Effect of Dialyzer Reprocessing Methods on Complement Activation and Hemodialyzer-Related Symptoms

The effects of different dialyzer processing methods and of reuse on complement activation and dialyzer-related symptoms were studied in 96 maintenance hemodialysis patients. New dialyzers were either unprocessed (Group 1) or machine-washed with bleach and stored in formaldehyde (Group 2). Reused dialyzers were manually cleansed using the combination of bleach and formaldehyde (Group 3), or machine-washed in formaldehyde (Group 4) or peracetic acid (Group 5). Prewashed new dialyzers (Group 2) were associated with greater complement activation during dialysis when compared with unprocessed, new dialyzers (Group 1) (p less than 0.05). Reused, unbleached but formaldehyde-treated or peracetic acid-treated dialyzers (Groups 4 and 5) were associated with reduced complement activation (p less than 0.05). Complement activation was not reduced when bleach was used for reprocessing (Group 3). The percentage of patients without symptoms during dialysis was significantly greater with reused dialyzers than with new dialyzers (Groups 3 through 5 versus Groups 1 and 2; 39 versus 25%; p = 0.035). The severity of total symptoms correlated significantly (p = 0.0004) with complement activation. Our results suggest that total symptoms during dialysis are correlated with the degree of complement activation. However, trends in the data pertaining to chest pain suggest that factors other than complement activation may be important in the pathogenesis of some dialyzer-related symptoms.     

Complement Activation During Hemodialysis: Clinical Observations, Proposed Mechanisms, and Theoretical Implications

Abstract: Human C3a radioimmunoassay techniques were employed to define both the temporal profile and the amount of complement activation taking place in the extracorporeal circuit during maintenance hemodialysis. Prospective studies demonstrated that C3a formation, like hemodialysis-associated leukopenia, was a transient phenomenon that occurred predominantly during the first 30 min of dialysis. Quantitative comparisons revealed that new Cuprophan hemodialyzers displayed somewhat greater complement-activating potential than cellulose acetate dialyzers. By contrast to new Cuprophan membranes, both reused Cuprophan and polyacrylonitrile dialyzers exhibited only a modest ability to activate human complement. These findings are compatible with the known mechanisms of complement activation and suggest that certain chemical and biochemical methods might be exploited to enhance the biocompatibility of cellulose dialysis membranes.     

Mechanisms of Acute Allergic Reactions

Abstract: Acute allergic reactions range from mild conditions of local tissue swelling and pruritis to severe multisystem syndromes including asthma, urticaria and/or angioedema, gastrointestinal distress, and vascular collapse. Such reactions share a common pathophysiology characterized by vasodilation and postcapillary permeability, resulting in increased extravasation of fluid within minutes after exposure to an eliciting substance. Smooth muscle contraction of the respiratory or gastrointestinal tracts may also be involved. Most of these changes can be explained by the release of chemical mediators from circulating basophilic leukocytes and tissue mast cells. Human basophils and mast cells can be activated to release chemical mediators by several known pathways: crosslinking by allergens of specific immunoglobulin E antibodies attached to basophils and mast cells; anaphylatoxin formation following immune complex activation of the classical complement pathway; anaphylatoxin formed from direct activation of the alternative complement pathway by negatively charged surfaces; non-complement, non-antibody-mediated direct histamine release; and idiosyncratic mechanisms involving physical exercise, psychological stress, or aspirin intolerance. Any or all of these mechanisms could be operative in patients experiencing acute allergic reactions at the commencement of hemodialysis.     

