost consciousness. Doctors have to worry about false negatives just as much as false positives with those things.

That this is okay?

https://rulings.cbp.gov/ruling/H335304 maybe this - from January 2025

It appears the patent is for "User-Worn Device for Noninvasively Measuring a Physiological Parameter of a User". So Apple is simply moving the logic to a non user-worn device - like a phone - to get around the problem. (this is my quick read / conjecture)

Here is the original patent https://patents.google.com/patent/US10912502B2/en

iPhone can control Apple TVs, and is able to detect which device you are nearest to and auto select it (if you have multiple)

Also all my TVs also have apps that function as a remote control.

Interestingly enough my main TV an LG has a remote that controls the tv using RF. I don’t even know if it would work with an IR blaster.