Vascular Tone and Reactivity as a Source of Inaccuracies at Evaluation of Blood Pressure with the Use of Compression Oscillometry Technique

Automatic and semi-automatic blood pressure (BP) monitors have been firmly established in medical diagnostic practice, including as devices for home self-monitoring, for over 50 years. However, published studies on the metrology of BP measurements using automatic BP monitors are scarce. The in fluence of individual viscoelastic properties of blood vessels, their vascular tone, and reactivity on BP readings remains insufficiently studied, even from a theoretical point of view. This theoretical study proposes and tests, for the first time, a simple physical and mathematical evaluation model for generating a sphygmogram signal in a BP monitor’s cuff, taking into account the elasticity of the brachial artery wall, its tone, and smooth muscle reactivity. Various situations of arterial wall elasticity, increased, normal, and decreased vascular tone are analyzed. It is shown, that not only the increased stiffness of vessel walls but also vascular tone significantly alter the sphygmogram shape, reducing the accuracy of BP assessment. Reactivity has a lesser effect on BP monotor’s readings, but hyperreactivity may also cause incorrect BP readings.