- Works with cuff-like accuracy
- Automatic measurements
- Low-key design
- Simple to use app
- Good battery life
- Only measures blood pressure & resting heart rate
- Little in terms of insights (this will change with future updates)
We are edging closer to the day when blood pressure monitoring from the wrist will be a normal thing. It might happen later this year, more likely in mid-to-late 2022 and beyond.
One of the first real entrants in this market is Swiss startup Aktiia. The outfit has just started selling its wrist-based optical blood pressure monitor (BMP) in the UK (view on aktiia.com). From early May, availability will be extended to Germany, Austria, France and Switzerland. This will be followed by the US in the near future, once FDA approval is secured.
Essential reading: Best fitness trackers and health gadgets
Many adults are affected by hypertension, but as many as one in three can be unaware they have the condition. They feel the odd twinge or headache, but simply put this down to feeling a little under the weather. And this is the paradox and the reason high blood pressure is sometimes called the silent killer. You don’t know you have a problem until it’s too late.
Home BPMs can be quite useful. Taking regular measurements is particularly important as you get older – the effects of an unhealthy lifestyle tend to build up over time.
Whether they are smart or traditional, BPMs typically come in one of two forms – those for the upper arm, and those for the wrist. Nearly all of these use some type of inflatable cuff technology.
We have yet to see a big brand come up with a wrist wearable that utilizes optical sensors to measure blood pressure with cuff-like accuracy. There is lots of stirring in this area, though.
Samsung is perhaps taking the lead with its Galaxy series. However, these measurements are not on par with cuff like accuracy. Fitbit has also just announced a study on whether its Sense smartwatch can take such readings.
Part of the problem is that the wrist arteries are narrower and not as deep under your skin as those of the forearm. Which makes taking blood pressure from that location more difficult.
There is, of course, the Omron HeartGuide. But this is a watch-sized sphygmanometer so does not use optical sensors. It’s basically a miniature cuff that is built into a smartwatch. Omron has filed more than 80 patents to create the thing a couple of years ago.
Which leaves us with traditional BPMs. They work well but many of us do not use them on a regular basis.
The Aktiia bracelet promises something never seen before. Automatic, clinically validated blood pressure measurements during the day and night taken from the wrist with optical sensors. No buttons to press, nothing to do except wear it.
Does it work as advertised? I’ve been living with the Aktiia bracelet for nearly a month. Read on to find out what I made of it. Also worth a read is my interview with Aktiia CEO, Micheal Kisch.
- discreet design
- no display, app shows data
- uses optical heart rate sensor & proprietary algorithms
- 9 day battery life
In the box the Aktiia system comes with the measuring bracelet, a traditional blood pressure cuff, charging cables and a small charging stand. There’s also a little instruction booklet if you care to read it. I typically dive straight in without spending much time on literature. Luckily the information in the smartphone app was sufficient to guide me through setup and use.
What surprised me a bit, though, was that there was an Aktiia-branded traditional cuff in the box. You’ll discover on initial setup that you do need to calibrate the device before first use, and then once per month. Not a big deal but something to be aware of.
The bracelet itself is very low key. It consists of a core unit made of metal attached to a velcro strap. The band slots through two rings on the main unit and is secured in place via a traditional watch buckle. Once on there’s no danger whatsoever of it falling off.
This is a one size fits all affair. But the strap is adjustable so can fit a variety of wrist sizes, 14 to 21 cm. The same is the case with the initialisation cuff. Aktiia says the cuff can accommodate arms with a circumference between 22 and 42 cm. That’s most people.
What I really liked is the small form factor of the Aktiia bracelet. The thing is not a substitute for a traditional activity band. It only captures blood pressure readings and resting heart rate. So if you have a fitness tracker and smartwatch that you use on a daily basis, the minimalistic design of Aktiia means you can wear it on the other wrist. Some might even mistake it for a piece of jewlery.
Under the hood
As far as the underlying technology, the Aktiia system uses common optical heart rate sensors and proprietary algorithms to measure an individual’s blood pressure at the wrist. The system works by analyzing the changing diameter of the arteries with each heartbeat. The monitoring is performed at regular intervals automatically, so users can see how their blood pressure changes at different times of the day and night.
The wearable has a battery life of 9 days so does not need charging often. Simply wear it as you would any fitness tracker and go about your day.
You do need to take it off, though, when taking a bath or going for a swim. That’s because the bracelet is only splash-proof. Keeping it on for a swim would be kind of pointless, anyway. Aktiia takes measurements only during rest periods. It will take readings when you are lying in bed and perhaps at times when you have been sitting down for a while.
After about a week, I found myself taking it off when I would head out the door. I did that in the knowledge that I won’t really be missing out on any data. Capturing blood pressure while you are walking or exercising is useless – even with a traditional measuring cuff.
To this end, the Aktiia bracelet has an accelerometer inside. But this is not to count your steps or calories burned. It’s to figure out if you are stationary. By gauging movement, the bracelet can assess when accurate measurements can be taken.
- readings are captured automatically
- works while you are at rest
- requires calibration once per month
Before first use you’ll need to calibrate the band with a traditional blood pressure cuff. As mentioned, this is included in the box.
