Electrode Optimization for Bioimpedance Based Central Aortic Blood Pressure Estimation

Abstract

Evidence suggests that assessment of the central aortic pressure (CAP) of blood is vital for accurate detection of cardiovascular events and for making treatment decisions. Direct CAP measurement is possible and is used in clinical environment, however it is both costly and carries increased risk, therefore it is not suitable for preliminary screening and monitoring. Indirect noninvasive assessment of CAP has been around for several years. Applanation tonometry which is largely based on the research by O’Rourke et al. is method of choice and sometimes even described as gold standard for the noninvasive assessment of the central pressures, the pulse wave velocity and the heart rate variability. Pressure sensor is typically placed on the radial artery, and central aortic pressure is estimated by generalized mathematical transformation of the recorded waveform. While widely used the method has serious drawback—strong dependence on operator skills. The electrical bioimpedance (EBI) has emerged as viable alternative in search for the measurement methods with better repeatability. Its applicability has been confirmed in several studies involving simultaneous invasive CAP measurement, and comparative measurements with AtCor Medical SphygmoCor device. Further refinement of the method is considered in proposed paper. Electrical attachment of the bioimpedance measurement unit to the body is investigated and discussed.