### Abstract

The native arteriovenous fistula creates a shunt that provides the high blood flow that is needed for dialysis. Lumped parameter hemodynamic models of the arteriovenous fistula can be used to predict shear stresses and pressure losses and can be applied to help understand unsolved problems such as the high rate of arteriovenous fistula maturation failure. These models combine together flow components, such as arteries, stenosis, anastomoses, arterial compliance, and blood inertia, and each component must be modeled with an appropriate pressure-flow relationship. Poiseuille flow is generally assumed for straight vessels, but the unique high flow rates within the brachial artery of an arteriovenous fistula are expected to induce entry flow effects that are neglected in this model. To estimate the importance of these effects, brachial artery flow was modeled in a low-resistance network, such as the one that occurs when an arteriovenous fistula is constructed, through the lumped parameter model, and the predicted flow rates and pressures were compared to those predicted by computational fluid dynamics. When Poiseuille flow was assumed, the flow rate from the lumped parameter model was consistently larger than that from computational fluid dynamics, with a cycle-averaged error of 36.8%. When an entry flow model (Shah) was assumed, the lumped parameter-based flow was 6% lower than the computational fluid dynamics model at the peak of the flow waveform, and the cycle-averaged error was reduced to 7.8%. Thus, in a low-resistance (high flow) arteriovenous fistula circuit, an entry flow model can account for steeper near-wall velocity gradients. This result can provide a useful guide for designing engineering models of the arteriovenous fistula.

Original language | English (US) |
---|---|

Pages (from-to) | 766-773 |

Number of pages | 8 |

Journal | Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine |

Volume | 231 |

Issue number | 8 |

DOIs | |

State | Published - Aug 1 2017 |

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### Keywords

- Arteriovenous fistula
- computational fluid dynamics
- hemodynamics modeling
- impedance: hemodynamics
- mathematical modeling (medical)
- vascular access
- waveforms: hemodynamics

### ASJC Scopus subject areas

- Mechanical Engineering

### Cite this

*Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine*,

*231*(8), 766-773. https://doi.org/10.1177/0954411917705910

**Applicability of an entry flow model of the brachial artery for flow models of the hemodialysis fistula.** / Bastola, Sulav; Paulson, William D; Jones, Steven A.

Research output: Contribution to journal › Article

*Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine*, vol. 231, no. 8, pp. 766-773. https://doi.org/10.1177/0954411917705910

}

TY - JOUR

T1 - Applicability of an entry flow model of the brachial artery for flow models of the hemodialysis fistula

AU - Bastola, Sulav

AU - Paulson, William D

AU - Jones, Steven A.

PY - 2017/8/1

Y1 - 2017/8/1

N2 - The native arteriovenous fistula creates a shunt that provides the high blood flow that is needed for dialysis. Lumped parameter hemodynamic models of the arteriovenous fistula can be used to predict shear stresses and pressure losses and can be applied to help understand unsolved problems such as the high rate of arteriovenous fistula maturation failure. These models combine together flow components, such as arteries, stenosis, anastomoses, arterial compliance, and blood inertia, and each component must be modeled with an appropriate pressure-flow relationship. Poiseuille flow is generally assumed for straight vessels, but the unique high flow rates within the brachial artery of an arteriovenous fistula are expected to induce entry flow effects that are neglected in this model. To estimate the importance of these effects, brachial artery flow was modeled in a low-resistance network, such as the one that occurs when an arteriovenous fistula is constructed, through the lumped parameter model, and the predicted flow rates and pressures were compared to those predicted by computational fluid dynamics. When Poiseuille flow was assumed, the flow rate from the lumped parameter model was consistently larger than that from computational fluid dynamics, with a cycle-averaged error of 36.8%. When an entry flow model (Shah) was assumed, the lumped parameter-based flow was 6% lower than the computational fluid dynamics model at the peak of the flow waveform, and the cycle-averaged error was reduced to 7.8%. Thus, in a low-resistance (high flow) arteriovenous fistula circuit, an entry flow model can account for steeper near-wall velocity gradients. This result can provide a useful guide for designing engineering models of the arteriovenous fistula.

AB - The native arteriovenous fistula creates a shunt that provides the high blood flow that is needed for dialysis. Lumped parameter hemodynamic models of the arteriovenous fistula can be used to predict shear stresses and pressure losses and can be applied to help understand unsolved problems such as the high rate of arteriovenous fistula maturation failure. These models combine together flow components, such as arteries, stenosis, anastomoses, arterial compliance, and blood inertia, and each component must be modeled with an appropriate pressure-flow relationship. Poiseuille flow is generally assumed for straight vessels, but the unique high flow rates within the brachial artery of an arteriovenous fistula are expected to induce entry flow effects that are neglected in this model. To estimate the importance of these effects, brachial artery flow was modeled in a low-resistance network, such as the one that occurs when an arteriovenous fistula is constructed, through the lumped parameter model, and the predicted flow rates and pressures were compared to those predicted by computational fluid dynamics. When Poiseuille flow was assumed, the flow rate from the lumped parameter model was consistently larger than that from computational fluid dynamics, with a cycle-averaged error of 36.8%. When an entry flow model (Shah) was assumed, the lumped parameter-based flow was 6% lower than the computational fluid dynamics model at the peak of the flow waveform, and the cycle-averaged error was reduced to 7.8%. Thus, in a low-resistance (high flow) arteriovenous fistula circuit, an entry flow model can account for steeper near-wall velocity gradients. This result can provide a useful guide for designing engineering models of the arteriovenous fistula.

KW - Arteriovenous fistula

KW - computational fluid dynamics

KW - hemodynamics modeling

KW - impedance: hemodynamics

KW - mathematical modeling (medical)

KW - vascular access

KW - waveforms: hemodynamics

UR - http://www.scopus.com/inward/record.url?scp=85027178775&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85027178775&partnerID=8YFLogxK

U2 - 10.1177/0954411917705910

DO - 10.1177/0954411917705910

M3 - Article

C2 - 28466757

AN - SCOPUS:85027178775

VL - 231

SP - 766

EP - 773

JO - Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine

JF - Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine

SN - 0954-4119

IS - 8

ER -