Manage hypertension with optical imaging

Washington: Monitoring blood pressure might one day become as easy as taking a video selfie, claims recent research.

Transdermal optical imaging measures blood pressure by detecting blood flow changes in smartphone-captured facial videos. Ambient light penetrates the skin's outer layer allowing digital optical sensors in smartphones to visualise and extract blood flow patterns, which transdermal optical imaging models can use to predict blood pressure.

The study was published in the journal 'Circulation: Cardiovascular Imaging.'

"High blood pressure is a major contributor to cardiovascular disease -- a leading cause of death and disability. To manage and prevent it, regular monitoring of one's blood pressure is essential," said Kang Lee, study's lead author.

"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," Lee added.

Lee and his colleagues measured the blood flow of 1,328 Canadian and Chinese adults by capturing two-minute videos using an iPhone equipped with transdermal optical imaging software.

The researchers compared systolic, diastolic and pulse pressure measurements captured from smartphone videos to blood pressure readings using a traditional cuff-based continuous blood pressure measurement device.

They found that on average, transdermal optical imaging predicted systolic blood pressure with nearly 95 per cent accuracy and diastolic blood pressure with pulse pressure at nearly 96 per cent accuracy.

All the people in the study had normal blood pressure. "If future studies confirm our results and show this method can be used to measure blood pressures that are clinically high or low, we will have the option of a contactless and non-invasive method to monitor blood pressures conveniently - perhaps anytime and anywhere - for health management purposes," Lee said.

Researchers videoed 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. Lee and 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.