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Wang X, Liu J, Li N, Ma J, Chen M, Feng Y, Li B, Liu J, Liu Y, Zhang L. Left and right coronary artery blood flow distribution method based on dominant type. Int J Numer Method Biomed Eng 2023; 39:e3681. [PMID: 36629761 DOI: 10.1002/cnm.3681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 12/30/2022] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
The purpose of the current study was to investigate the effects of left/right coronary artery flow distribution on calculation of fractional flow reserve derived from coronary computed tomography angiography (FFRct) in different dominant types. First, 195 patients were collected to count the distribution ratios of the three categories: right dominance (RD), balanced dominance (BD), and left dominance (LD). Ratios of diameters of the left/right coronary arteries (DLCA :DRCA ) of the three types were calculated and used to represent the ratio of flow distribution (QLCA :QRCA ) in the dominant type method. The other method was known as the fixed ratio method (QLCA :QRCA = 6:4). Second, a total of 73 patients with coronary artery disease (CAD) were enrolled for numerical calculation. A 0D/3D geometric multiscale model was used for the numerical simulation of FFR and the results of the fixed ratio method and the dominant type method were recorded as F-FFRct and D-FFRct. Lastly, invasive FFR(clinic-FFR)was used as a standard to evaluate the consistency and diagnostic performance of F-FFRct and D-FFRct. Corresponding flow distributions for the dominant type method were QLCA :QRCA = 5:5 for RD, QLCA :QRCA = 5.5:4.5 for BD, and QLCA :QRCA = 6:4 for LD. D-FFRct showed a better correlation than F-FFRct (r = 0.85 vs. r = 0.81, both p < .001); the AUC (95%CI) were 0.974 (0.906-0.997, p < .0001) and 0.960 (0.886-0.992, p < .0001). Accuracy, specificity, sensitivity, positive predictive value (PPV) and negative predictive values (NPV) for D-FFRct and F-FFRct were 94.52%, 93.75%, 94.74%, 83.33%, 98.18% and 90.41%, 87.50%, 91.23%, 73.68%, 96.30%, respectively. Overall, the left/right coronary artery flow distribution was affected by the dominant type and the dominant type method was superior to the fixed ratio method in detecting coronary ischemic lesions.
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Affiliation(s)
- Xue Wang
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Jincheng Liu
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Na Li
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Junling Ma
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Mingyan Chen
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Yili Feng
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Bao Li
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Jian Liu
- Department of Cardiology, Peking University People's Hospital, Beijing, China
| | - Youjun Liu
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
| | - Liyuan Zhang
- Department of Biomedical Engineering, Beijing University of Technology, Beijing, China
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2
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Xu Y, Umatheva U, Ghosh R. Evaluation of a Novel Cuboid Hollow Fiber Hemodialyzer Design Using Computational Fluid Dynamics. Membranes (Basel) 2023; 13:membranes13010093. [PMID: 36676900 PMCID: PMC9863327 DOI: 10.3390/membranes13010093] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 06/06/2023]
Abstract
Conventional hollow fiber hemodialyzers have a cylindrical shell-and-tube design. Due to their circular cross-section and radial flow distribution and collection in the headers, the flow of blood in the header as well as in the hollow fiber membranes is non-uniform. The creation of high shear stress and high shear rate zones or stagnation zones could result in problems, such as cell lysis and blood clotting. In this paper, a novel cuboid hemodialyzer design is proposed as an alternative to the conventional cylindrical hemodialyzer. The primary motivation behind the proposed design is to create uniform flow conditions and thereby minimize some of the above-mentioned adverse effects. The most salient feature of the proposed design is a cuboid shell within which the hollow fiber membrane bundle is potted. The lumen of the fibers is fed from one side using a flow distributor consisting of embedded primary and secondary channels, while the fibers are drained from the other side using a flow collector, which also has embedded primary and secondary channels. The flow characteristics of the lumen side of the cuboid hemodialyzer were compared with those of a conventional hemodialyzer based on computational fluid dynamics (CFD) simulations. The results of CFD simulations clearly indicated that the flow of liquid within the cuboid dialyzer was significantly more uniform. Consequently, the shear rate and shear stress were also more uniform. By adopting this new design, some of the problems associated with the conventional hemodialyzer design could potentially be addressed.
