Continuous and non-invasive blood pressure monitoring using ultrasonic methods

Abstract

This thesis presents a continuous and non-invasive arterial blood pressure (CNAP) monitoring technique using ultrasound. An arterial blood pressure (ABP) waveform provides valuable information in treating cardiovascular diseases. Although an invasive ABP measurement through arterial catheterization performed in an intensive care unit (ICU) is considered a gold standard, its invasive nature not only increases various patients' risks but makes its usage for cardiovascular studies expensive. Therefore, reliable non-invasive ABP waveform estimation has been desired for a long time by medical communities. This work details ABP waveform estimation based on a vessel cross-sectional area measurement combined with the elastic property of an arterial vessel, represented by a pulse wave velocity (PWV). Several ultrasound techniques including uniform insonation and echo-tracking are explored to measure the PWV using so-called QA method as well as the cross-sectional area. The physiological background of the arterial system and considerations for a clinical test are also presented. Experimental results validate the QA method and the proposed ABP waveform estimation method in a custom-designed experimental setup consisting of a diaphragm pump and a latex rubber tube using two commercially available single element ultrasonic transducers. The design of a portable CNAP monitoring device using ultrasound will fuel the exponential growth of a readily available, inexpensive but powerful cardiovascular diagnostic tool.