Arterial assessment obtained from non invasive oscillometric pressure waveforms

Cardiovascular disease, the leading cause of mortality in the Western world, has a very long asymptomatic phase of development. A significant association between increased arterial stiffness and the development of cardiovascular disease has led to the increased use of arterial stiffness in the clinical assessment of cardiovascular risk. Arterial stiffness is a general term that collectively describes distensiblility, compliance, and elastic modulus of the arterial vascular system. Elastic properties of the arterial wall are highly pressure dependent. Oscillometric non-invasive blood pressure measuring devices are based on recording the arterial pressure pulsation in an inflated cuff wrapped around a limb during the cuff deflation. The purpose of this study is to develop a simple and non invasive method of evaluating arterial elasticity using oscillometric measurements of blood pressure and time frequency analysis. A computer based oscillometric measurements of blood pressure analyzer was designed. The signal was obtained by a pressure sensor, which is attached to the blood pressure cuff to enable the measurement of small volumes changes of the arm as the cuff pressure is gradually reduced. It was converted into digital domain by a signal conditioning circuitry. The acquired signal was displayed using Labview® program and time frequency analyzed through Margenau-Hill Distribution using Matlab® program. A study with 40 people, 20 healthy volunteers and 20 subjects with previously diagnosed cardiovascular disease (atherosclerosis, hypertension, diabetes mellitus), was carried out. Healthy volunteers present in their analysis of Frequency-Magnitude, many components with significant magnitude in 1 Hz (heart rate) and higher and lower frequencies, whereas the analysis of Frequency-Magnitude from patients present significant magnitude in the frequency of heart rate near to 1 Hz, but not in other frequencies. In conclusion, oscillometric pressure waveform a- alysis has shown to be a non invasive method for vascular assessments.