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Affiliation(s)
| | | | - Raja Ghosh
- Correspondence: ; Tel.: +1-905-525-9140 (ext. 27415)
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3
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Kim H, Sheitt H, Wilton SB, White JA, Garcia J. Left Ventricular Flow Distribution as a Novel Flow Biomarker in Atrial Fibrillation. Front Bioeng Biotechnol 2021; 9:725121. [PMID: 34900953 PMCID: PMC8657405 DOI: 10.3389/fbioe.2021.725121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/19/2021] [Indexed: 11/23/2022] Open
Abstract
Introduction: Four-dimensional (4-D) flow cardiac magnetic resonance imaging can be used to elegantly describe the hemodynamic efficiency of left ventricular (LV) flow throughout the cardiac cycle. Patients with nonvalvular paroxysmal atrial fibrillation (PAF) may have occult LV disease. Flow distribution analysis, based on 4-D flow, may unmask the presence of LV disease by assessing flow components: direct flow, retained flow, delayed ejection, and residual volume. This study aimed to identify LV hemodynamic inefficiencies in patients with PAF and normal systolic function. We hypothesized that the fraction of direct flow to the total end-diastolic volume would be reduced in patients with PAF compared with controls. Methods: We used 4-D LV flow component analysis to compare hemodynamics in 30 healthy controls and 50 PAF patients in sinus rhythm. Results: PAF subjects and healthy controls had similar LV mass, volume, and ejection fraction. Direct flow was lower in the PAF group than in the controls (44.5 ± 11.2% vs. 50.0 ± 12.2%, p = 0.042) while delayed ejection was higher in the PAF group (21.6 ± 5.6% vs. 18.6 ± 5.7%, p = 0.022). Conclusion: PAF patients demonstrated a relative reduction in direct flow and elevation in delayed ejection.
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Affiliation(s)
- Hansuk Kim
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Stephenson Cardiac Imaging Centre, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute, University of Calgary, AB, Calgary, Canada
| | - Hana Sheitt
- Stephenson Cardiac Imaging Centre, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute, University of Calgary, AB, Calgary, Canada.,Department of Cardiac Sciences, University of Calgary, Calgary, AB, Canada.,Department of Radiology, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Stephen B Wilton
- Libin Cardiovascular Institute, University of Calgary, AB, Calgary, Canada.,Department of Cardiac Sciences, University of Calgary, Calgary, AB, Canada
| | - James A White
- Stephenson Cardiac Imaging Centre, University of Calgary, Calgary, AB, Canada.,Department of Cardiac Sciences, University of Calgary, Calgary, AB, Canada
| | - Julio Garcia
- Stephenson Cardiac Imaging Centre, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute, University of Calgary, AB, Calgary, Canada.,Department of Cardiac Sciences, University of Calgary, Calgary, AB, Canada.,Department of Radiology, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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4
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Wang Z, Guo Y, Wadbro E, Liu Z. Topology Optimization of Passive Cell Traps. Micromachines (Basel) 2021; 12:mi12070809. [PMID: 34357219 PMCID: PMC8303924 DOI: 10.3390/mi12070809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/06/2021] [Accepted: 07/06/2021] [Indexed: 11/16/2022]
Abstract
This paper discusses a flexible design method of cell traps based on the topology optimization of fluidic flows. Being different from the traditional method, this method obtains the periodic layout of the cell traps according to the cell trapping requirements by proposing a topology optimization model. Additionally, it satisfies the cell trapping function by restricting the flow distribution while taking into account the overall energy dissipation of the flow field. The dependence on the experience of the designer is reduced when this method is used to design a cell trap with acceptable trapping performance. By comparing the influence of the changes of various parameters on the optimization results, the flexibility of the topology optimization method for cell trap structure optimization is verified. The capability of this design method is validated by several performed comparisons between the obtained layouts and optimized designs in the published literature.
