For people living with conditions such as hypertension, knowing their blood pressure at all times certainly would be helpful. That's where a non-invasive new wearable system is designed to come in.
Currently, the standard method of measuring blood pressure involves utilizing an inflatable arm cuff – the device is officially known as a cuffed sphygmomanometer. While highly accurate, it certainly can't be worn by patients all day, as they go about their regular duties. It also only provides individual readings, as opposed to giving a continuous readout.
With these limitations in mind – and building upon previous research – scientists at Australia's Monash University developed the experimental new wireless setup.
Instead of an arm cuff, it incorporates a small continuous wave radar (CWR) sensor that's adhered to the sternum, and a photoplethysmogram sensor (PPG) that's clipped to the left earlobe. PPG sensors – typically taking the form of pulse oximeters – detect changes in blood volume by emitting light, and then analyzing how much of that light is absorbed by a patient's biological tissue.
Utilizing its two sensors, the new system is able to measure the amount of time that elapses between the heart's aortic valves pumping out blood, and that blood reaching the extremities (i.e: the earlobe) in the form of a pulse. Based on this information, the system is able to provide a real-time readout of the patient's blood pressure, regardless of where they are or what they're doing.
In lab tests, 43 healthy volunteers aged 40 to 65 wore both the experimental setup and a traditional cuffed sphygmomanometer while sitting, lying down, and cycling on a stationary bike. As compared to the arm cuff, the new system was found to be 93 percent accurate when the participants were resting, and 83 percent accurate when they were exercising. Those numbers should likely improve as the technology is developed further.
"Clinicians still cannot continuously measure blood pressure during sleep, nor during times of activity such as walking or running," says the lead scientist, Assoc. Prof. Mehmet Yuce. "This means people with high, low or irregular blood pressure can’t get the critical information they need about the state of their health around the clock. A wearable device that can provide comfort and portability while people are going about their daily lives will be a significant development for the health sector in Australia and internationally."
A paper on the research was recently published in the journal Scientific Reports.
Source: Monash University