MATHEMATICAL-MODELING OF NONINVASIVE BLOOD-PRESSURE ESTIMATION TECHNIQUES .2. BRACHIAL HEMODYNAMICS

The main biomechanical factors which may affect the accuracy of the os cillometric method for indirect blood pressure measurement are analyze d using a new model of brachial hemodynamics. In a first stage of this work the model has been used to reproduce some well-known responses o f collapsing arteries such as the sharp inn ease in compliance, and th e nonlinear pressure-flow characteristic with negative dynamic resista nce. In a second stage the model has been linked to the arm tissue mec hanics description presented in a previous work. The final model so ob tained has then been employed to analyze the pattern of the main hemod ynamic quantities (pressure pulsations in the cuffs, blood volume chan ges, blood flow upstream and downstream of the cuffs) during deflation manoeuvres. The simulation results agree with those found in the rece nt literature quite well. Results indicate that the cuff pressure valu e for maximum pulsations exhibits a large plateau, located approximate ly around the mean arterial pressure. However, stiffness of wall arter y, or stretching of the cuff internal surface, may significantly alter the obtained results causing a phenomena of ''pseudo-hypertension.''