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Affiliation(s)
- Zhiqi Wang
- Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences, Changchun 130033, China;
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuchen Guo
- Ji Hua Laboratory, Foshan 528000, China;
| | - Eddie Wadbro
- Department of Mathematics and Computer Science, Karlstad University, SE-651 88 Karlstad, Sweden;
| | - Zhenyu Liu
- Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences, Changchun 130033, China;
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence:
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5
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Adu D, Du J, Darko RO, Ofosu Antwi E, Aamir Shafique Khan M. Numerical and experimental characterization of splitter blade impact on pump as turbine performance. Sci Prog 2021; 104:36850421993247. [PMID: 33900840 PMCID: PMC10455009 DOI: 10.1177/0036850421993247] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several rivers and streams are available in Africa and Asian regions with great potentials not applicable for constructing large hydropower dams but feasible for small and mini hydro generation. This study strive for investigating the impact of splitter blade on pump as turbine performance considering different speed and flow rates. Two specific centrifugal pump models one with six blades without splitter and another with four blades and four splitters were used for the study. The inlet diameter and outlet diameters of both impellers were 104 mm/116 mm, and 160 mm respectively at a designed flow rate Q = 12.5 m3/h, head H = 16 m, rotational speed n = 1450 rpm and efficiency of 56%, outlet impeller width of 0.006 m, a blade outlet angle of 30° was used for the study. CFD simulations were conducted with the use of k-ε turbulence model. The influence of splitter blade position on the performance of pump as turbine in the selected specific pumps with and without splitter blades has been investigated both experimentally and numerically at three different flow rates and rotational speed. The simulated data were in good agreement with the experimental results, the maximum deviation error between the CFD and test for each model are 5.6%, 2.6%, for the head and efficiency; 7.5% and 3.6% at different flow conditions.
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Affiliation(s)
- Daniel Adu
- School of Management Science and Engineering, Jiangsu University, Zhenjiang, China
| | - Jianguo Du
- School of Management Science and Engineering, Jiangsu University, Zhenjiang, China
| | - Ransford O Darko
- Department of Energy Agricultural Engineering University of Cape Coast, Cape Coast, Central, Ghana
| | - Eric Ofosu Antwi
- Department of Energy and Environmental Engineering, University of Energy and Natural Resources Sunyani, Sunyani, Ghana
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Rong Y, Liu XC, He YX, Zhang WS, Jin PK. [Enhanced Nutrient Removal and Microbial Community Structure in a Step-feed A 2/O Process Treating Low-C/N Municipal Wastewater]. Huan Jing Ke Xue 2020; 40:4113-4120. [PMID: 31854875 DOI: 10.13227/j.hjkx.201903192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To resolve the issue of insufficient influent carbon sources in existing municipal wastewater treatment plants (WWTPs) in China, a pilot-scale step-feed A2/O process was used to treat low-C/N (C/N<5) municipal sewage with five different inflow distribution ratios. In this study, the effects of influent flow distribution on the removal efficiencies of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) were investigated. The results showed that optimal removal efficiencies of 89.41% for COD, 95.30% for NH4+-N, 83.00% for TN, and 90.09% for TP were obtained at an inflow QPA:QAN:QA distribution ratio of 0.1:0.2:0.3. The activated sludge exhibited excellent settleability characteristics, showing a sludge volume index (SVI)<120 mL·g-1 with an average volatile suspended solids (VSS) total suspended solids (TSS) ratio of 0.84 (Phase 5), and no filamentous bacteria bulking occurred during the 120-day experiment. Moreover, the microbial community structure in the oxic zone was detected by high-throughput sequencing. The results demonstrated that excellent nutrient removal and sludge settling performance of the system were closely related to the enrichment of six types of heterotrophic bacteria, four types of denitrifying bacteria, five types of polyphosphate-accumulating organisms (PAOs), and two types of zoogloea and the elimination of three types of filamentous bacteria.
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Affiliation(s)
- Yi Rong
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xiao-Chai Liu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yin-Xuan He
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Wu-Shou Zhang
- Shaanxi Langzheng Environmental Protection Technology Co., Ltd., Xi'an 710065, China
| | - Peng-Kang Jin
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
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7
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Hao Y, Wang Y. Optimization of thermo-hydraulic characteristics of solar cavity receiver under concentrated heat flux. Sci Prog 2020; 103:36850419875907. [PMID: 31829880 PMCID: PMC10358555 DOI: 10.1177/0036850419875907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is important to study the effects of heat flux on the thermo-hydraulic characteristics in a solar cavity receiver because of the non-uniform radiation flux temporally and spatially. In this article, we presented a mathematical model of thermo-hydraulic characteristics of a solar cavity receiver, considering the effect of heat flux distribution on the energy transfer (radiation-conduction-convection). Using the model, the thermo-hydraulic characteristics under high concentrated heat flux were studied and then optimized the characteristics from two aspects: tube diameter (22, 27, 32, and 38 mm) and connection structure of the heating surface (H-type, central inlet/outlet, and vertical U-type). It was found that flow distribution changed smoothly at the diameter of 27 mm with the increase of the heat flux; when the diameter of tubes at the certain distance (1.6σHF) from the spot center was replaced by 38 mm, the thermo-hydraulic characteristics were improved. For the evaporating surfaces, the thermo-hydraulic characteristics of working fluid (water) with the central inlet/outlet connection structure were better than those of the H-type connection structure. For the surperheated surfaces, the vertical U-type connection structure was applied to obtain the high temperature steam. These research findings are helpful for the safe and stable operation of the whole solar power system.
