Hemodialysis neutropenia and dialyzer reuse: role of the cleansing agent

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.

Dilemma of membrane biocompatibility and reuse

Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation, leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.

Comparison of first use and reuse of cuprophan membranes on interleukin-1 receptor antagonist and interleukin-1 beta production by blood mononuclear cells

The magnitude of the changes in a variety of blood constituents on exposure to the dialysis membrane has been used as an index of "biocompatibility," and dialyzer reuse has been postulated to improve biocompatibility by attenuating these changes. We studied the hemodialysis-induced changes in the in vitro production of interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1 beta (IL-1 beta) by peripheral blood mononuclear cells (PBMCs), and compared the effect of first use and reuse of cuprophan membranes on these changes. Studies were performed during dialysis with first use and third reuse of the same kidney. The cell content and production of IL-1Ra and IL-1 beta by unstimulated and endotoxin- or IgG-stimulated PBMCs were studied just prior to dialysis, and from the afferent and efferent limbs of the blood circuit 15 minutes after the start of dialysis. Interleukin-1 receptor antagonist and IL-1 beta were measured by specific radioimmunoassay and are expressed as picograms per 2.5 x 10(6) PBMCs. Fifteen minutes after the start of dialysis, the number of PBMCs harvested from 10 mL of blood decreased from 19.8 +/- 4.7 x 10(6) predialysis to 14 +/- 3 x 10(6) (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of reuse on dialyzer efficacy

The effect of reuse on dialyzer efficacy was examined by measuring blood compartment volume and dialyzer mass transfer coefficient (maximum dialyzer clearance) as a function of dialyzer use number. The 102 polysulfone dialyzers tested (F60 and HF80, Fresenius) were reprocessed on Renatron machines using peroxyacetic acid as the dual cleansing and sterilizing agent. Each dialyzer was used an average of 14.4 +/- 5.7SD times and was tested once (twice for 13/102 dialyzers) during a routine dialysis session at an arbitrary use number (7.6 +/- 5.3; range 1 to 24). The parameters tested were found to decrease only marginally with reuse, corresponding to a blood compartment volume loss of approximately 1% (R = 0.04) over a 5-week/15-use period and a decrease in dialyzer mass transfer coefficient of approximately 3% (R = 0.07 and 0.06) over the same period for urea and creatinine, respectively. It was concluded that the loss in dialyzer efficacy is negligible over the average use period of almost 5 weeks per dialyzer.

Reprocessing of hemodialyzers: a critical appraisal

The reprocessing of hemodialysis equipment was originally developed to conserve scarce resources and to reduce the time necessary to construct early dialyzers. Although most dialyzers in current use are marketed as disposable items, the majority of dialysis facilities in the United States reprocess these devices and use them multiple times on the same patient. Recent studies have shown that certain reprocessing techniques confer improved biological properties on dialyzers compared with new membranes as prepared by manufacturers. Several studies have suggested that these biological properties may lead to improved clinical outcomes. However, critics of dialyzer reprocessing argue that it may expose patients to risks that produce increased morbidity and mortality. This article critically reviews the available scientific information regarding reprocessing hemodialyzers.

Analysis of the complement C3 fragments associated with hemodialysis membranes

During hemodialysis with cuprophan membranes, bioactive peptides are generated because the alternative pathway of complement is activated. When cellulose acetate membranes are employed, complement activation is attenuated. The molecular basis for this improved biocompatibility is unknown. It has been postulated, however, that the complement activating potential of dialysis membranes is influenced by the availability of free hydroxyl groups which would provide an acceptor site for activated C3. To investigate this hypothesis, the forms of C3 associated with cellulose acetate and cuprophan membranes have been analyzed. By Western blot, the predominant form of C3 present on both types of membranes is C3c, a degradation product of C3 that lacks the thiolester necessary for covalent bonding. Minimal amounts of C3d (the region of C3 which contains the thiolester) were observed on both membranes; however, by ELISA, there was no difference in the amount bound to cellulose acetate compared to cuprophan. Further, membrane-associated C3d could be removed by urea, suggesting that it was not bound covalently. These studies indicate that the complement activating potential of dialysis membranes is not determined primarily by the availability of potential covalent binding sites for activated C3b.

Hypoxemia during hemodialysis: a critical review of the facts

The literature describing the fall in PaO2 during dialysis is intensively and critically reviewed. This phenomenon is related to both the type of membrane used (cellulosic v noncellulosic membrane), and to the composition of the dialysate (acetate v bicarbonate). It appears that a ventilation/perfusion mismatch due to pulmonary leukostasis can, in part, explain hypoxemia in patients dialyzed with cellulosic membranes. This phenomenon is especially apparent in patients with preexisting pulmonary abnormalities. However, hypoventilation remains the major cause of hypoxemia. This hypoventilation is mainly due to CO2 consumption during acetate metabolism (acetate dialysis), or alkalinization of the blood (bicarbonate dialysis). The metabolic consequences of acetate metabolism, and of bicarbonate and CO2 losses through the dialyzer are critically analyzed. The cause for the increment in oxygen consumption during acetate dialysis is examined. Finally, the respective role of these combined factors are described and used to explain the changes in VCO2, VO2, respiratory quotient (RQ), and PaO2 reported in the literature during dialysis against acetate and/or bicarbonate.

Dialyzer reuse following manual reprocessing with a new sterilant, RenNew-D

Dialysis patients are at risk for toxicity from formaldehyde used in the reprocessing of dialyzers for reuse; therefore, replacing formaldehyde as a dialyzer sterilant would be advantageous. The potential for RenNew-D as a sterilizing agent was investigated in seven stable in-center hemodialysis patients over 20 consecutive dialyses with cuprammonium cellulose hollow-fiber dialyzers. Treatment with RenNew-D showed no toxicity to patients or dialyzers except for two blood leaks occurring in one patient. The mean number of dialyzer uses was 4.9. In all the dialyzers that passed functional testing small solute clearances were maintained with reuse. The ability of RenNew-D to improve the biocompatibility of reused dialyzers was documented with mean neutrophil counts falling to only 78% of initial values during first reuse of dialyzers processed with RenNew-D compared with a decrease in neutrophil count to 2% of initial values during first use of the same dialyzers. Our results suggest that RenNew-D may be a useful alternative to formaldehyde for the purpose of dialyzer reuse. A reuse procedure that includes processing with RenNew-D is associated with improved biocompatibility, possibly because of maintenance of the blood-derived membrane coating established during prior dialysis.