Google's most significant health feature for its wearable lineup has finally made its way to American users after months of waiting. The FDA-cleared Loss of Pulse Detection capability, which can potentially save lives by automatically calling emergency services when it detects a stopped heartbeat, is now rolling out to Pixel Watch 3 owners in the United States.
Countries Where Loss of Pulse Detection is Available:
- United States (newly added)
- Austria, Belgium, Denmark, France, Germany, Ireland, Italy
- Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, UK
How Loss of Pulse Detection Works
The innovative feature works by continuously monitoring your heartbeat through the watch's sensors. If the watch detects that your heart has stopped beating—whether due to cardiac arrest, respiratory failure, circulatory failure, overdose, or poisoning—it initiates a sophisticated detection process. The system uses multiple gates to confirm a genuine emergency: first detecting a sudden drop in blood volume variation via the green photoplethysmography sensor, then calculating the probability of pulselessness, and finally performing an additional check using different LEDs and sensors to look for even a weak pulse.
When triggered, the watch activates its infrared LEDs for more accurate readings and analyzes motion data. If it determines you're unresponsive, it begins a countdown with vibration and audio alerts. The entire process takes approximately 60 seconds—40 seconds for initial detection followed by a 20-second countdown. If you don't respond during this time, the watch automatically places a call to emergency services, informing them that you don't have a pulse and sharing your location information to expedite assistance.
Loss of Pulse Detection Process:
- Initial detection: ~40 seconds (three-gate verification system)
- Countdown period: 20 seconds with alerts
- Total time before emergency call: ~60 seconds
Setting Up the Feature
Pixel Watch 3 users need to manually opt in to use this potentially life-saving feature. The setup process is straightforward: open the Pixel Watch app on your connected phone, navigate to Safety & emergency, select Loss of Pulse Detection, and follow the on-screen instructions. Users must be signed into Personal Safety with their Google account on the Pixel Watch 3 to enable the feature.
For those with the LTE model, the watch itself will place the emergency call. Users with the Wi-Fi/Bluetooth version will have the call routed through their connected smartphone. In either case, the watch also provides an option to speak directly with emergency operators if the wearer is able to do so.
Compatible Devices:
- Pixel Watch 3 only (not available on Pixel Watch or Pixel Watch 2)
- Works with both LTE and Wi-Fi/Bluetooth models
Development and Testing
Google developed this feature through extensive collaboration with cardiologists to understand what a loss of pulse looks like in watch sensor data. This medical expertise informed the creation of an AI algorithm that was then refined using hundreds of thousands of hours of real-life user data from diverse populations.
The testing process was particularly thorough, involving stunt actors wearing tourniquets to artificially create a lack of pulse at the wrist. These actors also simulated the types of falls that would likely occur when someone suddenly loses consciousness due to a cardiac event, helping Google's algorithms distinguish between genuine emergencies and false alarms.
Limitations and Availability
While Google acknowledges that Loss of Pulse Detection won't detect every loss of pulse event, and that medical assistance arriving a minute after cardiac arrest may not always be successful, the feature represents a significant advance in wearable health technology. Unlike existing safety features such as fall detection or crash detection, Loss of Pulse Detection required FDA clearance due to its medical nature.
The feature sets the Pixel Watch 3 apart from competitors like the Apple Watch, which typically checks heart rate only every 3 to 7 minutes by default. Google's implementation provides much more frequent monitoring, potentially reducing critical response time during emergencies.
Loss of Pulse Detection is exclusive to the Pixel Watch 3 and is not available on earlier models like the Pixel Watch or Pixel Watch 2. The feature is now rolling out in the United States, joining the list of countries where it was previously available: Austria, Belgium, Denmark, France, Germany, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the UK.
The rollout began this week but will take a few weeks to reach all Pixel Watch 3 users in the US. For those who don't see the option in their Pixel Watch app yet, it should appear in the coming days as the update continues its phased deployment.