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Affiliation(s)
- Yun Hao
- College of Mechanical Engineering, Xi’an Shiyou University, Xi’an, China
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, China
| | - Yueshe Wang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, China
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8
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Ofuchi CY, Eidt HK, Rodrigues CC, Dos Santos EN, Dos Santos PHD, da Silva MJ, Neves F Jr, Domingos PVSR, Morales REM. Multiple Wire-Mesh Sensors Applied to the Characterization of Two-Phase Flow inside a Cyclonic Flow Distribution System. Sensors (Basel) 2019; 19:E193. [PMID: 30621094 DOI: 10.3390/s19010193] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 11/22/2022]
Abstract
Wire-mesh sensors are used to determine the phase fraction of gas–liquid two-phase flow in many industrial applications. In this paper, we report the use of the sensor to study the flow behavior inside an offshore oil and gas industry device for subsea phase separation. The study focused on the behavior of gas–liquid slug flow inside a flow distribution device with four outlets, which is part of the subsea phase separator system. The void fraction profile and the flow symmetry across the outlets were investigated using tomographic wire-mesh sensors and a camera. Results showed an ascendant liquid film in the cyclonic chamber with the gas phase at the center of the pipe generating a symmetrical flow. Dispersed bubbles coalesced into a gas vortex due to the centrifugal force inside the cyclonic chamber. The behavior favored the separation of smaller bubbles from the liquid bulk, which was an important parameter for gas-liquid separator sizing. The void fraction analysis of the outlets showed an even flow distribution with less than 10% difference, which was a satisfactorily result that may contribute to a reduction on the subsea gas–liquid separators size. From the outcomes of this study, detailed information regarding this type of flow distribution system was extracted. Thereby, wire-mesh sensors were successfully applied to investigate a new type of equipment for the offshore oil and gas industry.
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9
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Jarvis K, Schnell S, Barker AJ, Rose M, Robinson JD, Rigsby CK, Markl M. Caval to pulmonary 3D flow distribution in patients with Fontan circulation and impact of potential 4D flow MRI error sources. Magn Reson Med 2018; 81:1205-1218. [PMID: 30277276 DOI: 10.1002/mrm.27455] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 06/07/2018] [Accepted: 06/26/2018] [Indexed: 11/08/2022]
Abstract
PURPOSE Uneven flow distribution in patients with Fontan circulation is suspected to lead to complications. 4D flow MRI offers evaluation using time-resolved pathlines; however, the potential error is not well understood. The aim of this study was to systematically assess variability in flow distribution caused by well-known sources of error. METHODS 4D flow MRI was acquired in 14 patients with Fontan circulation. Flow distribution was quantified by the % of caval venous flow pathlines reaching the left and right pulmonary arteries. Impact of data acquisition and data processing uncertainties were investigated by (1) probabilistic 4D blood flow tracking at varying noise levels, (2) down-sampling to mimic acquisition at different spatial resolutions, (3) pathline calculation with and without eddy current correction, and (4) varied segmentation of the Fontan geometry to mimic analysis errors. RESULTS Averaged among the cohort, uncertainties accounted for flow distribution errors from noise ≤3.2%, low spatial resolution ≤2.3% to 3.8%, eddy currents ≤6.4%, and inaccurate segmentation ≤3.9% to 9.1% (dilation and erosion, respectively). In a worst-case scenario (maximum additive errors for all 4 sources), flow distribution errors were as high as 22.5%. CONCLUSION Inaccuracies related to postprocessing (segmentation, eddy currents) resulted in the largest potential error (≤15.5% combined) whereas errors related to data acquisition (noise, low spatial resolution) had a lower impact (≤5.5%-7.0% combined). Whereas it is unlikely that these errors will be additive or affect the identification of severe asymmetry, these results illustrate the importance of eddy current correction and accurate segmentation to minimize Fontan flow distribution errors.
