Total stressed blood volume () and arterial elastance () are two potentially important, clinically applicable metrics for guiding treatment in patients with altered hemodynamic states. Defined as the total pressure generating blood in the circulation, is a potential direct measurement of tissue perfusion, a critical component in treatment of sepsis. is closely related to arterial tone thus provides insight into cardiac efficiency. However, it is not clinically feasible or ethical to measure in patients, so a three chambered cardiovascular system model using measured left ventricle pressure and volume, aortic pressure and central venous pressure is implemented to identify and from clinical data. and are identified from clinical data from six (6) pigs, who have undergone clinical procedures aimed at simulating septic shock and subsequent treatment, to identify clinically relevant changes. A novel, validated trend analysis method is used to adjudge clinically significant changes in state in the real-time and traces. Results matched hypothesised increases in during fluid therapy, with a mean change of + 21% during initial therapy, and hypothesised decreases during endotoxin induced sepsis, with a mean change of − 29%. displayed the hypothesised reciprocal behaviour with a mean changes of − 12 and + 30% during initial therapy and endotoxin induced sepsis, respectively. The overall results validate the efficacy of in tracking changes in hemodynamic state in septic shock and fluid therapy.