Measuring a patient’s blood pressure could one day be as simple as getting them to take a selfie.
A study found using a smartphone to video someone’s face for two minutes could produce a blood pressure reading that was 96 per cent accurate.
Regular monitoring is important for patients with high blood pressure – medically known as hypertension – to help them keep the killer condition under control.
But many patients often cannot be bothered to use the inflatable arm cuffs or other cumbersome devices, scientists say.
They added that, if tests of the ‘exciting’ technique continue to be successful, ‘obtaining blood pressure information with a click of a camera may become reality’.
By tracking the intensity and movement of light reflected from blood vessels in the face, researchers used artificial intelligence to work out someone’s blood pressure with 96 per cent accuracy
Researchers at the University of Toronto in Canada tried the iPhone-testing method on 1,328 people with normal blood pressure.
The technology works by picking up light reflected from blood vessels behind the skin in the face and using that to measure blood flow.
Face skin is so thin that light can travel through it and then bounce back off a red protein called haemoglobin, which carries oxygen in the blood.
Phone cameras are sensitive enough to pick up the specific colour of this reflected light and software can be used to track the blood’s movement around the face.
By scanning for the density and motion of blood in the cheeks, nose and forehead, scientists say they can work out blood pressure with 96 per cent accuracy.
‘High blood pressure is a major contributor to cardiovascular disease – a leading cause of death and disability,’ said Dr Kang Lee.
‘Cuff-based blood pressure measuring devices, while highly accurate, are inconvenient and uncomfortable.
The iPhone app videoed the patients’ faces for two minutes to pick up the movement of light reflected by blood
‘Users tend not to follow American Heart Association guidelines and device manufacturers’ suggestions to take multiple measurements each time.
‘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.’
Dr Lee’s study required people to take two-minute videos of themselves, but he hopes to be able to cut this down to 30 seconds without losing effectiveness.
The tests were also done in a studio with bright, controlled lighting – less reliable lighting at home or outside may reduce how well the camera works.
And the software has not been tested on people with very dark or very light skin, Dr Lee said, although it has worked on people with ‘a variety of skin tones’.
Dr Lee said the early tests have shown the technology is accurate enough to comply with international standards for a blood pressure measuring device.
A staggering 16million people in the UK – about one in three adults – have high blood pressure, according to the charity Blood Pressure UK.
And the American Heart Association says there are around 103million people in the US with the condition.
Having high blood pressure puts extra strain on the veins and arteries, heart, eyes, brain and kidneys.
The technology works because skin on the face is so thin that light can pass through it and then reflect back off a protein in the blood called haemoglobin, and this particular light can be picked up by an iPhone camera, the scientists said
It can increase the risk of heart disease, heart attack, stroke, heart failure, kidney disease or dementia.
People who are overweight, over 65, don’t eat enough fruit and vegetables, don’t exercise enough or smoke or drink are at a higher risk of the condition.
Those who fail to reduce their blood pressure by eating healthily, exercising and sleeping may have to rely on medication to keep it down.
Dr Ramakrishna Mukkamala, from Michigan State University, added: ‘If future studies could confirm this exciting result in [high blood pressure] patients and with video camera measurements made during daily life, then obtaining blood pressure information with a click of a camera may become reality.’
The research was published in the journal Circulation: Cardiovascular Imaging by the American Heart Association.