scholarly journals Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7260
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Measurement Errors ◽  
Present Method ◽  
Test Fluid ◽  
Constant Flow Rate ◽  
Rbc Aggregation ◽  
Sinusoidal Flow ◽  
Analytical Expressions

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

scholarly journals Blood Viscoelasticity Measurement Using Interface Variations in Coflowing Streams under Pulsatile Blood Flows

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 245 ◽  
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Sample ◽  
Flow Rate ◽  
Present Method ◽  
Experimental Results ◽  
Blood Samples ◽  
Constant Flow Rate ◽  
Blood Flows ◽  
The Status ◽  
Sinusoidal Flow ◽  
Linear Differential

Blood flows in microcirculation are determined by the mechanical properties of blood samples, which have been used to screen the status or progress of diseases. To achieve this, it is necessary to measure the viscoelasticity of blood samples under a pulsatile blood condition. In this study, viscoelasticity measurement is demonstrated by quantifying interface variations in coflowing streams. To demonstrate the present method, a T-shaped microfluidic device is designed to have two inlets (a, b), one outlet (a), two guiding channels (blood sample channel, reference fluid channel), and one coflowing channel. Two syringe pumps are employed to infuse a blood sample at a sinusoidal flow rate. The reference fluid is supplied at a constant flow rate. Using a discrete fluidic circuit model, a first-order linear differential equation for the interface is derived by including two approximate factors (F1 = 1.094, F2 = 1.1087). The viscosity and compliance are derived analytically as viscoelasticity. The experimental results showed that compliance is influenced substantially by the period. The hematocrit and diluent contributed to the varying viscosity and compliance. The viscoelasticity varied substantially for red blood cells fixed with higher concentrations of glutaraldehyde solution. The experimental results showed that the present method has the ability to monitor the viscoelasticity of blood samples under a sinusoidal flow-rate pattern.

Abnormal Red Cell Deformability and Aggregation in Sickle Cell Trait

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1001-1001
Author(s):  
Jon Detterich ◽  
Adam M Bush ◽  
Roberta Miyeko Kato ◽  
Rose Wenby ◽  
Thomas D. Coates ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Viscosity ◽  
Whole Blood ◽  
Red Cell ◽  
Cell Deformability ◽  
Autologous Plasma ◽  
Red Cell Deformability ◽  
Whole Blood Viscosity ◽  
Rbc Aggregation ◽  
Rbc Deformability

Abstract Abstract 1001 Introduction: SCT occurs in 8% of African Americans and is not commonly associated with clinical disease. Nonetheless, the United States Armed Forces has reported that SCT conveys a 30-fold risk of sudden cardiac arrest and a 200-fold risk from exertional rhabdomyolysis. In fact, rhabdomyolysis in athletes with SCT has been the principal cause of death in NCAA football players in the last decade, leading to recently mandated SCT testing in all Division-1 players. In SCT, RBC sickle only under extreme conditions and with slow kinetics. Therefore, rhabdomyolysis most likely occurs in SCT when a “perfect storm” of factors converges to critically imbalance oxygen supply and demand in muscles. We hypothesize that in SCT subjects, abnormal RBC rheology, particularly aggregation and deformability, play an important role in abnormal muscle blood flow supply and distribution to exercising muscle. To test this hypothesis, we examined whole blood viscosity, RBC aggregation, and RBC deformability in 11 SCT and 10 control subjects prior to and following maximum handgrip exercise. Methods: Maximum voluntary contraction (MVC) was assessed by handgrip dynamometer in the dominant arm. Baseline blood was collected for CBC, whole blood viscosity, RBC aggregation, and RBC deformability. Patients then maintained 60% MVC exercise until exhaustion. Following 8 minutes of recovery, a venous blood gas and blood for repeat viscosity assessments was collected from the antecubital fossa of the exercising limb. Whole blood viscosity over a shear rate range of 1–1, 000 1/s was determined by an automated tube viscometer, RBC deformability from 0.5–50 Pa via laser ektacytometry (LORCA) and RBC aggregation in both autologous plasma and 3% dextran 70 kDa using an automated cone-place aggregometer (Myrenne). Aggregation measurements included extent at stasis (M), strength of aggregation (GT min) and kinetics (T ½). Results: Baseline CBC and aggregation values are summarized in Table 1. Both static RBC aggregation in plasma and RBC aggregation in dextran (aggregability) were significantly increased in SCT (Table 1). The rate of aggregation formation trended higher in SCT but the strength of aggregation was not different between the two groups. In SCT subjects, red cell deformability was impaired at low shear stress but greater than controls at higher shear stress (Figure 1). Red cell deformability was completely independent of oxygenation status states in both SCT and control subjects. Whole blood viscosity did not different between the two groups whether oxygenated or deoxygenated and prior to or following handgrip exercise. Discussion: Three important hemorheological differences were observed for SCT subjects versus controls: a) RBC deformability was below control at low stress levels yet greater than control at higher stress; b) The extent of RBC aggregation in autologous plasma was about 40% greater; c) The extent of RBC aggregation for washed RBC re-suspended in an aggregating medium (i.e., 3% dextran 70 kDa) was about 30% higher. RBC deformability is a major determinant of in vivo blood flow dynamics, especially in the microcirculation; decreased deformability adversely affects tissue perfusion. RBC aggregation is also an important determinant since it affects both resistance to blood flow and RBC distribution in a vascular bed (e.g., plasma skimming). The finding of greater aggregability (i.e., higher aggregation in the defined dextran medium) indicates that RBC in SCT have an altered membrane surface in which the penetration of this polymer into the glycocalyx is abnormal. The combined effects of these three rheological parameters is likely to impair in vivo blood flow in SCT, perhaps to a degree resulting in pathophysiological changes of the cardiovascular system. Disclosures: Coates: Novartis: Speakers Bureau; Apopharma: Consultancy. Wood:Ferrokin Biosciences: Consultancy; Shire: Consultancy; Apotex: Consultancy, Honoraria; Novartis: Honoraria, Research Funding.

