ELLWEIN, LAURA MARIE. Cardiovascular and Respiratory Regulation, Modeling and Parameter Estimation.(Under the direction of Mette Sofie Olufsen.)

Short-term cardiovascular responses to postural and carbon dioxide challenges involve complex interactions between global and local regulatory mechanisms, which regulate blood pressure and perfusion. Mathematical models can be used to extract clinical markers that characterize these interactions which cannot be assessed noninvasively. To predict one such marker, cerebrovascular resistance, we present several lumped parameter compartmental models that can analyze dynamic changes in beat-to-beat arterial blood pressure, middle cerebral artery blood flow, and expiratory partial pressure of carbon dioxide. The cardiovascular submodels utilize compartments to describe blood pressure, blood flow, compliance, and resistance in the heart and systemic circulation. The respiratory submodel contains compartments describing tissue and pulmonary gas concentrations. Results of studies using models predicting postural change from sitting to standing showed that it is possible to predict cerebrovascular resistance, yet these studies did not allow unique identification of this physiological quantity.