scholarly journals Flushing and Locking of Venous Catheters: Available Evidence and Evidence Deficit

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Godelieve Alice Goossens
Keyword(s):  
Fluid Dynamics ◽  
Sodium Chloride ◽  
Clinical Sign ◽  
Chelating Agents ◽  
Antithrombotic Effect ◽  
Catheter Occlusion ◽  
Catheter Malfunction ◽  
Long Time ◽  
Catheter Lock ◽  
Intravenous Catheters

Flushing and locking of intravenous catheters are thought to be essential in the prevention of occlusion. The clinical sign of an occlusion is catheter malfunction and flushing is strongly recommended to ensure a well-functioning catheter. Therefore fluid dynamics, flushing techniques, and sufficient flushing volumes are important matters in adequate flushing in all catheter types. If a catheter is not in use, it is locked. For years, it has been thought that the catheter has to be filled with an anticoagulant to prevent catheter occlusion. Heparin has played a key role in locking venous catheters. However, the high number of risks associated with heparin forces us to look for alternatives. A long time ago, 0.9% sodium chloride was already introduced as locking solution in peripheral cannulas. More recently, a 0.9% sodium chloride lock has also been investigated in other types of catheters. Thrombolytic agents have also been studied as a locking solution because their antithrombotic effect was suggested as superior to heparin. Other catheter lock solutions focus on the anti-infective properties of the locks such as antibiotics and chelating agents. Still, the most effective locking solution will depend on the catheter type and the patient’s condition.

scholarly journals TIME-DEPENDENT RESCALINGS AND LYAPUNOV FUNCTIONALS FOR THE VLASOV–POISSON AND EULER–POISSON SYSTEMS, AND FOR RELATED MODELS OF KINETIC EQUATIONS, FLUID DYNAMICS AND QUANTUM PHYSICS

2001 ◽  
Vol 11 (03) ◽  
pp. 407-432 ◽  
Author(s):  
J. DOLBEAULT ◽  
G. REIN
Keyword(s):  
Fluid Dynamics ◽  
Quantum Physics ◽  
Kinetic Equations ◽  
Euler System ◽  
Lyapunov Functionals ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Poisson System ◽  
Dispersion Effects ◽  
Long Time

We investigate rescaling transformations for the Vlasov–Poisson and Euler–Poisson systems and derive in the plasma physics case Lyapunov functionals which can be used to analyze dispersion effects. The method is also used for studying the long time behavior of the solutions and can be applied to other models in kinetic theory (two-dimensional symmetric Vlasov–Poisson system with an external magnetic field), in fluid dynamics (Euler system for gases) and in quantum physics (Schrödinger–Poisson system, nonlinear Schrödinger equation).

scholarly journals A possible quantum fluid-dynamical approach to vortex motion in nuclei

2017 ◽  
Vol 26 (04) ◽  
pp. 1750020
Author(s):  
Seiya Nishiyama ◽  
João da Providência
Keyword(s):  
Fluid Dynamics ◽  
Rotational Motion ◽  
Collective Motion ◽  
Rotational Velocity ◽  
Fluid Motion ◽  
Vortex Motion ◽  
Representation Formula ◽  
Essential Point ◽  
Quantum Fluid ◽  
Long Time

The essential point of Bohr–Mottelson theory is to assume an irrotational flow. As was already suggested by Marumori and Watanabe, the internal rotational motion, i.e., the vortex motion, however, may exist also in nuclei. So, we must take the vortex motion into consideration. In classical fluid dynamics, there are various ways to treat the internal rotational velocity. The Clebsch representation, [Formula: see text] is very powerful and allows for the derivation of the equations of fluid motion from a Lagrangian. Making the best use of this advantage, Kronig–Thellung, Ziman and Ito obtained a Hamiltonian including the internal rotational motion, the vortex motion, through the term [Formula: see text]. Going to quantum fluid dynamics, Ziman and Thellung finally derived the roton spectrum of liquid Helium II postulated by Landau. Is it possible to follow a similar procedure in the description of the collective vortex motion in nuclei? The description of such a collective motion has not been considered in the context of the Bohr–Mottelson model (BMM) for a long time. In this paper, we will investigate the possibility of describing the vortex motion in nuclei on the basis of the theories of Ziman and Ito together with Marumori’s work.

