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1 – 10 of 64Yajing Hu, Botong Li, Xinhui Si, Jing Zhu and Linyu Meng
Atherosclerosis tends to occur in the distinctive carotid sinus, leading to vascular stenosis and then causing death. The purpose of this paper is to investigate the effect of…
Abstract
Purpose
Atherosclerosis tends to occur in the distinctive carotid sinus, leading to vascular stenosis and then causing death. The purpose of this paper is to investigate the effect of sinus sizes, positions and hematocrit on blood flow dynamics and heat transfer by different numerical approaches.
Design/methodology/approach
The fluid flow and heat transfer in the carotid artery with three different sinus sizes, three different sinus locations and four different hematocrits are studied by both computational fluid dynamics (CFD) and fluid-structure interaction (FSI) methods. An ideal geometric model and temperature-dependent non-Newtonian viscosity are adopted, while the wall heat flux concerning convection, radiation and evaporation is used.
Findings
With increasing sinus size, the average velocity and temperature of the blood fluid decrease, and the area of time average wall shear stress (TAWSS)with small values decreases. As the distances between sinuses and bifurcation points increase, the average temperature and the maximum TAWSS decrease. Atherosclerosis is more likely to develop when the sinuses are enlarged, when the sinuses are far from bifurcation points, or when the hematocrit is relatively large or small. The probability of thrombosis forming and developing becomes larger when the sinus becomes larger and the hematocrit is small enough. The movement of the arterial wall obviously reduces the velocity of blood flow, blood temperature and WSS. This study also suggests that the elastic role of arterial walls cannot be ignored.
Originality/value
The hemodynamics of the internal carotid artery sinus in a carotid artery with a bifurcation structure have been investigated thoroughly, on which the impacts of many factors have been considered, including the non-Newtonian behavior of blood and empirical boundary conditions. The results when the FSI is considered and absent are compared.
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Saeed Dinarvand, Mohammadreza Nademi Rostami, Rassoul Dinarvand and Ioan Pop
This paper aims to simulate the steady laminar mixed convection incompressible viscous and electrically conducting hybrid nanofluid (CuO-Cu/blood) flow near the plane…
Abstract
Purpose
This paper aims to simulate the steady laminar mixed convection incompressible viscous and electrically conducting hybrid nanofluid (CuO-Cu/blood) flow near the plane stagnation-point over a horizontal porous stretching sheet along with an external magnetic field and induced magnetic field effects that can be applicable in the biomedical fields like the flow dynamics of the micro-circulatory system and especially in drug delivery.
Design/methodology/approach
The basic partial differential equations (PDEs) are altered to a set of dimensionless ordinary differential equations (ODEs) with the help of suitable similarity variables which are then solved numerically using bvp4c scheme from MATLAB. Inasmuch as validation results have shown a good agreement with previous reports, the present novel mass-based algorithm can be used in this problem with great confidence. Governing parameters are both nanoparticle masses, base fluid mass, empirical shape factor of both nanoparticles, suction/injection parameter, magnetic parameter, reciprocal magnetic Prandtl number, Prandtl number, heat source parameter, mixed convection parameter, permeability parameter and frequency ratio. The effect of these parameters on the flow and heat transfer characteristics of the problem is discussed in detail.
Findings
It is shown that the use of CuO and Cu hybrid nanoparticles can reduce the hemodynamics effect of the capillary relative to pure blood case. Moreover, as the imposed magnetic field enhances, the velocity of the blood decreases. Besides, when the blade shapes for both nanoparticles are taken into account, the local heat transfer rate is maximum that is also compatible with experimental observations.
Originality/value
An innovative mass-based model of CuO-Cu/blood hybrid nanofluid has been applied. The novel attitude to one-phase hybrid nanofluid model corresponds to considering nanoparticles mass as well as base fluid mass to computing the solid equivalent volume fraction, the solid equivalent density and also solid equivalent specific heat.
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Mayumi Uemae, Tomohiro Uemae and Masayoshi Kamijo
The purpose of this paper is to examine the physique difference and psychophysiological response under clothing pressure by a waist belt.
Abstract
Purpose
The purpose of this paper is to examine the physique difference and psychophysiological response under clothing pressure by a waist belt.
Design/methodology/approach
The influences of clothing pressure on physiological and psychological responses were evaluated by the following measurements: functional near-infrared spectroscopy, electrocardiogram and sensory evaluation. The authors investigated the correlation between the anthropometric data and psychophysiological response data.
Findings
There were significant correlations between body fat and physiological responses. It was suggested that differences in body fat affect changes in cerebral hemodynamics and heart rate due to clothing pressure. It is inferred that the participants having lower body fat reacted more sensitively to the compression stimulus, while those having higher body fat were more tolerant of physiological reactions to compression stimulus.
Originality/value
This paper has presented the necessity of clothing comfort evaluation considering individual differences in physique due to body fat.
