Non-Invasive Monitoring of the Central Blood Pressure
Measuring central blood pressure using an ultrasound skin patch

As the world advances at a rapid rate, we, humans, have the unprecedented task of keeping up with it. A plethora of daily circumstances, especially long work-hours and our unending affliction towards smartphones, have resulted in the fragility of our physical bodies. According to the U.S. Centers for Disease Control and Prevention, around 33% of Americans suffer from high blood pressure – probably a result of constantly being on edge. Also known as hypertension, the condition is dubbed as the silent killer for it increases the risk of heart diseases and stroke without prior warning symptoms. It’s imperative, that the technological advancement that has caused an increase in hypertension among adults should also be used wisely to monitor our increasing blood pressure and detect prior signs of heart failure.

Researchers at the University of California, San Diego have now developed an ultrasound patch to enable the continuous monitoring of the central blood pressure. The team is led by Sheng Xu, a NanoEngineering Professor and his team of research graduates at the university. The researchers have focused on developing a device that monitors the central blood pressure as opposed to the peripheral blood pressure – which is usually measured with an inflatable cuff around the upper arm. The central blood pressure is a measure of pressure in the central aortic vessels that directly pumps blood from the heart to major organs in the body. While peripheral blood pressure is relatively easy to measure, it’s the central blood pressure that could help identify prevailing heart conditions and eventually predict a heart disease.

The patch, made from silicone elastomer polymer, send out ultrasonic waves that penetrate the skin and bounces off the user’s tissues and blood. The reflected waves are captured by the patch’s sensor and are processed to determine the central blood pressure. The patch can continuously keep a track of pressure in major arteries that are located 1.5-2 inches below the skin. The device is also non-invasive, making it the first known wearable device to sense blood pressure deep below the skin. While traditional systems use a catheter with a sensor that’s inserted near the heart, the patch can be placed on different parts of the body – although the researchers say that putting it on the neck was most effective.

Off late, several mobile apps that claim to measure the peripheral (and also central) blood pressure have become available.  A study that analyzed the top 107 apps for measuring “hypertension” and “high blood pressure” revealed that only 75% of them were anywhere close to giving the correct reading. Moreover, the lead author of the study and a Harvard Medical School instructor, Dr. Nilay Kumar, has said, “Such technologies are in a research-and-development stage. It’s not ready for clinical use. For now, we need to be careful that we are not using things that are inaccurate and could be potentially dangerous.”

In comparison, Xu’s ultrasound patch gave an acceptable range of error in blood pressure measurement when it was compared to a tonometer, another non-invasive but hard to use device that places a pressure sensor on the skin. Such an accurate patch that continuously measures our central blood pressure is bound to be a key technological device to not only predict heart diseases but also keep an eye on the vitality of the liver, lungs, and brain.