The raison d’être of wearables, such as fitness bands and smartwatches, lies mainly in activity and health measurement. Manufacturers are increasingly focusing on more accurate heart rate and step measurements. Heart rate monitors are already capable of measuring blood saturation and making heart films. The next logical step is blood pressure measurement. Can we expect smartwatches with blood pressure monitors soon?
Normally I come to an answer in the conclusion of my articles that is stated in the intro. When asked whether wearables with blood pressure measurement will soon appear on the market, the answer is more obvious. There are already smartwatches with blood pressure measurement available. You don’t even have to go to gray imports or dubious Chinese webshops. Samsung’s Galaxy Watch3 and Galaxy Watch Active2 are able to measure your blood pressure, and ASUS (yes, the Taiwanese PC manufacturer) also has a blood pressure-monitoring smartwatch: the Asus VivoWatch SP.
Why measure blood pressure?
The heart pumps blood throughout the body to supply the organs and muscles with blood. This puts pressure on the blood vessels, which is measured as blood pressure. High blood pressure can cause cardiovascular disease in the long term. Symptoms of low blood pressure are more immediately noticeable, for example through dizziness and fainting. Such a blood pressure measurement consists of two values: the upper pressure, actually the peak when the heart pumps, and the lower pressure, when the heart relaxes for its next beat. The Heart Foundation reports on the website that a blood pressure of 120/80 (or lower) is an ideal blood pressure.
Innovative field of work
It is not surprising that manufacturers are looking at the possibilities of measuring blood pressure using a smartwatch. A large part of the existence of smartwatches and activity trackers stems from movement and health. Sensors in the wearable equipment ensure that your steps are counted, your heart rate (with good wearables) is continuously measured, your sleep is monitored and your activities are accurately recorded, if possible even with GPS, so that you can track your (run) run – or cycling route on a map. Quite recently, the option has also been added to make a heart film (ECG) with a smartwatch from Fitbit, Samsung or Apple. These measurements are remarkably accurate, they have even passed a medical examination. I also learned earlier that cardiologists actually use these heart rate measurements when determining, for example, cardiac arrhythmias. Incidentally, these applications are not suitable for self-diagnosis. In fact, a cardiologist also needs more measurements and examinations for a solid medical conclusion. You can read more about how valuable these heart rate measurements are here.
Incidentally, these applications are not suitable for self-diagnosis. In fact, a cardiologist also needs more measurements and examinations for a solid medical conclusion. You can read more about how valuable these heart rate measurements are here.
A medical examination is required for such claims to be fulfilled
Next step: blood pressure
Not only is such a watch able to measure your heart rate, but also values such as blood saturation (the amount of oxygen in your blood) can be tracked. You can’t just make these kinds of medical claims. A medical examination is required for this. Also, for example, to circumvent any liability for incorrect measurements. If you’re wondering why you probably hadn’t heard of ASUS’ smartwatch with blood pressure monitor before, it could be the quality mark. Anna Oroschin, marketing specialist at ASUS explains: “A request has been made to the FDA for the ECG, we hope to be FDA certified by the third quarter of this year. As for the blood pressure and ECG app for CE, we need to get the ISO13485 for Quality Management System first, and our goal is to submit the CE in the third quarter of this year.”
Samsung smartwatches do have a European CE mark for blood pressure measurement. But the function is not really user-friendly. To pair your Samsung smartwatch, you need the Galaxy Wear app on your smartphone. To then synchronize the activity measurement, you need the Galaxy Fit app. You would expect that you will also find the health functions, such as the blood pressure measurement, here. But no, you need another app for this: the Galaxy Health Monitor app. This app only works on a smartphone with a Dutch SIM card, to ensure that the blood pressure measurement with its European quality mark is actually used in the Netherlands. “Based on the SIM card, it can be determined whether the feature is being used in any of the 28 approved countries so that the feature can be activated,” said a Samsung spokesperson. In practice, it makes the experience with the blood pressure monitor quite user-unfriendly. While as a manufacturer of a wearable you would like to encourage this health function: the more frequently you measure, the more you can do with the data. When asked why the user is saddled with a jumble of different apps, Samsung does not have a clarifying answer: “In Europe, the Samsung Health Monitor app has received a CE mark. The Samsung Health app is a fitness and wellness app without this approval”. A missed opportunity, which mainly seems to radiate uncertainty about the blood pressure monitor.