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Affiliation(s)
- Kelly Jarvis
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, Illinois
| | - Susanne Schnell
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Alex J Barker
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Michael Rose
- Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Joshua D Robinson
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois.,Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Cynthia K Rigsby
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois.,Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Michael Markl
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, Illinois
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10
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Ren S, Shi Y, Cai M, Zhao H, Zhang Z, Zhang XD. ANSYS-MATLAB co-simulation of mucus flow distribution and clearance effectiveness of a new simulated cough device. Int J Numer Method Biomed Eng 2018; 34:e2978. [PMID: 29504248 DOI: 10.1002/cnm.2978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/27/2018] [Accepted: 02/27/2018] [Indexed: 05/07/2023]
Abstract
Coughing is an irritable reaction that protects the respiratory system from infection and improves mucus clearance. However, for the patients who cannot cough autonomously, an assisted cough device is essential for mucus clearance. Considering the low efficiency of current assisted cough devices, a new simulated cough device based on the pneumatic system is proposed in this paper. Given the uncertainty of airflow rates necessary to clear mucus from airways, the computational fluid dynamics Eulerian wall film model and cough efficiency (CE) were used in this study to simulate the cough process and evaluate cough effectiveness. The Ansys-Matlab co-simulation model was set up and verified through experimental studies using Newtonian fluids. Next, model simulations were performed using non-Newtonian fluids, and peak cough flow (PCF) and PCF duration time were analyzed to determine their influence on mucus clearance. CE growth rate (λ) was calculated to reflect the CE variation trend. From the numerical simulation results, we find that CE rises as PCF increases while the growth rate trends to slow as PCF increases; when PCF changes from 60 to 360 L/min, CE changes from 3.2% to 51.5% which is approximately 16 times the initial value. Meanwhile, keeping a long PCF duration time could greatly improve CE under the same cough expired volume and PCF. The results indicated that increasing the PCF and PCF duration time can improve the efficiency of mucus clearance. This paper provides a new approach and a research direction for control strategy in simulated cough devices for airway mucus clearance.
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Affiliation(s)
- Shuai Ren
- School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| | - Yan Shi
- School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
- The State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou, China
- Department of Pulmonary and Critical Care Medicine, China-Japan Friendship Hospital, Beijing, China
| | - Maolin Cai
- School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| | - Hongmei Zhao
- Department of Pulmonary and Critical Care Medicine, China-Japan Friendship Hospital, Beijing, China
| | - Zhaozhi Zhang
- Department of Statistical Science, Duke University, Durham, NC, USA
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11
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Venema LH, Sharma AS, Simons AP, Bekers O, Weerwind PW. Contemporary Oxygenator Design Relative to Hemolysis. J Extra Corpor Technol 2014; 46:212-216. [PMID: 26357786 PMCID: PMC4566829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 06/29/2014] [Indexed: 06/05/2023]
Abstract
Hemolysis is a well-known phenomenon during cardiovascular surgery and generally attributed to cardiopulmonary bypass, particularly when using high-resistant oxygenators. This study aimed at investigating whether transoxygenator pressure drop can be considered an independent factor of hemolysis. Additionally, intraoxygenator blood distribution and shear stress were assessed. A low-resistant (LR, n = 3), a moderate-resistant (MR, n = 3), and a high-resistant (HR, n = 3) clinically used membrane oxygenator were tested in vitro using a roller pump and freshly drawn heparinized porcine blood. Flow rates were set to 2 and 4 L/min and maximum flow compliant to the oxygenator type for 1 hour each. As a control, the oxygenator was excluded from the system. Blood samples were taken every 30 minutes for plasma-free hemoglobin assay and transoxygenator pressure was measured inline. Intraoxygenator blood distribution was assessed using an ultrasound dilution technique. Despite the relatively broad spectrum of pressure drop and resultant transoxygenator pressure drops (LR: 14-41 mmHg, MR: 29-115 mmHg, HR: 77-284 mmHg, respectively), no significant association (R2 = .074, p = .22) was found with the normalized index of hemolysis. The shear stress of each oxygenator at maximum flow rate amounted to 3.0 N/m2 (LR), 5.7 N/m2 (MR), and 8.4 N/m2 (HR), respectively. Analysis of blood flow distribution curves (kurtosis and skewness) revealed intraoxygenator blood flow distribution to become more homogeneous when blood flow rates increased. Contemporary oxygenators were shown not to be a predominant factor for red blood cell damage.
