心室辅助装置多相流流场数值模拟及溶血性能分析

The simulation of multiphase flow field in ventricular assist device and analysis of hemolytic capability

目的:探讨多相流模型对轴流式血泵溶血性能预报的研究。方法:利用计算流体动力学对轴流泵的水动力性能、流场、切应力分布进行分析,建立一种基于切应力的溶血预报模型。体外6次溶血实验,每次应用2000 ml新鲜抗凝小牛血,在流量为5 L/min,流出道压力100 mmHg(13.3 kPa),转机4 h,每30 min取血样本,测量血浆中游离血红蛋白(free hemoglobin,FHB)含量和红细胞压积(hematocrit,HCT),同时留静置的牛血作为对照组,计算标准溶血指数(normal index of hemolysis,NIH)。结果:计算预测FHB变化与体外溶血实验基本吻合,体外验证实验计算NIH结果0.0055 g/100L,与多相流模型预测NIH结果一致。结论:多相流模型可用于心室辅助装置溶血液性能的定量预报,该方法可应用于血泵设计选型阶段。

Objective The hemolytic prediction model of the axial flow impeller blood pump is carried out by using a computational fluid dynamics(CFD)multiphase flow model.Methods The hydrodynamic performance of the pump and the flow field in the pump,and the shear stress distribution are analyzed.A hemolytic prediction model based on the shear stress is built based on the calculation results.Hemolysis tests in vitro were performed 6 times with fresh bovine blood.At each time,the flow of the ventricular assist device(VAD)is 5 L/min and the outflow tract pressure is 100 mmHg(13.3kPa).According to the tests,the plasma free hemoglobin(FHB)content and the hematocrit(HCT)are measured every half hour.At the end of each experiment Normal Index of Hemolysis(NIH)is calculated.Results The average of NIH is 0.0055 g/100L,almost identical with that obtained from the hemolytic prediction model.Conclusion Multiphase flow model can be used for quantitative predictions of the hemolytic behavior of a VAD.This method can be applied in the selection stage of a blood pump.