“The goal of IV fluid administration is to restore and maintain tissue fluid and electrolyte homeostasis and central euvolemia, while avoiding salt and water excess. This will in turn facilitate tissue oxygen delivery without causing harm” Miller & Myles, 2009
Currently practiced methods for perioperative volume management, where intravenous fluids are given based on body weight are not based on physiological principles. The lack of standard criteria for fluid therapy results in significant clinical variability. What is assumed about the fluid status of patients can be incorrect. Occult overhydration and underhydration states continue to be a factor that can negatively impact outcomes.
The integration of kinetic modelling of blood volume changes with fluid response and hemodynamic parameters will lead to better – physiologically based targeting of fluid administration
This means that anesthetists can more effectively achieve the practical goals of fluid administration
OFIS® Trainer is the name of the platform technology * that TOB1 have developed for patient fluid management educational use, through computer simulation of the impact of IV fluid administration on the blood and tissue fluid compartments
OFIS® Trainer performs computer simulation, using fluid kinetics derived from studies during general anesthesia, to model compartment volume changes
OFIS® Trainer estimates the impact of fluid administration on blood volume by applying pharmacokinetic modelling to user determined inputs of IV fluid challenges and maintenance fluids
OFIS® Trainer simulates distribution and elimination kinetics for IV administration of colloids and crystalloids in subjects under anesthetic conditions
OFIS® Trainer helps users understand how to design fluid challenges to achieve consistent and standardised changes in blood volume
OFIS® Trainer trends the impact of the IV fluid administration during surgery on the blood volume and resulting accumulation of fluid in the interstitial fluid compartment
OFIS® Trainer summarises fluid balance following inputs of IV bolus and maintenance fluids
¹ Distribution of crystalloid fluid infused during onset of anesthesia-induced hypotension: a retrospective population kinetic analysis. R. G. Hahn Perioperative Medicine (2021)
² Hahn RG, O’Brien T. Attenuation of the plasma volume response to crystalloid fluid used for goal-directed fluid therapy. Ann Intensive Care 2025; 15: 83.
*Both the OFIS® Trainer and OFIS® Trainer⁺ Models are only for use as an educational aide and are not intended, or registered for use as medical devices in medical practice.
The OFIS® Trainer⁺ model adds Frank-Starling analysis of the stroke volume impact of a fluid challenge – this analysis uses a novel and proprietary method for identifying a pre-load dependent and a pre-load independent blood volume range to manage IV administration
Uniquely OFIS® Trainer⁺ simulates the trend for actual and % change in blood volume for all fluid challenges administered in a stroke volume optimisation procedure
OFIS® Trainer⁺ plots a Frank-Starling curve of the change in stroke volume with the blood volume expansion
OFIS® Trainer⁺ introduces the novel concept of assessing the “fluid effectiveness” of a fluid challenge – these are quality control steps indicating pre-load dependency (green) and if, and where, the blood volume increase reaches a non-dependent level (red)
OFIS® Trainer⁺ uses the “fluid effectiveness” parameter ratio (∆SV%/∆BV%) to define both the pre-load dependent range and the transition point to fluid non-responsiveness
OFIS® Trainer⁺ displays the Frank Starling curve with the pre-load dependent/fluid responsive blood volume range highlighted (green)
OFIS® Trainer⁺ allows users to vary the maintenance fluid rate and simulates the trend in blood volume following a fluid challenge exercise in relationship to the defined fluid responsive zone
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