Blood Oxygen Monitoring Returns with iOS 18.6.1 and watchOS 11.6.1

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Originally published at: Blood Oxygen Monitoring Returns with iOS 18.6.1 and watchOS 11.6.1 - TidBITS

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.

Updates to bring back blood oxygen tracking

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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.

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John Gruber has a full explanation of what’s going on at Daring Fireball:

After the iOS 18.6.1 and WatchOS 11.6.1 software updates, the iPhone and Apple Watch need to download an over-the-air asset to enable the redesigned Blood Oxygen feature. This apparently may take up to 24 hours. Until this asset download happens, the Blood Oxygen app on your Apple Watch will still say “The Blood Oxygen app is no longer available”. To jump-start the download, users can open the Health app on their iPhone, and the ECG app on their Apple Watch. … UPDATE: I am reliably informed that you don’t need to take an ECG reading on the watch. Just opening the ECG app is enough to trigger the asset download needed by the Blood Oxygen app.

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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.

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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?

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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.)

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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.

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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.

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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.

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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:

  • Oxygen level
  • Pulse rate
  • Perfusion Index
  • Heart rate (based on ECG waveform)
  • Activity (motion)
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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…

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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.

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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.

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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.

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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 …

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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?

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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.

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Apple provides no interface for skipping, but you don’t have to let any update install.

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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?

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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 …