Non-Invasive Blood Pressure Monitoring with In-ear Infrasonic Hemodynography for Preventative Cardiovascular Care

Infrasonic Hemodynography (IH) is a novel, non-invasive technology that captures low-frequency cardiovascular vibrations transmitted to the ear canal and detected by in-ear microphones, offering a new approach to continuous blood pressure monitoring. In this study, we demonstrate a strong correlation between IH waveforms and gold-standard invasive aortic blood pressure measurements obtained via cardiac catheterization (CC), as illustrated in Wiggers diagrams with an average cross-correlation of 0.95. Temporal analysis confirmed the aortic origin of IH signals, with minimal differences in aortic valve opening (AVO) timings between IH and CC data (1.6 ± 12.1 ms), effectively rejecting the hypothesis of a peripheral arterial origin. Motivated by the high fidelity of the IH waveforms and the breadth of extractable cardiac features, we tested an approach to predict systolic (SBP) and diastolic (DBP) blood pressure based on waveform morphology, independent of amplitude. The standard deviations of the differences between predicted and reference BP values averaged across 12 subjects were 4.1 mmHg (SBP) and 2.4 mmHg (DBP) for CC data, and 5.8 mmHg (SBP) and 3.7 mmHg (DBP) for IH data. These results demonstrate that BP information is encoded in waveform shape dynamics, highlighting the potential of IH technology for non-invasive blood pressure monitoring. With larger and more diverse datasets, this approach could support the development of robust, generalizable BP prediction models for widespread clinical and consumer applications. Combined with advances in artificial intelligence and the widespread use of earbuds, IH technology has the potential to transform predictive and proactive healthcare. By capturing precise cardiovascular signals non-invasively, IH could enable earlier intervention and more personalized treatment, paving the way for significant improvements in the management of hypertension and overall cardiovascular care.