New Fitbit Labs Study: Can Measuring Pulse Arrival Time at the Wrist Track Blood Pressure?

High blood pressure is called a silent killer for a reason.¹ Symptoms are rarely obvious but uncontrolled high blood pressure can increase the risk for heart disease and stroke, two leading causes of death for people in the United States.² Nearly one out of two adults in the U.S. has high blood pressure, but many don’t know they have it.³/⁴

Checking your blood pressure isn’t always easy, especially if people don’t have a blood pressure cuff at home and only go to the doctor’s office once or twice a year. And because blood pressure can fluctuate for a variety of reasons, ideally people need to repeat this process at the same time over a period of months. So, how can we make it easier for people to monitor their blood pressure?

Investigating Pulse Arrival Time at the Wrist 

Starting this month, Fitbit Labs is launching a study to look at how Fitbit devices can potentially measure something called Pulse Arrival Time (PAT), which is the time it takes for a pulse of blood to reach your wrist after your heart beats, and explore the potential link to tracking blood pressure.⁵  

While the ability to easily measure and monitor blood pressure in a wearable, non-cuff application has been of great interest, it has been rather elusive to date, and the ability to capture blood pressure readings in a non-cuff wrist-wearable has not yet been achieved.

Previous research has found a correlation between PAT and blood pressure, but the correlation was not strong enough to predict blood pressure. These investigations were limited to either small data sets or specific environments like an intensive care unit. Fitbit Labs also found a correlation between PAT and blood pressure in a small, 3-week internal study. The new study will extend this work to a broader population in order to learn more about how PAT measurements change under a variety of conditions.

“If high blood pressure was easier to measure, people could manage it earlier, which might help avoid preventable deaths from heart disease and stroke,” said Shelten Yuen, Principal Scientist at Fitbit, who is leading this work “It’s a hard scientific challenge, and a lot of work remains to be done to understand the best way to do this, but we have a history of advancing technology to make previously inaccessible health metrics available to Fitbit users from their wrist, so it’s a challenge we’re very passionate about solving.”

Having easy access to blood pressure readings is important for people with hypertension, so, assuming we can correlate PAT and blood pressure, being able to track PAT with a Fitbit device might give people more power to manage their condition in between doctors visits. 

How to Participate

Fitbit Sense users in the U.S. who are at least 20 years old, will receive a notification on their app if they are eligible to participate in the month-long study. Diversity in our research is essential, so it’s important for eligible Sense users across all demographics to sign up.

Advancing the Future of Wearables

Fitbit’s mission has always been to make everyone in the world healthier by making health more accessible. Fitbit pioneered the 10,000 steps phenomenon, and since then has introduced many other innovations, including heart rate monitoring on the wrist with our Pure Pulse technology, which has continued to advance over the years. With the Fitbit ECG App,⁶ we’re assessing users’ heart rhythms for signs of AFib, an irregular heart rhythm which increases the risk of serious heart conditions like stroke. These innovations — as well as our newest and most advanced sensors — are not only the foundation for many important health features, they also can be used to explore novel technologies, like measuring PAT in this new study.

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¹ https://www.heart.org/en/health-topics/high-blood-pressure/why-high-blood-pressure-is-a-silent-killer

² https://www.cdc.gov/bloodpressure/index.htm

³ https://www.cdc.gov/bloodpressure/facts.htm

⁴https://www.cdc.gov/bloodpressure/5_surprising_facts.htm#:~:text=3.,don’t%20have%20any%20symptoms

⁵ Please note: Pulse Arrival Time readings are intended for research purposes only and will be used for future product development. These readings should not be interpreted as conveying important health information and should not be used or relied on for any medical purposes.

⁶ The Fitbit EGG App is only available in select countries; not intended for use by people under 22 years old. See fitbit.com/ecg for additional details.