Modeling and Simulation of the Pneumatic System of an Intra-Aortic Balloon Pump

Sammanfattning

Cardiovascular disease is the leading cause of death globally, and mechanical circulatory support devices such as the intra-aortic balloon pump (IABP) play a vital role in treatment in acute care. This thesis develops and validates a lumped-parameter Simscape model of the pneumatic system in Getinge's CardioSave IABP. The model incorporates conservation of mass, momentum and energy for compressible gas flow, and includes the compressor, safety disk (SD), tubing, and balloon. Three balloon representations were compared: (i) linear spring-damper, (ii) nonlinear spring-damper, and (iii) a soft spring with check valves to capture inflation and deflation thresholds. Parameters were estimated using least-squares optimization and the model was validated against experiments using a 40 cc balloon under external pressures of 25, 50 and 100 mmHg (gauge). The check valve model best reproduced the observed threshold behavior and achieved the lowest average shuttle pressure error. A use case study across atmospheric pressures of 450-760 mmHg and heart rates 30-200 bpm showed 10-90 % inflation and deflation times < 0.12 s, with full inflation volumes within acceptance limits. The index-1 DAE system was solved with an NDF2-based implicit solver, yielding stable and efficient simulations with small dispersive errors. While the simplified compressor model does not capture measured LPM-RPM curves across altitudes, the system-level dynamics are reproduced, making it useful for evaluating control strategies and design verification.