The Realization of a Pulsatile Implantable Impeller Pump with Low Hemolysis

A pulsatile implantable impeller pump with low hemolysis was developed without markedly increasing the complexity of the system compared with the nonpulsatile pump. The key to the question is to design a three-dimensional impeller with twisted vanes, compacted by an axial helical spiral and a radial logarithmic spiral so as to reduce the turbulent shear in the pump as the impeller changes its rotations per minute periodically to generate a physiologic pulsatile flow. Both mathematic computation of velocity distribution in the impeller and geometric illustration of the velocity triangle at the top of the vane have demonstrated that the peripheral velocity variation of blood cells in a twisted impeller will be less than that in an untwisted impeller. Thus, the main mechanical factor of hemolysis in the impeller pump, namely, the turbulent shear, should be reduced because it is proportional to the product of velocity variations measured in two perpendicular directions. In the in vitro experiments, the pump delivered 4 L/min mean flow at 100 mm Hg mean pressure (pulsed between 80-120 mm Hg) for more than 3 h in a circulatory model containing 700 ml of fresh citrated porcine blood. Every half hour, the free hemoglobin level in the plasma was tested, and the resulting index of hemolysis was about 0.020, slightly more than that of a nonpulsatile impeller pump developed in Shanghai. To compare hemolysis, the index of hemolysis of this pump is about 1/6 of that of the self-made diaphragm pump and 1/13 of that of the Polystan Pulsatile Pump.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Next Generation Baylor C-Gyro Pump: Antithrombogenic "Free Impeller" Design for Long-Term Centrifugal VAD

Abstract: The new generation centrifugal blood pump, the C2 Gyro Pump "Free Impeller Model" specifically designed for long-term ventricular assistance and a bridge to transplantation, has been developed. In the free impeller design, the impeller was completely freed from mechanical tethers by eliminating the shaft. This unique design allowed the incorporation of a center-penetrating hole in the impeller, called the center conduit, which accelerates the secondary blood flow from the bottom to the top of the impeller. During in vitro performance tests, two characteristic impeller motions, called floating mode and wandering rotational axis, were observed. In the floating mode, the impeller seemed to be floating without touching the pump casing and resulted in the idea of no bearing contact. Also, the rotational axis of the impeller exhibited a small circular motion and illustrated the idea of no stationary area in the blood path. These three characteristics are expected to be advantageous for antithrombogenesity and low hemolysis which are essential for a long-term centrifugal VAD.     

轴向流搅拌桨发酵罐生产红霉素的研究

基于影响搅拌式生物反应器的非生物参数、生物参数及流变学特性的分析研究,开发了高效轴向流搅拌器。经过小型冷、热模实验研究发现该搅拌器具有使全釜流体混合均匀、氧传递速度快、转化率高和功耗低等优点,更为适合高粘度非牛顿流体物系的发酵。经进一步改进设计并在红霉素工业发酵中应用的初步结果表明,在使用原菌种及发酵工艺的基础上,保持原有效价不变的条件下,功耗下降３５￣４５％。     

Numerical Analyses for Low Reynolds Flow in a Ventricular Assist Device

Scientific and technological advances in blood pump developments have been driven by their importance in cardiac patient treatments and in the expansion of life quality in assisted people. To improve and optimize the design and development, numerical tools were incorporated into the analyses of these mechanisms and have become indispensable in their advances. This study analyzes the flow behavior with low impeller Reynolds number, for which there is no consensus on the full development of turbulence in ventricular assist devices (VAD). For supporting analyses, computational numerical simulations were carried out in different scenarios with the same rotation speed. Two modeling approaches were applied: laminar flow and turbulent flow with the standard, RNG and realizable κ ? ε; the standard and SST κ ? ω models; and Spalart–Allmaras models. The results agree with the literature for VAD and the range for transient flows in stirred tanks with an impeller Reynolds number around 2800 for the tested scenarios. The turbulent models were compared, and it is suggested, based on the expected physical behavior, the use of RNG, standard and SST , and Spalart–Allmaras models to numerical analyses for low impeller Reynolds numbers according to the tested flow scenarios.     

轴流式血泵的现状与代表技术

轴流泵的研究已经成为全球人工心脏辅助装置的重点和热点。经过大量调研介绍了国外最赋代表性的3种轴流泵的结构、性能、关键技术和临床实验状况，为广大从事轴流泵设计制作的同仁提供参考。     

人工心脏电动叶轮血泵的动物实验研究

作者报道了左心室辅助及双心室辅助叶轮血泵的急性实验和存活实验。证明离心型人工心脏在可植入性，血液相容性及机械可靠性等方面具有一定优势。并讨论了叶轮血泵的密封问题，从而为叶轮血泵的进一步动物实验，为过渡至急性心脏梗塞后心源性休克和心脏手术后的短期辅助为目标的临床应用准备条件，对于心脏移植前心室辅助超过２周甚至长达数月的叶轮血泵尚需作进一步的研究。     

离心叶轮和扩压器相互作用研究

采用定常和非定常数值模拟技术,研究了某跨音离心压气机级内的复杂流动,分析了叶轮与径向扩压器之间的非定常相互作用。结果表明,扩压器的势干扰使叶轮出口静压发生周期性地变化,引起叶轮后部负荷、叶尖泄漏和损失等也产生周期性地变化,影响范围达30％流向弦长。叶轮出口流场的周向不均匀性及非定常性使扩压器进口参数发生周期性的变化,导致扩压器负荷、总压恢复系数分布呈现出较强的非定常性,影响范围贯穿整个扩压器通道。     

机械搅拌釜中翼型组合桨持气特性的神经网络模型

研究了内径0.382～1.16m机械搅拌釜中翼型组合桨气液两相的持气特性,建立了气含率与结构参数(包括翼型桨径、桨间距、桨下距离、通气位置、挡板形式及翼型桨排出流方向)和操作参数(包括搅拌转速及通气量)间关联的神经网络模型。考察了所建立的网络模型中各参数对气含率的影响规律。结果表明,模型具有很好的泛化能力,其泛化相对误差在±10%以内。采用开槽挡板、低位通气、适宜的桨径、桨间距和翼型桨的排出流向上的方案,在较宽的桨下距离范围内可获得较高的气含率。由于模型使用了与规模无关的无因次参数建模,因此可用于离线预测、参数优化及放大设计。     

关于叶轮血泵血栓问题的研究进展

叶轮血泵具有体积小、重量轻、效率高等优点 ,是心室辅助装置 (VAD)发展的一大主流。在美国、日本及欧洲一些国家已得到了临床应用 ,取得了较好的效果。但是 ,在研究过程中也发现一些问题 :血栓形成、血液破坏、密封等 ,严重阻碍了它的发展。血栓形成一直是研究者们设法解决的问题。优化血泵的结构、改良与血液接触的表面材料是减少血栓形成的主要方法     

双吸离心泵隔舌区压力脉动特性及改进

针对某石化股份有限公司双吸离心泵振动超标的问题,研究了叶轮外径对双吸离心泵隔舌处压力脉动特性的影响。采用雷诺时均法和滑移网格技术,对双吸离心泵内部流场进行三维非定常数值模拟,分析了隔舌处流场和压力脉动情况。研究结果表明:隔舌处的压力脉动幅值大小与流量呈正相关;不同工况以及不同叶轮外径情况下,隔舌区的脉动频率均以叶片通过频率为主;随着叶轮外径切割量的增加,隔舌处压力脉动幅值呈现减小趋势,说明合理地切割叶轮外径能降低压力脉动幅值。