Transit time measurement of a pressure wave through an elastic tube based on LVDT sensors

Transit time is the propagation time of a pressure wave travelling between two sites in a medium. Such parameter is mainly implied in the biomedical field as a surrogate for the estimation of important markers of the cardiovascular system (e.g. blood pressure and arterial stiffness). The non-invasive transit time measurement is commonly used in clinical practice because it allows the continuous recording and monitoring of blood pressure. The development of an in vitro system able to reproduce the main cardiovascular characteristics is of primary importance for further investigations of the relationship between transit time and the arterial stiffness in order to predict the cardiovascular risk factors. The present work focuses on the development of a LVDT-based experimental set-up able to simulate transit time variations due to transmural pressure changes on an elastic tube. As validated in in vivo measurements, transit time and maximum radial tube displacement increment decrease with decreasing transmural pressure.