Blood pressure is a critical vital sign and patients, particularly those with cardiovascular conditions, are often directed to take readings on their own on a regular basis. Of course too few of them do as prescribed, and the lack of motivation has a lot to do with the fact that blood pressure measurement devices tend to be bulky, unwieldy, and not always easily accessible. Turns out that modern smartphones already have nearly all the technology needed to measure blood pressure with nearly the same accuracy as commercial devices.
A team at Michigan State University have developed a smartphone attachment that measures blood pressure from the transverse palmar arch artery in the index finger. The finger is placed over the sensor on the smartphone attachment and pressed against it with a bit of force. The device measures the amount of force and guides the user to reduce or increase it to get it within a desired range. A cheap optical component then measures how light penetrating through the finger changes its characteristics and the system converts these readings into blood pressure measurements.
The technology was tested against upper arm cuffs and finger cuffs, achieving close results to upper arm cuffs and near the same results as the slightly less accurate finger cuffs.
From the study in Science Translational Medicine:
We prospectively tested the smartphone-based device for real-time BP monitoring in human subjects to evaluate usability (n = 30) and accuracy against a standard automatic cuff-based device (n = 32). We likewise tested a finger cuff device, which uses the volume-clamp method of BP detection. About 90% of the users learned the finger actuation required by the smartphone-based device after one or two practice trials. The device yielded bias and precision errors of 3.3 and 8.8 mmHg for systolic BP and −5.6 and 7.7 mmHg for diastolic BP over a 40 to 50 mmHg range of BP.
Here’s a video from American Association for the Advancement of Science about the technology:
Study in Science Translational Medicine: Smartphone-based blood pressure monitoring via the oscillometric finger-pressing method…
Via: Michigan State…