Sticking plaster that can check your blood pressure
A PLASTER stuck on the side of the neck could be a simple new way to monitor blood pressure. The 1in patch is placed over one of the two carotid arteries — located in either side of the neck — which supply blood to the head, neck and face.
once in place, it beams sound waves through the skin into the artery. sensors in the patch then monitor the rate at which the waves are reflected back. The speed at which they travel is used to calculate how pliable the artery walls are.
When blood pressure is healthy, artery walls are elastic, stretchy and dilate easily to let blood pass smoothly. When blood pressure is too high, called hypertension, the walls are stiff, less pliable and blood moves less smoothly.
A microchip inside the patch stores the findings, which are wirelessly beamed to a computer that converts them into blood pressure readings.
High blood pressure is a reading above 140/90 and it is responsible for half of all heart attacks and strokes. The majority of patients need pills to control it.
But diagnosis can be difficult, as blood pressure can vary greatly over a day and many patients with otherwise normal readings can experience a spike brought on by anxiety during a visit to a doctor.
To avoid this, patients can wear a cuff around the upper arm attached to a blood pressure monitor that clips on to a waistband and takes round-the-clock readings. But these devices are bulky and uncomfortable.
The new patch, developed at the University of California, san Diego, may be a convenient alternative.
Made from stretchy silicone, it resembles a normal plaster, but contains 20 electrodes. Alongside each is a transducer, a miniature device that converts electrical signals into sound waves.
The battery-powered electrodes constantly send an electrical charge to each adjacent transducer, which converts the charge into sound waves that travel through the skin. Their speed of travel is recorded in the plaster and this provides minute-byminute blood pressure readings.
scientists predict the patch could give a more accurate assessment of blood pressure than the standard technique of inflating a cuff around a patient’s arm.
A more accurate way of predicting heart disease is using core blood pressure readings, where doctors track readings in blood vessels in and around the heart and lungs. Getting these generally involves using a tonometer, a pen-like probe held by a doctor on the skin above a major blood vessel.
But the device has to be held at precisely the right angle and with a specific amount of pressure.
The patch — which is still at prototype stage and will need several years’ testing before it can be widely used — could be more convenient than the tonometer.
The patch has only been tested on one male, who wore it for several days. He then had his blood pressure checked with a tonometer. The patch gave more precise and consistent findings, reports the journal Nature Biomedical Engineering.
Dr Cara Hendry, a consultant cardiologist at the Manchester Heart Centre, said: ‘This interesting device could provide valuable data on arterial stiffness, which is directly related to the risk of stroke and heart disease. But much more research is needed.’