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Loss of Pulse Detection

by Fitbit · Based in United States →

Cardiology Critical Care Emergency Medicine

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Regulatory Status Disclosed

Overview

The Loss of Pulse Detection feature by Fitbit, available on compatible devices like the Pixel Watch 3, is a first-of-its-kind safety tool designed to detect potential loss of pulse events. Utilizing photoplethysmography (PPG) and accelerometry sensors, the software analyzes pulse data to identify when a user’s heart may have stopped beating due to events such as primary cardiac arrest, respiratory or circulatory failure, overdose, or poisoning.

Upon detection, the feature triggers haptic and audio alerts to the user. If the user remains unresponsive to these notifications, the system can automatically prompt a call to emergency services through the user’s connected compatible hardware, such as a smartphone or smartwatch, and share an automated message with critical context and location. This opt-in feature is intended for over-the-counter (OTC) use and aims to provide potentially life-saving assistance, especially for individuals who might experience such an event alone.

Fitbit, now part of Google, has a broader commitment to digital health, offering solutions for healthcare providers to leverage wearable data for population health, chronic condition management, and clinical research. With user consent, health data from Fitbit devices, including irregular heart rhythm notifications, can be accessed by healthcare partners through a secure Fitbit Web API.

Reviewed by Pouyan Golshani, MD — Interventional Radiologist

Key Features

Automatic loss of pulse detection
Utilizes PPG and accelerometry sensors
Haptic and audio alerts to the user
Automated emergency service calling if unresponsive
Shares location with emergency services
Opt-in feature for user control
Software-only mobile medical application
Integrated with compatible smartwatches (e.g., Pixel Watch 3)

Use Cases

Providing immediate assistance during sudden cardiac events or other causes of pulse loss
Enhancing personal safety for individuals at risk or living alone
Complementing existing emergency response systems
Offering peace of mind for users and their families regarding critical health events

What Physicians Need to Know

ECG/EKG Analysis Capability

Fitbit devices, particularly models like the Sense 2 and Charge 6, offer an ECG app for spot-check heart rhythm assessments to detect atrial fibrillation (AFib). This allows users to proactively screen for AFib and share ECG tracings with healthcare providers. The ECG feature has been clinically validated against standard ECG equipment and is considered highly accurate for consumer-grade health monitoring. However, it's important to note that while Fitbit's ECG readings are precise, they are intended for general wellness and not as a replacement for professional medical equipment. The Loss of Pulse Detection feature itself uses photoplethysmography (PPG) and accelerometer sensors, not ECG technology, to detect loss of pulse.

Arrhythmia Detection Accuracy

Fitbit's photoplethysmography (PPG) algorithm for irregular heart rhythm notifications, which helps spot AFib, accurately identified undiagnosed AFib 98% of the time as confirmed by ECG patch monitors in the Fitbit Heart Study. This algorithm assesses heart rhythms in the background while users are still or asleep. The Loss of Pulse Detection feature, which uses PPG and accelerometer sensors, had a sensitivity of 69.3% in one clinical study. Another study on the Loss of Pulse Detection algorithm reported a sensitivity of 67.23% in a prospective arterial occlusion cardiac arrest simulation model. The specificity was 99.965% in a day-level analysis. It's important to note that while Fitbit devices have FDA approval and are CE-marked to detect AFib, an ECG should still be used to formally diagnose arrhythmias.

Cardiac Monitoring Integration

Fitbit devices offer 24/7 heart rate tracking, which can aid in long-term heart rhythm assessment. The Loss of Pulse Detection feature uses photoplethysmography (PPG) and accelerometer sensors present in wrist-worn consumer wearable devices to analyze pulse data. The algorithm includes a machine learning component that analyzes data from these sensors. Fitbit's API allows for integration of biometric data, sleep cycles, heart rate, and ECG readings into healthcare platforms, supporting remote patient monitoring and chronic disease management.

AHA/ACC Guideline Alignment

Both Fitbit's ECG app for AFib detection and the 'Loss of Pulse Detection' feature on Google Pixel Watch have received FDA clearance. The Fitbit Heart Study, which validated Fitbit's PPG algorithm for AFib detection, presented its data at the American Heart Association Scientific Sessions.

Real-Time Alert Capability

The Loss of Pulse Detection feature is designed to provide audio, visual, and haptic alerts and notifications to the user upon detection of a loss of pulse. If the user remains unresponsive to these alerts, the feature will attempt to prompt a call to emergency services through the user's connected compatible hardware, such as a smartphone or smartwatch. This is an opt-in feature and is off by default. The feature is intended to opportunistically surface an alert of possible loss of pulsatility when sufficient data are available for analysis, and these data are only captured when the user is still.