scholarly journals Improving the Quality of Sardine Fish Oil by Degumming Using Sodium Cholride Solution

2017 ◽  
Vol 20 (1) ◽  
pp. 199
Author(s):  
Dian Prima Christiani Hulu ◽  
Sugeng Heri Suseno ◽  
Uju Uju
Keyword(s):  
Fatty Acid ◽  
Sodium Chloride ◽  
Fish Oil ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Total Oxidation ◽  
Long Time ◽  
Degumming Process ◽  
Alkali Neutralization

The quality of fish oil is determined by some parameters such as primary and secondary grade oxidation, fatty acid profile and physical qualities which include viscosity, density, color and clarity. Sardine fish oil by-products of fish meal processing can be a source of polyunsaturated fatty acids (PUFAs), particularly<br />eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Degumming is one of steps that can be carried out to improve the quality of sardine fish oil. The processing will help to reduce oxidation and eliminate the impurity of the oil that influence the quality of fish oil. The purpose of this study was to determine the effect of sodium chloride solution degumming on the quality of sardine fish oil to fulfill International Fish Oil Standard (IFOS). Fish oil purification was done by degumming of 5% H2O,  followed<br />by sodium chloride solution with ratio of fish oil and sodium chloride solution were 1:1; 1:3, and 1:5. The sodium chloride solution concentrations of 5% and 8% for 20, 30 and 40 minutes. The next steps after degumming process were followed by alkali neutralization and bleached by absorbent. The best treatment<br />was at  concentration of 5%  sodium chloride solution, ratio fish oil with sodium chloride solution 1:1 on a long time degumming processed 20 minutes. The best quality of fish oil, according to IFOS, was resulted from the treatments combination of free fatty acid 0.21±0.00%, peroxide value 0.43±0.06 mEq/kg, anisidin <br />value 2.22±0.04 mEq/kg and total oxidation 3.11±0.14  mEq/kg.<br /><br />

A computational model of the collective fluid dynamics of motile micro-organisms

2002 ◽  
Vol 455 ◽  
pp. 149-174 ◽  
Author(s):  
MATTHEW M. HOPKINS ◽  
LISA J. FAUCI
Keyword(s):  
Fluid Dynamics ◽  
Stokes Equations ◽  
Temporal Dynamics ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Point Sources ◽  
Physical Factors ◽  
Modelling Framework ◽  
Long Time ◽  
Micro Organisms

A mathematical model and numerical method for studying the collective dynamics of geotactic, gyrotactic and chemotactic micro-organisms immersed in a viscous fluid is presented. The Navier–Stokes equations of fluid dynamics are solved in the presence of a discrete collection of micro-organisms. These microbes act as point sources of gravitational force in the fluid equations, and thus affect the fluid flow. Physical factors, e.g. vorticity and gravity, as well as sensory factors affect swimming speed and direction. In the case of chemotactic microbes, the swimming orientation is a function of a molecular field. In the model considered here, the molecules are a nutrient whose consumption results in an upward gradient of concentration that drives its downward diffusion. The resultant upward chemotactically induced accumulation of cells results in (Rayleigh–Taylor) instability and eventually in steady or chaotic convection that transports molecules and affects the translocation of organisms. Computational results that examine the long-time behaviour of the full nonlinear system are presented.The actual dynamical system consisting of fluid and suspended swimming organisms is obviously three-dimensional, as are the basic modelling equations. While the computations presented in this paper are two-dimensional, they provide results that match remarkably well the spatial patterns and long-time temporal dynamics of actual experiments; various physically applicable assumptions yield steady states, chaotic states, and bottom-standing plumes. The simplified representation of microbes as point particles allows the variation of input parameters and modelling details, while performing calculations with very large numbers of particles (≈104–105), enough so that realistic cell concentrations and macroscopic fluid effects can be modelled with one particle representing one microbe, rather than some collection of microbes. It is demonstrated that this modelling framework can be used to test hypotheses concerning the coupled effects of microbial behaviour, fluid dynamics and molecular mixing. Thus, not only are insights provided into the differing dynamics concerning purely geotactic and gyrotactic microbes, the dynamics of competing strategies for chemotaxis, but it is demonstrated that relatively economical explorations in two dimensions can deliver striking insights and distinguish among hypotheses.

