Patient-Specific Monitoring and Trend Analysis of Model-Based Markers of Fluid Responsiveness in Sepsis: A Proof-of-Concept Animal Study
© 2019, Biomedical Engineering Society. Total stressed blood volume (SBVT) and arterial elastance (Ea) 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, SBVT is a potential direct measurement of tissue perfusion, a critical component in treatment of sepsis. Ea is closely related to arterial tone thus provides insight into cardiac efficiency. However, it is not clinically feasible or ethical to measure SBVT 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 SBVT and Ea from clinical data. SBVT and Ea 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 Ea and SBVT traces. Results matched hypothesised increases in SBVT 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%. Ea 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 SBVT in tracking changes in hemodynamic state in septic shock and fluid therapy.