How researchers are using patient selfies to monitor blood pressure

A study published this week in Circulation: Cardiovascular Imaging details how one Canadian scientist and his team are using 2-minute video selfies to track patients’ blood pressure.

Lead author Kang Lee, PhD, a professor and research chair in developmental neuroscience at the University of Toronto, and colleagues leveraged a technique called transdermal optical imaging to measure the blood flow of 1,328 Canadian and Chinese adults, comparing those results to measurements taken in a more traditional way. In a release, Lee said that while managing and preventing hypertension is crucial to staving off CVD, it can be difficult for patients to keep up with a routine.

“Cuff-based blood pressure measuring devices, while highly accurate, are inconvenient and uncomfortable,” he said. “Users tend not to follow American Heart Association guidelines and device manufacturers’ suggestion to take multiple measurements each time.”

All the participants in Lee et al.’s study were instructed to record 2-minute videos using an iPhone equipped with transdermal optical imaging software. With transdermal optical imaging, digital optical sensors within smartphones are able to visualize and extract blood flow patterns from videos of users’ faces, ultimately synthesizing that data to predict BP values.

The authors compared systolic, diastolic and pulse pressure measurements between the smartphone captures and regular cuff readings and used that information to teach the transdermal tech to more accurately identify blood pressure. On average, the researchers’ transdermal optical imaging approach predicted systolic BP with nearly 95% accuracy and diastolic blood pressure with pulse pressure with nearly 96% accuracy.

The accuracy values are in line with international standards for BP monitoring devices, Lee said, but his team’s research still falls short in places. Researchers themselves videoed patients’ faces in a controlled environment with fixed lighting, so it’s unknown whether the transdermal technology would function as well in less controlled environments, and they need to test the technique’s accuracy on a wider range of skin tones.

In addition, the team is working to cut video selfie lengths from 2 minutes to 30 seconds.

“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 noninvasive method to monitor blood pressures conveniently—perhaps anytime and anywhere—for health management purposes,” Lee said.