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Particle accumulation in ureteral stents is governed by fluid dynamics: in vitro study using a “stent-on-chip” model

Particle accumulation in ureteral stents is governed by fluid dynamics: in vitro study using a “stent-on-chip” model
Particle accumulation in ureteral stents is governed by fluid dynamics: in vitro study using a “stent-on-chip” model
Objective: To investigate the correlation between fluid dynamic processes and deposition of encrusting particles in ureteral stents.

Materials and Methods: Microfluidic models (referred to as “stent-on-chip” or SOC) were developed to replicate relevant hydrodynamic regions of a stented ureter, including drainage holes and the cavity formed by a ureteral obstruction. Computational fluid dynamic simulations were performed to determine the wall shear stress (WSS) field over the solid surfaces of the model, and the computational flow field was validated experimentally. Artificial urine was conveyed through the SOCs to measure the temporal evolution of encrustation through optical microscopy.

Results: It was revealed that drainage holes located well downstream of the obstruction had almost stagnant flow and low WSS (average 0.01 Pa, at 1 mL/min), and thus suffered from higher encrustation rates. On the contrary, higher levels of WSS in holes proximal to the obstruction (average ∼0.04 Pa, at 1 mL/min) resulted in lower encrustation rates in these regions. The cavity located nearby the obstruction was characterized by high levels of encrustation, because of the low WSS (average 1.6 × 10−4 Pa, at 1 mL/min) and the presence of flow vortices. Increasing the drainage flow rate from 1 to 10 mL/min resulted in significantly lower deposition of encrusting crystals.

Conclusion: This study demonstrated an inverse correlation between deposition of encrusting bodies and the local WSS in a stented ureter model. Critical regions with low WSS and susceptible to encrustation were identified, including “inactive” side holes (i.e., with minimal or absent flow exchange between stent and ureter) and the cavity formed by a ureteral occlusion. Findings from this study can open new avenues for improving the stent's design through fluid dynamic optimization.
0892-7790
639-646
Mosayyebi, Ali
ab9cf6da-58c4-4441-993b-7d03d5d3549a
Yue, Qi Yann
fa887406-7e2a-4abb-9dad-5ebb5723a610
Somani, Bhaskar K.
7ed77b4e-3ffc-43ef-bc61-bd1c1544518c
Zhang, Xunli
d7cf1181-3276-4da1-9150-e212b333abb1
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Carugo, Dario
0a4be6cd-e309-4ed8-a620-20256ce01179
Mosayyebi, Ali
ab9cf6da-58c4-4441-993b-7d03d5d3549a
Yue, Qi Yann
fa887406-7e2a-4abb-9dad-5ebb5723a610
Somani, Bhaskar K.
7ed77b4e-3ffc-43ef-bc61-bd1c1544518c
Zhang, Xunli
d7cf1181-3276-4da1-9150-e212b333abb1
Manes, Costantino
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Carugo, Dario
0a4be6cd-e309-4ed8-a620-20256ce01179

Mosayyebi, Ali, Yue, Qi Yann, Somani, Bhaskar K., Zhang, Xunli, Manes, Costantino and Carugo, Dario (2018) Particle accumulation in ureteral stents is governed by fluid dynamics: in vitro study using a “stent-on-chip” model. Journal of Endourology, 32 (7), 639-646. (doi:10.1089/end.2017.0946).

Record type: Article

Abstract

Objective: To investigate the correlation between fluid dynamic processes and deposition of encrusting particles in ureteral stents.

Materials and Methods: Microfluidic models (referred to as “stent-on-chip” or SOC) were developed to replicate relevant hydrodynamic regions of a stented ureter, including drainage holes and the cavity formed by a ureteral obstruction. Computational fluid dynamic simulations were performed to determine the wall shear stress (WSS) field over the solid surfaces of the model, and the computational flow field was validated experimentally. Artificial urine was conveyed through the SOCs to measure the temporal evolution of encrustation through optical microscopy.

Results: It was revealed that drainage holes located well downstream of the obstruction had almost stagnant flow and low WSS (average 0.01 Pa, at 1 mL/min), and thus suffered from higher encrustation rates. On the contrary, higher levels of WSS in holes proximal to the obstruction (average ∼0.04 Pa, at 1 mL/min) resulted in lower encrustation rates in these regions. The cavity located nearby the obstruction was characterized by high levels of encrustation, because of the low WSS (average 1.6 × 10−4 Pa, at 1 mL/min) and the presence of flow vortices. Increasing the drainage flow rate from 1 to 10 mL/min resulted in significantly lower deposition of encrusting crystals.

Conclusion: This study demonstrated an inverse correlation between deposition of encrusting bodies and the local WSS in a stented ureter model. Critical regions with low WSS and susceptible to encrustation were identified, including “inactive” side holes (i.e., with minimal or absent flow exchange between stent and ureter) and the cavity formed by a ureteral occlusion. Findings from this study can open new avenues for improving the stent's design through fluid dynamic optimization.

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D Carugo - J Endourology - 2018 - Accepted Manuscript
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e-pub ahead of print date: 12 June 2018
Published date: July 2018

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Local EPrints ID: 421962
URI: https://eprints.soton.ac.uk/id/eprint/421962
ISSN: 0892-7790
PURE UUID: 92b21b95-1828-4799-847b-e2499549ae3b

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Date deposited: 12 Jul 2018 16:30
Last modified: 13 Mar 2019 18:17

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