Cardiovascular system (CVS) dysfunction, shock and cardiac surgery are leading causes of intensive care unit (ICU) admission, cost and mortality. These patients comprise >30% of all ICU admissions (>450/year in Christchurch, >3000/year for NZ). In practice, circulatory management of these patients with inotropes, vasopressors or fluids is poorly titrated to clinical surrogates, such as blood pressure or (invasive) infrequent cardiac output (CO) measurements, leading to highly variable care, increased organ failure, longer ICU stay, and death. A real-time, beat-to-beat measurement of ventricular stroke-volume (SV) would provide a direct metric of the desired treatment outcome as increased SV leads to increased circulatory perfusion and reduced organ failure. It would thus enable optimal titration of treatments and personalised care. Current methods estimate cardiac output, which averages SV over many beats and is further affected by the impact of systemic vascular compliances, and thus cannot accurately capture clinically important transient changes in SV. Recent modeling advances at the University of Canterbury offer a way to measure beat-to-beat SV. We will develop and validate our recent modeling advance that enables real-time, beat-to-beat estimation of SV from existing catheter measurements. This new capability will enable more optimised and personalised circulatory care that is not currently possible. We will do this research jointly with our existing University of Liege (ULG; Belgium) collaborators and expand it to include the GIGA Cardiovascular Sciences group at ULG and its medical school at CHU de Liege Hospital. There is no equivalent capability or experience in New Zealand for the complex cardiovascular animal trials proposed. It will also increase our ability to access diverse ICU patients and data to test successful research outcomes.