Comparison of catheter thrombogenicity in a modified chandler loop model using goat blood

2018 ◽  
Vol 106 (12) ◽  
pp. 3143-3151
Author(s):  
Aaron L. Olsen ◽  
Michael Long
Keyword(s):  
Loop Model ◽  
Chandler Loop

scholarly journals Bioengineering of Improved Biomaterials Coatings for Extracorporeal Circulation Requires Extended Observation of Blood-Biomaterial Interaction under Flow

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Kris N. J. Stevens ◽  
Yvette B. J. Aldenhoff ◽  
Frederik H. van der Veen ◽  
Jos G. Maessen ◽  
Leo H. Koole
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Thrombus Formation ◽  
Blood Parameters ◽  
Systematic Evaluation ◽  
Loop Model ◽  
Biomaterial Surfaces ◽  
Chandler Loop ◽  
Scanning Electron

Extended use of cardiopulmonary bypass (CPB) systems is often hampered by thrombus formation and infection. Part of these problems relates to imperfect hemocompatibility of the CPB circuitry. The engineering of biomaterial surfaces with genuine long-term hemocompatibility is essentially virgin territory in biomaterials science. For example, most experiments with the well-known Chandler loop model, for evaluation of blood-biomaterial interactions under flow, have been described for a maximum duration of 2 hours only. This study reports a systematic evaluation of two commercial CPB tubings, each with a hemocompatible coating, and one uncoated control. The experiments comprised (i) testing over 5 hours under flow, with human whole blood from 4 different donors; (ii) measurement of essential blood parameters of hemocompatibility; (iii) analysis of the luminal surfaces by scanning electron microscopy and thrombin generation time measurements. The dataset indicated differences in hemocompatibility of the tubings. Furthermore, it appeared that discrimination between biomaterial coatings can be made only after several hours of blood-biomaterial contact. Platelet counting, myeloperoxidase quantification, and scanning electron microscopy proved to be the most useful methods. These findings are believed to be relevant with respect to the bioengineering of extracorporeal devices that should function in contact with blood for extended time.

scholarly journals Blood Compatibility of Widely used Central Venous Catheters; an Experimental Study

2021 ◽  
Author(s):  
Hulda Thorarinsdottir ◽  
Thomas Kander ◽  
Dorota Johansson ◽  
Bo Nilsson ◽  
Bengt Klarin ◽  
...  
Keyword(s):  
Blood Compatibility ◽  
Thrombus Formation ◽  
Venous Catheter ◽  
Host Defence ◽  
Loop Model ◽  
Central Venous ◽  
Cell Counts ◽  
Chandler Loop ◽  
The Impact ◽  
The Complement System

Abstract Background: An inserted central venous catheter (CVC) is considered foreign material by the inert host defence systems and induce inflammation and thrombus formation. The objective of this study was to evaluate blood compatibility of six commonly used CVCs.Methods: Three coated and three uncoated CVC materials were tested in a modified Chandler loop model. Each catheter material circulated in blood from ten different healthy volunteers for 1 hour. Blood cell counts and measurements of the inert host defence systems were performed on blood samples from the loop.Results: All the tested catheters demonstrated impact on blood cells, contact coagulation, the complement system, or inflammatory markers, although the impact varied significantly.Conclusions: Of the catheters we evaluated, the most unfavourable blood compatibility profile was found for the polyurethane CVC coated with chlorohexidine and silver sulfadiazine. The greatest variation in blood compatibility between test runs was noted for the silicone dialysis catheter. Poor blood compatibility should be taken seriously but given the experimental design of the current study the clinical significance remains to be evaluated.

PVC-plasticizer DEHP in medical products: do thin coatings really reduce DEHP leaching into blood?

Perfusion ◽  
2005 ◽  
Vol 20 (6) ◽  
pp. 351-357 ◽  
Author(s):  
Sibylle L Hildenbrand ◽  
Hans-Dieter Lehmann ◽  
Roman Wodarz ◽  
Gerhard Ziemer ◽  
Hans P Wendel
Keyword(s):  
Blood Circulation ◽  
Surface Coatings ◽  
Oxidation Products ◽  
Loop Model ◽  
Thin Coatings ◽  
Plasticized Pvc ◽  
Human Fertility ◽  
Chandler Loop ◽  
Extracorporeal Blood Circulation ◽  
Ethylhexyl Phthalate

The hemocompatibility of artificial surfaces in extracorporeal blood circulation systems can be improved by coatings. According to the literature, heparin coatings should avoid the leaching of the plasticizer di(2-ethylhexyl) phthalate (DEHP) into the blood from components made from plasticized polyvinyl chloride (PVC). DEHP and its metabolites are known to impair the fertility of male rodents; effects on human fertility are assumed. Three different surface coatings with and without heparin were examined in a Chandler Loop model at 37°C using fresh human blood to evaluate their hemocompatibility and barrier property to plasticizer. The levels of toxic oxidation products of DEHP generated in the blood, particularly, were found as high as in the uncoated tubing. The coatings improved the hemocompatibility, but are not safe protection against the hazardous metabolites of DEHP. For pregnant women, neonates and children, we would recommend using the available surface-coated plasticized PVC tubing sets, but free of DEHP.

