Design and Implementation of a Generic Circuit Solver for Physiological Lumped-Parameter Modeling.

The Pulse Physiology Engine is comprised of mechanistic physiological system models that use lumped-parameter compartments to deterministically compute the instantaneous state of a patient each time-step. These compartments are networked with fluid or thermal electrical circuit component analogs. We have designed and implemented a circuit solver inside the Pulse Engine to extract the lumped-parameter circuit math from within the individual systems and centralize the generic calculations. The Circuit Solver efficiently performs a transient DC analysis with highly dynamic components to allow faster than real-time simulations. Circuit networks are defined in the software data model through paths connected by source and target nodes with unlimited adding, removing, and changing of components during simulations. The Circuit Solver ensures adherence to physics principles and removes much of the computational burden on Pulse modelers. These fluid mechanics and thermodynamics algorithms provide the foundation for the Pulse physics-based models.