Retention of cytokine-inducing substances inside high-flux dialyzers

Damage-Associated Molecular Patterns as Mediators of Thrombus Formation on Dialyzer Membrane in Critically Ill Patients

This prospective study investigated the relationship between inflammation, damage-associated molecular patterns (DAMPs), and thrombus formation on dialyzer membranes in critically ill patients undergoing renal replacement therapy (RRT) from July 2020 to August 2022, identifying mechanisms and interventions to prevent clotting. The patients were divided into two groups: inflammatory (n = 56, serum C-reactive protein >10 mg/dl) and noninflammatory control (n = 45, serum C-reactive protein <5 mg/dl). Cell-free deoxyribonucleic acid (DNA) levels, high mobility group box 1 protein (HMGB1), histone H3, and myeloperoxidase (MPO) in the lumen of the hollow fiber membrane of the dialyzer were quantified. Immunostaining assessed leukocytes, fibrin fibers, and platelet thrombi on the luminal surface of the hollow fiber membrane. The inflammatory group, compared to controls, exhibited elevated cell-free DNA, HMGB1, and MPO levels, although histone H3 remained unchanged. Damage-associated molecular patterns increased with disseminated intravascular coagulation (DIC) severity. Immunostaining in the inflammatory group revealed leukocytes, amorphous nuclei, neutrophil extracellular trap-like structures, fibrin fibers, and platelet thrombi on the hollow fiber membrane's luminal surface. Elevated DAMP levels in severely inflamed patients' dialyzer membranes, correlating with DIC severity, indicate a link between inflammation, coagulation activation, and dialyzer clotting. Research into thrombus prevention in RRT for DIC-affected critically ill patients is warranted.

Intercurrent clinical events are predictive of plasma C-reactive protein levels in hemodialysis patients

BACKGROUND

In chronic hemodialysis (HD) patients, the repetitive induction of the acute phase response (APR) may induce a chronic micro-inflammatory state, leading to various long-term complications.

METHODS

The present prospective study was designed to assess the alterations in the APR in 74 patients who were randomized to HD with a high-flux polysulfone (PS; F 60S), a super-flux PS (F 500S), or a super-flux cellulosic tri-acetate (CTA and CTA with filtered dialysate, CTA(f)) dialyzer. Blood samples collected at the start of the study and after twelve weeks were analyzed for interleukin-6 (IL-6) and C-reactive protein (CRP). In addition to the microbiological quality of the dialysate, the appearance of a "clinical event" was assessed.

RESULTS

At baseline, mean IL-6 levels were within the reference range whereas mean CRP levels were slightly elevated. Mean values did not change after 12 weeks of HD with either modality. After subdividing the patients in quartiles with increasing change in plasma CRP, 23.0% of the patients showed a change of more than 8.0 mg/L. In a multiple regression analysis, CRP levels appeared to be independent of the degree of dialysate contamination, the material and the flux characteristics of the devices. In fact, the variable "clinical events" was the only significant predictor of the plasma CRP levels (P < 0.001).

CONCLUSIONS

Based on these results, both PS and CTA super-flux dialyzers appear safe for clinical use. Whether changes in CRP values, which are associated with intercurrent clinical events, influence the long-term prognosis of chronic HD patients remains to be established.

