Baroreflex control model for cardiovascular system subjected to postural changes under normal and orthostatic conditions.

Baroreflex dysfunction is one of the common causes associated with the cardiovascular system. The buffering capability and baroreflex gain influences large variation in blood pressure for short term control. For regulating the blood pressure, an integrated analytical model for baroreflex control along with the cardiovascular system is presented to study the complex interactions between autonomic nervous system and cardiovascular system. In the proposed model, the autonomic nervous system utilizes sympathetic and parasympathetic nerve activities. This comprises a heart modeled by Mulier's approach, systemic vasculature, baroreceptor sensor using stress-strain based Voigt model and Hodgkin-Huxley based autonomic nervous control. This model can handle the distribution of total blood volume changes under the influence of gravity upon postural changes by means of short term baroreflex control. The simulation is carried out for the integrated model along with (i) non pulsatile and (ii) pulsatile model of heart. The proposed model is validated for supine to standing position under influence of gravity. To show the efficiency of the proposed model, the simulation is carried out further for (i) postural changes like supine to standing and standing to supine under normal condition and (ii) Orthostatic hypotension and hypertension conditions. Also the robustness of the proposed pulsatile model is tested by introducing disturbance signal in mean arterial pressure under various postural changes.