scholarly journals Microfluidic-Based Technique for Measuring RBC Aggregation and Blood Viscosity in a Continuous and Simultaneous Fashion

Micromachines ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 467 ◽  
Author(s):  
Yang Kang
Keyword(s):  
Blood Flow ◽  
Blood Viscosity ◽  
Blood Flow Rate ◽  
Aggregation Index ◽  
Simple Method ◽  
Blood Flows ◽  
Wide Channel ◽  
Rbc Aggregation ◽  
The Right

Hemorheological properties such as viscosity, deformability, and aggregation have been employed to monitor or screen patients with cardiovascular diseases. To effectively evaluate blood circulating within an in vitro closed circuit, it is important to quantify its hemorheological properties consistently and accurately. A simple method for measuring red blood cell (RBC) aggregation and blood viscosity is proposed for analyzing blood flow in a microfluidic device, especially in a continuous and simultaneous fashion. To measure RBC aggregation, blood flows through three channels: the left wide channel, the narrow channel and the right wide channel sequentially. After quantifying the image intensity of RBCs aggregated in the left channel (<IRA>) and the RBCs disaggregated in the right channel (<IRD>), the RBC aggregation index (AIPM) is obtained by dividing <IRA> by <IRD>. Simultaneously, based on a modified parallel flow method, blood viscosity is obtained by detecting the interface between two fluids in the right wide channel. RBC aggregation and blood viscosity were first evaluated under constant and pulsatile blood flows. AIPM varies significantly with respect to blood flow rate (for both its amplitude and period) and the concentration of the dextran solution used. According to our quantitative comparison between the proposed aggregation index (AIPM) and the conventional aggregation index (AICM), it is found that AIPM provides consistent results. Finally, the suggested method is employed to obtain the RBC aggregation and blood viscosity of blood circulating within an in vitro fluidic circuit. The experimental results lead to the conclusion that the proposed method can be successfully used to measure RBC aggregation and blood viscosity, especially in a continuous and simultaneous fashion.

scholarly journals Computational Fluid Dynamic Technique for Assessment of How Changing Character of Blood Flow and Different Value of Hct Influence Blood Hemodynamic in Dissected Aorta

Diagnostics ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1866
Author(s):  
Andrzej Polanczyk ◽  
Aleksandra Piechota-Polanczyk ◽  
Ihor Huk ◽  
Christoph Neumayer ◽  
Julia Balcer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Fluid Dynamic ◽  
Wall Stress ◽  
Acute Type ◽  
Type B ◽  
Type B Dissection

Using computer tomography angiography (CTA) and computational structural analysis, we present a non-invasive method of mass flow rate/velocity and wall stress analysis in type B aortic dissection. Three-dimensional (3D) computer models of the aorta were calculated using pre-operative (baseline) and post-operative CT data from 12 male patients (aged from 51 to 64 years) who were treated for acute type B dissection. A computational fluid dynamics (CFD) technique was used to quantify the displacement forces acting on the aortic wall in the areas of endografts placement. The mass flow rate and wall stress were measured and quantified using the CFD technique. The CFD model indicated the places with a lower value of blood velocity and shear rate, which corelated with higher blood viscosity and a probability of thrombus appearance. Moreover, with the increase in Hct, blood viscosity also increased, while the intensity of blood flow provoked changing viscosity values in these areas. Furthermore, the velocity gradient near the tear surface caused high wall WSS; this could lead to a decreased resistance in the aorta’s wall with further implications to a patient.