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Affiliation(s)
- Leonie H. Venema
- Department of Cardiothoracic Surgery, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
| | - Ajay S. Sharma
- Department of Cardiothoracic Surgery, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
| | - Antoine P. Simons
- Department of Cardiothoracic Surgery, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
| | - Otto Bekers
- Department of Clinical Chemistry, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
| | - Patrick W. Weerwind
- Department of Cardiothoracic Surgery, Maastricht University Medical Center and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
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Abstract
This study used high-frequency ultrasound to evaluate the flow distribution in the mouse fetal circulation at late gestation. We studied 12 fetuses (embryonic day 17.5) from 12 pregnant CD1 mice with 40 MHz ultrasound to assess the flow in 11 vessels based on Doppler measurements of blood velocity and M-mode measurements of diameter. Specifically, the intrahepatic umbilical vein (UVIH), ductus venosus (DV), foramen ovale (FO), ascending aorta (AA), main pulmonary artery (MPA), ductus arteriosus (DA), descending thoracic aorta (DTA), common carotid artery (CCA), inferior vena cava (IVC), and right and left superior vena cavae (RSVC, LSVC) were examined, and anatomically confirmed by micro-CT. The mouse fetal circulatory system was found to be similar to that of the humans in terms of the major circuit and three shunts, but characterized by bilateral superior vena cavae and a single umbilical artery. The combined cardiac output (CCO) was 1.22 ± 0.05 ml/min, with the left ventricle (flow in AA) contributing 47.8 ± 2.3% and the right ventricle (flow in MPA) 52.2 ± 2.3%. Relative to the CCO, the flow percentages were 13.6 ± 1.0% for the UVIH, 10.4 ± 1.1% for the DV, 35.6 ± 2.4% for the DA, 41.9 ± 2.6% for the DTA, 3.8 ± 0.3% for the CCA, 29.5 ± 2.2% for the IVC, 12.7 ± 1.0% for the RSVC, and 9.9 ± 0.9% for the LSVC. The calculated flow percentage was 16.6 ± 3.4% for the pulmonary circulation and 31.2 ± 5.3% for the FO. In conclusion, the flow in mouse fetal circulation can be comprehensively evaluated with ultrasound. The baseline data of the flow distribution in normal mouse fetus serve as the reference range for future studies.
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Affiliation(s)
- Yu-Qing Zhou
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada;
| | - Lindsay S Cahill
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael D Wong
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Mike Seed
- Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Christopher K Macgowan
- Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John G Sled
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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13
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Zhou YQ, Cahill LS, Wong MD, Seed M, Macgowan CK, Sled JG. Assessment of flow distribution in the mouse fetal circulation at late gestation by high-frequency Doppler ultrasound. Physiol Genomics 2014; 46:602-14. [PMID: 24963005 DOI: 10.1152/physiolgenomics.00049.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
This study used high-frequency ultrasound to evaluate the flow distribution in the mouse fetal circulation at late gestation. We studied 12 fetuses (embryonic day 17.5) from 12 pregnant CD1 mice with 40 MHz ultrasound to assess the flow in 11 vessels based on Doppler measurements of blood velocity and M-mode measurements of diameter. Specifically, the intrahepatic umbilical vein (UVIH), ductus venosus (DV), foramen ovale (FO), ascending aorta (AA), main pulmonary artery (MPA), ductus arteriosus (DA), descending thoracic aorta (DTA), common carotid artery (CCA), inferior vena cava (IVC), and right and left superior vena cavae (RSVC, LSVC) were examined, and anatomically confirmed by micro-CT. The mouse fetal circulatory system was found to be similar to that of the humans in terms of the major circuit and three shunts, but characterized by bilateral superior vena cavae and a single umbilical artery. The combined cardiac output (CCO) was 1.22 ± 0.05 ml/min, with the left ventricle (flow in AA) contributing 47.8 ± 2.3% and the right ventricle (flow in MPA) 52.2 ± 2.3%. Relative to the CCO, the flow percentages were 13.6 ± 1.0% for the UVIH, 10.4 ± 1.1% for the DV, 35.6 ± 2.4% for the DA, 41.9 ± 2.6% for the DTA, 3.8 ± 0.3% for the CCA, 29.5 ± 2.2% for the IVC, 12.7 ± 1.0% for the RSVC, and 9.9 ± 0.9% for the LSVC. The calculated flow percentage was 16.6 ± 3.4% for the pulmonary circulation and 31.2 ± 5.3% for the FO. In conclusion, the flow in mouse fetal circulation can be comprehensively evaluated with ultrasound. The baseline data of the flow distribution in normal mouse fetus serve as the reference range for future studies.
