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Dialysis Discussion => Dialysis: News Articles => Topic started by: ahamner on April 17, 2008, 09:40:52 AM
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What Do I Need to Know About Reuse of Hemodialyzers?
By Rachel Burdick, MD & Friedrich Port, MD, MS, FACP
Hemodialzyer reuse is commonly practiced in the United States. Reuse is the process of sterilizing the patients' dialyzer and reusing it during the next scheduled treatment. The principal reason for the use of this practice in the United States is economic. Eighty percent of the hemodialysis units in the United States reprocess dialyzers and the percent of patients who reuse dialyzers is similar.1 Since studies have raised concerns about the risks associated with the reuse of hemodialyzers, it is important for patients and their families, as well as dialysis facility personnel, to be fully informed of the risks and benefits of dialyzer reuse. Specific issues include the effects of reuse on death (mortality), on the efficiency of delivered hemodialysis and choice of hemodialyzer, symptoms developing during dialysis, infections and the potential toxicity of germicides (chemicals used to kill germs) used in the reprocessing and sterilization of dialyzers for reuse.
MORTALITY
In the past 20 years, several national studies have examined the relationship between mortality and the reuse of hemodialyzers. Based on more recent studies, there is no conclusive evidence that either morbidity (causing other diseases and healthcare problems) or mortality differs among reuse techniques. However, there does seem to be an association between increased mortality and the reprocessing agent glutaraldehyde, and also an association between increased mortality and the reprocessing mixture of peracetic acid, hydrogen peroxide, and acetic acid.2 The most recent national study showed an association to be small and of borderline statistical significance.3
The reprocessing agent formaldehyde has not been associated with an increase in mortality. Heat sterilization appears to be an effective method. However, data have not been sufficient for large scale comparisons with other reuse methods. Several factors make the study of a possible association between reuse and mortality difficult. Differences in mortality associated with free-standing dialysis units need to be accounted for to evaluate mortality related to the processing agent. The described difference in mortality risk accounted for differences between free-standing dialysis units and hospital-based dialysis units and considered the amount of dialysis delivered.
It should be noted that none of the studies examining the relationship between dialyzer reuse, processing agent and mortality, are randomized controlled trials. This means that none of the studies that show an association establishes a cause and effect relationship. Continued surveillance of outcomes by reuse and reuse technique is recommended, since a randomized trial does not seem feasible.
DELIVERY OF HEMODIALYSIS DOSE
The currently accepted standards for the practice of reuse in the United States are those issued by the American Association for the Advancement of Medical Instrumentation (AAMI). AAMI guidelines impose only one guideline for the continued use of a dialyzer. This guideline is that the dialyzer urea clearance stays within 90 to 110 percent of the original value.4 Since the AAMI recognizes that it is not practical to determine a urea clearance value before each reuse, the AAMI standards regard measurement of the blood compartment volume of the dialyzer, referred to as the "total cell volume" (TCV) as equally satisfactory. A TCV of greater than 80 percent usually maintains clearance within the acceptable range.
However, use of this volume method for assessing changes in small molecule clearances will not show the loss of performance attributable to dialysate shunting. For this reason, 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 measure dialysis adequacy. Monthly measurements are also recommended by DOQI (Dialysis Outcomes Quality Initiative). Since repeated uses of a dialyzer can lead to a decrease in efficiency, the National Kidney Foundation Task Force recommends that 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.5 This practice makes allowance for any possible reuse-induced reduction in dialyzer efficiency.
Researchers and clinicians have been concerned about the loss of dialyzer membrane surface area, the decreased dose of dialysis and the possible effect on patient mortality. A recent study analyzed the actual practice of dialysis in data from the US Renal Data System (USRDS). This study found that nonreuse patients were more likely to be treated with low-flux dialyzers and receive a lower dialysis dose, than patients treated with dialyzers that were reused.6
INTRADIALYTIC SYMPTOMS
It has been suggested that reused dialyzers are associated with a decreased incidence of symptoms during dialysis such as muscle cramps, hypotension, nausea, vomiting, chest pain, back pain, dyspnea (shortness of breath), itching and chills, when compared with new but otherwise similar dialyzers. Investigators have also reported decreased incidence of intradialytic (symptoms during the dialysis treatment) occurring during the reuse of dialyzers reprocessed with formaldehyde or peracetic acid, when compared with the first use of the same dialyzers.7,8
Since recent studies could not show such differences in symptoms, improvements in new dialyzers regarding residues in the dialyzer and complement activation (see explanation on next page) may have occurred. Better removal of residual noxious substances during the production of new dialyzers may explain the finding that first dialyzer symptoms have become rare. In the past, residual ethylene oxide dialyzers used for factory sterilization have been associated with clinical signs and symptoms including anaphylaxis (immediate allergic reaction).9 In the hemodialysis setting, this constellation of signs and symptoms is known as the first-use syndrome, or the new dialyzer syndrome. For reasons that are unclear, there is a higher incidence of first-use syndrome in centers that reuse.10 To reduce the risk of first-use syndrome, some centers subject all new dialyzers to the reprocessing procedure before first use which should minimize the exposure of patients to undesirable residuals (the reprocessing chemical residue left in the dialyzer filter after the filter has been cleaned).
Most dialysis membranes activate the complement system. The complement system consists of a group of proteins that the body uses to fight infection. Commercial dialyzer membranes activate the complement system to variable degrees. The clinical relevance of complement activation is not clear, but there is concern that complement activation leads to a chronic inflammatory state, that may be harmful in the long term. After dialysis, plasma proteins from the patient's blood coat the surface of the dialyzer membrane. This coating of plasma protein reduces the direct exposure of the blood to the dialyzer membrane and decreases complement activation during subsequent uses. This protective effect is reduced when bleach is used during the reprocessing, since bleach removes the protein layer.
