Minimally Invasive Model Based Stressed Blood Volume as an Index of Fluid Responsiveness

Model based total stressed blood volume (SBVT ) has been shown to be a potential index of fluid responsiveness. However, current models rely on the availability of highly invasive and uncommon measurements to derive model parameters. In this work, a simple method for obtaining the necessary model parameters from currently available intensive care unit (ICU) measurements is established. The model is tested on three (3) porcine subjects administered a typical 500ml saline bolus fluid therapy and then subjected to endotoxin induced sepsis to provide a range of hemodynamic states. When compared to stressed blood volume derived from a model utilising direct measurements mean percentage error was 10.3% over a total of 716 beats. This work also examined the hypothesis a stressed blood volume below a clinically specified threshold of 145ml would yield a positive response. Increases of 37.9%, 44.7% and 22.6%, with baseline levels of 180, 120 and 75ml, were seen for pigs 1, 2 and 3, respectively. This research demonstrates the clinical validity of this model based SBVT measure, bringing it closer to clinical feasibility