Opportunities
You wear such a smartwatch continuously on your body, so that you can continuously measure values such as the heart rate and the number of steps taken. Measuring blood pressure as continuously as possible sounds like a valuable addition. For example, for the determination of conditions by doctors or for useful health recommendations by the health app of the smartwatch. Current blood pressure readings go through a band around your arm (cuff). By inflating the cuff, the arteries are closed for a while. A stethoscope listens for blood flowing through the arteries again when the air is removed from the cuff. By further reducing the pressure of the cuff and continuing to listen with the stethoscope, the negative pressure can be determined. However, such a measurement is a snapshot. The values are variable and can be influenced by external factors such as food, emotions, stress or activities.
Modern blood pressure monitors work differently and use the so-called oscillometric method. But in principle the operation is not much different. The inflation and deflation of the cuff is automatic, as is the pressure measurement.
Challenges
Such a cuff can therefore be inflated to measure blood pressure, but a smartwatch or fitness band cannot. In order to obtain reliable measurements, other methods must therefore be invented. As with ASUS’ smartwatch: “The Asus VivoWatch SP has a unique design with two types of sensors dedicated to the accurate measurement of both instantaneous blood pressure and blood pressure over time. First, the ECG sensor listens for the pounding of the heart, also known as the electrocardiographic wave. As the blood flows to the wrist, the ppg sensor then detects the wearer’s pulse. This gives us the Pulse Transmission Time (PTT) from the heart to the measurement site, the finger. Using our specially developed algorithm, we can then convert the data into a blood pressure measurement.”
To make a long story short: these are measurements based on complicated formulas and algorithms, based on three sensors on the watch. We know one of these, those are the green and sometimes red lights on the bottom of the watch that measure the heart rate. The other values for the complicated formula are measured by two sensors on the side of the watch that you place your thumb and forefinger on during the measurement. This does of course mean that your blood pressure cannot be measured continuously, but must still be started manually and thus remains a snapshot.
Samsung seems especially insecure about the performance of the blood pressure monitor
Measurement with one sensor
Samsung does have a CE mark and the measurement does not require a second sensor. In addition to the app maze, these smartwatches have another stumbling block: the blood pressure monitor must be calibrated once a month with a real blood pressure monitor for reliable results. Whether you do this at home with your own blood pressure monitor or at the doctor’s: it is a big hurdle that makes you wonder whether such a measurement is really of added value. In addition, such a measurement is also a snapshot with the Samsung watches, because it has to be started manually.
Everything must be measured
According to the Heart Foundation, keeping a record of your blood pressure is especially recommended after your 40s. How useful it would be if this was done accurately and frequently via your smartwatch. Health is more alive than ever, so measuring as many body values as possible offers huge opportunities for smartwatch makers. For example, Fitbit has equipped its recent smartwatch with a thermometer. A smart idea, because your body temperature tells a lot about your health and a fever can be an indicator of Covid-19, among other things. However, there is one problem: the thermometer is not able to measure body temperature, but measures your skin temperature. What can you measure with that? That your bedroom is colder if you sleep with the window open. Unless Fitbit invents groundbreaking algorithms, this skin temperature measurement is not of added value for the time being. At least for health purposes.
Blood pressure measurement in practice
It is clear that measuring blood pressure is something that is on the radar of smartwatch manufacturers. But in practice, that turns out to be quite a task, and you can see from everything that the manufacturers who do dare to use it on the market are anything but confident. ASUS’ smartwatch is scarce and Samsung is almost frantically throwing up app hordes and monthly calibration. Also, little marketing attention is given to it.
That’s not entirely unjustified either. In practice, both watches were not yet able to measure flawlessly. At Samsung, the values sometimes fluctuate or the smartwatch is not able to measure a blood pressure value, after which a next attempt turned out to be necessary. I couldn’t measure my blood pressure at all with the ASUS smartwatch. These experiences are of course personal and can differ per wrist.
It is not surprising that the manufacturers are unsure, because the blood pressure measurement method has to be completely reinvented with smartwatches. Algorithms and formulas should replace an inflatable cuff with a gauge. Those are headaches that Samsung and ASUS already dare to venture into. It remains to be seen for companies like Fitbit and Apple to develop their own blood pressure measurement methods, which are preferably accurate and continuous.
