Smarter monitoring of blood pressure with Esperto

Blood pressure monitoring technology is evolving rapidly, with various non-invasive methods available on the market. But many of the existing devices measure relative changes in blood pressure rather than providing precise, absolute readings. The startup Esperto Medical uses resonance sonomanometry to deliver accurate, real-time blood pressure measurements.

Alaina Rajagopal and Aditya Rajagopal explain how their device can address common issues such as calibration errors and motion artifacts while integrating seamlessly into healthcare systems for both clinical and remote care.

How does the device differentiate itself from other non-invasive blood pressure measurement technologies currently available on the market?

Alaina Rajagopal: There are many devices on the market or in development that are attempting to deliver clinical-grade blood pressure readings. However, existing methods like PPG (pulse wave analysis, pulse transit time), tonometry, volume clamping, or capacitance are only capable of taking relative measurements or metrics that correlate to blood pressure. They can measure the difference between the systolic and diastolic peaks, but struggle to determine the exact values, for example, 120/80 versus 130/90.

Many use machine learning or require input of patient demographic data to get a better sense of these values. However, the measurement becomes only as good as the underlying dataset, which can never encompass all possible scenarios. Even millions of points in the dataset are not enough to predict every possible blood pressure in every scenario, patient demographic, or patient comorbidity.

Esperto takes an absolute blood pressure measurement using resonance sonomanometry. This method captures the actual pressure, not just relative differences, with measurements occurring multiple times per second. Additionally, because of the high frequency of measurements, resonance sonomanometry is not predisposed to measurement errors due to divergence from the last calibration point. There is no need for repeated calibration, because the measurement is absolute. 

Can you explain how the non-invasive technology in your device works to continually measure blood pressure?

Aditya Rajagopal: Resonance sonomanometry uses audio frequency to generate a resonant frequency in the arterial wall. This resonance frequency allows the calculation of arterial wall tension, which directly relates to internal pressure. By measuring arterial radius and wall thickness alongside this tension, the device can accurately compute blood pressure. These parameters are measured multiple times per second, ensuring precision during dynamic changes, without the need for calibration.

The Esperto device uses a sound transducer, similar to a bone-conducting headphone, to transmit sound to the artery. An ultrasound camera then identifies the resonant frequency and captures the arterial dimensions. These data are processed to calculate blood pressure in real-time.

How does the device handle issues that might interfere with accurate blood pressure readings?

Aditya Rajagopal: The first device is intended for clinical use cases. Future devices will be designed specifically for outpatient use cases. One of the major issues with existing technologies is the motion artifact caused by patient movement. To address this, our device will continuously identify and track the artery, using algorithms similar in spirit to GPS, ensuring it remains within the field of view. Since our measurements are taken faster than the artery moves, we can achieve high-fidelity tracking and accurate readings, even during motion.

What kind of data interoperability and electronic health record (EHR) integration does your startup offer?

Aditya Rajagopal: We intend to market the first device to hospitals and health care systems. The key factor here is making sure that the device fits into current workflows and alleviates burdens from overworked care providers. We intend for the device to interface with existing hospital monitors as an arterial catheter would interface with the monitor. Looking ahead, we plan to collaborate with EHR companies to enable seamless integration, whether the patient is in the hospital or receiving outpatient care.

What are the key benefits for both patients and healthcare providers in using this device for remote care?

Alaina Rajagopal: There are many benefits for patients and providers. One glaringly obvious use case is related to hospital overcrowding. With the Esperto device, patients could be discharged earlier and continue to be monitored from the comfort of their home. This would allow for early detection of any concerning trends in vital sign data, enabling prompt notifications for both the patient and their healthcare provider if any issues arise.

Over the course of the pandemic, telemedicine had a dramatic rise in popularity, but it comes with limitations—clinicians often lack access to vital sign data. A patient might appear healthy on a video call but could have an elevated heart rate or dangerously high blood pressure. With an Esperto monitor, they could wear the device for the call, and have the readings transmitted directly to their provider. This would give the clinician a clearer clinical picture and enable more accurate assessments.

What future developments do you envision for blood pressure monitoring?

Alaina Rajagopal: The future for patient monitoring is exciting. With continuous monitoring of not only blood pressure, but other metrics such as arterial stiffness, arterial radius, arterial wall thickness, and more, we will be able to provide a “cardiovascular microscope” so to speak. Because these metrics have never been measured longitudinally, there is a wealth of information that could eventually allow prediction of diseases such as stroke, cardiac arrest, preeclampsia, myocardial infarction, and more.