Central blood pressure monitoring method oriented to wearable devices

Abstract

Arterial hypertension affects a quarter of the world’s population and is a major risk factor for cardiovascular disease. Blood pressure (BP) is one of the most relevant parameters used for continual monitoring of possible hypertension states in the elderly population. Furthermore, emerging evidence suggests that central blood pressure is a more accurate predictor of future cardiovascular events than brachial pressure, thus potentially providing a better hemodynamic determinant for clinical outcomes. This work presents a non-invasive Central (Aortic) blood pressure estimation method based on the pulse transit time (ptt) principle estimated from electrocardiogram (ECG) and ballistocardiogram (BCG) recordings. As the measured transit time presented takes place mainly within the aortic domain, we estimate aortic blood pressure instead of brachial pressure. Validation of the proposed method was performed with a small sample of healthy volunteers at a local gym. An Atcor Medical SphygmoCor device was used to monitor central and brachial blood pressure (systolic, mean, and diastolic) during rests of the strength maneuvers. Pulse transit time was estimated from ECG and BCG recordings and simultaneously recorded with all BP readings. Results showed that Systolic and Mean central blood pressures were most strongly correlated with ppt-estimated blood pressure in comparison to all other blood pressure readings; Bland-Altman plots showed an almost zero mean error (|μ|< 0.02mmHg) and bounded standard deviation σ< 5mmHg for all systolic and mean central BP readings. Experimental data, thus showed promissory results for monitoring aortic blood pressure via ptt. The scope of this pilot work is to provide initial validation of this method in order to develop a compact miniaturized device that allows the integration of wireless blood pressure monitoring into a wearable system.