Researchers at the University of California San Diego (UCSD) have announced the clinical validation of a wearable ultrasound patch designed for continuous and noninvasive blood pressure monitoring. The patch has undergone rigorous testing on over 100 patients in various settings, demonstrating its safety and performance. This technology could provide a significant advancement in blood pressure management by offering a continuous stream of data, potentially revealing critical patterns missed by traditional cuff measurements.
The research, published in Nature Biomedical Engineering, details the development and validation of the soft and stretchy patch, which adheres to the skin and uses ultrasound to monitor blood pressure deep within the body. The device is constructed from a silicone elastomer housing an array of small piezoelectric transducers sandwiched between stretchable copper electrodes. These transducers emit and receive ultrasound waves, tracking changes in blood vessel diameter, which are then converted into blood pressure values.
Technical Improvements and Clinical Validation
The wearable patch represents an improvement over earlier prototypes from Sheng Xu's lab at UCSD. Key enhancements include packing the piezoelectric transducers closer together for wider coverage of smaller, clinically relevant arteries like the brachial and radial arteries. Additionally, a backing layer was added to dampen redundant vibrations, improving signal clarity and the accuracy of arterial wall tracking.
Clinical validation studies involved 117 participants engaged in a range of activities, including cycling, mental arithmetic, and posture changes. The patch's performance was evaluated in diverse settings such as at home, outpatient clinics, cardiac catheterization labs, and intensive care units (ICUs). Results from the patch closely matched those obtained from traditional blood pressure cuffs and arterial lines. In a cardiac catheterization laboratory and ICU, the patch measurements agreed closely with results from the arterial line, showcasing its potential as a noninvasive alternative.
Expert Commentary and Future Directions
Sheng Xu emphasized the thoroughness of the validation process, stating, "A big advance of this work is how thoroughly we validated this technology, thanks to the work of our medical collaborators. Blood pressure can be all over the place depending on factors like white coat syndrome, masked hypertension, daily activities or use of medication, which makes it tricky to get an accurate diagnosis or manage treatment. That’s why it was so important for us to test this device in a wide variety of real-world and clinical settings. Many studies on wearable devices skip these steps during development, but we made sure to cover it all."
The research team plans to conduct large-scale clinical trials and integrate machine learning to further enhance the device's capabilities. They are also working on a wireless, battery-powered version for long-term use and seamless integration with existing hospital systems. Sai Zhou, study co-first author, founded CircuCare to develop a wearable ultrasound device for automated, continuous medical imaging.
