Technologies for Hemodynamic Measurements: Past, Present and Future

This chapter will describe the most known and commonly used technologies for hemodynamic monitoring. We gave this term a “quite wide” meaning, trying to include all the techniques used to measure and acquire the two most common physical parameters used to describe the dynamics of blood moving inside the vessels: the pressure and the flow. We decided to include techniques used both in specialized units, for example, intensive care units, surgical, and invasive cardiovascular laboratories, and in common clinical practice settings. Most of the described techniques are “old” (e.g., introduced in the past and currently well-established), but their usage has been improved in the last decades together with the technology advancements in the field of medical instrumentation. We did not deepen the described numerical methods and the biomechanical models underlying these approaches, since it would be out of the scope of this chapter, but we made the effort to introduce the bibliography addressing these concepts. We chose to not include the techniques to measure other important parameters (distance, areas, and volumes), strictly correlated to “dynamics,” since it would have involved a thorough discussion of all the technologies and techniques related to medical imaging. Together with the pressure and flow measurement techniques, we decided to describe some complementary approaches to measure additional parameters directly correlated to hemodynamics (i.e., pulse wave velocity, oxygen saturation, ballistocardiography, cardiac contractility, cardiac wall motion, etc.), since their measuring and monitoring are quite common in different hospital settings. The chapter is divided into paragraphs related to each single parameter of interest, and each paragraph contains both invasive and noninvasive measurement methods. At the beginning of each paragraph, a table summarizes the techniques considered for each parameter, which are then described in detail. At the end of the chapter, we included a short appendix describing the basic functioning principles of the most common pressure transducers.