Mathematical analysis of the oscillometric technique for indirect blood pressure evaluation

The biomechanical factors which may affect the accuracy of non-invasive blood pressure measurement with the oscillometric technique are analyzed with a parameter mathematical model. The model includes compliance of the occluding cuff, pressure transmission from the cuff to the brachial artery through arm soft tissue, and blood volume changes occurring in the collapsing brachial artery under the external load. Simulation results, concerning blood volume changes under the cuff and cuff pressure pulsations, turn out in good qualitative agreement with those reported in the recent literature. Finally, the effect of alterations in some biomechanical parameters of clinical relevance (such as arterial wall rigidity and tissue compliance) on results of the oscillometric technique are evaluated with the model. A phenomenon of pseudo-hypertension is observed when brachial artery becomes excessively rigid, as in old-aged patients.