Blood pressure monitoring via wearables

Blood pressure monitoring via wearables

The advantages and disadvantages of taking your blood pressure from your wrist:

High blood pressure, often known as hypertension, affects one out of every four men and one out of every five women worldwide. They may be more susceptible to heart attacks and strokes as a result of this. This high blood pressure can be measured by using multiple blood pressure monitoring wearables. Hypertension has symptoms like headaches and visual problems. Many individuals don’t experience them, thus diagnosis and treatment are often delayed. This is why everyone, especially those at high risk, should have their blood pressure checked on a regular basis.

A blood pressure monitor cuff, or more technically, a sphygmomanometer, is the most common technique to diagnose hypertension. This is a cuff that is connected to a tiny screen gadget. The cuff is wrapped around the upper arm and tightens to reduce blood flow. This enables pressure sensors inside to monitor the force with which your blood pushes against your arteries as it circulates throughout your body – your blood pressure.

Why do we need additional solutions when this one is very simple and accurate?

Blood pressure monitoring’s drawbacks:

Hypertension sufferers should monitor blood pressure twice a day, according to experts. However, according to a 2020 survey by wearable sensor startup Valencell, 31% of US adults with hypertension only check their blood pressure once a month, and another 31% only check it once a year. This could be due to patients forgetting, not having the necessary equipment on hand or a lack of funding.

‘“We do not have time or ability to do regular blood pressure measurements or take accurate blood pressure readings, ‘says Dr. Jordana Cohen, an Assistant Professor of Medicine and Epidemiology who specializes in hypertension research at the University of Pennsylvania.

If a patient starts a new medicine, for example, numerous readings should be taken on the same day and over the next few days to assess how they respond – but this isn’t always practicable.

Traditional blood pressure monitoring?

Traditional blood pressure monitoring is particularly inaccurate, according to Dr. Cohen, because of a variety of unique situations. Whitecoat hypertension, for example, occurs when a person’s blood pressure rises while they are among doctors but not at home. Masked hypertension occurs when blood pressure monitoring is normal in the doctor’s office but high at home. Alternatively, nocturnal hypertension occurs when blood pressure rises while sleeping.

Those with persistent hypertension may require ambulatory blood pressure monitoring (ABPM). This is when they are given a portable blood pressure monitor with a cuff to wear throughout the day by their doctor. Every half-hour or so, the cuff takes a reading and saves it for later.

Cuff blood pressure monitoring, whether done in a clinic or at home, is inconvenient for a number of reasons: it can’t be done at night, it might raise blood pressure when the cuff inflates, and it can be difficult to wear during the day for those who work, are on the go, are disabled, or are older. This is why wearable tech companies are working on solutions to make reading as simple and unobtrusive as wearing a fitness tracker on your wrist that gathers measures throughout the day — less stress, no cuff.

Cuffless blood pressure monitoring: What is it and how does it work?

There are already a variety of cuffless monitoring options being investigated and developed, according to Dr. Ghalib Janjua, a lecturer in electronic and electrical engineering at Robert Gordon University who specializes in bioengineering and cuffless blood pressure monitoring. Pulse arrival time, pulse transit time, pulse wave analysis, and pulse wave velocity are some of the metrics used in these.

“These are all restricted in accuracy and require periodic calibration against the sphygmomanometer devices,” Dr. Janjua cautions. This implies that, although some devices can already take cuffless readings, you’ll need a device with a cuff – a sphygmomanometer gadget – to double-check their accuracy on a frequent basis.

PPG (photoplethysmography):

Some of these technologies have just recently been developed in such a way that cuffless blood pressure monitoring is now a practical alternative for us all to use at home. The PPG (photoplethysmography) sensor, which can be found on the underside of an Apple Watch or a Fitbit Versa and is used to detect heart rate, is employed in the majority of devices. It can, however, determine blood pressure by taking optical measurements of your arteries.

Search Amazon for a variety of blood pressure monitoring wearables. Also for the fitness trackers that promise to be able to measure your blood pressure using a PPG sensor. Many of them, however, are estimations and are not authorized medical devices, but rather lifestyle wearables targeted at providing a general picture of your overall health — not detecting major diseases. But all of that might change very soon.

There have been several reports that other wearable companies, such as Fitbit and Apple, may soon release comparable functionalities. This might imply utilizing data from PPG sensors, such as those manufactured by Samsung, or utilizing pressure sensor technology similar to that found in a blood pressure monitor cuff. For example, in 2020, Apple registered a patent describing how to assess blood pressure using pressure sensors in a wearable bracelet.

Aktiia: Is it possible to monitor your blood pressure 24/7?

Aktiia is a new entry to the wearable blood pressure monitoring market (it is now available for pre-order in the UK for £159.99, with international availability coming soon). This is a cuffless device that you wear on your wrist.

We got our hands on a trial unit of the Aktiia and can confirm that it’s even thinner and comfier than a fitness tracker — the key difference is that it doesn’t have a screen. I enjoy viewing statistics in real-time, but I see why a more subtle approach is not only more attractive to a broader audience but also decreases the anxiety that some individuals have when thinking about and monitoring their blood pressure.