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Angelo Rosa, Teresa Angela Trunfio, Giuliano Marolla, Antonietta Costantino, Davide Nardella and Olivia McDermott
Cardiovascular diseases are the leading cause of death worldwide. In Italy, acute myocardial infarction (AMI) is a major cause of hospitalization and healthcare costs. AMI is a…
Abstract
Purpose
Cardiovascular diseases are the leading cause of death worldwide. In Italy, acute myocardial infarction (AMI) is a major cause of hospitalization and healthcare costs. AMI is a myocardial necrosis event caused by an unstable ischemic syndrome. The Italian government has defined an indicator called “AMI: 30-day mortality” to assess the quality of the overall care pathway of the heart attacked patient. In order to guarantee high standards, all hospitals had to implement techniques to increase the quality of care pathway. The aim of the paper is to identify the root cause and understand the mortality rate for AMI and redesign the patient management process in order to improve it.
Design/methodology/approach
A Lean Six Sigma (LSS) approach was used in this study to analyze the patient flow in order to reduce 30-days mortality rate from AMI registered by Complex Operative Unit (COU) of Cardiology of an Italian hospital. Value stream mapping (VSM) and Ishikawa diagrams were implemented as tools of analysis.
Findings
Process improvement using LSS methodology made it possible to reduce the overall times from 115 minutes to 75 minutes, with a reduction of 35%. In addition, the corrective actions such as the activation of a post-discharge outpatient clinic and telephone contacts allowed the 30-day mortality rate to be lowered from 16% before the project to 8% after the project. In this way, the limit value set by the Italian government was reached.
Research limitations/implications
The limitation of the study is that it is single-centered and was applied to a facility with a limited number of cases.
Practical implications
The LSS approach has brought significant benefits to the process of managing patients with AMI. Corrective actions such as the activation of an effective shared protocol or telephone interview with checklist can become the gold standard in reducing mortality. The limitation of the study is that it is single-centered and was applied to a facility with a limited number of cases.
Originality/value
LSS, applied for the first time to the management of cardiovascular diseases in Italy, is a methodology which has proved to be strategic for the improvement of healthcare process. The simple solutions implemented could serve as a guide for other hospitals to pursue the national AMI mortality target.
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Ying He, Ryutaro Himeno, Hao Liu, Hideo Yokota and Zhi Gang Sun
The purpose of this paper is to investigate the blood flow and temperature distribution in human extremities.
Abstract
Purpose
The purpose of this paper is to investigate the blood flow and temperature distribution in human extremities.
Design/methodology/approach
The simulation is carried out from three aspects. Firstly, the hemodynamics in the human upper limb is analyzed by one‐dimensional model for pulsalite flow in an elastic tube. Secondly, the blood flow and heat transfer through living tissues are described basing on porous media theory, and the tissue model is coupled with the one‐dimensional blood flow model. With respect to geometric modeling, MR‐image‐based modeling method is employed to construct a realistic model of the human finger.
Findings
It is found that the temperature variation is closely related to the blood flow variation in the fingertip and the blood flow distribution in the tissue is dependent on the locations of large arteries and veins.
Originality/value
Blood flow and temperature distribution in a 3D realistic human finger are firstly obtained by coupling the blood circulation and porous media model.
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Ray O. Prather, Alain Kassab, Marcus William Ni, Eduardo Divo, Ricardo Argueta-Morales and William M. DeCampli
Predictive models implemented in medical procedures can potentially bring great benefit to patients and represent a step forward in targeted treatments based on a patient’s…
Abstract
Purpose
Predictive models implemented in medical procedures can potentially bring great benefit to patients and represent a step forward in targeted treatments based on a patient’s physiological condition. It is the purpose of this paper to outline such a model.
Design/methodology/approach
A multi-scale 0D-3D model based on patient specific geometry combines a 0-dimensional lumped parameter model (LPM) with a 3D computational fluid dynamics (CFD) analysis coupled in time, to obtain physiologically viable flow parameters.
Findings
A comparison of physiological data gathered from literature with flow-field measurements in this model shows the viability of this method in relation to potential predictions of pathological flows repercussions and candidate treatments.
Research limitations/implications
A limitation of the model is the absence of compliance in the walls in the CFD fluid domain; however, compliance of the peripheral vasculature is accounted for by the LPM. Currently, an attempt is in progress to extend this multi-scale model to account for the fluid-structure interaction of the ventricular assist device vasculature and hemodynamics.
Originality/value
This work reports on a predictive pulsatile flow model that can be used to investigate surgical alternatives to reduce strokes in LVADs.
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Shivangi Agarwal and Shalini Juneja
The purpose of this paper is to understand compression garment in the area of medical industry, compression garments were used initially for patients with circulatory problems…
Abstract
Purpose
The purpose of this paper is to understand compression garment in the area of medical industry, compression garments were used initially for patients with circulatory problems. External pressure was created by compression garments on the body surface which prevents blood clots, leg swelling and improves venous hemodynamics.
