The smartphone case that takes your blood pressure

They’re used to make calls, send messages, browse the web, play music, watch TV and a million and one other things. And soon your smartphone could… take your blood pressure.

A team of US researchers has developed a blood pressure monitoring prototype that could one day make measuring the major risk factor for heart attack and stroke as simple as pressing your fingertip down on your phone.

The special phone case uses high-tech 3D printing technology that is embedded with an optical sensor, which measures blood pressure through force applied to an artery in a finger. It is claimed to provide a blood pressure reading in the same way that a blood pressure cuff squeezes an artery in the arm.

Trial results from a group of 30 participants, published in the journal Science Translational Medicine, showed blood pressure readings were similar to those from a standard arm cuff device and finger-cuff device. Nine out of ten participants were able to position their finger correctly on the phone and get consistent readings after two attempts, the paper said.

Last year, the Heart Foundation warned that millions of Australians were “ticking time-bombs”, unaware that they are at risk of a heart attack or stroke because of dangerously high blood pressure. Meanwhile, data from the Australian Bureau of Statistics shows that a quarter of adults have high blood pressure that is either untreated or treated inadequately.

“In Australia, more deaths can be put down to high blood pressure than to any other single risk factor,” said Heart Foundation CEO, Adjunct Professor John Kelly.

The ‘gold-standard’ of blood pressure tests

While influenced by a number of factors, including family history, high blood pressure is usually a result of lifestyle habits, including stress and poor diet. Seeing a doctor is the first step to getting an accurate blood pressure measurement, but the nerves that some people feel when visiting the GP can adversely affect their reading, said James Sharman of the University of Tasmania.

“To confirm someone’s underlying blood pressure, the recommendation is to take a series of readings outside of the clinical environment, so away from the doctor,” Professor Sharman told the ABC.

In Australia, the gold-standard of home blood pressure monitoring is said to be 24-hour ambulatory monitoring. But this is expensive, requires infrastructure and is not readily available or accessible.

“What that involves is wearing a cuff attached to a device that is fitted by a health professional. It takes measurements of your blood pressure usually every 20 minutes during the day and every 30 minutes at night. After 24 hours, you get an average of all those readings,” explained Professor Sharman.

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