Blood Oxygen Monitoring Returns with iOS 18.6.1 and watchOS 11.6.1
A U.S. Customs ruling has allowed Apple to restore blood oxygen readings for U.S. Apple Watch buyers for whom the feature was disabled in early 2024. For these users, the redesigned approach works by measuring on the Apple Watch, processing data on the iPhone, and displaying results in the Health app.
After medical device maker Masimo’s patent infringement complaint regarding the blood oxygen sensor on the Apple Watch, Apple was compelled in late 2023 to cease selling the Apple Watch Series 9 and Apple Watch Ultra 2 in the U.S. (see “Apple to Stop Selling Two Apple Watch Models in the US Due to Import Ban,” 18 December 2023). Soon after, Apple negotiated a workaround that allowed it to resume sales by throwing a software switch that disabled the blood oxygen sensor for new Apple Watch buyers in the U.S. (see “Apple Disables Blood Oxygen App in New Apple Watches,” 18 January 2024). Hardware remained unchanged, and models with blood oxygen sensors sold before the ban continued to have access to the watchOS Blood Oxygen app. Sales of Apple Watch models in other countries were also unaffected.
Apple has been fighting the legal case all this time and seems either unwilling or unable to settle with Masimo. However, a recent U.S. Customs ruling has enabled Apple to make a technical compromise. Apple says:
Users with these models in the U.S. who currently do not have the Blood Oxygen feature will have access to the redesigned Blood Oxygen feature by updating their paired iPhone to iOS 18.6.1 and their Apple Watch to watchOS 11.6.1. Following this update, sensor data from the Blood Oxygen app on Apple Watch will be measured and calculated on the paired iPhone, and results can be viewed in the Respiratory section of the Health app.
This new iPhone-focused experience won’t apply to earlier Apple Watch units that still have the Blood Oxygen app, nor to units purchased outside the United States.
It’s possible that Apple hasn’t been interested in settling with Masimo because the feature isn’t that important for everyday wellness. As Rich Mogull wrote in “The Paramedic’s Guide to Blood Oxygen and the Apple Watch Series 6” (22 October 2020), those with known lung disease can use it to determine if their condition is worsening, and people who suspect respiratory issues like pneumonia or COVID-19 can use it to decide if they need immediate help. Useful, but not something most people would use regularly.
Rich also said it could theoretically help identify sleep apnea, but he felt the data collected during sleep wasn’t reliable enough. Last year, Apple introduced sleep apnea notifications in watchOS 11, saying that it uses the accelerometer to detect interruptions in normal respiratory patterns, a technique Apple validated in a clinical study.
In short, if you have an Apple Watch Series 9, Apple Watch Series 10, or Apple Watch Ultra 2 on which the blood oxygen sensor is disabled, update to iOS 18.6.1 via Software Update and to watchOS 11.6.1 through the Watch app. After updating, you can view blood oxygen data on your iPhone in Health > Browse > Respiratory > Blood Oxygen. Apple doesn’t call out any other changes or security fixes in these updates, so if your Apple Watch isn’t affected or you’re not interested in tracking blood oxygen, you can ignore these updates.
I installed the updates on my iPhone and Apple Watch 10, but the Blood Oxygen app still claimed that it couldn’t work. I tried a variety of things to activate it with no success. However, a tip on MacRumours (initially from Reddit) worked — open the ECG app and run an ECG. Afterwards, the Blood Oxygen app worked as it was supposed to.
I think that manually taking my heart rate via the Heart Rate app would have also awakened the Blood Oxygen app.
John Gruber has a full explanation of what’s going on at Daring Fireball:
I still haven’t seen a full explanation of exactly why it was updated to work this way. The assumption is that it’s to work around the patents, but the patents still seem to cover this same method. The ruling has been mentioned, but I’m not sure what about the ruling changes things in this way. I don’t understand why it was allowed to come back like this but not as it was.
With regard to settling, my understanding is that on Masimo’s list of settlement demands is a written, public apology for infringing on their technology. I believe, and this is speculation, that this is the bridge too far for Apple. As I recall, Masimo thought they had a deal with Apple for the technology and that Apple broke that deal and went ahead without them, and they feel personally insulted.
With regard to the functionality coming back, on my S10 as soon as I opened the app immediately after updating, the “not available” screen flashed up then immediately went away to be replaced by the new instructions.
