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 µm, 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.
There seems to be a relative consensus on the need for adequate pre-hydration to avoid CI-AKI, but recommendations to define at-risk populations for whom these measures should be applied and how they should be implemented differ substantially. Based on accumulating evidence, more recent guidelines do not recommend iso-osmolar over low-osmolar contrast media, whereas all recommend avoiding hypertonic agents.
Background Different strategies can be used to counteract coagulation of extracorporeal systems. Systemic anticoagulation is most widely used in routine clinical practice, but can be contraindicated in specific settings. The Solacea™ dialyser, containing the asymmetric triacetate membrane, claims improved biocompatibility, which should result in decreased tendency for coagulation. We quantified the performance of the Solacea™ versus the FX800CORDIAX dialyser regarding resistance to fibre blocking as assessed by micro-computed tomography (CT). Methods This cross-over study with four arms randomized consecutively 10 maintenance haemodialysis patients to a 4-h post-dilution haemodiafiltration session at midweek, using either Solacea™ 19 H or FX800CORDIAX, with either regular or half dose of anticoagulation (EC2017/1459-NCT03820401). Dialyser fibre blocking was visualized in the dialyser outlet potting using a 3D CT scanning technique on micrometre resolution. Extraction ratios of middle molecules [myoglobin, lambda and kappa free light chains (FLCs)] were determined. Results The relative number of open fibres post-dialysis was lower in FX800CORDIAX versus Solacea™ dialyser, and this was irrespective of the anticoagulation dose used or the threshold for counting open fibres. Extraction ratios of FLCs were not different at regular anticoagulation between Solacea™ and FX800CORDIAX (21% ± 4% for kappa and 32% ± 8% for lambda with Solacea™ versus 23% ± 7% and 38% ± 6% for FX800CORDIAX), but were superior with the Solacea™ (34% ± 12% versus 22% ± 8% with FX800CORDIAX; P = 0.02) for myoglobin in case of halving anticoagulation dose. No clinically relevant albumin loss was detected. Conclusions The Solacea™ dialyser seems to be promising for use in conditions where systemic anticoagulation is contraindicated, as even under conditions of low systemic anticoagulation, virtually no signs of fibre blocking could be observed using the sensitive micro-CT scanning technique. This finding is in line with its presumed good performance in terms of biocompatibility.
Introduction : We present the results of the COVID-19 rule-out protocol at Ghent University Hospital, a step-wise testing approach which included repeat NFS SARS-CoV-2 rRT-PCR, respiratory multiplex RT-PCR, low-dose chest CT and bronchoscopy with BAL to confirm or rule-out SARS-CoV-2 infection in patients admitted with symptoms suggestive of COVID-19. Results : Between 19 March 2020 and 30 April 2020, 455 non-critically ill patients with symptoms suspect for COVID-19 were admitted. The initial NFS for SARS-CoV-2 rRT-PCR yielded 66.9%, the second NFS 25.4% and bronchoscopy with BAL 5.9% of total COVID-19 diagnoses. In the BAL fluid, other respiratory pathogens were detected in 65% (13/20) of the COVID-19 negative patients and only in 1/7 COVID-19 positive patients. Retrospective antibody testing at the time around BAL sampling showed a positive IgA or IgG in 42.9 % of the COVID-19 positive and 10.5% of the COVID-19 negative group. Follow-up serology showed 100% COVID-19 positivity in the COVID-19 positive group and 100% IgG negativity in the COVID-19 negative group. Conclusion : In our experience, bronchoscopy with BAL can have an added value to rule-in or rule-out COVID-19 in patients with clinical and radiographical high-likelihood of COVID-19 and repeated negative NFS testing. Furthermore, culture and respiratory multiplex PCR on BAL fluid can aid to identify alternative microbial etiological agents in this group. Retrospective analysis of antibody development in this selected group of patients suggests that the implementation of serological assays in the routine testing protocol will decrease the need for invasive procedures like bronchoscopy.
In patients with enhanced risk for bleeding, heparin‐free hemodialysis (HD) with conventional dialyzers is routinely used. To explore the potential benefit of using heparin‐coated dialyzers, we used a reference CT‐scanning technique and registered different clotting parameters to quantify coagulation with heparin‐coated versus non‐coated dialyzers. Six HD patients with thrombocytopenia were dialyzed 240 min in a randomized crossover study with Evodial 1.3 or FX600 Cordiax, each without anticoagulation. Blood samples were taken from the vascular access predialysis, and from the dialyzer inlet and outlet at 5 and 240 min after dialysis start. Predialysis blood samples were analyzed for hemoglobin, hematocrit, thrombocytes, fibrinogen, and activated partial thromboplastin time. On dialyzer inlet and outlet blood samples, a viscoelastic measurement of blood coagulation was performed using a Sonoclot analyzer. After dialysis, dialyzers were visually scored, subsequently dried for 24 h, weighed, and scanned with micro‐CT at a resolution of 25 µm. After image reconstruction, the open, non‐coagulated fibers were counted in a representative cross‐section at the dialyzer outlet. No sessions were terminated prematurely for circuit clotting. Heparin‐coated dialyzers had more patent fibers on micro‐CT versus non‐coated dialyzers and also had a better score of subjective visual assessment of fiber clotting. There was no difference in subjective assessment of clotting at the venous drip chamber. With both dialyzers, all ACT values remained in the normal range, and were lower at the dialyzer outlet versus inlet. In conclusion, dialysis with a heparin‐coated versus non heparin‐coated membrane results in substantially less coagulated fibers during 4 h hemodialysis without systemic anticoagulation. Eventual leaching of heparin, immobilized on the fiber membrane, does not result in measurable systemic anticoagulation.
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