Case Report of Anti-Thrombogenicity

The Toray Filtryzer^™-NF is a new polymethyl methacrylate (PMMA) filter with improved hemocompatibility, as a result of a modified filter surface, but with the same protein adsorption properties as the conventional PMMA membrane [[1]. In recent publications, such as by Oshihara et al. [[2], it is reported that the fibrinogen adsorption and platelet adhesion and thus the influence on the platelet count on the filter membrane were significantly lower with the above-mentioned filter than with conventional PMMA membranes (shown in Fig. 1) [[2, 3]. Furthermore, it could be shown that the number of platelets was less affected by the use of the Toray Filtryzer^™-NF [[1]. This leads to the conclusion that a reduction in anticoagulation may be possible when performing dialysis with the Toray Filtryzer^™-NF. This possibility of reducing anticoagulation could be of greater importance, especially in patients at high risk of bleeding. Here, although there is a possibility of anticoagulation by means of citrate dialysis, a regional anticoagulation is effective only in the extracorporeal procedure. However, there is a risk of metabolic alkalosis or severe hypocalcemia, and double-lumen dialysis access is essential.

Assuming this hypothesis, we dialyzed 5 hemodialysis patients post surgery or after kidney biopsy, who had a contraindication for full anticoagulation, with the Filtryzer^™-NF. The patients were dialyzed 1 to 3 times with the Filtryzer^™-NF −1.6 H until full anticoagulation was possible again.

Dialysis duration per treatment was between 240 and 300 min, dialysate flow was always 500 mL/min, and blood flow was between 200 and 300 mL/min. There was a significant reduction in heparin administration with an initial heparin bolus of 500 IU in 4 patients, without continuous heparin administration in all patients. One patient was dialyzed completely without heparin. According to the previous dialysis protocols, the heparin bolus before the switch was between 1,000 and 2,500 IU and the continuous heparin administration between 750 and 2,000 IU/h with a dialysis time of 4–5 h (shown in Fig. 2). Despite the significantly reduced doses of heparin, no thrombosis of the system occurred during the hemodialysis. There were also no bleeding complications under the minimal dose of heparin, although the patients had a significantly increased risk of bleeding.

It can be said that hemodialysis using the Toray Filtryzer^™-NF is an effective, cheaper, and possibly less complicated alternative to hemodialysis with citrate anticoagulation, whenever full anticoagulation with heparin/low molecular weight heparin is contraindicated. This would be particularly important for patients with an increased risk of bleeding, e.g., postoperatively and the presence of a single-lumen atrial catheter, for whom citrate anticoagulation on dialysis is not possible. It would also be an option for outpatient dialysis centers that do not have the option of citrate anticoagulation to perform dialysis to treat patients at increased risk of bleeding. In a further study, the activation of coagulation and platelets when using the Toray Filtryzer^™-NF will be examined in more detail. Furthermore, it should be investigated to what extent a long-term benefit of the Toray filter, with its significantly better biocompatibility, improves the long-term outcome of chronic dialysis patients. However, a possible improved tolerability with a reduction of the chronic inflammatory reaction is opposed by the currently available higher therapy costs. Further studies are therefore eagerly awaited.

This retrospective review of patient data did not require ethical approval in accordance with local/national guidelines. Written informed consent from participants was not required in accordance with local and national guidelines.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The research received no external funding.

Conceptualization: Simone Cosima Boedecker-Lips and Julia Weinmann-Menke. Investigation: Pascal Klimpke, Stefan Holtz, and Simone Cosima Boedecker-Lips. Supervision: Daniel Kraus and Julia Weinmann-Menke. Writing – original draft: Simone Cosima Boedecker-Lips and Kathrina Batzke. Writing – review and editing: Simone Cosima Boedecker-Lips and Julia Weinmann-Menke.

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.