344 research outputs found

    Where and when to inject low molecular weight heparin in hemodiafiltration? : a cross over randomised trial

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    Background and Objective : Low molecular weight heparins (LMWHs) are small enough to pass large pore dialysis membranes. Removal of LMWH if injected before the start of the session is possible during high-flux dialysis and hemodiafiltration. The aim of this study was to determine the optimal mode (place and time) of tinzaparin administration during postdilution hemodiafiltration. Study Design, Setting, Patients : In 13 chronic hemodiafiltration patients, 3 approaches of injection were compared in a randomised cross over trial: i) before the start of the session at the inlet blood line filled with rinsing solution (IN0), ii) 5 min after the start at the inlet line filled with blood (IN5) and iii) before the start of the session at the outlet blood line (OUT0). Anti-Xa activity, thrombin generation, visual clotting score and reduction ratios of urea and beta2microglobulin were measured. Results : Anti-Xa activity was lower with IN0 compared with IN5 and OUT0, and also more thrombin generation was observed with IN0. No differences were observed in visual clotting scores and no clinically relevant differences were observed in solute reduction ratio. An anti-Xa of 0.3 IU/mL was discriminative for thrombin generation. Anti-Xa levels below 0.3 IU/mL at the end of the session were associated with worse clotting scores and lower reduction ratio of urea and beta2microglobulin. Conclusions : Injection of tinzaparin at the inlet line before the start of postdilution hemodiafiltration is associated with loss of anticoagulant activity and can therefore not be recommended. Additionally, we found that an anti-Xa above 0.3 IU/mL at the end of the session is associated with less clotting and higher dialysis adequacy

    Modeling the arterial input function for blood pool agents in DCE-MRI

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    Swirlgraft versus conventional straight graft as vascular access: a full CFD-analysis

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    Two 3D models of an arterio-venous graft, a connection between an artery and a vein as vascular access for hemodialysis, were studied. One model of a conventional straight loop graft, the other of a graft with helical configuration (e.g. SwirlGraft (Veryan Medical, London, UK)). The statement that the helical design reduces Intimal Hyperplasia (IH) formation was studied by evaluating low wall shear stress and high oscillatory shear stress zones next to the helicity flow index. The IH-inducing zones were reduced but were not eliminated and the helicity of the flow was increased. The statement that the SwirlGraft avoids stenosis should however be considered with care in clinical practice

    Low flow extracorporeal CO2 removal in ARDS patients : a prospective short-term crossover pilot study

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    Background: Lung protective mechanical ventilation (MV) is the corner stone of therapy for ARDS. However, its use may be limited by respiratory acidosis. This study explored feasibility of, effectiveness and safety of low flow extracorporeal CO2 removal (ECCO2R). Methods: This was a prospective pilot study, using the Abylcap (R) (Bellco) ECCO2R, with crossover off-on-off design (2-h blocks) under stable MV settings, and follow up till end of ECCO2R. Primary endpoint for effectiveness was a 20% reduction of PaCO2 after the first 2-h. Adverse events (AE) were recorded prospectively. We included 10 ARDS patients on MV, with PaO2/FiO(2) = 5 cmH(2)O, FiO(2) titrated to SaO(2) 88-95%, plateau pressure >= 28 cmH(2)O, and respiratory acidosis (pH < 7.25). Results: After 2-h of ECCO2R, 6 patients had a >= 20% decrease in PaCO2 (60%); PaCO2 decreased 28.4% (from 58.4 to 48. 7 mmHg, p = 0.005), and pH increased (1.59%, p = 0.005). ECCO2R was hemodynamically well tolerated. During the whole period of ECCO2R, 6 patients had an AE (60%); bleeding occurred in 5 patients (50%) and circuit thrombosis in 3 patients (30%), these were judged not to be life threatening. Conclusions: In ARDS patients, low flow ECCO2R significantly reduced PaCO2 after 2 h, Follow up during the entire ECCO2R period revealed a high incidence of bleeding and circuit thrombosis

    Micro-computed tomography for the quantification of blocked fibers in hemodialyzers