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Affiliation(s)
- Yu-Qing Zhou
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada;
| | - Lindsay S Cahill
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael D Wong
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Mike Seed
- Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Christopher K Macgowan
- Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John G Sled
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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14
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Abstract
Considerable spatial heterogeneity has been observed in regional myocardial blood flow in isolated hearts and in both anesthetized and conscious animals. In order to study how local blood flow varies with time, the data obtained by King et al. (1985) from ten awake, healthy baboons were analyzed to estimate the role of temporal fluctuations. Four to six distributions of regional flows were estimated at intervals of 4 min to 27 h, using 15 mu diameter microspheres and dividing each heart into 204 locatable pieces (average piece mass = 0.17 g). The technique averages over the 40 s of the injection giving no measure of fluctuations over a few seconds. The temporal variation in regional blood flow, expressed as the relative dispersion (SD/mean) of the temporally separated measurements about the mean flow for each piece and corrected for methodological noise, was 12% for the whole heart (10828 observations). For the left ventricle, the temporal variation was 10% (8806 observations), for the right ventricle 14% (1455 observations), and for the atria 22% (567 observations). On a relative basis, temporal fluctuation was greatest in regions having low flows. Since the magnitude of the changes in flow distributions was the same after 4 min as it was in several hours, we conclude that much of the "twinkling" is a high frequency phenomenon occurring over seconds to a few minutes. Further, it is concluded that regional myocardial blood flow in conscious primates is relatively stable with time, temporal fluctuations causing only about one third of the variation between regions.
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Affiliation(s)
- R B King
- Center for Bioengineering, University of Washington, Seattle 98195
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15
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Abstract
Regional myocardial blood flow has been thought to be relatively uniform, in accord with the singular function of myocardial cells. However, considerable spatial heterogeneity has been observed in the hearts of anesthetized animals and in isolated hearts. Studies were undertaken in a total of 13 baboons. Eleven were awake, healthy animals sitting in chairs at rest or feeding, some performed mild leg exercise (wheel turning), and others were subjected to whole body heating; two were anesthetized, methodological controls. Microspheres (15 +/- 3 micron diameter, 0.5 X 10(6)/kg body weight) were injected via a catheter into the apex of the left ventricle while arterial blood was sampled at a constant rate for calculating cardiac output. Microspheres with different labels were injected at six intervals of 20 minutes to several hours. On sacrifice, the hearts were sectioned into 204 locatable pieces (left ventricle, 168; right ventricle, 27; and atria, 9). Average resting myocardial flow was 2.1 +/- 0.2 ml/g per min (mean +/- SD, n = 11). Left and right ventricles and atria comprised 70 +/- 2% (n = 13), 20 +/- 2%, and 10 +/- 2% respectively of the total heart mass while receiving 80 +/- 3%, 16 +/- 2%, and 4 +/- 2% of the total myocardial flow. Thus, mean left ventricular flow was 114 +/- 5% of the average for the whole heart, right ventricular flow was 81 +/- 13%, and atrial flow was 41 +/- 13%. Myocardial flow heterogeneity was marked; in left ventricle, regional flows ranged from one-third to two times the mean, the relative dispersion (= standard deviation/mean) of regional flows, corrected for methodological scatter and temporal variation, was 0.33 +/- 0.06 (n = 67) in the whole heart, 0.26 +/- 0.07 in left ventricle, 0.32 +/- 0.11 in right ventricle, and 0.22 +/- 0.19 in the atria. The pattern of regional flows in each heart tended to remain stable with time. In each piece averaged over time, the relative dispersion due to temporal heterogeneity was 0.11 +/- 0.03 (n = 2040) in the whole heart, 0.09 +/- 0.03 in the left ventricle, 0.15 +/- 0.05 in the right ventricle, and 0.23 +/- 0.06 in the atria. The conclusion is that the degree of spatial heterogeneity of local myocardial flows in conscious primates is similar to that of anesthetized animals and isolated hearts, and is much greater than that due to temporal fluctuations.
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