Design/methodology/approach
Compression rehabilitation is a significant element in the effective management of lower limb problems of people associated with venous, lymphatic, fat disorders like lipoedema.
Findings
Compression garments have been attributed primarily for the increase in blood flow, improvement in recovery, reduction in muscle vibration that increase stability, improvement in thermoregulation, decrease in muscle pain, elimination of blood lactate and creatine kinase after exercise.
Originality/value
Compression garments are extraordinary clothes that contain elastomeric yarns or fibers that are responsible for applying significant mechanical pressure on the required body surface for compressing, stabilizing and supporting underlying tissues.
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Mingyang Liu, Huifen Zhu, Guangjun Gao, Chen Jiang and G.R Liu
The purpose of this paper is to investigate a novel stabilization scheme to handle convection and pressure oscillation in the process of solving incompressible laminar flows by…
Abstract
Purpose
The purpose of this paper is to investigate a novel stabilization scheme to handle convection and pressure oscillation in the process of solving incompressible laminar flows by finite element method (FEM).
Design/methodology/approach
The semi-implicit stabilization scheme, characteristic-based polynomial pressure projection (CBP3) consists of the Characteristic-Galerkin method and polynomial pressure projection. Theoretically, the proposed scheme works for any type of element using equal-order approximation for velocity and pressure. In this work, linear 3-node triangular and 4-node tetrahedral elements are the focus, which are the simplest but most difficult elements for pressure stabilizations.
Findings
The present paper proposes a new scheme, which can stabilize FEM solution for flows of both low and relatively high Reynolds numbers. And the influence of stabilization parameters of the CBP3 scheme has also been investigated.
Research limitations/implications
The research in this work is limited to the laminar incompressible flow.
Practical implications
The verification and validation of the CBP3 scheme are conducted by several 2 D and 3 D numerical examples. The scheme could be used to deal with more practical fluid problems.
Social implications
The application of scheme to study complex hemodynamics of patient-specific abdominal aortic aneurysm is also presented, which demonstrates its potential to solve bio-flows.
Originality/value
The paper simulated 2 D and 3 D numerical examples with superior results compared to existing results and experiments. The novel CBP3 scheme is verified to be very effective in handling convection and pressure oscillation.
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Fariba Hosseinpour, Mahyar Seddighi, Mohammad Amerzadeh and Sima Rafiei
This study aimed to compare mortality rate, length of stay (LOS) and hospitalization costs at different priority levels for a patient admitted to an intensive care unit (ICU) at a…
Abstract
Purpose
This study aimed to compare mortality rate, length of stay (LOS) and hospitalization costs at different priority levels for a patient admitted to an intensive care unit (ICU) at a public tertiary hospital in Qazvin, Iran. This study also aimed to predict influencing factors on patients’ mortality, ICU LOS and hospitalization costs in different admission groups.
Design/methodology/approach
The authors conducted a retrospective cohort study among patients who mainly suffered from internal diseases admitted to an ICU of a public hospital. This study was conducted among 127 patients admitted to ICU from July to September 2019. The authors categorized patients into four groups based on two crucial hemodynamic and respiratory status criteria. The authors used a logistic regression model to predict the likelihood of mortality in ICU admitted patients during hospitalizations for the four prioritization groups. Furthermore, the authors conducted a multivariate analysis using the “enter” method to identify risk factors for LOS.
Findings
Results showed a statistically significant relationship between the priority of being admitted to ICU and hospitalization costs. The authors’ findings revealed that age, LOS and levels of consciousness had a predictability role in determining in-hospital mortality. Besides, age, gender, consciousness level of patients and type of the disease were mentioned as affecting factors of LOS.
Originality/value
This study’s findings emphasize the necessity of categorizing patients according to specific criteria to efficiently use available resources to help health-care authorities reduce the costs and allocate the budget to different health sectors.
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Bin Xiao and Yuwen Zhang
The purpose of this paper is to investigate the geometric effects and pulsatile characteristics during the stenotic flows in tapering arteries.
Abstract
Purpose
The purpose of this paper is to investigate the geometric effects and pulsatile characteristics during the stenotic flows in tapering arteries.
Design/methodology/approach
The low Reynolds number k − ω turbulence model is applied to describe the stenotic flows in the tapering arteries in this paper. The results are divided into two sections. The first section characterizes the geometric effects on the turbulent flow under steady condition. The second section illustrates the key physiological parameters including the pressure drop and wall stress during the periodic cycle of the pulsatile flow in the arteries.
Findings
The tapering and stenoses severity intensify the turbulent flow and stretch the recirculation zones in the turbulent arterial flow. The wall shear stress, pressure drop and velocity vary most intensively at the peak phase during the periodic cycle of the pulsatile turbulent flow.
Originality/value
This paper provides a comprehensive understanding of the spatial‐temporal fluid dynamics involved in turbulent and transitional arterial flow with stenoses. The low Reynolds number k − ω turbulence model method is applied for the analyses of the geometric effects on the arterial flow and fluid feature during the periodic cycle.
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