Pixel Watch 3 Can Now Call 911 If Your Heart Stops
Updated On: February 27, 2025
Google has officially received FDA clearance for the Pixel Watch 3’s Loss of Pulse Detection feature, marking a significant step in wearable health technology. The feature, designed to detect the absence of a pulse and automatically contact emergency services, is set to roll out to U.S. users by the end of March.
This feature utilizes the Pixel Watch 3’s advanced heart rate sensor to monitor pulse activity in real-time. If the watch detects a loss of pulse while being worn, it initiates a multi-step process to confirm the event. The watch first performs additional checks for about 20 seconds, using brighter optical heart rate sensors and accelerometers to rule out false alarms.
If the watch does not detect movement or a pulse, it vibrates and prompts the wearer with an “I’m OK” button. If there is no response within 15 seconds, it escalates the alert by playing an audible alarm while displaying a 20-second countdown. If no action is taken, the watch calls emergency services via LTE or a connected smartphone. The automated call provides the wearer’s approximate location and informs responders of a potential loss of pulse.
The feature has been available in several European countries, including Austria, France, Germany, and the UK, since late 2024. However, in the U.S., Google had to wait for FDA clearance. Now, with regulatory approval secured, the feature will soon be accessible to American users.
The FDA’s approval does not guarantee that the feature is foolproof. Google emphasizes that the Loss of Pulse Detection feature is not a replacement for medical monitoring devices and should not be relied upon as a primary means of detecting or preventing cardiac arrest. However, it offers an added layer of safety, particularly for individuals at risk of “unwitnessed” cardiac arrests.
In clinical trials, Google’s Loss of Pulse Detection demonstrated a sensitivity rate of 69.3%, meaning it correctly identified a loss of pulse in roughly 69% of cases. However, it failed to detect such events about 30% of the time. On the other hand, the feature showed a relatively low false positive rate—about one false emergency call for every 7.75 years of user wear time.
Google has also acknowledged potential limitations. Factors like tattoos, poor blood circulation, and ambient light interference could impact accuracy. Additionally, the feature has not been extensively tested on individuals under 22, those with cognitive impairments, or those with conditions like sickle cell disease that may affect circulation.
Once available in the U.S., Loss of Pulse Detection will not be enabled by default. Users can activate or deactivate the feature in the Pixel Watch app under the “Safety & Emergency” settings.