scholarly journals Substitution of Citrate with Tissue Plasminogen Activator (rt-PA) for Catheter Lock Does Not Improve Patency of Tunneled Hemodialysis Catheters in a Randomized Trial

2020 ◽  
Author(s):  
Pavlina Richtrova ◽  
Jan Mares ◽  
Lukas Kielberger ◽  
Jan Klaboch ◽  
Jaromir Eiselt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Statistical Significance ◽  
Trisodium Citrate ◽  
Time Interval ◽  
Hemodialysis Catheter ◽  
Post Hoc Analysis ◽  
Catheter Malfunction ◽  
Catheter Lock ◽  
Post Hoc ◽  
Previous Session

Abstract Background: The study aim was to establish if substitution of citrate with rt-PA for catheter lock once weekly can reduce the incidence of catheter-related blood stream infections (CR-BSI) or improve patency of tunneled hemodialysis catheters.Methods: All incident patients undergoing insertion of a tunneled hemodialysis catheter were screened and included except those suffering infection or using oral anticoagulation. Study participants were randomized into two arms according to the solution applied as catheter lock: receiving either trisodium citrate (Citra-LockTM 4%) only or rt-PA (Actilyse® 1mg/ml) on the middle session each week with citrate used on the first and third sessions. The incidence of CR-BSI (confirmed by positive blood culture), catheter non-function (complete obstruction), and malfunction (blood flow <250ml/min) was recorded. Statistical significance was tested with ANOVA, post hoc analysis was performed by means of multiple linear regression.Results: Totally, 18 patients were included and followed during 655 hemodialysis sessions. No episode of CR-BSI was detected while 6 catheter non-functions (0.9% sessions) and 101 malfunctions (15.4% sessions) were recorded. The incidence of both events was equal between the study arms: 4 non-functions and 55 malfunctions in the rt-PA arm and 2 non-functions and 46 malfunctions in the citrate arm (p=0.47 and p=0.24, respectively). Additionally, the mean blood flow achieved did not differ significantly between the arms: 326±1,8 and 326±1,9 ml/min (p=0.95) in rt-PA and citrate arms, respectively. Post hoc analysis identified time elapsed since previous session (β=0.12, p=0.005) and malfunction on previous session (β=0.25, p<0.001) as significant factors affecting the occurrence of malfunction. By contrast, the study arm, rt-PA application on previous session, and catheter vintage did not enter the model.Conclusion: Substitution of citrate with rt-PA for catheter lock does not reduce the incidence of catheter malfunction neither does it affect the blood flow achieved during hemodialysis. Catheter patency is related rather to the time interval between sessions and to previous malfunction (thus probably reflecting undefined individual factors). The incidence of CR-BSI within pre-selected hemodialysis population is sporadic (less than 1 per 4.3 patient years in our sample).Trial registration: The study was registered on the ACTRN 12612000152820

CFD Analysis of Reversed Installation on Flow Measurements by a Plate Orifice

2019 ◽  
Author(s):  
Dezhi Zheng ◽  
Haibo Ma ◽  
Armin K. Silaen ◽  
Chenn Q. Zhou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Orifice Plate ◽  
Cfd Analysis ◽  
Cfd Model ◽  
Flow Measurements ◽  
Significant Difference ◽  
Long Time ◽  
Computational Fluid Dynamics Cfd

