Computational model of the fluid dynamics of a cannula inserted in a vessel: incidence of the presence of side holes in blood flow
Computational model of the fluid dynamics of a cannula inserted in a vessel: incidence of the presence of side holes in blood flow
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DOI：
10.1016/s0021-9290(02)00231-2
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发表时间：
2002-12-01
影响因子：
2.4
通讯作者：
Barbaro, V
中科院分区：
文献类型：
--
作者：
Grigioni, M;Daniele, C;Barbaro, V
通过将导管插入血管的血管通路方法可能会干扰血液的生理流动，引起非生理性的压力变化和剪切应力。迄今为止，已经通过使用一维方法从体外实验中获得的管内压力损失-流量关系来评估管内的流体动力学行为；这种方法既不能提供有关局部流体动力学的信息，也不能提供特定临床工作条件下建立的流场。由于剪切应力是人工循环装置设计中的一个关键因素，因此有必要对插管过程中血流动力学参数假设的局部值有更多的了解。数值研究给出了另一种尽可能精确地研究流体动力学的方法。建立了同心放置于刚性壁面血管内的导管三维模型，采用有限元方法对两种不同的静脉插管案例进行了稳态流场数值模拟，其中两种导管分别具有一个中心孔和两个或四个侧孔，边界条件相同。在中心孔的上游有四个侧孔的模型中，由于相对于有两个侧孔的模型，流动对称性和入口面积增加，在导管的入口流交汇处和流向导管出口的区域中，计算出了较低的速度和剪应力峰值。从不同的套管设计的调查开始，数值评估局部流体动力学，可以得出适应症，以支持设计阶段和设备的最佳临床使用，以限制生物力学起源的风险。因此，四个侧孔的存在意味着，由于入口面积更大，对称性增加，血流受到的干扰更少，同时剪切应力值也降低了。此外，数值模拟还为血管与导管的相互作用提供了有用的信息，例如在导管插入后留下的自由腔空间中建立的流体动力学。(C) 2002 Elsevier Science Ltd.版权所有。
Vascular access methods, performed by the insertion of cannulae into vessels, may disturb the physiological flow of blood, giving rise to non-physiological pressure variations and shear stresses. To date, the hydrodynamic behaviour of the cannulae has been evaluated comparing their pressure loss-flow rate relationships, as obtained from in vitro experiments using a monodimensional approach; this methodology neither furnish information about the local fluid dynamics nor the established flow field in specific clinical work conditions. Since the shear stress is a critical factor in the design of artificial circulatory devices, more knowledge should be necessary about the local values assumed by the haemodynamic parameters during cannulation. An alternative way to investigate the fluid dynamic as accurately as possible is given by numeric studies. A 3D model of cannula concentrically placed in a rigid wall vessel is presented, with the finite element methodology used to numerically simulate the steady-state flow field in two different venous cannulation case studies, with two cannulae having a central hole and two or four side holes, respectively, with the same boundary conditions. Lower velocity and shear stress peak values have been computed for the model with four side holes upstream of the central hole, in the region of the cannula where the inlet flows meet and towards cannula's outlet, due to the increased flow symmetry and inlet area with respect to the model with two side holes. Starting from the investigation of different cannula designs, numerically assessing the local fluid dynamics, indications can be drawn to support both the design phase and the device optimal clinical use, in order to limit risks of biomechanical origin. Thus the presence of four side holes implied, as a consequence of the greater inlet area and of the increased symmetry, a less disturbed blood flow, together with reduced shear stress values. Furthermore, results show that the numerical simulations furnished useful informations on the interaction between vessel and cannula, e.g. on the fluid dynamics establishing in the free luminal space left, in the vessel, by the inserted cannula. (C) 2002 Elsevier Science Ltd. All rights reserved.