Researchers have combined wireless and ultrasound technologies to develop a wearable patch that can monitor blood pressure (BP) in arteries deep beneath the skin. This ultrasound patch provides an easy way to help people detect cardiovascular problems earlier on and with greater precision. A team of researchers led by the University of California San Diego describe their work in a paper published in Nature Biomedical Engineering.Applications include real-time, continuous monitoring of BP changes in patients with heart or lung disease, as well as patients who are critically ill or undergoing surgery. Physicians involved with the study say the technology would be useful in various inpatient procedures. “This has the potential to be a great addition to cardiovascular medicine,” says co-author Dr. Brady Huang, a radiologist at UC San Diego Health. “In the operating room, especially in complex cardiopulmonary procedures, accurate real-time assessment of central blood pressure is needed this is where this device has the potential to supplant traditional methods.”The device measures central blood pressure in major arteries as deep as four centimetres (more than one inch) below the skin. Central blood pressure is the pressure in the central blood vessels, which send blood directly from the heart to other major organs throughout the body. It differs from the blood pressure that’s measured with an inflatable cuff strapped around the upper arm, known as peripheral blood pressure. Medical experts consider central blood pressure more accurate than peripheral blood pressure and also say it’s better at predicting heart disease. The state-of-the-art clinical method for measuring central blood pressure is invasive, involving a catheter inserted into a blood vessel in a patient’s arm, groin or neck and guiding it to the heart. A non-invasive method exists, but it can’t consistently produce accurate readings. It involves holding a pen-like probe, called a tonometer, on the skin directly above a major blood vessel. To get a good reading, the tonometer must be held steady, at just the right angle and with the right amount of pressure each time. But this can vary between tests and different technicians. Tonometers also require the patient to sit still which makes continuous monitoring difficult and are not sensitive enough to get good readings through fatty tissue.The UC San Diego-led team has developed a convenient alternative a soft, stretchy ultrasound patch that can be worn on the skin and provide accurate, precise readings of central blood pressure each time, even while the user is moving. And it can still get a good reading through fatty tissue.The researchers tested the patch on a male subject, who wore it on the forearm, wrist, neck and foot. Tests were performed both while the subject was stationary and during exercise. The patch recordings were more consistent and precise than recordings from a commercial tonometer; these were also comparable to recordings collected with a traditional ultrasound probe.

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