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    A novel technique based on micro-CT scanning is developed to quantify coagulation in fibers of hemodialyzers. This objectivation is needed to allow accurate assessment of thrombogenicity of dialyzers used during hemodialysis, for example when comparing different strategies to avoid coagulation and/or fiber blocking. The protocol allowed imaging at a resolution of 25 mu m, making it possible to count the open, non-coagulated fibers in a non-invasive way. In 3 fresh, non-used FX600 hemodialyzers, patent fiber counts were extremely consistent (10748 +/- 2). To illustrate the potential of this technique, different dialysis parameters currently used as surrogates for fiber blocking were evaluated during 20 hemodialysis sessions. After dialysis, the FX600 dialyzers were visually scored for clotting, dried and subsequently weighed and scanned. The number of patent fibers (10003 [ 8763,10330], range 534-10692) did not correlate with any of the recorded surrogate parameters. Micro-CT scanning is a feasible, objective, non-invasive, accurate and reproducible tool for quantification of the degree of fiber blocking in a hemodialyzer after use, making it a potential gold standard for use in studies on fiber blocking during renal replacement therapies

    The screening score of Mini Nutritional Assessment (MNA) is a useful routine screening tool for malnutrition risk in patients on maintenance dialysis

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    PURPOSE: Malnutrition is prevalent in patients on dialysis and is associated with morbidity and mortality. Nutritional status can be assessed by a variety of biochemical and physical parameters or nutritional assessment scores. Most of these methods are expensive or cumbersome to use and are not suitable for routine repetitive follow-up in dialysis patients. The Mini Nutritional Assessment (MNA) has a short form screening set (MNA-SF), which would be suitable as a screening tool, but has not been validated yet in dialysis patients. We aimed to assess whether the MNA is an appropriate tool for identifying nutritional problems in dialysis patients. METHOD: MNA, routine biochemistry, physical parameters, comorbidities were assessed in cross-sectional multicentric cohorts of hemodialysis and peritoneal dialysis patients with a longitudinal follow up of 2 years for mortality. RESULTS: In this cohort of 216 patients, mortality was 27.3% at a follow up of 750±350 days. The mean MNA-SF score was 9.9±1.8, with 30.1%, 59.3% and 10.6% of patients categorized as having normal nutritional status, at risk for malnutrition and malnourished, respectively. The screening score was associated with mortality (HR 0.86, 95% CI 0.75-0.98 per point). With normal nutrition as reference, adjusted mortality was 2.50 (95% CI 1.16-5.37) and 3.89 (95% CI 1.48-10.13) for patients at risk for malnutrition and with malnutrition, respectively. After recalibrating the MNA full score for the specificity of some of its domains for dialysis patients, the MNA-SF had a good sensitivity and specificity for not being well nourished (0.95 and 0.63 respectively) in the full score, and a high negative predictive value (0.91). CONCLUSION: The MNA-SF is independently associated with 2 year mortality in dialysis patients. It has a high negative predictive value for excluding being at risk or having malnutrition in the full score. Therefore, it can be advocated as a screening tool for nutritional status in dialysis patients

    Detection of hemodialysis vascular access stenosis by intravascular pulse pressure analysis: an in-vitro study

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    Purpose: Vascular access (VA) thrombosis, due to significant stenoses (>50%), is the main cause of VA failure in hemodialysis patients. Flow measurements enable detection of stenoses >70% and not >50%. Flow measurements regularly fail to prevent thrombosis. The purpose of the study was to test a new technique for detection of significant stenoses (>50%). Methods and Materials: A pulsatile in-vitro model of a radio-cephalic arteriovenous fistula with silicone tubes, a reservoir and a pump was created. A 15G needle was introduced at 5 and 10 cm downstream of the anastomosis. Intravascular pulse pressure amplitude (systolic minus diastolic pressure = PP) was measured in the arterial inflow and at the arterial needle. PP ratios were calculated (PP-needle/PP-inflow*100%). A 50% stenosis was introduced in the arterial inflow, between needles and in the venous outflow, successively. Measurements were repeated at different heart rates (60-90 beats/min) and different flows (500-1.300 ml/min). ANOVA analysis and post-hoc tests were used to evaluate the relation between the PP ratio and the presence of a stenosis in different conditions. Results: PP ratios were 20.26 ± 4.55% (no stenosis), 7.69 ± 2.08% (arterial inflow stenosis), 36.20 ± 2.12% (between needles stenosis) and 32.38 ± 2.17% (venous outflow stenosis). Stenoses can be located upstream and downstream of the needle (P < 0.001). Between needles stenoses and venous outflow stenoses could also be distinguished (P < 0.001). Conclusion: Pulse pressure analysis enables detection of 50% stenosis independent of heart rate and flow volume. It also enables stenoses localization, in contrast to flow measurements. This promising new method needs clinical validation
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