Wireless blood pressure monitor allows continuous readings

Monash University researchers develop wireless blood pressure monitor
Monash University researchers developed a wireless blood pressure monitor that allows continuous patient monitoring. (Monash University)

Researchers at Monash University have created a portable, wireless blood pressure monitoring device that can provide data continuously to patients in the comfort of their home. The device is designed to overcome the disadvantages of traditional cuffed spygmonanometers, and the discomfort and potential hazards of invasive blood pressure monitors.

In a global study led by Associate Professor Mehmet Yuce from Monash University’s Department of Electrical and Computer Systems Engineering, 43 Australian participants trialed a wireless blood pressure monitoring device, developed by the research team, which provided continual readings across a 24-hour period.

Data was recorded during a range of sedentary and physical activities during the participants’ regular day. Results were published in the international journal Nature Scientific Reports.

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The familiar method of measuring blood pressure is using the cuffed sphygmomanometer, commonly seen at GP clinics and hospitals. “For close to a century, the health sector has used the cuff device to measure blood pressure. More invasive measures are used to monitor the continuous blood pressure of critically ill patients, which are uncomfortable and could potentially cause infection due to ischemia,” Associate Professor Yuce said.

The Monash researchers used continuous wave radar (CWR) and photoplethysmogram (PPG) sensors to calculate continuous blood pressure measurements. The CWR and PPG sensors were placed on the sternum and left earlobe respectively.

Using radar technology, researchers were able to calculate the pre-ejection period (PEP)—the mechanical delay associated with heart movements ejecting the blood—and the pulse transit time to estimate blood pressure in patients while sitting, laying down or exercising.

A trial was conducted on 43 participants, between the ages of 40 and 65, with no previous cardiovascular problems. Participants wore both the cuff device and the chest-based prototype to monitor the difference between blood pressure readings.

Blood pressure data was recorded on all participants while sitting, standing and laying in the supine position (facing upwards). Subsequent tests were also conducted with patients holding a handgrip for two minutes; cycling at a fixed speed across three different resistance levels; and at the recovery stage after the cycling tasks.

Results on subjects participating in posture tasks were 93 per cent accurate, while those performing exercises achieved an 83 per cent success rate.

The technology can provide real-time access to data and give doctors an overview of how their patients’ blood pressure changes over the course of a day, rather than only at the time of testing.

Associate Professor Yuce and his research team have developed several prototypes of the blood pressure device, and will conduct further tests to make it more accurate and suitable for clinical use.

“The CWR sensors present a low-power, continuous and potentially wearable system with minimal body contact to monitor aortic valve activities directly. Doctors would be interested to see such information for long-term better diagnosis of their patients,” Yuce said.

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