The Optimization Study on Time Sequence of Enhanced External Counter-Pulsation in AEI-CPR

To improve the aortic pressure and myocardial perfusion pressure during cardiac arrest, this study is designed to optimize sequence of Enhanced External Counter-Pulsation (EECP) for a cardiopulmonary resuscitation (CPR) technique — Active Compression-Decompression CPR coupled with EECP and Inspiratory Impedance Threshold Valve (AEI-CPR). EECP is lower-limbs compression equipment for AEI-CPR that enhanced blood regurgitation during chest decompression. Different occasion for EECP performance would bring different hemodynamic effect. A mathematical model of human circulatory system used to research AEI-CPR has been established. And then the AEI-CPR hemodynamic effect to the blood circulatory system is performed on the model. A genetic algorithm (GA) that used to find optimum sequence of the EECP is performed on the model when other parameters of external force for AEI-CPR are definite. At first, set the maximum strength of chest compression, chest decompression and lower-limbs compression at 400Nt, 160Nt and 300mmHg, respectively. Set the frequency of CPR at 100min and the ratio of chest compression compared to LLCP at 1:1. Then, after genetic algorithm is performed on the established model, fifty groups of optimal results are obtained. The maximum coronary perfusion pressure (CPP) takes place when the EECP begin its compression at 0.2s and the interval among crural, femoral and iliac compression is 0.05s. By applying the optimization algorithm on the CPR mathematical model, the optimum sequence of the EECP could be found. And the experiment results indicate that obvious hemodynamic effect is attained when the EECP began compression at the end of chest compression.