Which brings me back to why I find this new method strange. It’s more or less functionally equivalent, just that it doesn’t show the result on the watch. Maybe they always intended to start doing it this way and just weren’t able to implement it.
Isn’t the workaround that processing and display no longer occur on Watch itself, but rather on iPhone, while the Massimo patent can be interpreted to apply to processing and display directly on the wearable?
Although I have an Apple Watch series 7, which isn’t subject to the ban, my experience with the oximeter has been less than satisfactory. Most other biometric features on the watch work well.
I was particularly interested in an oximeter for high altitude flights I made (~20,000 ft) using an O2 mask or cannula. The watch oximeter never worked in the plane due to slight motions which prevented a reading. I recently tested the device (on the ground) and it took about 3 tries to get a reading. Others might have a better experience but I wouldn’t miss its absence in a new watch (also, relying on the phone is an awkward work-around).
I seem to remember a Washington Post article which related similar experiences with the accuracy of the device. With cheap oximeters readily available (and very reliable and easy to use), I am not sure how useful an oximeter on the watch really is. (Though a continuous monitoring of blood O2 can be useful for health monitoring, particularly with covid still active.)
Isn’t Masimo a patent troll, not a company that actually designs, manufactures, and sells products? If it isn’t then what it is doing is certainly typical of patent trolls.
I agree that it’s not so useful for spot readings. It is quite useful for tracking during sleep and preserving a record via the Health app.
John Gruber thinks so, but Masimo produces quite a lot of health care specific products (Masimo - Wikipedia ).
Let’s remember the sequence of events – Apple & Masimo met in 2013 to talk about Masimo’s pulse oximetry technology, failed to come to agreement, and Apple promptly hired away the engineer that designed it and 30 others who had worked on it to create the capability in the Apple Watch. That’s not definitive, but it’s sure sketchy, and sketchy enough that the judge found Apple liable.
Whether they’ve found a genuine workaround is not clear (the customs court decision isn’t availably publicly yet), but I wouldn’t trust Apple’s words on it.
Not at all true. But they sell professional medical devices, usually through doctors and hospitals, not directly to consumers.
I’m sure the Apple Watch is seriously cutting into sales of their W1 heath monitor watch.
It’s a smart watch designed specifically for doctors to have continuous monitoring of patients for post-surgical recovery, chronic care and patient management.
It is focused on doctors, not on the users wearing it, but it measures many of the same things the Apple Watch does:
I guess this is good news? I was lucky enough to snag the Ultra as an Open Box before Apple stopped the feature on further watch sales. And agree with @warrennn that it’s not a stellar oximeter. During Covid, we picked up an O2 meter (pinches your finger and gives pulse and O2) that was consistent and higher than the Apple watch version. Maybe not as convenient as you have to add batteries and put on your finger, while the watch is mostly worn on the wrist daily.
Future thinking ahead, it would be great to have a glucose/O2/temp/pressure/ovulation device in a wearable like a watch. And able to send the data to your physician on request, and securely/encrypted.
In other news, Apple’s watchband prices are crazy. $100 for a nylon strap? I guess I was lucky a friend got me a Coach leather strap as a gift…
For the Ultra series, yes. But even $50 for the series and SE watches is ridiculous.
That said: I’ve tried a few off-brand straps and I hated them all.
I’m hoping one day Apple will allow you to buy a watch without a strap for those of us who already have plenty.
I’m perfectly fine with the new method. I don’t really need to see the data directly; I find it more useful as one of the many metrics being tracked by the Apple Health app. If I want to see it directly for some reason, I use the fingertip sensor similar to what my doctor’s office uses - but I rarely need that unless I’m sick. Having the aggregate data over time in the health app seems more useful overall for health tracking.
If you know where to look, you can find genuine Apple bands in discontinued colors at steep discounts. For example, Woot currently has nylon solo loops for $15(list $49) and braided solo loops for $30 (list $99).
Note that solo loops must be fitted in advance; they are not adjustable.
my watch is a series 8 and blood oxygen has always (sorta) worked. however, apple is still insisting upon installation of the 11.6.1 update. skipping is not an option.
meanwhile the phone has said nothing about 18.6.1 …
update: the phone is now demanding an update.
being paranoid and all, can anyone confirm that the update won’t change the behaviour of older machines?
Nobody can guarantee that, but I’ve seen no reports from anybody yet of any new issue. Considering that the change is quite minor, it would seem to be a no-brainer to update, especially if you want the blood-ox feature.
