Efficient implementation of non-linear valve law and ventricular interaction dynamics in the minimal cardiac model

et al. 2008

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A cardiovascular system (CVS) model has previously been validated in simulated cardiac and circulatory disease states. It has also been shown to accurately capture all main hemodynamic trends in a porcine model of pulmonary embolism. In this research, a slightly extended CVS model and parameter identification process are presented and validated in a porcine experiment of positive end-expiratory pressure (PEEP) titrations at different volemic levels.The model is extended to more physiologically represent the separation of venous and arterial circulation. Errors for the identified model are within 5% 1 when re-simulated and compared to clinical data. All identified parameter trends match clinically expected changes. This work represents another clinical validation of the underlying fundamental CVS model, and the methods and approach of using them for cardiovascular diagnosis in critical care.

Section: Cvs Modelmentioning

confidence: 99%

Model-based identification of PEEP titrations during different volemic levels

Starfinger

et al. 2008

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“…The CVS model employed is a lumped parameter model based on earlier work [8,[10][11][12][13]. This original model consisted of six elastic chambers, including two active chambers for the left and right ventricles.…”

Section: Cvs Modelmentioning

confidence: 99%

Prediction of hemodynamic changes towards PEEP titrations at different volemic levels using a minimal cardiovascular model

Starfinger

et al. 2008

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(stroke volume). These results validate the general applicability of such a rule, which is not pig-specific, but holds over for all analyzed pigs. This rule enables physiological simulation and prediction of patient response. Overall, the prediction accuracy achieved represents a further clinical validation of these models, methods and overall approach to cardiovascular diagnosis and therapy guidance.

“…Eq. (12) is solved for V spt at each time step using a semi-analytical approach [15] for computational efficiency. …”

Section: Cardiac Modelmentioning

confidence: 99%

“…Lumped parameter models (LPM) are a common approach to minimizing complexity in the cardiovascular system [12][13][14][15][16] but there are still many parameters involved. Thus typically, only small subsets of the parameter set can be identified (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…A common method of modelling the CVS is by a series of elastic chambers connected by resistors with a time varying elastance. This approach has been well developed and validated in the literature [12][13][14][15][16] so it serves as a good starting point to test the methods and concepts in this paper. The specific baseline model structure considered is a six chamber cardiovascular model including ventricular interaction and inertial effects that has been previously developed [16] and validated in clinical animal trials [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Unique parameter identification for cardiac diagnosis in critical care using minimal data sets

Desaive

et al. 2010

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Lumped parameter approaches for modelling the cardiovascular system typically have many parameters of which a significant percentage are often not identifiable from limited data sets. Hence, significant parts of the model are required to be simulated with little overall effect on the accuracy of data fitting, as well as dramatically increasing the complexity of parameter identification. This separates sub-structures of more complex cardiovascular system models to create uniquely identifiable simplified models that are one to one with the measurements. In addition, a new concept of parameter identification is presented where the changes in the parameters are treated as an actuation force into a feed back control system, and the reference output is taken to be steady state values of measured volume and pressure. The major advantage of the method is that when it converges, it must be at the global minimum so that the solution that best fits the data is always found.By utilizing continuous information from the arterial/pulmonary pressure waveforms and the end-diastolic time, it is shown that potentially, the ventricle volume is not required in the data set, which was a requirement in earlier published work. The simplified models can also act as a bridge to identifying more sophisticated cardiac models, by providing an initial set of patient specific parameters that can reveal trends and interactions in the data over time. The goal is to apply the simplified models to retrospective data on groups of patients to help characterize population trends or un-modelled dynamics within known bounds. These trends can assist in improved prediction of patient responses to cardiac disturbance and therapy intervention with potentially smaller and less invasive data sets. In this way a more complex model that takes into account individual patient variation can be developed, and applied to the improvement of cardiovascular management in critical care. Keywords :Model-based cardiac diagnosis ; Cardiovascular system ; Integral-based parameter identification ; Pressure waveform ; ECG ; Intensive care unit IntroductionIn critical care, cardiovascular dysfunction can be easily misdiagnosed due to incomplete information and the complexities involved, leading to premature discharge or non-optimal treatment [1][2][3]. It is also a major cause of increased length of stay and death [4,5]. Demand for critical care is growing dramatically severely affecting healthcare delivery [6][7][8]. The overall goal of this research is to use computational cardiac models to better aggregate available clinical data in an intensive care unit (ICU) into a more readily understood physiological context for clinicians. The computational models can be used to reveal non-linear dynamics and interactions that are not readily apparent in the data.A major difficulty faced with cardiovascular modelling in general, is the level of detail these models typically include. For example multi-scale modelling approaches utilizing finite elements have successfully expl...