Patient-Specific Monitoring and Trend Analysis of Model-Based Markers of Fluid Responsiveness in Sepsis: A Proof-of-Concept Animal Study.

Abstract

Total stressed blood volume ([Formula: see text]) and arterial elastance ([Formula: see text]) 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, [Formula: see text] is a potential direct measurement of tissue perfusion, a critical component in treatment of sepsis. [Formula: see text] is closely related to arterial tone thus provides insight into cardiac efficiency. However, it is not clinically feasible or ethical to measure [Formula: see text] 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 [Formula: see text] and [Formula: see text] from clinical data. [Formula: see text] and [Formula: see text] 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 [Formula: see text] and [Formula: see text] traces. Results matched hypothesised increases in [Formula: see text] 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%. [Formula: see text] 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 [Formula: see text] in tracking changes in hemodynamic state in septic shock and fluid therapy.