Google has unveiled a groundbreaking feature for its Pixel Watch 3: Loss of Pulse Detection. This innovative technology is designed to identify instances where a user’s heart ceases to beat—such as during cardiac arrest, respiratory failure, overdose, or poisoning—and automatically contact emergency services if the user is unresponsive.
Understanding Loss of Pulse Detection
Loss of pulse, or pulselessness, occurs when the heart stops beating, leading to a cessation of blood flow. This medical emergency can result from various causes, including primary cardiac arrest, respiratory or circulatory failure, overdose, or poisoning. Prompt medical intervention is crucial, as survival rates decrease significantly with each passing minute without resuscitation.
Traditionally, the survival of individuals experiencing loss of pulse events depends on the presence of bystanders who can recognize the emergency and call for help. However, many such incidents occur when the person is alone, drastically reducing the chances of timely assistance. Google’s Loss of Pulse Detection feature aims to bridge this gap by ensuring that help is summoned even in the absence of witnesses.
How the Feature Operates
The Loss of Pulse Detection feature leverages the Pixel Watch 3’s advanced sensors and artificial intelligence algorithms to monitor the user’s heart activity continuously. The process unfolds as follows:
1. Initial Detection: The watch’s heart rate sensor, utilizing green light photoplethysmography (PPG), monitors the user’s pulse. If a sudden drop in the pulse signal is detected, suggesting a transition to a pulseless state, the system initiates further checks.
2. Secondary Confirmation: Infrared and red lights are activated to seek additional signs of a pulse. Simultaneously, the accelerometer assesses for any movement. An AI-based algorithm integrates these signals to confirm the absence of a pulse.
3. User Responsiveness Check: If pulselessness is confirmed, the watch prompts the user with visual, haptic, and audio notifications, asking if they are okay. If the user responds or movement is detected, the alert is dismissed.
4. Emergency Call Initiation: If there is no response and no movement, the watch escalates the alert with an audio alarm and countdown. If the user remains unresponsive, the device automatically places a call to emergency services, providing details about the detected loss of pulse and the user’s location.
Development and Testing
Developing such a critical feature required meticulous research and testing. Google collaborated with cardiologists and conducted studies involving patients with implanted defibrillators to understand how loss of pulse manifests in wearable sensor data. To validate the feature’s effectiveness, the company partnered with stunt actors to simulate real-world scenarios of pulselessness, ensuring the system’s accuracy and reliability.
To minimize false positives, the feature incorporates multiple safeguards:
– Multi-Stage Verification: The system requires several indicators of pulselessness before initiating an emergency call.
– User Prompts: Before contacting emergency services, the watch provides multiple prompts to the user, allowing them to cancel the alert if they are responsive.
– Sensor Cross-Verification: The use of multiple sensors and AI algorithms ensures that the detection is accurate and not triggered by external factors like the watch being removed or worn incorrectly.
Availability and Regulatory Approval
The Loss of Pulse Detection feature was initially introduced in Europe in 2024, following clearance from relevant regulatory bodies. In the United States, the feature received clearance from the Food and Drug Administration (FDA) and began rolling out in April 2025. Users can enable the feature by updating the Personal Safety app on their Pixel Watch 3 and following the setup instructions in the companion app on their smartphone.
Considerations and Limitations
While the Loss of Pulse Detection feature represents a significant advancement in wearable health technology, it is important to note its limitations:
– Not a Substitute for Medical Devices: The feature is not intended for users with pre-existing heart conditions or those who require continuous cardiac monitoring.
– Detection Limitations: It may not detect every instance of loss of pulse and does not diagnose or treat any medical condition.
– Dependence on Device Functionality: The effectiveness of the feature relies on the watch being charged and having adequate cellular connectivity to place emergency calls.
Conclusion
Google’s introduction of the Loss of Pulse Detection feature in the Pixel Watch 3 marks a significant step forward in integrating health monitoring capabilities into consumer wearables. By providing a mechanism to detect life-threatening events and automatically summon help, this feature has the potential to save lives, particularly in situations where individuals are alone and unable to seek assistance. As wearable technology continues to evolve, such innovations underscore the growing role of these devices in personal health and safety.