Physician Tip

For 'Loss of Pulse Detection' and related cardiac features on Fitbit/Pixel Watch, physicians should consider these tools as supplementary to traditional medical diagnostics. While Fitbit's ECG app and irregular heart rhythm notifications can help in early detection of conditions like AFib, formal diagnosis of arrhythmias still requires an ECG. The Loss of Pulse Detection feature is not intended to replace traditional methods of diagnosis, treatment, or monitoring, nor is it intended for individuals under 22 years of age or those with a high risk for sudden cardiac death. The data from Fitbit devices can provide valuable insights into physiological patterns and can be integrated into healthcare platforms for remote patient monitoring. However, it's crucial to understand the limitations, such as potential inaccuracies in heart rate measurements during high-motion activities or stress, and that the device does not provide a diagnosis.

Fitbit offers an API that allows for the integration of its biometric data, including heart rate, sleep cycles, and ECG readings, into healthcare platforms. This integration can support chronic disease management, wellness programs, and remote patient monitoring. ConnectHealth, for example, standardizes Fitbit output to FHIR/HL7, enabling care teams to receive structured, actionable patient data without custom middleware. This facilitates a comprehensive overview of patient health and supports a proactive approach to wellness management.

At a glance

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Details

Category	Cardiology AI, Triage & ER/ICU AI, Wearables & Remote Monitoring (RPM)
Pricing	Unknown
Mobile App	Yes
Compliance
BAA Available	Yes AI-estimated
HIPAA Compliant	Yes AI-estimated
FDA Status	Cleared AI-estimated
Integrations
EHR	Not specified
Specialties	Cardiology, Critical Care, Emergency Medicine

What the Web Says

Fitbit's "Loss of Pulse Detection" feature, primarily available on the Pixel Watch 3 and newer models, is an FDA-cleared technology designed to detect a loss of pulse and automatically prompt a call to emergency services if the user is unresponsive. This feature is part of a broader expansion of health and safety tools within the Fitbit ecosystem, integrated with the Google Health app. While generally viewed as a potentially life-saving innovation, some discussions highlight concerns about its accuracy, potential for false alarms, and the necessity of cellular connectivity for full functionality.

Overall: Mixed

Strengths

FDA-cleared and can prompt emergency services, potentially saving lives.
Integrates with the Google Health app for a comprehensive health overview.
Adds to a suite of safety features including fall detection and irregular heart rhythm notifications.
Offers peace of mind for users, especially those in higher-risk groups.
Represents a significant advancement in wearable health technology.
Data is captured only when the user is still, aiming for more reliable readings.

Limitations

May not detect every instance of a loss of pulse and is not intended for users with preexisting heart conditions or those requiring cardiac monitoring.
Emergency calling is dependent on cellular connectivity and phone/watch charge.
Concerns about potential false alarms and their consequences have been raised by both patients and physicians.
Some users have reported issues with heart rate accuracy in general Fitbit devices, which could impact the reliability of pulse detection.
Not available on all Fitbit devices; primarily featured on Pixel Watch 3 and newer.
The feature was not tested for and is not intended for people under 22 years of age.

Based on reviews from: chatgate.ai, rhizomeai.com, wadrago.com, google.com, tomsguide.com, androidcentral.com, askvora.com, cybernews.com, nih.gov, bmj.com, youtube.com, walmart.com, kygo.app, illuminatelabs.org, reddit.com, healthaidb.com, wareable.com, researchgate.net, acast.com, fountainbuild.ai, counterpointresearch.com, cnet.com

Last updated: 2026-10-30

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Press & Coverage

blog.google

Loss of Pulse Detection has received U.S. FDA clearance, and is now available on Pixel Watch 3.

Google has received FDA clearance for its Loss of Pulse Detection feature on the Pixel Watch 3, which can detect a loss of pulse and automatically contact emergency services if the user is unresponsive.

2025-02

pharmacytimes.com

Google's Pixel Watch 3 Loss of Pulse Detection Feature Receives FDA Clearance

The FDA granted clearance to Google's Pixel Watch 3 for its Loss of Pulse Detection feature, which detects when the wearer has experienced a loss of pulse and automatically prompts a call to emergency services if the watch detects the wearer as unresponsive.

2025-03

rhizomeai.com

Fitbit FDA Medical Device Authorizations: A Regulatory Overview

Fitbit's Loss of Pulse Detection feature, cleared for OTC use with compatible consumer wrist-worn products, analyzes pulse data to identify loss-of-pulse events and notify the user, attempting to prompt a call to emergency services if the user remains unresponsive.

2026-07

fda.gov

FDA 510(k) Premarket Notification K242967

The FDA's 510(k) clearance for Loss of Pulse Detection outlines its intended use as a software-only mobile medical application for over-the-counter use with compatible wrist-worn products to analyze pulse data and identify loss of pulse events.

2025-02

arxiv.org

Automated loss of pulse detection on a consumer smartwatch.

A peer-reviewed study on Loss of Pulse Detection was published in Nature, a respected scientific journal, after its release in late 2024.

2026-06

tomsguide.com

The Fitbit Edge vs. Fitbit Charge 6: Which fitness tracker should you buy?