Aktiia uses a PPG sensor to take blood pressure readings every 90 minutes during the day and night. The results are then delivered to your phone, where you can view them. You will need a cuff for the initial setup (which comes in the package with the Aktiia). It confirms everything is working properly. The idea is that you will rarely need one to ‘check’ the Aktiia’s readings after that.

We know that cuff devices work by limiting blood flow to analyze the pulse that goes along your arteries. Aktiia’s technology performs the same function, but without the cuff.

“Our system also analyses pulse waves flowing through arteries to provide blood pressure estimates,” says Dr. Josep Sola, Aktiia’s creator, and CTO.  In spite, Aktiia’s algorithms use optical sensors to assess the changing diameter of the arteries at the wrist, rather than pressure sensors.

Advantages of Aktiia:

One of the most significant advantages of Aktiia is that readings are taken repeatedly. This means you won’t have to be worried about your readings, which can cause your blood pressure to rise. It does not require you to click a button, sit stationary, or even be awake for it to function.

Dr. Sola explains, “It assists clinicians in making more precise diagnoses, providing more personalized treatment regimens, and evaluating the success of therapy”. He also demonstrates how 24/7 monitoring may provide patients with real-time insights about the influence of what they eat, how often they exercise, how well they sleep, and how they deal with stress on their blood pressure.

Aktiia has big ambitions. Dr. Sola tells me that Aktiia’s mission is to assist 100 million individuals to better understand and manage their blood pressure over the next ten years. Although the main purpose is to sell customers a new item, the information gathered might have a far more positive impact. Dr. Sola explains, “We are constructing the world’s biggest, continuous, 24/7 blood pressure dataset, which will allow considerable changes to the present standard of care, including diagnosis, treatment, and monitoring.”

Furthermore, Aktiia’s technology may be used more broadly in the near future. Dr. Sola informs me that the team is in discussion to offer its software and services to more third-party blood-pressure monitoring wearables, though no specifics have been finalized.

What is the accuracy of the cuffless blood pressure monitor?

Aktiia has a bright future ahead. It’s now legally classified as a medical device, which means it complies with European health and safety regulations. But, whether it’s Aktiia or any other cuffless blood pressure monitoring gadget in development, the fundamental issue is: how accurate are they?

Devices meant to be worn on the wrist, on the other hand, may cause issues. Blood pressure measurements should only be collected from the upper arm, according to the American Heart Association. It argues that other sites, such as your wrist or finger, may not be as accurate.

Doctors’ reviews:

“Rather of directly measuring blood pressure, Aktiia and all existing cuff-based blood pressure monitors provide estimates,” adds Dr. Sola.

“Blood pressure is monitored in clinical settings while the individual is in a steady sitting posture, which maintains the blood pressure in the brachial artery constant,” Dr. Janjua says. “The signal is captured at the radial artery at the wrist and/or finger site in the wearable device, which is lower than the heart level and might cause hydrostatic fluctuation. These changes lead to inaccurate blood pressure readings.”

Although a wrist-worn blood pressure monitor may be more convenient. It allows you to gather more readings, obtaining these measures from your wrist may mean they aren’t as reliable.

Furthermore, it’s possible that cuffless monitors are already at a disadvantage. “Without the cuff, device algorithms must make several assumptions. It tries to anticipate what the findings of utilizing a cuff could have shown,” Dr. Jordana Cohen explains.

“Emerging technologies may be able to solve this difficulty in the future. We need to do meticulous studies to show that they are consistently valid in a wide variety of patients. It also utilizes suitable and rigorous procedures created by specialists in this field,” Dr. Jordana Cohen adds. “This includes people who will not profit from the sale of these devices.”


What is the solution? More testing, data collecting, and validation are all needed. There are several worldwide organizations that judge whether a device can be used to reliably evaluate blood pressure. Each of them will require proof that cuffless, wearable devices are as accurate as they promise. This may occur soon, but patience and accuracy are required.

“While these may prove to be an interesting and useful new approach to monitor blood pressure in the future,” Dr. Cohen warns, “we must be careful of the pitfalls of acting on blood pressure readings that may be extremely inaccurate”. “People’s hypertension may be severely over-or under-treated, putting them at risk for serious harm.”

Blood pressure monitoring in the future:

Is it feasible that these technologies may someday replace the use of a cuff to measure blood pressure? I met with experts who were both excited and concerned. Dr. Janjua explains that it is the start of a century-old technology being modernized. It’s an area that’s yielding promising results.

People are encouraged to check readings on both a cuffless and cuff-based device in-home solutions to address accuracy problems. Expecting individuals to own and utilize two distinct techniques, on the other hand, makes them feel more inaccessible, not less.

So hold off on getting rid of your cuff-based blood pressure monitor. But, in near future, expect to see additional Aktiia gadgets, as well as more blood pressure monitoring wearable.

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