Influence of Hemodialysis on Plasma Chemotactic Activity and the Chemotactic Responsiveness of Polymorphonuclear Neutrophils

Thirty patients with chronic renal failure on maintenance hemodialysis (HD) were studied. Plasma chemotactic activity was estimated using the "under agarose" chemotaxis assay during the first 2 h of HD. It was found that in the fifth minute of HD, patients' plasma became chemotactic, reaching the maximum activity at the tenth minute. The chemotactic activity appearance correlated significantly with the decline in the number of the peripheral neutrophils. Patients' neutrophils, after a single passage through the cellophane coil of the dialyzer, revealed significant impairment of directed migration toward both complementary and bacterial chemoattractants. Moreover, the chemotactic properties of neutrophils obtained from dialyzed patients before HD were significantly lower than had been estimated in 15 nondialyzed patients with chronic renal failure. The results confirm HD-induced complement activation and might explain the mechanisms of the increased susceptibility of dialyzed patients to bacterial infections.     

Hemodialysis with Cellulose Membranes Primes the Neutrophil Oxidative Burst

Abstract: Hemodialysis with cellulose membranes causes a complement-mediated neutropenia. Changes in neutrophil function have also been reported; however, it is unclear if these changes indicate a direct effect of the membrane on neutrophils or if they are a consequence of the neutropenia. We tested the hypothesis that neutrophil oxidative burst activity is enhanced during dialysis with cellulose membranes. Resting and Staphylococcus aureus -stimulated H₂O₂ production were determined predialysis and in blood entering and leaving the dialyzer during the first 30 min of dialysis and in blood leaving the membrane module in a single-pass on-line model of hemodialysis. Resting H₂O₂ production increased slightly but significantly during the first 30 min of dialysis. Transit of neutrophils through the dialyzer caused a marked increase in stimulated H₂O₂ production, indicating priming of the oxidative burst. However, priming was limited to the first 5 min of dialysis before the onset of neutropenia. In contrast, stimulation and priming of H₂O₂ production persisted throughout 30 min of single-pass on-line perfusion. These results indicate that cellulose membranes both stimulate and prime neutrophil oxidative burst activity but that these effects are partially obscured by neutropenia.     

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.     

An Outbreak of Pyrogenic Reactions in Chronic Hemodialysis Patients Associated with Hemodialyzer Reuse

Abstract: In February 1992, 22 patients undergoing chronic hemodialysis at an outpatient dialysis center experienced pyrogenic reactions (PR). The PR rate was significantly greater (p < 0.001) during the epidemic (February 3–5) than the pre-epidemic period (November 1, 1992-February 1, 1992). All patients with PR used dialyz-ers that had been manually reprocessed either on February 1 or 3. These dialyzers contained up to 120.8 EU/ml of endotoxin in the blood compartment. The only dialyzer reprocessed before February 1 that was available for analysis was found to contain no detectable endotoxin, while dialyzers reprocessed during the epidemic period contained a median endotoxin concentration of 52.8 EU/ ml. The bioburden of water used to prepare dialysate was in excess of the Association for the Advancement of Medical Instrumentation (AAMI) standard for water, ≤200 colony forming units (CFU)/ml. Samples of treated water collected in the reuse area were within AAMI standards at the time of the investigation (February 11 and February 26), but before the investigation, water samples were assayed with a culture method that could not detect micro-bial concentrations below 10³ CFU/ml. In addition, the treated water feed line to the disinfectant container may never have been disinfected. However, no samples were collected from this line during the investigation. This outbreak emphasizes the need to use water that meets the AAMI bacteriologic and endotoxin standards of ≤200 CFU/ml and/or 5 EU/ml, respectively, for reprocessing hemodialyzers and to ensure that appropriate culture techniques are used for treated water and dialysate.     

Dialysis in Rats with Acute Renal Failure: Evaluation of Three Different Dialyzer Membranes