The Fitbit Edge, a follow-up to the Fitbit Charge 6, includes important health safety tools like Loss of Pulse Detection and Breathing Emergency Alerts.

2026-10

lifehacker.com

What is (and isn't) loss of pulse detection good for?

The Loss of Pulse Detection feature is designed to sound an alarm and contact emergency services if the wearer loses their pulse due to events like a heart attack, poisoning, or overdose.

2025-04

nih.gov

Patients' and physicians' perspectives on smartwatch-based out-of-hospital cardiac arrest detection: a qualitative interview study

This study explores patient and physician perspectives on smartwatch-based out-of-hospital cardiac arrest detection, noting the Google Pixel Watch 3's 'Loss of Pulse' detection as the first to commercially integrate pulselessness detection.

2024-06

Videos

Product demos, reviews, and walkthroughs for Loss of Pulse Detection.

#MadebyGoogle u201824: Loss of Pulse Detection on Google Pixel Watch 3

Fitbit: The future of personalized Health | The Check Up with Google '25

The Pixel Watch 4 info you need in under 3 minutes! u231a #googlepixel #smartwatch #tech #madebygoogle

View all on YouTube

Frequently Asked Questions

How does Fitbit's Loss of Pulse Detection work and what are its intended uses in a clinical context?

Fitbit's Loss of Pulse Detection is a software-only mobile medical application intended for over-the-counter use with compatible wrist-worn products. It analyzes pulse data using photoplethysmography (PPG) and accelerometry sensors, employing a machine learning algorithm with a convolutional neural network to identify potential loss of pulse events. If a loss of pulse is detected and the user is unresponsive to alerts, it attempts to prompt a call to emergency services. However, it is not intended to replace traditional methods of diagnosis, treatment, or monitoring, nor is it meant to provide a notification on every loss of pulse event.

What are the limitations and accuracy concerns of Fitbit's Loss of Pulse Detection and other heart rate monitoring features for medical diagnosis?

Fitbit's Loss of Pulse Detection is not intended for individuals under 22 years of age or those with a high risk for sudden cardiac death, such as those with coronary artery disease, cardiomyopathy, or unexplained syncope/fainting. While Fitbit's ECG feature has been clinically validated for detecting AFib, and its irregular rhythm notifications have a high positive predictive value, these are intended for general wellness and not as a replacement for professional medical equipment or a definitive diagnosis. The accuracy of PPG technology in consumer wearables can be affected by motion artifacts and may show diminished accuracy during high-intensity exercise. Some studies have also indicated potential underestimation of heart rate by Fitbit devices compared to gold-standard ECG.

How does Fitbit ensure compliance with medical device regulations for its Loss of Pulse Detection feature?

Fitbit's Loss of Pulse Detection feature received FDA clearance in February 2025 for over-the-counter use. This indicates it has undergone regulatory review to ensure its safety and effectiveness for its intended purpose. The feature is designed to opportunistically surface alerts when sufficient data are available and is not intended to provide a notification on every event.

Are there alternatives to Fitbit for pulse detection and irregular heart rhythm monitoring that offer higher accuracy or different features for clinical use?

Yes, several alternatives exist. For instance, Garmin Venu 3 is noted for significantly better accuracy and deeper analytics without a subscription, while Polar Ignite 3 is recommended for fitness-focused users prioritizing workout accuracy, especially for elevated heart rates. Apple Watch Series 10 is a strong alternative for iPhone users, and the Oura Ring 5 offers advanced sleep tracking. These alternatives often provide core health features without a subscription, unlike some Fitbit features that may require a Premium subscription.

What is the pricing model for Fitbit devices with Loss of Pulse Detection and related AI-powered cardiology features, and is it covered by insurance?

The pricing for Fitbit devices varies, with models like the Fitbit Charge 6 launching around $160 and often dropping to $99.95, while the newer Fitbit Edge lists at $179.99. The Google Health app, which integrates with Fitbit, has a free tier and an optional paid Premium tier, typically costing $10 per month or $100 annually, which unlocks more advanced features like an AI-powered fitness coach. There is no evidence that insurers currently cover the cost of Fitbit devices or the Premium subscription.

Can AI-powered features in Fitbit devices, such as Loss of Pulse Detection, be integrated into existing cardiology AI systems or electronic health records for better patient management?

While Fitbit data can be valuable for understanding patient activity and heart rate, integrating it into existing cardiology AI systems or EHRs presents challenges. Physicians have expressed interest in utilizing activity trackers to positively influence patient habits and personalize recommendations. However, the challenge lies in analyzing, curating, and delivering this data to healthcare teams in an actionable form within a manageable workflow. Studies have shown that AI can help predict hospitalization risks using Fitbit data, but the devices are not intended to replace traditional diagnostic methods.

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Suggest an Edit → | Report an issue | Last Verified: 2026-04-18 | First Added: 2026-04-18