Blood pressure monitoring with a video selfie
Chinese and Canadian researchers have developed an imaging method that could one day make blood pressure monitoring as easy as taking a video selfie, with the results of their work published in the journal Circulation: Cardiovascular Imaging.
Finding an accessible, easy way to monitor blood pressure is important given that nearly half of American adults have high blood pressure and many don’t even know they have it, according to the American Heart Association. As noted by the University of Toronto’s Professor Kang Lee, “Cuff-based blood pressure measuring devices, while highly accurate, are inconvenient and uncomfortable. Users tend not to follow American Heart Association guidelines and device manufacturers’ suggestion to take multiple measurements each time.”
With this in mind, Prof Lee and his colleagues measured the blood flow of 1328 Canadian and Chinese adults by capturing 2 min videos using an iPhone equipped with transdermal optical imaging software, which visualises and extracts blood flow patterns. They then compared systolic, diastolic and pulse pressure measurements captured from the smartphone videos to blood pressure readings using a traditional cuff-based continuous blood pressure measurement device.
The researchers used the data they gathered to teach the imaging technology how to accurately determine blood pressure and pulse from facial blood flow patterns. They found that on average, transdermal optical imaging predicted systolic blood pressure with nearly 95% accuracy and diastolic blood pressure with pulse pressure at nearly 96% accuracy. This is within international standards for devices used to measure blood pressure, according to Prof Lee.
The researchers acknowledged that they filmed faces in a well-controlled environment with fixed lighting, so it’s unclear whether the technology can accurately measure blood pressure in less controlled environments, including homes. Also, while the study’s participants had a variety of skin tones, the sample lacked subjects with either extremely dark or fair skin tones.
People in the study all had normal blood pressure, so future studies will need to show that the method can be used to measure blood pressures that are clinically high or low. The colleagues are also looking into reducing the needed video length from 2 minutes to 30 seconds, in order to make the technology more user-friendly.
“This study shows that facial video can contain some information about systolic blood pressure,” said Professor Ramakrishna Mukkamala, editorial author of Circulation Imaging. “If future studies could confirm this exciting result in hypertensive patients and with video camera measurements made during daily life, then obtaining blood pressure information with a click of a camera may become reality.”
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