Abstract: Exposure to complement-activating cellulosic dialysis membranes has been claimed to adversely affect the course of acute renal failure (ARF). To test this hypothesis, male Sprague-Dawley rats were allocated to 2 groups: in Group t, ARF was induced by bilateral renal artery clamping whereas in Group 2, animals underwent a sham procedure. In each group, rats were further allocated to undergo hemodialysis with either a Cu-prophan, a Hemophan, or a polyacrylonitrile minidialyzer on Days 4 and 8 after surgery, or no dialysis. Renal function was measured by inulin clearance on the days after dialysis. Additionally, total complement activity (CH₅₀) was estimated on Days 1, 2, 4, and 8, and complement factor C3 was detected immunohistochemically. The degree of renal failure and the rate of recovery of renal function were similar in all the ARF groups irrespective of whether they had undergone dialysis or not, or of the type of the dialysis membrane. Furthermore, there were no significant differences in the course of CH₅₀ or in the amount and distribution of complement factor C3 in the kidney tissue between the rats of Groups 1 and 2. Our findings refute the hypothesis that in ischemic ARF exposure to complement-activating cellulosic dialysis membranes impairs the recovery of renal function in rats.     

Leukotriene B4 in Hemodialysis

Leukotrienes are eicosanoids arising from arachidonic acid via 5 lipooxygenase, an enzyme essentially present in leukocyte cells. Leukotriene B4 might be an indicator of neutropolymorphonuclear leukocyte activation when there is contact with artificial membranes. The level of plasmatic leukotriene B4 was measured at three different times during the hemodialysis treatment in several patients undergoing dialysis on three different membranes (one cellulosic and two synthetics). A moderate increase of leukotriene B4 was observed early (at 15 min), comparable among the three membranes, but levels returned to baseline at 180 min. Leukotriene B4 production proved leukocyte activation and was probably related to a direct interaction with dialysis membrane. Nevertheless, complement intervention could not be excluded. Leukotriene B4 is one molecule more among the group of inflammatory mediators produced during hemodialysis treatment.     

Differences in Bio-incompatibility among Four Biocompatible Dialyzer Membranes Using in Maintenance Hemodialysis Patients

Abstract

Background: Following the introduction of modified cellulosic and then synthetic membrane dialyzers, it was realized that the dialyzer bio-incompatibility depends on the membrane composition. We designed a prospective, randomized, cohort study of 6 months to determine several parameters of biocompatibility in maintenance hemodialysis (MHD) patients treated with four different membrane dialyzers. Methods: There were 60 MHD patients enrolled in the study. In baseline, synthetic low-flux dialyzer, polysulfone (PS) membrane was used in all patients for at least 3 months. Then the patients were randomly divided into three groups according to different dialyzer membranes. Synthetic high-flux dialyzer group, ployethersulfone membrane, cellulose triacetate (CTA) high-flux membrane, and synthetic low-flux dialyzer, polymethylmethacrylate (PMMA) membrane were used in 6 months. A new dialyzer was used for each study treatment, and there was no dialyzer reuse. The biocompatibility markers and solutes removal markers were detected repeatedly at different time points. Results: The blood levels of highly sensitive C reactive protein, interleukin (IL)-1β, and interleukin (IL)-13 showed no difference among different groups at al time points. However, the blood complement levels and white blood cell counts were significantly different among three groups. When the dialyzers changed from PS to PMMA membrane, C3a levels and white blood cell counts changed significantly (p < 0.05). Moreover, the changes of C5a levels were significantly different between group CTA and group PMMA in month 3 (p < 0.05). Conclusion: There were much more differences on bio-incompatibility among different dialyzer membranes.     

Complement Activation During Hemodialysis: Laboratory Evaluation of Hemodialyzers

A laboratory method that facilitates delineation of the complement-activating characteristics of various dialyzers under defined conditions has been developed. Results obtained by circulating reconstituted human serum through these devices and measuring time-dependent production of both C3a and C5a antigens are entirely consistent with previous clinical observations. For example, the complement-activating potential of dialyzer membranes could be described as high (cuprammonium cellulose), moderate (cellulose acetate), or low (polycarbonate or polyacrylonitrile). Furthermore, these techniques provided the opportunity to identify membrane characteristics that are not readily defined by clinical studies alone. Specifically, membranes that transported and absorbed C5a antigen were readily identified by these methods. Additionally, laboratory evaluation provided the unique ability to define the efficiency of complement activation taking place on the membrane surface. Results of these investigations are compatible with a hypothetical model that not only describes the properties of a typical dialyzer membrane but may be generally applicable to other biomaterials as well.     

