title: The Hemodynamic Effects of Hemodialysis Needle Rotation and Orientation in an Idealized Computational Model.
abstract: Maintaining the patency of vascular access is essential for performing efficient hemodialysis. Appropriate cannulation technique is critical in maintaining the integrity of vascular access. This study focused on analyzing the hemodynamic effect of needle rotation, which is performed to alleviate the pressure if the needle becomes attached to the blood vessel wall. The hemodynamic benefits (normal wall shear stress [WSS] and smooth flow with no oscillatory motion) of this technique are investigated in an idealized model of the cephalic vein in order to determine a needle position that will reduce conditions known to contribute to vascular access failure. A computational fluid dynamics study was conducted, with antegrade and retrograde orientations simulated on the arterial needle, whereas the venous needle is placed in the antegrade orientation. In every case, needle rotation offered no hemodynamic benefit in minimizing the conditions known to cause endothelial damage, a precursor to vascular access failure. Venous needle rotation reduced the maximum WSS by 30%. However, the WSS was above the range, which may damage the endothelial layer. The arterial needle in the antegrade orientation produced a large region of oscillatory shear, whereas a retrograde orientation produced a region of smooth flow in the vicinity of the needle with only a small region of oscillatory shear. The flow through the venous needle back eye was negligible, whereas the arterial needle back eye was more efficient in the retrograde orientation. Therefore, the venous needle should not be rotated, whereas the arterial needle may be rotated to alleviate pressure with consideration given to the orientation of the needle.
authors.affiliation: School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Fulker
authors.affiliation: School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Anne
authors.initials: A
authors.lastname: Simmons
authors.affiliation: School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Kaveh
authors.initials: K
authors.lastname: Kabir
authors.affiliation: Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Kark
authors.affiliation: School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Tracie
authors.initials: T
authors.lastname: Barber
mesh_terms: D003198:Computer Simulation; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D008954:Models, Biological; D009339:Needles; D006435:Renal Dialysis / Q000295:instrumentation*; D012399:Rotation; D014654:Vascular Patency
keywords: Arteriovenous fistula; Computational fluid dynamics; Hemodialysis; Needle; Rotation; Vascular access