I'm not dead yet Pixel Watch 3 gets FDA approval to alert you if youre dying But you'll have to wait a bit longer to turn the feature on. Ryan Whitwam Feb 26, 2025 4:35 pm | 20 Story textSizeSmallStandardLargeWidth *StandardWideLinksStandardOrange* Subscribers only Learn moreGoogle released the Pixel Watch 3 last fall alongside the Pixel 9 family, sporting the same curvy look as the last two versions. The Pixel Watch 3 came with a new feature called Loss of Pulse Detection, which can detect impending death due to a stopped heart. Google wasn't allowed to unlock that feature in the US until it got regulatory approval, but the Food and Drug Administration has finally given Google the go-ahead to activate Loss of Pulse Detection.Numerous smartwatches can use health sensors to monitor for sudden health events. For example, the Pixel Watch, Apple Watch, and others can detect atrial fibrillation (AFib), a type of irregular heartbeat that could indicate an impending stroke or heart attack. Google claims Loss of Pulse Detection goes further, offering new functionality on a consumer wearable.Like the EKG features that became standard a few years back, Loss of Pulse Detection requires regulatory approval. Google was able to get clearance to ship the Pixel Watch 3 with Loss of Pulse Detection in a few European countries, eventually expanding to 14 nations: Austria, Belgium, Denmark, France, Germany, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. It noted at the time more countries would get access as regulators approved the feature, and the FDA was apparently the first to come through outside of Europe, boosting support to 15 countries.The Pixel Watch 3 doesn't include any new or unique sensors to power Loss of Pulse Detectionit's just using the sensors common to smartwatches in slightly different ways. The watch uses a "multi-path" heart rate sensor that is capable of taking readings once per second. When the sensor no longer detects a pulse, that usually means you've taken the watch off. It's quick to make that determination, locking the watch in about a second. That's great for security but a little annoying if you were readjusting it on your wrist.Under normal circumstances, second-by-second heart rate data from the Pixel Watch 3 is logged in the Fitbit app. Remove the watch, and that data stream is interrupted without triggering an emergency call. However, the wearable can rope in other sensors, like the body temperature sensor and the accelerometer, to determine if your pulse has vanished not because you've removed the Pixel Watch but because your heart has stopped beating.So your heart stopped beatingA stopped heart is obviously a big problem, leaving your average human being just a few minutes to get help. The Pixel Watch 3 could theoretically help make the most of those crucial minutes following cardiac arrest, overdose, or another event that causes a heart stoppage.Google says the feature relies on a multi-step check that was tested with hundreds of thousands of hours of data. The goal was to ensure Loss of Pulse Detection can take action when you need it without false positives. The FDA's approval doesn't mean the feature will always work, but it's accurate enough to release to the public. Still not sure? Google Research has also published a paper in the journal Nature today, which explains how Google validated the technology. Loss of Pulse Detection When Loss of Pulse Detection is triggered, the Pixel Watch 3 sounds an alarm and gives you a 20-second countdown. If you clear the warning or simply move around, the watch will know you aren't dying. If not, it calls emergency services with an automated message requesting help. However, Google notes (as required by law) that the Pixel Watch 3's pulse loss feature is not intended for those with pre-existing heart conditions requiring medical monitoring. It's not a replacement for proper medical oversight or follow-up care.Despite scoring regulatory approval, Google isn't releasing the feature in the US right away. An update will begin rolling out in late March that enables Loss of Pulse Detection. You may get a notification about the feature, but it won't be enabled by default. In supported regions, the feature must be activated in the Pixel Watch app under Safety & emergency and then Loss of Pulse Detection.Ryan WhitwamSenior Technology ReporterRyan WhitwamSenior Technology Reporter Ryan Whitwam is a senior technology reporter at Ars Technica, covering the ways Google, AI, and mobile technology continue to change the world. Over his 20-year career, he's written for Android Police, ExtremeTech, Wirecutter, NY Times, and more. He has reviewed more phones than most people will ever own. You can follow him on Bluesky, where you will see photos of his dozens of mechanical keyboards. 20 Comments