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A smartphone video-based measurement tool accurately predicted blood pressure (BP) readings in a proof-of-concept study recently published in Circulation: Cardiovascular Imaging. The technology, dubbed transdermal optical imaging, records facial blood flow using a standard smartphone video camera.
The technique captures light reflecting off of hemoglobin in blood under the skin. Using machine learning, researchers trained and tested software to interpret light modulations in facial videos from 1126 adults. These modulations correlate with pulsating arteries under the skin, which in turn correlate with BP. In a separate group of 202 participants, the model predicted systolic BP, diastolic BP, and pulse pressure with around 95% accuracy compared with a standard continuous BP monitor.
Kang Lee, PhD, of the University of Toronto, the study’s co–senior author, noted several limitations that could affect the findings’ generalizability. The study included only normotensive adults. Future studies will need to include participants with both high and low BP, some of them treated with medications. More diverse races and skin tones should also be represented. And the technology should be validated against gold-standard measurement techniques, such as intra-arterial pressure. Finally, the approach needs to be tested in real-world scenarios—with the phone held in the hand instead of mounted on a tripod, for example.
“This paper shows for the first time that we can use the video camera in the smartphone to measure our blood pressure non-invasively and accurately without contact,” Lee said. “It opens up the possibility that we can use our smartphone to regularly and conveniently monitor our blood pressure.”
Abbasi J. Cuffless Blood Pressure Monitoring. JAMA. 2019;322(14):1343. doi:10.1001/jama.2019.15537
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