Novel online infusate-assisted dialysis system performs microbiologically safely

Administration of adequate amounts of commercial infusion fluids renders modern convective dialysis modalities, such as hemodiafiltration, labor-intensive and costly. Preparation of infusate by cold sterilization of dialysis fluid, which is abundantly available, and its immediate (online) use, in contrast, enables a large volume fluid exchange in a cost-effective manner. Recent developments aimed at more hygienic and user-friendly online systems with increased operational flexibility. As a result the novel ONLINEplus system does not only provide online prepared infusate for convective dialysis therapy, but also for priming and rinsing of the extracorporeal blood circuit, for intradialytic bolus administration, and for re-infusion of patients' blood as well. Production of infusate from potentially impure dialysis fluid containing endotoxins and other pyrogens raises severe concerns of affecting the patients' well-being. To assess its safety, the online system was challenged with microbially contaminated dialysis fluid. Despite high levels of microbial counts (7.5 x 104 +/- 105 CFU/ml), endotoxin concentration (14.1 +/- 7.7 IU/ml and 9.265 +/- 3.000 IU/ml, as measured turbidimetrically and chromogenically, respectively) and cytokine-inducing activity (20,827 +/- 3,082 pg IL-1Ra/Mio WBC), we failed to detect contaminants in the final infusate during a 5 week laboratory testing period. In addition, infusate samples complied consistently with the European Pharmacopeia test for sterility. The present online system is comprehensive, operates user-friendly, and provides microbiologically safe infusate in large quantities. In this way, both patients and dialysis staff will benefit from improved dialysis therapy and reduced treatment-related labor burden, respectively. Moreover, convective dialysis modalities will become less expensive.

National Kidney Foundation report on dialyzer reuse. Task Force on Reuse of Dialyzers, Council on Dialysis, National Kidney Foundation

The Council on Dialysis of the National Kidney Foundation convened an expert panel to evaluate the current practice and literature related to the reuse of hemodialyzers. The panel reviewed and evaluated literature related to reuse since the last report of the National Kidney Foundation recommendations on reuse was published in 1988. The group sought to develop a consensus concerning the effect of reuse of hemodialyzers on mortality; the efficiency of delivered hemodialysis when reused hemodialyzers are used in the clinical setting; the clinical effects of reused dialyzers as compared with dialyzers not reused on intradialytic symptoms; infections in patients using reused dialyzers; and the effect of reused dialyzers on complement activation, cytokine production, and beta2-microglobulin metabolism and clearance. In addition, the panel reviewed the literature on the potential toxicity of germicides used in the processing of dialyzers for reuse as well as recent changes in federally mandated regulations concerning labeling of dialyzers for reuse, the monitoring of the reuse process, and the effectiveness of reused dialyzers to achieve a prescribed delivered clearance as estimated by urea kinetic modeling or by percent urea reduction. The National Kidney Foundation takes no position for or against dialyzer reuse. The principal reason for the practice of reuse is economical. In view of the uncertainties related to the safety and biological impact of reuse procedures, the task force recommends that a full discussion of the issue of reuse and its potential beneficial and detrimental effects be undertaken with each patient. There is no conclusive evidence to substantiate the notion that either morbidity or mortality associated with single use or reuse is different. Microbial contamination of the water used for dialyzer reprocessing increases patient morbidity. The chemical quality of water used for dialyzer reprocessing should, at least, fall within the same standards as those recommended for product water intended for hemodialysis. Dialyzers should not be reprocessed from patients who have tested positive for hepatitis B surface antigen. The effects of reprocessing high-flux dialyzers on beta2-microglobulin clearance are dependent on the reprocessing technique, the number of reuses, and the nature of the dialyzer membrane used. There are insufficient data on the effects of reuse on beta2-microglobulin behavior to make uniform recommendations. Untoward effects of reused dialyzers may still occur in spite of rigorous adherence to the AAMI guidelines. For example, use of the total cell volume method for assessing changes in small molecule clearances will not show the loss of performance attributable to dialysate shunting. For this reason, the measurement of Kt/V for urea as recommended by the AAMI or the determination of the urea reduction ratio (URR) is strongly recommended at least monthly to gauge the adequacy of the dialysis procedure. Given the significant fall in dialyzer efficiency for urea removal that can occur after repeated uses of a dialyzer, dialysis prescriptions in units practicing reuse should be designed to deliver a Kt/V or URR value that exceeds the dose used for patients treated with single-use dialyzers to make allowance for any possible reuse-induced reduction in dialyzer efficiency. Technicians and other personnel responsible for the reprocessing of dialyzers should receive proper training. These health care providers should be certified in reprocessing by an examining body so that professional competency can be assured.