Accelerometric patch probe for cuffless blood pressure evaluation from carotid local pulse wave velocity: design, development, and in vivo experimental study

Objective : In this work, we demonstrate an accelerometric patch probe and associated measurement system for local pulse wave velocity (PWV) measurement and its application in cuffless blood pressure (BP) measurement. Approach: The proposed system consists of dual accelerometric patch probe to capture acceleration plethysmography (APG) signals from the carotid artery. The probe was integrated to an application-specific analog front-end circuitry with negligible inter-channel delay and a data acquisition module. Real-time signal processing and local PWV evaluation were performed using custom software. The functionality of the developed system and the relationship between local PWV and reference BP parameters were experimentally validated by multiple in vivo studies on a cohort of 26 subjects. Inter- and intra-subject BP-local pulse transit time (PTT) models were developed and used for cuffless BP measurement. Further, the reliability of the proposed method in long-term BP monitoring was validated by performing a study over a week. Main results: Reliability of the proposed novel approach for local PWV measurement using APG signals has been demonstrated. Measured baseline carotid local PWV values were in the range of 3–4.2 m s −1 , with high reproducibility (R = 0.94) and with an inter-beat variation range of 2.61%–15.5%. Mean local PTT versus brachial systolic, diastolic, and mean arterial BP obtained from both sitting and standing posture correlated well with an R-value > 0.8. Beat-by-beat BP parameters and local PWV during the post-exercise recovery of each individual yielded statistically significant intra-subject trends. Cuffless BP estimation with intra-subject BP-local PTT models results in more reliable assessments of BP parameters than inter-subject models. The developed BP prediction models found to be reliable over a period of one week with a root-mean-square error ≤1.7 mmHg. Significance: A non-invasive cost-effective system for continuous monitoring central aortic BP parameters and local arterial stiffness indices.