The calibration is done via the Aktiia smartphone app. This will take you through a brief setup procedure. You’ll also be guided on the correct way to wear the bracelet. The instructions say the band should be snug but not too tight. They suggest leaving enough space for a pencil to slide through between the strap and your wrist.
I followed the instructions to the letter. In the end I found that it’s actually better to keep the strap close-fitting as it captures readings more frequently. So if the device fails to register measurements often enough, try tightening the band. Ensuring, of course, that there’s still a comfortable fit.
The app will also help you calibrate the device. With the Aktiia bracelet and the traditional cuff on, you’ll need to capture readings from both at the same time while being in a seated, comfortable position. Two individual readings will be taken one after the other to ensure accuracy.
The process can be a little finicky and requires a bit of trial and error. It took me about 5 minutes to perform the calibration the first time. For some reason the band worked much better from my right wrist than my left wrist. To make sure all was ok I did a few more calibrations. On subsequent tries it was much easier and worked flawlessly.
Aktiia says the bracelet should be recalibrated at least once a month. Rather usefully, the app shows the date by which you need to do the next calibraiton.
If the initialisation is not performed within the required date, accuracy cannot be ensured. This is the reason the company displays a disclaimer on the box. The data might not be accurate if the initialization is not performed in due time.
After setup and calibration you are good to go. The small form factor of the Aktiia bracelet coupled with the fact that it’s very light means you’ll quickly forget you are wearing it. In this sense, I think it actually helps that the wearable doesn’t have a display. Just make sure you charge the bracelet every week or so.
- readings can only be seen in the app
- daily, weekly, month trends
- PDF summary report
The results can be viewed in the accompanying smartphone app. This allows you to see individual readings, averages and share a summary report with others.
As with all such devices, a sync is performed via a Bluetooth connection. This typically takes less than a minute.
The app itself is a rather simple affair. There are three tabs along the bottom. The Home tab is where your blood pressure readings sit. Next to it is the Devices tab where you can view battery level of both the bracelet and cuff. The final tab shows your Profile and settings.
Readings can be viewed and charted on a daily, weekly and monthly basis. I estimate that on average the bracelet would take 9-10 measurements per day.
What’s most important is that these readings meet the ISO81060-2 standard for accuracy. Hence, the wearable has the CE marking as a Class IIa medical device (for users within the age group 21-65, excluding contraindications due to certain health conditions). Lots of research went into creating the Aktiia system. This includes 5 clinical trials and 1 million measurements to date. You can read more about accuracy on this link.
I sometimes take blood pressure measurements in the morning with a traditional blood pressure cuff. The systolic and diastolic values would typically be about 8-10 points above the readings from Aktiia. Which makes sense. The Aktiia measurements are taken while you are asleep or at rest. I take readings with a traditional cuff in a sitting position during the day.
The app also collates averages. For me, the readings did not change very much from day to day. But they would go up or down by a couple of points. This would depend on my activity the previous day.
For example, if I did a particularly stressful bout of exercise, my readings would go slightly up during the night. Also, the week after a plane flight – the readings steadily fell each day as I recovered from the trip.
But you can see the potential. The fact that Aktiia works automatically 24/7 means you can experiment how changes in exercise, diet and sleep effect your cardiovascular health. The app will chart the measurements so you or your doctor can spot patterns.
What I would have liked to have seen is a bit more analysis. Apart from the daily, weekly and monthly averages, it ends with weekday vs weekend averages.
But this is on the company’s to-do list. According to Aktiia CEO, future software updates will bring insights such as day vs. night analysis, the ability to “label” the data so that the user and their physician better understand the specific impact of diet, exercise, medication and stress on their cardiovascular health and targeted heart health tips based upon each user’s unique blood pressure pattern.
Another useful part off the system is reports. You can generate a summary document for a set time period. This can then be viewed on your phone, downloaded as PDF or sent to your health care provider.
Here’s an example of the summary report. Click on the image below to enlarge.
The Aktiia bracelet is not meant as a replacement for a fitness band or smartwatch. It uses optical sensors to track blood pressure from the wrist, along with resting heart rate. Nothing else. But it does this with clinical-grade accuracy, automatically, multiple times during the day and night. At the moment, this is the only product of its kind.
The small form factor of the bracelet means you can put it on and forget about it. Just remember to charge it every week or so. And do the calibration with a traditional cuff once per month.
All in all, I found the Aktiia bracelet works very well. In a 24 hour period it would capture about 10 readings. This is all charted for you in the simple to use app, plus you can generate a report to share with your doctor. The readings were where I expected them to be. What adds confidence is the clinical validation and the fact that the wearable has the CE Mark clearance for accuracy.
The system is ideal for someone who wants to keep a closer eye on their cardiovascular health. It can also be useful for those that are at risk for or have already been diagnosed with high blood pressure. The wearable provides a great tool to help you make lifestyle changes that benefit your cardiovascular health.
The Aktiia bracelet can be purchased by those living in select countries. Others will follow soon. You can add your email to the waitlist on the website to be notified when Aktiia will be available in your country.
The bracelet costs £129.99 with an on-going £6.99 monthly subscriptions to access the Aktiia 24/7 Monitoring Service. The £199.99 annual plan includes the monthly subscription cost.
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