Abstract The accidental reversal installation of an orifice plate could occur during maintenance operations and a long time may have elapsed before being noticed. The reversal installation can result in a significant mismeasurement of flow in a pipe. In the paper, a computational fluid dynamics (CFD) model has been developed to simulate the pressure and velocity distribution in a pipe with the correct and the reversed installation of an orifice plate. The results shown that there is a significant difference between the correct and reversed installation in terms of pressure. Using the CFD pressure drop results for flows in both installations, an estimate correlation between those installations was found. This result provides the method to solve the issue about the accidental reversal of an orifice plate using a correction factor.

scholarly journals Impact of Different Catheter Lock Strategies on Bacterial Colonization of Permanent Central Venous Hemodialysis Catheters

2013 ◽  
Vol 34 (12) ◽  
pp. 1314-1317 ◽  
Author(s):  
Stefan Erb ◽  
Andreas F. Widmer ◽  
Sarah Tschudin-Sutter ◽  
Ursula Neff ◽  
Manuela Fischer ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Confidence Interval ◽  
Odds Ratio ◽  
Bacterial Colonization ◽  
Hemodialysis Patients ◽  
Central Venous Catheters ◽  
Catheter Colonization ◽  
Central Venous ◽  
Lock Solution ◽  
Catheter Lock

Thirty-nine hemodialysis patients with permanent central venous catheters were analyzed for bacterial catheter colonization comparing different catheter-lock strategies. The closed needleless Tego connector with sodium chloride lock solution was significantly more frequently colonized with bacteria than the standard catheter caps with antimicrobially active citrate lock solution (odds ratio, 0.22 [95% confidence interval, 0.07–0.71]; P = .011).

scholarly journals Multiplicative noise and the diffusion of conserved densities

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Jingyi Chao ◽  
Thomas Schäfer
Keyword(s):  
Fluid Dynamics ◽  
Multiplicative Noise ◽  
Transport Coefficients ◽  
Momentum Density ◽  
Density Model ◽  
Long Time Tails ◽  
Tensor Correlation ◽  
Long Time ◽  
Conserved Density ◽  
Stochastic Fluid

Abstract Stochastic fluid dynamics governs the long time tails of hydrodynamic correlation functions, and the critical slowing down of relaxation phenomena in the vicinity of a critical point in the phase diagram. In this work we study the role of multiplicative noise in stochastic fluid dynamics. Multiplicative noise arises from the dependence of transport coefficients, such as the diffusion constants for charge and momentum, on fluctuating hydrodynamic variables. We study long time tails and relaxation in the diffusion of a conserved density (model B), and a conserved density coupled to the transverse momentum density (model H). Careful attention is paid to fluctuation-dissipation relations. We observe that multiplicative noise contributes at the same order as non-linear interactions in model B, but is a higher order correction to the relaxation of a scalar density and the tail of the stress tensor correlation function in model H.

scholarly journals Orthodontic Elastic Embedded in Gingiva for 7 Years

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Shruti Tandon ◽  
Abdul Ahad ◽  
Arundeep Kaur ◽  
Farrukh Faraz ◽  
Zainab Chaudhary
Keyword(s):  
Bone Loss ◽  
Inflammatory Response ◽  
Clinical Sign ◽  
Local Anaesthesia ◽  
Orthodontic Treatment ◽  
Dental Materials ◽  
Elastic Band ◽  
Crestal Bone Loss ◽  
Healthy Female ◽  
Long Time

Dental materials especially orthodontic elastics often get embedded in gingival tissues due to iatrogenic factors. If retained for a long time, inflammatory response starts as asymptomatic crestal bone loss and may progress to severe periodontal abscess. Unsupported orthodontic elastics used for diastema closure may result in exfoliation of teeth, while elastic separators may get embedded in interdental gingiva if banding is performed without removing it. These cases of negligence are detrimental for survival of affected teeth. This paper highlights a case of orthodontic elastic embedded in interproximal gingiva of a 23-year-old healthy female for 7 years after completion of fixed orthodontic treatment. Surprisingly, there was no clinical sign of inflammation around elastic band and it was removed easily without any local anaesthesia. However, mild crestal bone loss was observed on periapical radiograph. The gingiva healed completely after sub gingival debridement.

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