Apple provides no interface for skipping, but you don’t have to let any update install.
My husband is one of those with a chronic issue (interstitial lung disease) and he’s kept his “older” watch with the oxygen sensing/reporting for that specific reason. When we’re out hiking in the hills, he always has his watch and phone–carrying an extra pulse oximeter to track his oxygen is just one more thing to bring. That said, the ease of using the watch is tough–it sometimes takes three or more tries to work; even a little bit of movement of his arm throws the sensor off it seems. I’m wondering if a newer watch has a less-touchy sensor system for oxygen testing?
true enough but my watch buzzes me daily to install the update. also the prompt for ignoring the update is just “remind me later” not “go away; not interested”.
in the past certain updates were not offered to devices to which they didn’t apply. word is this update doesn’t apply to my watch yet there it is …
I have an Ultra 1 and and Watch 6 which I got during the pandemic. I’m monitor blood oxygen on a daily basis. I’ve compared to a finger pulsiometer and find the results to track closely. I disagree about the usefulness of it on the watch. This upgrade makes my getting an Ultra 3 more likely.
My theory is that the measurement device requires direct, hard contact with the skin to function correctly. If the wrist moves at all, contact will be lost, and no reading will occur. Fingertip oximeters use spring tension to keep contact. I’ve also done a sleep apnea test where the oximeter surrounds the finger, and an air bladder is used to secure the finger.
I think if you attached the watch tightly enough to hurt, you’d get a reading every time.
Now if we could only get a decent continuous glucose monitor (CGM) on an Apple Watch. My current CGM button has a ¼" needle on it, so CGM on a watch would require some sort of new and novel skin sensor (??) since my watch moves around a bit on my wrist and visits a charger at least once per day.
Curious. I’ve been ignoring 11.6.1 and haven’t been alerted yet. It’s not worth stressing over little things like this.
The customs ruling has been released.
https://rulings.cbp.gov/ruling/H351038
I’m not a lawyer, but my quick read of this is that Apple successfully argued that watches imported into the US could not calculate blood oxygen levels on their own (without the companion iPhone), so the watch was no longer infringing on the specific wording of the Masimo patent(s) in question. Personally I’m not sure I’m persuaded that this is relevant, but, again, im not qualified really to evaluate the ruling.
I would say that it would depend on the specific nature of the patent.
If the patent is on the basic tech of measuring blood oxygen through light-reflection (vs. transmission, the way most pulse-ox meters do), then I don’t think Apple’s change affects anything.
But if the patent is on the application of the tech to a wrist-mounted monitoring device, well that’s different.
IANAL either, but this seems to suggest the issue isn’t with the actual hardware in the unaltered watches, but with the software system that processes it, which always seems to be an area of patent law that looks questionable to someone like me.
In any case, I’m glad to have the feature back, even if it is a bit less convenient having to look on the iPhone to get the result rather than on the watch itself.
My understanding is the relevant patent expires in 2027, and I’m going to guess the Blood Oxygen app reappears fully functional on the Apple watches as a x.1 update as soon as it does.
I’d be interested to learn if the hardware itself is changed in the new watches that are supposed to be released this fall, though my guess is Apple
Kevin
I’m yet another non-lawyer commenting, but I think this is more a jurisdictional issue - the ruling comes from the International Trade Commision. They are not actually ruling on the validity of the patent, just on how the infringement of an assumedly valid patent affects Masimo’s international trade - and since they do not make phones, there is no “unfair trade” when importing a phone that violates the patent.
A ruling on the validity of the patent itself would need to come from a different court.
So, processing the collected data on the phone rather than the watch does not violate the patent. Couldn’t Apple take it a step further so that after processing the data, the iPhone sends the results back to the Apple Watch so that they can be seen there? The only time there would be a significant delay would be if the phone were not currently able to communicate with the watch, so that the results would not appear until the data were transferred to the phone.
From the ruling:
So Apple is saying because the watch is not showing output, it’s not infringing, suggesting that if it was showing output then Apple could not make that argument.
So one amusing (to me at least) outcome of this thread is that it made me look at my Series 8 watch to see if it had the Blood Oxygen app, which I had never used. So I did, and it does. But my measurement is “100%”. So either it’s not very accurate, or I’m in such good health that it doesn’t matter.