scholarly journals Microfluidic-Based Biosensor for Sequential Measurement of Blood Pressure and RBC Aggregation Over Continuously Varying Blood Flows

Micromachines ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 577 ◽  
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Microfluidic Device ◽  
Blood Viscosity ◽  
Blood Samples ◽  
Image Intensity ◽  
Blood Flows ◽  
Pressure Index ◽  
Sequential Measurement ◽  
Rbc Aggregation

Aggregation of red blood cells (RBCs) varies substantially depending on changes of several factors such as hematocrit, membrane deformability, and plasma proteins. Among these factors, hematocrit has a strong influence on the aggregation of RBCs. Thus, while measuring RBCs aggregation, it is necessary to monitor hematocrit or, additionally, the effect of hematocrit (i.e., blood viscosity or pressure). In this study, the sequential measurement method of pressure and RBC aggregation is proposed by quantifying blood flow (i.e., velocity and image intensity) through a microfluidic device, in which an air-compressed syringe (ACS) is used to control the sample injection. The microfluidic device used is composed of two channels (pressure channel (PC), and blood channel (BC)), an inlet, and an outlet. A single ACS (i.e., air suction = 0.4 mL, blood suction = 0.4 mL, and air compression = 0.3 mL) is employed to supply blood into the microfluidic channel. At an initial time (t < 10 s), the pressure index (PI) is evaluated by analyzing the intensity of microscopy images of blood samples collected inside PC. During blood delivery with ACS, shear rates of blood flows vary continuously over time. After a certain amount of time has elapsed (t > 30 s), two RBC aggregation indices (i.e., SEAI: without information on shear rate, and erythrocyte aggregation index (EAI): with information on shear rate) are quantified by analyzing the image intensity and velocity field of blood flow in BC. According to experimental results, PI depends significantly on the characteristics of the blood samples (i.e., hematocrit or base solutions) and can be used effectively as an alternative to blood viscosity. In addition, SEAI and EAI also depend significantly on the degree of RBC aggregation. In conclusion, on the basis of three indices (two RBC aggregation indices and pressure index), the proposed method is capable of measuring RBCs aggregation consistently using a microfluidic device.

Methodology for system-level analysis of a fan–motor design for a vacuum cleaner

2016 ◽  
Vol 231 (20) ◽  
pp. 3840-3854
Author(s):  
Changhwan Park ◽  
Sangook Jun ◽  
Kyunghyun Park ◽  
Sangjong Lee ◽  
Kyoungsik Chang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Rate ◽  
Present Method ◽  
Flow Resistance ◽  
System Level ◽  
Component Level ◽  
Vacuum Cleaner ◽  
Constant Flow Rate ◽  
Level Analysis

In the present study, a methodology for conducting a system-level analysis of a fan–motor assembly in a vacuum cleaner is presented. This system consisted of three components, a fan, motor, and the flow resistance of the motor, or of the vacuum cleaner. The combined characteristics of the fan and the motor were obtained from torque matching at a constant throttling condition, and a pressure drop was implemented under a constant flow rate to account for the flow resistance. By combining these two steps, the performance characteristics of the fan–motor assembly and the vacuum cleaner system could be predicted over the whole range of operation, based on the characteristics of each component. The predicted performance for power, flow rate, pressure, and efficiency using the present method agreed well with the experimental results obtained for an equivalent system, within 2% difference at best efficiency point. Three models of the fan–motor assembly (S1, S2, and S3) were analyzed at the component level, and the decrease in efficiency produced by flow resistance was estimated to be 1% (S1 and S3 models) or 4.7% (S2 model) using the present method. The characteristics of the fan, extracted from those of the fan–motor assembly, were used for validating the computational fluid dynamics. The computational fluid dynamics results of this study predicted higher efficiency due to simplification of the geometry, but an accurate prediction of best efficiency point location was obtained. The proposed method is also applicable for detecting system leakage and identifying system resistance without direct measurement.

