Particle Image Velocimetry–Validated, Computational Fluid Dynamics–Based Design to Reduce Shear Stress and Residence Time in Central Venous Hemodialysis Catheters

Abstract

As crucial factors in blood clot formation, shear stress distribution and low flow zones are assessed in different central venous catheter tip designs by using a combined numeric and experimental approach. Computational Fluid Dynamics was validated with Particle Image Velocimetry by comparing simulated and measured velocities and shear strains in three designs of the blood withdrawing arterial lumen: cylindrical and with tip (1) cut straight, (2) cut at an angle, or (3) cut straight with a sleeve entrance. After validation, four additional designs were studied: (4) with two side holes and tip cut straight or (5) at an angle, (6) concentric lumens, and (7) Ash Split-based. In these seven designs, shear stress (SS), blood residence time (RT), and Platelet Lysis Index, which combines the influence of shear stress magnitude and exposure time, were simulated. Concentric catheter was discarded due to highly elevated SS. Ash Split-based design had elevated RT values in the distal tip zone as major inflow occurs through the most proximal side holes, but this is compensated by low average SS. A straight-cut tip and possibly two side holes are preferred when aiming at minimal SS and RT. These data may lead to more patent catheters.

Review of Experimental Modelling in Vascular Access for Hemodialysis

“…Principle Quantity Measurement type pressure sensor [37,17,18,4,6,39,38,11,10,26] various pressure bulk, instantaneous, ≥ kHz flow sensor [35,37,17,18,6,39,38,11,10,26] various flow rate bulk, instantaneous, ≥ kHz LDV [35] optical velocity point, instantaneous, ≥ kHz VDUS [22,21] acoustic velocity point, average * , O(10) Hz PIV [4,19,12,2,27,15,28,3] optical velocity grid of points, instantaneous, O(10) Hz UIV [20] acoustic velocity grid of points, instantaneous, O(10 − 1000) Hz PLIF [3] optical concentration 2D plane, instantaneous, O(10) Hz CDUS [22,21] acoustic velocity 2D plane, average * , O(10) Hz Different methods exist to measure bulk pressure and flow rate, including Pitot tube-type and piezo-electric pressure sensors, and paddle wheel or ultrasoundbased flow rate sensors (for more information, see e.g. [36]).…”

“…Literature on experimental modelling in research on CVCs is rather limited. One example is the paper by Mareels et al [28], in which PIV is used to validate CFD studies of three different CVC geometries. Transparent silicone models, scaled up by a factor of 2.8, were used for the experimental set-up.…”

“…Geometry Material Mareels et al [28] Step-tip catheter Silicone Barbour et al [3] Split-tip catheter --Data not available Experimental modelling is frequently employed to study different aspects of the hemodynamics in an in-vitro vascular access model, either to support computational modelling work, or as a tool on its own. The experimental methods that are used (see also table 1) are mostly well-established, their worth proven in other fields of fluid mechanics.…”

An In Vitro Fluid Dynamic Study of Pediatric Cannulae: The Value of Animal Studies to Predict Human Flow

“…The blood residence times also varied between the different geometries. The straight cut catheter was the preferred design because it appeared to have the least potential for platelet activation, due to lower shear stresses and local residence times [12]. Muehrcke et al showed cannula mediated atheroembolism in the ascending aorta.…”

“…Therefore, some cannula geometries may produce better results than others and this should be considered during the development of the devices. Cannulae geometries have long been examined for non-VAD use [12][13][14]. For example, catheter geometries were extensively studied after it was found that high local shear stresses and low flow zones in catheters strongly affected blood clot formation.…”