Continuous Blood Pressure Monitoring: Caltech's Revolutionary Ultrasound Technology

Continuous Blood Pressure Monitoring: A Game-Changer for Health

Continuous Blood Pressure Monitoring: Caltech's Revolutionary Ultrasound Technology

Traditionally, blood pressure has been measured using a pressure cuff that provides only a brief snapshot of your cardiovascular health. While continuous monitoring is possible, it usually requires invasive methods, such as inserting a transducer into an artery. 

However, researchers at Caltech have developed a groundbreaking technology that could soon allow for continuous blood pressure monitoring from almost any part of the body.

How Resonance Sonomanometry Revolutionizes Blood Pressure Measurement

The new technology, known as resonance sonomanometry (RSM), was detailed by the Caltech researchers in a paper published in July in PNAS Nexus. RSM utilizes ultrasound to measure the dimensions of artery walls and employs sound waves to identify resonant frequencies within these walls. These resonant frequencies help determine the tension of the arterial walls, which in turn reveals the absolute pressure within the artery at any given moment. 

Unlike other non-invasive methods that require periodic calibration, RSM provides continuous, calibration-free readings, making it a more reliable tool for monitoring blood pressure.

Validation and Application of RSM Technology

To validate their approach, the researchers first tested the RSM system on an arterial model using thin-walled rubber tubing and varying the pressure with a syringe. The technology was then tested on human subjects by measuring their carotid arteries (located in the neck) while intermittently using a standard pressure cuff for comparison. 

The RSM technology produced clear and consistent results, which were also successfully replicated on the axillary (shoulder), brachial (arm), and femoral (leg) arteries. The accuracy of these readings was so precise that the researchers believe they could even detect blood pressure variations related to respiration.

RSM system on an arterial model using thin-walled rubber tubing and varying the pressure with a syringe
Image credit: IEEE Spectrum 

RSM's Potential to Transform Healthcare

The ability to monitor blood pressure continuously throughout the entire heartbeat cycle, rather than just during systolic and diastolic phases, sets RSM apart from traditional methods. Additionally, because RSM works with arteries of different sizes, it is applicable across various body types and sizes. The use of ultrasound also avoids complications that can arise with light-based devices, such as issues related to skin coloration.

Caltech's development has already led to the creation of a spinoff company, Esperto Medical, which is focused on commercializing the RSM technology. The company has designed a transducer module smaller than a deck of cards, which could be integrated into a wearable armband. 

The ultimate goal is to miniaturize this technology further so it can be incorporated into wrist-worn devices, like smartwatches. Raymond Jimenez, Esperto Medical’s chief technology officer, highlighted the potential of this technology to provide accurate, calibration-free blood pressure measurements in various settings, including clinics, gyms, and homes.

Consumer Demand for Health Monitoring Features

The market demand for such a product is significant. According to Elizabeth Parks, president of the Internet of Things consulting firm Parks Associates, "92 percent of consumers who intend to buy a wearable device are willing to pay extra for a health-related feature, and blood pressure ranks first among such features." 

This suggests that in the near future, smartwatches might not only monitor heart rate but also provide continuous blood pressure readings throughout the day, eliminating the need for traditional, arm-squeezing cuffs. 

Expert Opinions on Continuous Monitoring

Nick van Terheyden, M.D., a digital health leader with Iodine Software, emphasized the importance of continuous monitoring for making informed healthcare decisions. He stated, “A yearly blood pressure reading in the doctor’s office is insufficient for decision making. A new approach based on good old rules of math and physics is an exciting development.”

This advancement in blood pressure monitoring represents a significant leap forward in healthcare technology, with the potential to improve patient outcomes and provide more accurate, continuous health data.