ROLE OF SLIP VELOCITY IN BLOOD FLOW THROUGH STENOSED ARTERIES: A NON-NEWTONIAN MODEL

2007 ◽  
Vol 07 (03) ◽  
pp. 337-353 ◽  
Author(s):  
J. C. MISRA ◽  
G. C. SHIT
Keyword(s):  
Blood Flow ◽  
Skin Friction ◽  
Flow Rate ◽  
Slip Velocity ◽  
Flow Resistance ◽  
Volumetric Flow Rate ◽  
Flow Through ◽  
Analytical Expressions ◽  
Insight Into

A mathematical model is developed in this paper for studying blood flow through a stenosed arterial segment by taking into account the slip velocity at the wall of the artery. Consideration of the non-Newtonian character of blood is made, where a constitutive relation of blood is described by the Herschel–Bulkley equation. The effect of slip at the arterial wall in the presence of mild, moderate, and severe stenosis growth at the lumen of an artery is investigated. Analytical expressions for skin friction, flow resistance, and the flow rate are derived by using the model. The derived expressions are computed numerically by considering an illustrative example. The study provides an insight into the effects of slip velocity on the volumetric flow rate of blood, flow resistance, and skin friction.

Development, Validation and Application of HPLC Method for Metformin in Rabbit Plasma

2019 ◽  
Vol 15 (6) ◽  
pp. 574-579
Author(s):  
Muhammad Ubaid ◽  
Mahmood Ahmad ◽  
Farhan Ahmad Khan ◽  
Ghulam Murtaza
Keyword(s):  
Flow Rate ◽  
Present Method ◽  
Mobile Phase ◽  
Hplc Method ◽  
Plasma Samples ◽  
Rabbit Plasma ◽  
Uv Detector ◽  
Reverse Phase ◽  
T Values ◽  
Pharmacokinetic Evaluation

Objective:This study was aimed at conducting a pharmacokinetic evaluation of metformin in rabbit plasma samples using rapid and sensitive HPLC method and UV detection.Methods:Acetonitrile was used for protein precipitation in the preparation of plasma samples. Reverse phase chromatography technique with silica gel column (250 mm × 4.6 mm, 5 μm) at 30°was used for the separation purpose. Methanol and phosphate buffer (pH 3.2) mixture was used as a mobile phase with flow rate 0.8 ml/min. The wavelength of UV detector was adjusted at 240 nm.Results:The calibration curve was linear in a range of 0.1-1 µg/ml with R² = 0.9982. The precision (RSD, %) values were less than 2%, whereas, accuracy of method was higher than 92.37 %. The percentage recovery values ranged between 90.14 % and 94.97 %. LOD and LOQ values were 25 ng/ml and 60 ng/ml, respectively. Cmax and AUC0-t values were found to be 1154.67 ± 243.37 ng/ml and 7281.83 ± 210.84 ng/ml.h, respectively after treating rabbits with a formulation containing 250 mg metformin.Conclusion:Based on the above findings, it can be concluded that present method is simple, precise, rapid, accurate and specific and thus, can be efficiently used for the pharmacokinetic study of metformin.

scholarly journals EFFECT OF TUBE PITCH ON HEAR TRANSFER IN SPRINKLED TUBE BUNDLE

2015 ◽  
Vol 55 (5) ◽  
pp. 329 ◽  
Author(s):  
Petr Kracík ◽  
Jiří Pospíšil
Keyword(s):  
Flow Rate ◽  
Tube Bundle ◽  
Thin Liquid Film ◽  
Thermal Conditions ◽  
Tube Length ◽  
Falling Film ◽  
Constant Flow Rate ◽  
Physical Conditions ◽  
The Individual ◽  
Tube Pitch

Water flowing on a sprinkled tube bundle forms three basic modes: the Droplet mode (the liquid drips from one tube to another), the Jet mode (with an increasing flow rate, the droplets merge into a column) and the Membrane (Sheet) mode (with a further increase in the flow rate of the falling film liquid, the columns merge and create sheets between the tubes. With a sufficient flow rate, the sheets merge at this stage, and the tube bundle is completely covered by a thin liquid film). There are several factors influencing both the individual modes and the heat transfer. Beside the above-mentioned falling film liquid flow rate, these are for instance the tube diameters, the tube pitches in the tube bundle, or the physical conditions of the falling film liquid. This paper presents a summary of data measured at atmospheric pressure, with a tube bundle consisting of copper tubes of 12 millimetres in diameter, and with a studied tube length of one meter. The tubes are situated horizontally one above another at a pitch of 15 to 30 mm, and there is a distribution tube placed above them with water flowing through apertures of 1.0mm in diameter at a 9.2mm span. Two thermal conditions have been tested with all pitches: 15 °C to 40 °C and 15 °C to 45 °C. The temperature of the falling film liquid, which was heated during the flow through the exchanger, was 15 °C at the distribution tube input. The temperature of the heating liquid at the exchanger input, which had a constant flow rate of approx. 7.2. litres per minute, was 40 °C, or alternatively 45 °C.

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