Smartphone-based blood pressure monitoring via the oscillometric finger-pressing method

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Science Translational Medicine  07 Mar 2018:
Vol. 10, Issue 431, eaap8674
DOI: 10.1126/scitranslmed.aap8674

Blood pressure at your fingertips

Managing high blood pressure can reduce the risk of cardiovascular disease. Standard blood pressure measurement devices use an inflatable arm cuff to vary the pressure applied to the brachial artery. For the smartphone device developed by Chandrasekhar et al., the user provides external pressure on an artery in the finger by pressing an optical sensor overlaying a force transducer on the back of a modified smartphone. The phone runs an app to ensure that the user maintains sufficient finger contact while computing brachial artery blood pressures from the finger-based measurements. The authors showed that blood pressure readings were similar using their smartphone device, a standard arm cuff device, and a finger-cuff device in a group of participants. This smartphone-based device could help make measuring blood pressure more accessible.


High blood pressure (BP) is a major cardiovascular risk factor that is treatable, yet hypertension awareness and control rates are low. Ubiquitous BP monitoring technology could improve hypertension management, but existing devices require an inflatable cuff and are not compatible with such anytime, anywhere measurement of BP. We extended the oscillometric principle, which is used by most automatic cuff devices, to develop a cuff-less BP monitoring device using a smartphone. As the user presses her/his finger against the smartphone, the external pressure of the underlying artery is steadily increased while the phone measures the applied pressure and resulting variable-amplitude blood volume oscillations. A smartphone application provides visual feedback to guide the amount of pressure applied over time via the finger pressing and computes systolic and diastolic BP from the measurements. 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. These errors were comparable to the finger cuff device. Cuff-less and calibration-free monitoring of systolic and diastolic BP may be feasible via a smartphone.

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