Researchers in Australia recently developed a wireless blood pressure monitor for continuous blood pressure monitoring.
About 1.25 billion people worldwide suffer from blood pressure abnormalities, such as high or low blood pressure. Blood pressure abnormalities are serious risk factors in many illnesses.
Traditionally blood pressure is measured using a blood pressure cuff (known as a sphygmomanometer) and a stethoscope. However, this method can cause discomfort, especially for critically ill patients. When continuous monitoring is required, a needle must be placed in the patient’s artery, which can lead to infection or even loss of limbs.
Researchers from Monash University in Australia have developed a wireless blood pressure monitor that can continuously track blood pressure without invasive means. Their results were published in Nature.
Researchers have developed devices that use radar technology to measure blood pressure continuously. The methods developed previously were unable to find a method that was comfortable for patients or provide accurate data. They wanted to be able to have a method that would track blood pressure throughout the day. This would enable the study of blood pressure during daily activity.
The wireless blood pressure monitor in this study was developed using a combination of a radar sensor placed on the patient’s breastbone, a sensor on their left earlobe, and ECG electrodes on the chest.
Forty-three volunteers participated in the study. Each was fitted with the wireless blood pressure monitor and wore a calibrated blood pressure cuff. There were two sessions during which the experiments were conducted. All participants took part in session one.
During session one, participants sat for six minutes, stood for six minutes, and lay down for six minutes. The continuous blood pressure monitor measured signals from the breastbone sensor, earlobe sensor, and ECG.
Twenty-six of the participants were randomly selected to participate in session two. During session two, participants held a handgrip for two minutes and then rested for one minute. They then cycled at three different resistances – low, medium, and heavy. At each resistance, they cycled at a fixed speed for two minutes, and then rested for one minute. Finally, they sat on the bicycles for two minutes doing nothing.
Throughout the study, the wireless blood pressure monitor signals were recorded throughout all activity and recovery periods. Blood pressure was also measured every three minutes from the blood pressure cuffs.
Researchers found that the wireless blood pressure monitor was 93% accurate during session one, and 83% accurate during session two.
According to one of the researchers, Mehmet Yet, “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. Results of this study demonstrate the potential superiority of CWR-based PEP extraction for various medical monitoring applications, including blood pressure monitoring.”
Written by Rebecca K. Blankenship, B.Sc.
Pour Ebrahim, M., Heydari, F., Wu, T. et al. Blood Pressure Estimation Using On-body Continuous Wave Radar and Photoplethysmogram in Various Posture and Exercise Conditions. Sci Rep 9, 16346 (2019). https://doi.org/10.1038/s41598-019-52710-8
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