Nonlinear dynamic model of baroreceptor blood pressure regulation

The body´s ability to regulate blood pressure through the carotid baroreflex, as well as the reflex´s adaptation in hypertensive systems, are explored in this work with special attention to nonlinear properties. Previous model-based studies have produced linear mathematical representations aimed to simulate the body´s response to changing arterial blood pressure. These models are limited to the applications of modern linearfeedback control theory, and are successful in analyzing the basics of blood pressure homeostasis. However, they are limited to normotensive pressures and fall short when confronted with pathological extremes in pressure such as for hypo- and hypertensive levels. More recently, studies suggest that nonlinear-control mechanisms should be used. Computer modeling, blood vessel mechanics, and nonlinear-control theory are used to simulate physiological conditions found in normal and hypertensive systems. Using Simulink and a sigmoid function, a dynamic model was created of the carotid sinus´ regulatory behavior on blood pressure in response to changing mean arterial blood pressure. One of the main goals was to understand sigmoidal factors that change in hypertension. Results supported that two sigmoid-function parameters (s and μ) affect the pressure and the speed of convergence of the system. It was concluded that a physiologically realistic model of blood pressure regulation is possible once the nonlinear vessel function is incorporated. This new model eliminates the assumptions of the more common linear feedback models, and permits analysis of pathological, hypertensive, conditions.