'Wearable ultrasound patch monitors BP inside body'

Scientists have developed a new wearable ultrasound patch that can non-invasively monitor blood pressure in arteries deep beneath the skin.

The advance by researchers from the University of California - San Diego in the US could help people detect cardiovascular problems earlier on and with greater precision.

Applications include real-time, continuous monitoring of blood pressure changes in patients with heart or lung disease, as well as patients who are critically ill or undergoing surgery, according to the research published in the journal Nature Biomedical Engineering.

The patch uses ultrasound, so it could potentially be used to non-invasively track other vital signs and physiological signals from places deep inside the body, researchers said.

"Wearable devices have so far been limited to sensing signals either on the surface of the skin or right beneath it. But this is like seeing just the tip of the iceberg," said Sheng Xu, a professor at the UC San Diego.

"By integrating ultrasound technology into wearables, we can start to capture a whole lot of other signals, biological events and activities going on way below the surface in a non-invasive manner," Xu said.

The new ultrasound patch can continuously monitor central blood pressure in major arteries as deep as four centimeters below the skin.

The technology would be useful in various inpatient procedures, researchers said.

"This has the potential to be a great addition to cardiovascular medicine," said 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," Huang said.

The device measures central blood pressure -- which differs from the blood pressure that is measured with an inflatable cuff strapped around the upper arm, known as peripheral blood pressure.

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.

Medical experts consider central blood pressure more accurate than peripheral blood pressure and also say it is better at predicting heart disease.

Measuring central blood pressure is not typically done in routine exams, however.

The state-of-the-art clinical method is invasive, involving a catheter inserted into a blood vessel in a patient's arm, groin or neck and guiding it to the heart.