REUSE-RELATED INFECTION RISK
Fever and sepsis (a toxic condition resulting from the spread of bacteria) may occur in dialysis patients. The Centers for Disease Control and Prevention (CDC) has reported that these take place more frequently in facilities reusing dialyzers than in those not reusing. One report suggests that the incidence of pyrogenic reactions (reactions involving a high fever) may be more common among centers that reused dialyzers more than 20 times.11 The AAMI recommends that 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. Centers that adhere strictly to AAMI practice guidelines for dialyzer reprocessing, and that reuse each dialyzer 15 times or less, have a much lower incidence of pyrogenic reactions.
Another potential concern is the transmission of infection from one patient to another by the reused dialyzer. Dialyzers should not be reprocessed from patients who have tested positive for Hepatitis B surface antigen, for protection of the dialysis unit staff.4 The CDC has not opposed the reuse of dialyzers in the case of Hepatitis C and Human Immunodeficiency Virus, as the risk for transmission of either of these viruses from one patient to another via the dialysis filter is low to nonexistent, and also since precautions should be applied to all patients ("universal precautions").4 Reused dialyzers need to be labeled with the patient's name since they are to be used only on the same patients. Therefore, patients are encouraged to verify that they are assigned their own filter.
USE OF GERMICIDE FOR REPROCESSING
A variety of germicides are used for reprocessing. In 2000, 59 percent of facilities used peracetic acid, 31 percent used formaldehyde, 5 percent used glutaraldehyde and 4 percent used heat for disinfection during reprocessing.1
Formaldehyde has been associated with some side effects on red blood cells, which may lead to some hemolysis (the breaking apart of blood cells), particularly in the cold (anti I antibodies). Although continuous exposure to high-level formaldehyde fumes may predispose to the development of cancers in certain animals, there is no evidence for increased incidence of malignancy in humans. Dialysis units thoroughly rinse each dialyzer and test for traces of formalin after rinsing to minimize patient germicide exposure.
SUMMARY
There is no conclusive evidence that either morbidity or mortality associated with single use or reuse is different. In view of 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 pros and cons be undertaken with each patient. Each patient must be allowed to decline reuse if he or she is concerned enough about the practice in general, or the way that it is performed in a particular setting. Reuse appears to allow efficiency of dialysis with better and larger dialyzers that may, on balance, be of benefit to patients.
References:
Tokars JI, Alter MJ, Arduino MJ: National Surveillance of Dialysis-Associated Diseases in the United States, 2000. Available at http: www.cdc.gov/ncidod/hip/Dialysis/dialysis.htm. Accessed January 10, 2002.
Held PJ, Wolfe RA, Gaylin DS, Port FK, Levin NW, Turenne MN: Analysis of the Association of Dialyzer Reuse Practices and Patient Outcomes, Am J Kidney Dis 23:692-708, 1994.
Port FK, Wolfe RA, Hulbert-Shearon TE, Daugirdas JT, Agodoa L, Jones C, Orzol SM, Held PJ: Mortality Risk by Hemodialyzer Reuse Practice and Dialzyer Membrane Characteristics: Results From the USRDS Dialysis Morbidity and Mortality Study. Am J Kidney Dis 37:276-286, 2001.
Reuse of hemodialyzers, in AAMI Standards and Recommended Practices, Volume 3: Dialysis, chap ANSI/AAMI RD 47. Arlington, VA, Association for the Advancement of Medical Instrumentation, 1993, pp 85-118.
Task Force on Reuse of Dialzyers, Council on Dialysis, National Kidney Foundation: National Kidney Foundation Report on Dialyzer Reuse. Am J Kidney Dis 30:859-871, 1997.
Okechukwu CN, Orzol SM, Held PJ, Pereira JG, Agodoa A, Wolfe RA: Characteristics and Treatment of Patients Not Reusing Dialyzers in Reuse Units. Am J Kidney Dis 36(5): 991-999, 2000.
Bok DV, Pascual L, Herberger C, Sawyer R, Levin NW: Effect of Multiple Use Dialyzers on Intradialytic Symptoms. Proc Clin Dial Transplant Forum 10:92-99, 1980.
Fleming SJ, Foreman K, Shanley K, Mihrshahi R, Siskind V: Dialyzer Reprocessing with Renalin. Am J Nephrol 11:27-31, 1991.
Daugirdas JT, Ing TS: First-use reactions during hemodialysis: A definition of subtypes. Kidney Int 33:S37-S43, 1988 (suppl 24).
Tokars JI, Alter MJ, Favero MS, Moyer LA, Miller E, Bland LA: National Surveillance of Dialysis Associated Diseases in the United States, 1992. ASAIO J 40:1020-1031, 1994.
Tokars JI, Alter MJ, Favero MS, Moyer LA, Miller E, Bland LA: National Surveillance of Dialysis Associated Diseases in the United States, 1993. ASAIO J 42:219-229, 1996.
Dr. Rachel Burdick is a senior nephrology fellow at the University of Michigan. She is currently completing a master's degree in biostatistics. Dr. Burdick plans to pursue academic nephrology, with an emphasis on renal epidemiology and outcomes research.
Dr. Friedrich Port is a Professor of Medicine and Epidemiology at the University of Michigan Schools of Medicine and Public Health. Dr. Port has 27 years of experience in quantitative analyses of dialysis and renal transplant patients. Dr. Port is a prominent member of the renal research community with a national and international reputation for outcomes research.
This article originally appeared in aakpRENALIFE January 2002, Vol. 17, No. 4.