The inimitable D C Rainmaker noted the reintroduction of SpO2 on Apple Watch in his short article Apple Watch US Users (Re)Gain Blood Oxygen Feature. I believe, after reading several of his in-depth reviews on SpO2 monitoring on the Apple and other devices, that he is sceptical about the usability of this monitoring, for athletes at least.
I see there is a 2019 Mayo clinic paper concluding that “Although smartwatches are able to provide SpO2 readings, their overall accuracy may not be sufficient to replace the standard photoplethysmography technology in detecting hypoxia in patients with COVID-19.” Is hypoxia the main issue patients (rather than athletes) are looking to detect, and has tech improved much since then, I wonder?
Yeah, as I was wondering over multiple threads — does Masimo agree with this? The answer is no:
This doesn’t surprise me. If you are checking for an actual condition, using a more traditional monitor (e.g. a clip on your finger) should definitely be used.
But a monitor that is continuously taking measurements (e.g. a watch) that can alert you to something unusual is also of benefit even if the alert is only accurate enough to ask you to take a reading with a better device.
I’m interested to know if this is the case. If false positives or false negatives occur more than – say – 10% of the time, is a watch useful for this important data?
I guess this is similar to the fact that most sports watches struggle to get good heart rate readings because wrists are just a terrible place to read that information. My Polar H1 monitor, which I put on my upper arm, provides comparatively rock solid readings.
The watch format is fun but using the case as a sensor station doesn’t suit all cases, and I wonder if SpO2 is one of those.
I’d say that if you’re wearing a smart watch for the purpose of measuring health data like SpO2 levels, then you’re making a mistake and should instead use a device meant for that purpose.
But, if you’re wearing a smart watch anyway (e.g. because you like taking phone calls on your wrist or running its apps, etc.) and the health monitoring is something you get for free, then I don’t see a problem. Just like the other things it monitors in the background, like fall detection and AFIB detection. If it alerts you, then you can follow up by consulting with your doctor.
If it fails to alert you (false negative), then it’s no worse than if you weren’t wearing it. And if it alerts you too often (false positive), I assume you’ll be able to turn it off. As long as you don’t assume that a lack of alerts is the same as a diagnosed clean bill of health, then what’s the problem? (Of course, some people will do that, but people believe all kinds of unreasonable things.)
As somebody who has had blood oxygen background readings for almost three years, since buying the Ultra, and as somebody who is very healthy and doesn’t really need to monitor blood oxygen levels, I wouldn’t miss it if it doesn’t ship with the (presumed) Ultra 3 this autumn when I am ready to upgrade. It seems mostly accurate, with occasionally laughable readings in the 80s, but otherwise readings in the 95-100 range for me. At any doctor’s office visits I am always 99-ish. But I’d welcome it if I had a health condition where monitoring blood oxygen would be helpful, so it would be nice if Apple shipped it. It would be nicer if they hadn’t blatantly used someone else’s patented technology without a license and with the full knowledge that the patents existed.
The heart rate sensor itself has been great since I’ve owned an Apple Watch, since early 2017.
My graph for the last year:
Really any reading under 95 is probably not right. I just took a manual reading, using Apple’s suggestion for a proper reading - “Stay still, and make sure your wrist is flat with the Apple Watch facing up; Tap Start, then keep your arm steady for 15 seconds” - 100%.
That’s great. Since I’m a bit of a sceptic about the accuracy of write-based heart readings (never mind SpO2), I’d be interested to know if you verified those results with a chest strap or something similar.
I don’t know enough about Bayesian theory to know if inaccurate test results are worth having; I guess it depends on the degree of inaccuracy.
Not a chest strap - I used an upper arm strap for a short while after I first got my Apple Watch (I used it for a while before the Apple Watch), but stopped bothering when I realized that the watch was matching it.
The 3 year old cover for my iPad is falling apart. Apple can’t claim that it is a quality product, although it has a quality price.
A quick read was that Massimo uses signal processing to improve accuracy. These sort of patents are difficult because it is fairly obvious that is the way to improve accuracy, so there needs to be something clever in the processing. It may be that Massimo made a mess of the patent and made it for devices only in contact with the user.
Yes, basically you are healthy. Sitting in front of a computer there is no reason that someone healthy should be short of oxygen. Feeling that you aren’t getting enough air in when you breathe is likely a good sign that your blood oxygen is low. Maybe try it after running or strenuous walking.