Abstract Body: Background: Wearables for continuous blood pressure monitoring hold the promise to drastically improve hypertension management, but current solutions still lack the required accuracy. Ultrasounds might be able to overcome this limitation because they can measure quantitative parameters highly correlated with blood pressure, such as artery diameter, its motion over the cardiac cycle (AWM) and local pulse wave velocity (PWV). Here we validate radial PWV measurement with an ultrasound method that can be integrated in low power wearables.
Methods: The study was conducted on 8 healthy subjects at rest. The ultrasound scan was performed on the left arm with a research scanner and two linear probes held at a fixed distance and used to image two transversal sections of the radial artery at 11.5 kHz for 10 seconds. The first image of each section is segmented to identify the artery walls and AWM is reconstructed by tracking the phase of the wall echo. PWV is extracted from the delay of artery wall motion waveforms on the 2 sections. Reference values of carotid-radial PWV were acquired with Diatecne PulsePen ETT immediately after the ultrasound acquisition on the same arm.
Results: The estimate and accuracy of the local radial PWV of proposed ultrasound method is in agreement with the reference carotid-radial PWV obtained with the tonometer. The accuracy of the methods is estimated from the beat-to-beat variability of the delays between the waves used for the estimates.
Conclusions: The proposed method allows to measure the radial pulse wave within shorter distances compatible with integration in wearables. Leveraging TDK ultrasound MEMS platform, this paves the route for low power wearable for continuous cardio-vascular monitoring.