No Role for Cuffless BP Monitoring at Present: ESH Statement

June 23, 2022

Cuffless blood pressure measurement is a fast-growing and promising field with considerable potential for improving hypertension awareness, management, and control, but because the accuracy of these new devices has not yet been validated, they are not suitable for clinical use at present, concludes a new statement from the European Society of Hypertension.

The statement was published online June 17 in the Journal of Hypertension.  

It explains that cuffless blood pressure monitors use a variety of novel technologies, some of which require individual user cuff calibration, and they all have specific accuracy issues that are different and more complex than those of the cuff blood pressure devices.

There is an urgent need to develop an internationally accepted accuracy standard that is specific for the validation of cuffless blood pressure devices, and the clinical usefulness of these devices must be proven in healthy people and those with suspected or diagnosed hypertension when applied together or instead of the currently recommended blood pressure measurement methods, the statement says.

Until these issues have been properly addressed, cuffless blood pressure devices should not be used for the evaluation or management of hypertension in clinical practice, the authors conclude.

"While we believe cuffless blood pressure monitoring has great potential and could become a very useful tool in future, people need to understand that they have not yet been validated, and we do not know if the results they are giving are accurate," lead author of ESH consensus document, George Stergiou, MD, National and Kapodistrian University of Athens, Greece, told | Medscape Cardiology.

"In addition, there are many different types of cuffless blood pressure monitoring devices which use many different technologies, so the validation process is very complex," Stergiou added. "We need to figure out the protocol for validation which will be different for each type of devices. We don't have these data at the moment, so we cannot recommend these devices for clinical use."

The statement authors — a team of 24 experts — note that the currently recommended upper-arm cuff blood pressure measurement technique has two important limitations. It provides only intermittent measurements in static conditions, so is unable to detect and record the rapid and dynamic blood pressure changes in response to physical and mental challenges of daily life, they note. The use of a cuff introduces errors related to its size, shape, and positioning, and compression of the limb during inflation may alert the user, inducing anxiety and discomfort during daily activities and sleep, factors that can affect the level of measured blood pressure.

In an aim to provide a solution to these issues, several approaches have recently been developed that use cuffless technologies to estimate blood pressure based on sensors, signal processing, and algorithms embedded in wearable devices, smartphones, pocket devices, and other types of devices.

The promise of cuffless wearable blood pressure monitoring devices is to record BP comfortably and continuously with minimal user intervention, the statement says, adding that the new technologies could provide detailed and unbiased information regarding circadian blood pressure patterns and variability.

However, wearable monitors might report transient excessively raised blood pressure values during daily life activities, which are likely to be harmless if they last for a short time but could cause anxiety and even unnecessary clinic or emergency visits, it adds.

Many cuffless blood pressure monitoring devices are now available on the market, and some doctors, patients, and members of the public are eager to use them, despite little understanding of their limitations and special issues in assessing their accuracy, the statement says.  

"While these devices are available for the public to buy and they give a value for blood pressure, this may not be the same measurement that would be recorded with a cuff device, and we don't know if it is an overestimate or an underestimate," Stergiou explained.

He does not believe these new devices are even suitable for home use to give someone an idea of whether they need to get their blood pressure checked in a clinical setting.

"The problem is that we just don't know what the information these devices are giving means. It gives you a number, but we don't know how to interpret that number, as we don't know what is normal on that particular device. So, we don't think it is useful information," he commented.

"In my opinion, every measurement needs to be accurate. If the measures are not accurate, then they can mislead people. If the measurement is higher than the actual value, then this leads to unnecessary testing, use of resources and stress for the individual. And if it is lower than the real measurement, then it could give a false reassurance," he added. "We need to know that the measurement is valid. At the present time, there is no cuffless technology that is believed to be accurate enough to replace what we have for the clinical diagnosis of hypertension."

Stergiou pointed out that the major issue with these new devices is that they are not just using one new technology.

"There are many different approaches being employed in the different devices. Some use a finger on a mobile phone, some use a video of your face, others are something you wear, and some devices require calibration while others do not. Each is based on different principles and has different issues, with different approaches required for validation," he explained.

"We don't have a universal standard on how to assess the accuracy of these new devices. But we do know that the standard for cuff blood pressure measurement devices does not work for these cuffless devices, so we need a new standard."

He said there is a lot of work going on to develop standards on how to validate such devices. "But the problem is that all the devices are different, and one standard is not going to be applicable to all devices. We will have to have a different standard for each different technology.

Still, he said, "we are very happy to adopt new technology. The idea of cuffless blood pressure measurement is a great one, but we are not there yet. This consensus statement is a warning to healthcare professional colleagues that we need to wait for these devices to be validated before we know if some of them can be useful."

Stergiou has conducted validation studies for various manufacturers of blood pressure measurement technologies and advised manufacturers on device and software development.

J Hypertens. Published online June 17, 2022. Full text

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