A Simple Cardiovascular Model for the Study of Hemorrhagic Shock

Figure 1

Schema of the ZenCur model. At the top center, the pulsing univentricular heart goes from end-diastolic to end-systolic volume . Via a system of valves, the blood is driven (clockwise in the figure) into the arterial compartment. The pressure generated must overcome the total peripheral resistance and guarantees blood flow to the venous compartment which feeds back into the heart. Variations from the set point of arterial pressure determine corresponding variations in actuators. These include heart rate , , myocardial contractility , and unstressed venous volume . Of note: variations of are processed through a sigmoidal nonlinearity and a linear element with first-order low-pass filter characteristics. Our model accounts for bleeding and for the physiological compensatory mechanism called transcapillary refill (adapted from Figure 2 in Zenker S, Rubin J, Clermont G., From Inverse Problems in Mathematical Physiology to Quantitative Differential Diagnoses, PLoS Computational Biology, 3 (2007), 2074).