Smartwatches have become portable mini diagnostic centers, in small part thanks to Apple’s efforts for sensors that track various aspects of user health. These sensors have come a long way and are now able to monitor not only the pulse, but also the level of oxygen in the blood, the quality of sleep, and even the ECG. Still, there are a few more biometric values that can’t be easily measured with just a fitness tracker or smartwatch, like glucose levels or blood pressure, and Fitbit’s research labs are trying to find a way to at least make the latter easier.
In addition to arrhythmia or irregular heartbeat, high blood pressure or hypertension are considered one of the biggest silent killers. You only detect its presence when it is too late, unless you monitor your blood pressure regularly. But people don’t do that because they need specialized and sometimes inconvenient devices to monitor blood pressure that few people own even at home, or at least regular visits to a doctor that few people do.
There is great interest in blood pressure monitors that do not require the typical handcuffs that tighten around the upper arm, but no progress has been made so far. Smartwatches and smart trackers are almost perfect for this purpose, but the technology for it has not yet matured to the point that it is as reliable as simply measuring your heart rate. Even Samsung’s much-vaunted feature in its latest Galaxy Watches still needs to be calibrated with traditional cuff-based measurements.
Fitbit Labs, however, is investigating another indirect method of measuring blood pressure, this time using Pulse Arrival Time or PAT. In short, it measures the time it takes for the blood to pulsate from the heart to the joint and relates this to blood pressure. It does not specify whether it needs a calibration value such as Samsung’s Pulse Wave Analysis (PWA) method.
PAT studies are not new, but are generally tested in a very limited number or controlled scenarios. Fitbit invites users of its Sense smartwatch in the US to participate in a one-month study to expand that audience, and we hope to establish the method as a reliable way to make blood pressure monitoring more accessible to everyone.