Dialyzer Membranes: Effect of Surface Area and Chemical Modification of Cellulose on Complement and Platelet Activation

Using an ex vivo model, the effects of membrane composition and surface area on both the complement system (as reflected by plasma C3a levels) and platelets [as indicated by plasma concentrations of thromboxane B2 (TXB2) and platelet factor 4 (PF4)] were studied. In this model, polyacrylonitrile (PAN) was associated with less complement activation than cuprammonium cellulose (CC). A new "modified cellulose" (MC) membrane, in which a small number of the free hydroxyl groups on cellulose are substituted with a tertiary amino compound, was also associated with a low degree of complement activation, similar to that with PAN. However, the extent of hydroxyl group substitution in four MC membrane subtypes did not correlate with the reduction in complement activation. In studies using CC, the amount of generated C3a correlated with the membrane surface area, although the relationship was curvilinear. Plasma concentrations at the "dialyzer" outlet of TXB2 and PF4 were similar with CC, PAN, and MC. In studies with the MC subtypes, increasing the extent of hydroxyl group substitution paradoxically increased, albeit slightly, the amount of TXB2 generation. In studies with CC, a linear relationship between membrane surface area and TXB2 generation was found. The results suggest a dissociation between platelet and complement effects among different dialyzer membranes, and underline the importance of membrane surface area.     

Adsorption of Hepatitis C Virus Particles Onto the Dialyzer Membrane

Abstract: It was recently found that the blood level of hepatitis C virus (HCV) RNA is significantly reduced after each dialysis procedure in patients on chronic hemodialysis. This study was designed to elucidate the mechanism for this phenomenon. In two patients with high serum levels of HCV RNA, the filtrate through the dialyzer (TF-α, Teijin Co., Tokyo, Japan) was analyzed for viral RNA using the polymerase chain reaction. At the end of dialysis, the filter was washed with saline, and during the saline washing, aliquots were taken for quantification of RNA by the branched DNA method. The HCV core antigen was quantified as a measure of viral particles, and hemoglobin was also measured for correcting for blood contamination. After the clearance of the blood, the filter was washed with guanidinium isothiocyanate, and the recovery of RNA was measured. The filtrate did not contain detectable RNA.
The saline washing of the filter after dialysis contained a significant amount of RNA. Washing with guanidinium isothiocyanate of the thoroughly saline washed filter also recovered a significant amount of RNA. During saline dashing, the recovery of RNA in the washing was much delayed behind that of hemoglobin, suggesting the adsorption of the former onto the filter membrane. There was a discordant recovery of RNA and HCV core antigen in the washing, the recovery of the former being delayed behind that of the latter. These results indicate that viral particles are adsorbed onto the inner surface of the filter membrane during dialysis. Some of these adsorbed viral particles are perhaps destroyed by hydraulic pressure applied to blood for dialysis.     

Clinical Evaluation of a New Water Removal Measuring Device in Standard Dialysis

A new device measuring water removal during standard dialysis is evaluated. The filtrate, collected from a small hemofilter inserted into a normal Cuprophan hollow-fiber dialyzer, was used to evaluate the total water removed from the patient. The device was tested in 46 patients undergoing regular dialysis treatment; the body weight loss ranged from 300 to 5,600 ml for a total of 71 dialysis sessions. Results confirmed the reliability of the device, as the mean prediction error was 5.4%. No influence of the dialyzer blood rest volume on the prediction error was observed. The authors propose this system as an alternative to bed or armchair scales and emphasize its usefulness for experimental purposes.     

Morbidity and Mortality in Hemodialysis: The Role of Schedules

Abstract: Hemodialysis is an efficient therapy for end-stage renal failure. This treatment, however, must be used in an optimal fashion, i.e., with the best technology and the most adequate schedules. Unfortunately and especially for economic reasons, these basic therapeutic principles are often not respected. As a consequence, morbidity and mortality in maintenance hemodialysis patients have increased. This article underlines four points that could influence mortality in maintenance hemodialysis patients: nutrition, adequacy of hemodialysis, blood pressure control and treatment time.     

