JEvery third person in Germany has high blood pressure according to a study by the Robert Koch Institute (RKI). Since high blood pressure can cause many other diseases, such as a heart attack, a stroke or severe kidney disease, it is recommended that people aged 35 and over take their blood pressure regularly.
If you don’t have any abnormalities, you can measure about twice a year. For many sufferers, it is sufficient to measure the blood pressure values regularly with a conventional blood pressure measuring device on the upper arm or wrist.
If the risk profile is very pronounced, evidence of high blood pressure is particularly important. These could be high cholesterol, diabetes or heart disease in the family. A 24 hour blood pressure measurement may be required in these patients.
Here there is an increased likelihood of suffering a heart attack or stroke. Or they could be affected by peripheral arterial occlusive disease (“intermittent claudication”). And there are millions in Germany too.
The Swiss start-up Aktiia is particularly aimed at this group of people, who want to use a bracelet to monitor blood pressure over a longer period of time around the clock.
Blood pressure measurements without a tight cuff
The classic method of 24-hour blood pressure measurement is very stressful for the patient: every 15 minutes the cuff on the upper arm inflates, blocks the blood flow, and the blood pressure is measured.
At night, the device measures every half hour. However, this measurement does not take place permanently, but only occasionally to check the blood pressure.
Aktiia’s bracelet, which looks like a simple fitness tracker, uses a different technique. With the so-called pulse wave analysis, optical signals on the patient’s wrist are processed and the blood pressure is estimated very precisely. The inside of the bracelet glows with green light to determine how the arteries under the surface of the skin are pulsing.
This process is also known from heart rate monitors or smartwatches with a heart rate monitor. The Aktiia device not only counts the heartbeats, but also scrutinizes the pulse shaping with artificial intelligence.
Aktiia bracelet has a nutty calibration
The process was developed over 15 years by a team led by the researchers Mattia Bertschi and Josep Solà at the CSEM Tech Center (Center Suisse d’Electronique et de Microtechnique) in Switzerland. This is where the world’s first quartz wristwatch was invented over 50 years ago.
The wristband cannot do without traditional measuring technology either: it has to be calibrated with the enclosed cuff measuring device before it is used for the first time and then once a month. The practical test showed a weak point here.
The comparison between the reference cuff and the bracelet turned out to be very fiddly and only succeeded after several attempts. After all, you have a month of rest after a successful calibration.
The bracelet can be worn for over a week because it only needs to be charged every nine days. The charging stop then takes a good two hours.
Measurement data is available in the Aktiia app or via PDF
The Aktiia system includes an app that makes contact with the cuff and bracelet via Bluetooth. In the application, on the one hand, you can see the course in the two-hour period over the day. But you can also have weekly or monthly reports compiled, which you can also export as a PDF for a doctor’s visit.
Unfortunately, Aktiia does not allow the raw data to be exported in a spreadsheet or via the Apple and Google health applications to display it in a larger context with other data such as body weight.
In the daily overview it is noticeable that every now and then an entry is missing in the two-hour period. The Aktiia bracelet only measures blood pressure when it is at rest. If users do physical activity or move their wrist briskly, the measurements are paused.
Aktiia bracelet: measuring blood pressure without standing still
Since smartwatches like the Galaxy Watch Active2 or Galaxy Watch3 from Samsung are now able to estimate blood pressure with a similar method, the question arises whether a special solution from Aktiia makes sense at all, especially since a smartwatch has many more functions .
Compared to smartwatch solutions, Aktiia can also measure when users are not sitting still, putting their wrists on a table or holding their arm in a certain position.
You do not have to initiate the measurement yourself. With a solution like the measuring bracelet from Switzerland, a series of measurements at night that is free of disturbances for patients is possible in the first place.
Conclusion: Aktiia’s bracelet that doesn’t feel very high quality isn’t cheap. It costs 200 euros or 208 euros in an installment program.
For comparison: The test winner from Stiftung Warentest (2016) among conventional blood pressure monitors is available in stores for just under 40 euros. With conventional devices, however, it is not possible to keep an eye on the nightly blood pressure values without being disturbed.