Aortic Frequency Response Determination via Bioimpedance Plethysmography

Abstract

Objective: Arterial stiffness is an important marker to predict cardio vascular events. Common measurement techniques to determine the condition of the aorta are limited to the acquisition of the arterial pulse wave at the extremities. The goal of this work is to enable non-invasive measurements of the aortic pulse wave velocity, instead. An additional aim is to extract further information, related to the conditions of the aorta, from the pulse wave signal instead of only its velocity. Methods: After discussing the problems of common pulse wave analysis procedures, an approach to determine the frequency response of the aorta is presented. Therefore, the aorta is modelled as an electrical equivalent circuit. To determine the specific numeric values of this system, a measurement approach is presented, which is based on non-invasive bioimpedance plethysmography measurements above the aortic arch and at the inguinal region. The conversion of the measurement results to the system parameters is realized by a digital algorithm, which is proposed in this work as well. To evaluate the approach, a study on three subjects is performed. Results: The measurement results demonstrate that the proposed approach yields realistic frequency responses. For better approximation of the aortic system function, more complex models are recommended to investigate in the future. Since this study is limited to three subjects without a ground truth, further measurements will be necessary. Significance: The proposed approach could solve problems of current methods to determine the condition of the aorta. Its application is non-invasive, harmless and easy to execute.Index Terms-Arterial stiffness, pulse wave analysis, pulse wave velocity, aortic system function, bioimpedance, impedance plethysmography, equivalent circuit.

Printed soft skin electrodes for seamless bio-impedance measurements

“…Peaks, troughs and MS points for each pulse were successfully detected and marked automatically. These characteristics are commonly used to evaluate the impedance change, which translates to the volume change of the artery, as well as the pulse transit time which can be used to evaluate blood pressure [34]. Both electrode types measure the same phenomena, albeit the printed electrodes achieve the measurement with dramatically smaller form factor.…”

Predictive value of novel inflammatory markers platelet-to-lymphocyte ratio, neutrophil-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio in arterial stiffness in patients with diabetes: A propensity score–matched analysis

“…BaPWV is more suitable for epidemiological studies involving large populations and its reliability has been clinically verified ( 28 ). In addition to arterial tonometry and oscillometry, the other modalities for PWV measurement include ultrasound imaging ( 29 ), bioimpedance plethysmography ( 30 ), photoplethysmography ( 31 ), and magnetic resonance imaging ( 32 ). However, these methods are rarely used in clinical practice owing to limitations such as high price, complex operation protocols, and limited results.…”

A Wearable Dual-Channel Bioimpedance Spectrometer for Real-Time Muscle Contraction Detection

“…If the electrical bioimpedance is recorded as a function of time, further applications can be realized. Popular applications in research are impedance cardiography to approximate cardiac output or detection of arterial pulse waves to estimate arterial stiffness [24], [27]- [30]. In addition, there is preliminary work that focuses on EIM as a function of time so that the timing of muscle contractions can be detected.…”