The Lysis of Artificial Thrombi

1980 ◽  
Vol 43 (01) ◽  
pp. 034-037 ◽  
Author(s):  
Michael J Metcalf
Keyword(s):  
Human Blood ◽  
Final Concentration ◽  
Rabbit Blood ◽  
Factors Influencing ◽  
Dextran 70 ◽  
Chandler Loop ◽  
Loop Technique

SummaryThe susceptibility to lysis of artificial thrombi formed from native rabbit blood in the presence or absence of dextran was determined using the Chandler loop technique. Thrombi of identical weight were formed in the presence of saline or dextran and when spontaneous thrombolysis was allowed to take place, thrombi formed in the presence of dextran 70 were lysed to a greater extent than those formed under control conditions.The possible factors influencing this observation were studied. Increasing concentrations of streptokinase increased the extent of thrombolysis in both control and dextran treated thrombi. Maximal streptokinase induced thrombolysis occurred in the presence of a 2 per cent final concentration of dextran Mw 40,000 and 500,000 and dextran 70 at a final concentration of 1.2 per cent.Increased thrombolysis was not observed when albumin was substituted for dextran.Finally, similar observations were recorded for streptokinase induced thrombolysis using human blood.

Inhibition of Fibrinolytic Activity In-Vivo by Dexamethasone Is Counterbalanced by an Inhibition of Platelet Aggregation

1992 ◽  
Vol 68 (01) ◽  
pp. 069-073 ◽  
Author(s):  
J J J van Giezen ◽  
J W C M Jansen
Keyword(s):  
Platelet Aggregation ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Dose Range ◽  
Coagulation System ◽  
Loop Model ◽  
Prothrombotic State ◽  
Inhibition Of Platelet Aggregation ◽  
Pai 1

SummaryDexamethasone decreases the fibrinolytic activity in cultured medium of several cell types by an induction of PAI-1 synthesis. As a result of this enhanced PAI-1 synthesis a prothrombotic state is expected in patients treated with dexamethasone. However, such a prothrombotic state is not reported as a major adverse effect. We have studied the effects of dexamethasone (dose range: 0.1–3.0 mg/kg) on the fibrinolytic system of rats after a 5 day pretreatment period. It appeared that dexamethasone dose dependently decreased the fibrinolytic activity (a dose of 1 mg/kg showed a reduction of about 40%). This reduced fibrinolytic activity could be functionally translated into an increased thrombus size as measured with a venous thrombosis model: thrombus size was increased by 50% with 1 mg/kg dexamethasone. No effects could be measured on the coagulation system, but it appeared that ex-vivo measured platelet aggregation was dose dependently inhibited by dexamethasone treatment. This effect resulted in-vivo in prolonged obstruction times as measured with a modified aorta-loop model. These results indicate that the expected prothrombotic state due to a diminished fibrinolytic activity caused by dexamethasone is counterbalanced by an inhibition of platelet aggregation.

scholarly journals Continuous Control Set Predictive Current Control for Induction Machine

2021 ◽  
Vol 11 (13) ◽  
pp. 6230
Author(s):  
Toni Varga ◽  
Tin Benšić ◽  
Vedrana Jerković Štil ◽  
Marinko Barukčić
Keyword(s):  
Control Method ◽  
Induction Machine ◽  
Current Control ◽  
Continuous Control ◽  
Loop Model ◽  
Voltage Reference ◽  
Control Loop ◽  
Speed Tracking ◽  
Finite Control ◽  
Control Set

A speed tracking control method for induction machine is shown in this paper. The method consists of outer speed control loop and inner current control loop. Model predictive current control method without the need for calculation of the weighing factors is utilized for the inner control loop, which generates a continuous set of voltage reference values that can be modulated and applied by the inverter to the induction machine. Interesting parallels are drawn between the developed method and state feedback principles that helped with the analysis of the stability and controllability. Simple speed and rotor flux estimator is implemented that helps achieve sensorless control. Simulation is conducted and the method shows great performance for speed tracking in a steady state, and during transients as well. Additionally, compared to the finite control set predictive current control, it shows less harmonic content in the generated torque on the rotor shaft.

scholarly journals Quasiclassical calculations of Landau level spectrum for 20.5-nm-wide H gTe quantum well: “extremum loop” model and effects of cubic symmetry

2021 ◽  
Vol 47 (1) ◽  
pp. 7-13
Author(s):  
S. V. Gudina ◽  
A. S. Bogolubskiy ◽  
V. N. Neverov ◽  
K. V. Turutkin ◽  
N. G. Shelushinina ◽  
...  
Keyword(s):  
Quantum Well ◽  
Landau Level ◽  
Loop Model ◽  
Cubic Symmetry ◽  
Level Spectrum
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