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Despite an ongoing critical need and a monumnetal financial investment in technological innovation in recent years, there is currently no commercially available, accurate, continuous, non-invasive blood pressure (cNIBP) monitoring device.
The limitations of standard-of-care measurement
The occlusive arm-cuff device, which is today’s standard of care for BP monitoring, has been universally accepted and widely used for well over a century. However, its utility is compromised by 3 critical flaws that limit the ability to determine an individual’s true BP:
■ Overall inaccuracy
■ Inability to measure continuously
■ Inability to provide nocturnal measurement
The question of accuracy
Arm-cuff devices do not measure pressure directly, but rather oscillations in the blood which are converted to BP via a formula that indirectly estimates systolic and diastolic pressures. This conversion process introduces considerable inaccuracies on its own. In addition, cuff devices introduce a range of other inaccuracies due to: inappropriate cuff size, incorrect arm position, changes in overall body position, and activities such as deep breathing, arm movement relative the heart, and talking. Studies have shown that cuff-based devices provide inaccurate BP readings 50% to 70% of the time.
The question of continuous measurement
Another limitation is that occlusive arm-cuff devices can only measure BP at a single point in time. However, BP is dynamic, ranging widely over the course of the day and night. Studies have shown that 24-hour BP parameters, such as mean BP taken over the course of the day at home and outside of the home, nighttime BP, and BP variability over 24-hours, are better predictors for the risk of heart attack and stroke than single-time measurements.
As a result of inaccuracy and the inability to provide continuous measurement, current standard-of-care for BP measurement provides only a surrogate measure of a patient’s true BP at best.
Misdiagnose hypertension in
30%
of patients
Contribute to lack of control in
>50%
of hypertensive patients in the US
Result in monitoring gaps in
~30%
of patients in intensive care units requiring invasive arterial lines for continuous BP monitoring, which increase the risk for complications
Arm-cuff devices:
Why accurate continuous BP monitoring is critical to improving healthcare
Low BP, also known as hypotension, poses a serious risk factor, especially to the critically ill
■ Raises risk for 27M patients undergoing major surgery each year in the US
■ A major cause of post-operative death, which is the third leading cause of mortality
■ Increased risk for heart attack/kidney failure events per year ~3M
■ Increased risk for unexpected cardiac arrests per year ~300K, most of which are in the intensive care unit (ICU)
High BP, also known as hypertension, increases risk for 1.4B people globally
#1 cause of stroke and heart attacks
■ Undiagnosed nighttime hypertension is a major cause of mortality—nocturnal BP cannot be monitored with an occulsive device
■ Hypertension is misdiagnosed in 30% of patients
Of course, a number of newer methodologies, such as pulse analysis, pulse transit time, tonometry, and the volume clamp have all claimed to meet the need for more accurate BP measurement. Indeed, devices based on these methodologies have even received FDA clearance to got to market, but like the century-old occlusive methodology, they are based on proxy measures to indirectly estimate systolic and diastolic BP vs actual BP. As such, their use is contingent on extrernal calibration with single-time point measurements taken with cuff-based oscillometric. devices, so in addition to being cumbersome and inconvenient, they are not reliable. as such, none of these methodologies have been adopted by the medical community.
In 2015, the NIH issued a request to academia and industry for a standalone, accurate and continuous, noninvasive blood pressure (cNIBP) monitor