Improved Biocompatibility by Modified Cellulosic Membranes: The Case of Hemophan

The rising problem of biocompatibility is encouraging the development of new dialysis membranes, but the high cost of synthetic ones precludes their wide use. The authors compared the biocompatibility of cuprophan (CU), cellulose acetate (CA), and hemophan (HE), evaluating both in vitro and in vivo polymorphonuclear leukocyte (PMN) oxidative metabolism activation by resting chemiluminescence and complement activation by C3a; in vivo PMN counts during dialysis were also performed. The lowest increase in in vitro PMN resting chemiluminescence using HE was + 71.3% with CA, +49.3% with CU, and + 21.4% with HE (p less than 0.001 versus CA and CU); furthermore, HE did not significantly stimulate PMN resting chemiluminescence during in vivo hemodialysis: + 56.6% with CA, + 38.8% with CU, and + 3.7% with HE (p less than 0.01 versus CU and p less than 0.001 versus CA). C3a concentration increased with all membranes both in vitro and in vivo, but HE (in both experimental conditions) showed the lowest increase at any time (p less than 0.001 versus CA and CU). After 15 min of dialysis, PMN count dropped to 20.3% of basal values with CU, to 49.8% with CA, and to 76.5% with HE (p less than 0.001 versus CU and CA). Among cellulosic membranes, HE is the most biocompatible and appears to be an important step in preventing blood-membrane interactions and related complications.     

Role of cytokines in anaphylactoid reaction with marked eosinophilia in a hemodialysis patient

Hemodialysis is rarely terminated by events associated with anticoagulants. A 69-year-old woman on hemodialysis due to chronic renal failure (CRF) developed an anaphylactoid reaction with hypereosinophilia. On the basis of clinical and laboratory findings, we concluded that the causes of this anaphylactoid reaction were low-molecular-weight heparin and heparin. Our patient also showed high levels of soluble interleukin-2 receptor (sIL-2R) and eosinophil cationic protein (ECP), which decreased after the cessation of hemo-dialysis. To date, there has been no report of high levels of cytokines induced by hemodialysis-associated anaphylactoid reaction. In this report, we discuss the mechanism underlying drug-induced anaphylactoid reaction, particularly that involving eosinophilia and cytokines.     

Activation of Basophils Is a New and Sensitive Marker of Biocompatibility in Hemodialysis

The hemodialysis procedure involves contact between peripheral blood and the surface of dialyzer membranes, which may lead to alterations in the pathways of innate and adaptive immunity. We aimed to study the effect of blood–membrane interaction on human peripheral basophils and neutrophils in hemodialysis with high‐ and low‐permeability polysulfone dialyzers. The surface expression of CD203c (basophil selection marker) and CD63 (activation marker) after activation by the bacterial peptide formyl‐methionyl‐leucyl‐phenylalanine (fMLP) or anti‐Fcε receptor I (FcεRI) antibody and the absolute number of basophils was investigated before and after hemodialysis with each of the dialyzers. Moreover, the expression on neutrophils of CD11b, the CD11b active epitope, and CD88 was analyzed in the same groups of individuals. The expression of CD63 in basophils following activation by fMLP was significantly higher in the patient group compared with that in healthy controls, but no differences were observed after activation by anti‐FcεRI. During the hemodialysis procedure, the low‐flux membrane induced up‐regulation of CD63 expression on basophils, while passage through the high‐flux membrane did not significantly alter the responsiveness. In addition, the absolute number of basophils was unchanged after hemodialysis with either of the dialyzers and compared with healthy controls. We found no significant differences in the expression of the neutrophil activation markers (CD11b, the active epitope of CD11b, and CD88) comparing the two different dialyzers before and after dialysis and healthy controls. Together, these findings suggest that alterations in basophil activity may be a useful marker of membrane bioincompatibility in hemodialysis.