Smartwatches have become portable mini diagnostic centers, in no small part thanks to Apple’s push for sensors that keep track of various aspects of the wearer’s health. Those sensors have come a long way and are now able to track not just heart rate but also blood oxygen levels, sleep quality, and even ECG. There are, however, still a few biometrics that can’t be easily measured using just a fitness tracker or smartwatch, like glucose levels or blood pressure, and Fitbit’s research Labs is trying to find a way to make at least the latter easier.
Next to arrhythmia or irregular heart rate, high blood pressure or hypertension is considered one of the biggest silent killers. You only discover its presence when it’s too late unless you keep regular tabs on your blood pressure. But people don’t because monitoring blood pressure requires specialized and sometimes inconvenient devices that few own even at home or at least regular doctor visits that few people do.
There has been a big interest in blood pressure monitors that don’t require the typical cuffs that compress around your upper arm but there has been no headway made so far. Smartwatches and smart trackers are almost perfect for that purpose but the technology to do that hasn’t matured yet to the point of being as reliable as simply measuring heart rate. Even Samsung’s much-boasted feature in its latest Galaxy Watches still needs to be calibrated with a traditional cuff-based measurement.
Fitbit Labs, however, is looking into yet another indirect method of measuring blood pressure, this time using Pulse Arrival Time or PAT. In a nutshell, it measures the time it takes for a pulse of blood to travel from heart to wrist and links that to blood pressure. It doesn’t say whether it needs a calibration value like Samsung’s Pulse Wave Analysis (PWA) method.
PAT studies aren’t new but they have mostly been tested in very limited numbers or controlled scenarios. Fitbit is inviting users of its Sense smartwatch in the US to participate in a month-long study to expand that audience and hopefully establish the method as a reliable way to make blood pressure monitoring more accessible to all.