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Alfred K Cheung

Publications and source records attributed to Alfred K Cheung.

At least 37 records · Page 2Linked to original sources
PubMed2005

Dialyzer membranes as determinants of the adequacy of dialysis.

Hemodialysis membranes have undergone a gradual but substantial evolution over the past few decades. Classification of modern dialyzer membranes by chemical composition bears little relationship to their functional characteristics. The fundamental properties that determine the capacity of the membrane to remove solutes and fluids are its surface area, thickness, pore size, pore density, and potential to adsorb proteins. Dialyzer membrane performance is characterized clinically by its efficiency, defined as the potential to remove urea and presented as the mass-transfer area coefficient (KoA) and ultrafiltration coefficient (K(uf) ),defined as the potential to remove water adjusted for the transmembrane pressure. The parameter K(uf) usually, but not invariably, correlates with the membrane permeability, defined as the potential to remove middle molecules, with beta2-microglobulin being the currently popular marker. The sieving coefficient reflects the membrane potential to transport solutes by convection and is particularly useful for hemofiltration. Enhancing solute clearance is accomplished clinically by increasing blood and dialysate flow rates, strategies that also are applicable to middle molecules for highly permeable membranes. Novel designs of dialyzers include the optimization of fluid flow path geometry and increasing the membrane pore selectivity for solutes by using nanotechnology.

Humans↗
PubMed2005

The role of pretransplantation renal replacement therapy modality in kidney allograft and recipient survival.

BACKGROUND: The effect of pretransplantation renal replacement therapy (RRT) modality on allograft and recipient survival outcome is not well understood. METHODS: We studied allograft and recipient survival by using US Renal Data System records from January 1, 1990, to December 31, 1999, with a follow-up period through December 31, 2000 (n = 92,844; 60% males; 70% white; 23% black). Pretransplantation and predominant RRT modality during the end-stage renal disease (ESRD) period and number and specific combinations of RRT modalities were evaluated. RESULTS: Compared with hemodialysis (HD), a Cox model showed that peritoneal dialysis (PD) immediately before transplantation predicts a 3% lower risk for graft failure (P < 0.05) and 6% lower risk for recipient death (P < 0.001). When predominant RRT modality was analyzed (modality used for > 50% of the ESRD time), PD (hazard ratio [HR], 0.97; P < 0.05) had a protective effect for graft survival compared with HD. Better recipient survival also was associated with PD (HR, 0.96; P < 0.05). Increased number of RRT modalities during the ESRD course was associated with increased risk for graft failure (HR, 1.04 per additional modality used; P < 0.005) and recipient death (HR, 1.11 per additional modality used; P < 0.001). Any combination or any single modality (except for PD + HD for graft survival and PD + HD and PD + HD + transplantation for recipient survival) had protective effects on graft and recipient survival compared with HD. CONCLUSION: Our results suggest that compared with PD, HD as an RRT modality immediately before transplantation or as a predominant RRT modality during the ESRD course, used alone or in combination with other RRT modalities, is associated with increased risks for graft failure and recipient death. Increased number of RRT modalities used during the ESRD course is associated with worsening of graft and recipient survival.

Adolescent↗
PubMed2005

Associations of metabolic syndrome with inflammation in CKD: results From the Third National Health and Nutrition Examination Survey (NHANES III).

BACKGROUND: Although metabolic syndrome is associated with inflammation in the general population, it is unknown whether similar associations exist in patients with chronic kidney disease. METHODS: +7 cross-sectional associations of metabolic syndrome and its component conditions (diabetes, hypertension, hypertriglyceridemia, abdominal obesity, and low high-density lipoprotein cholesterol level) with inflammation (C-reactive protein level > 3 mg/L) were examined by using logistic regression models in groups with high (>90 mL/min/1.73 m2 [>1.50 mL/s]), moderate (45 to 89 mL/min/1.73 m2 [0.75 to 1.49 mL/s]), and low (<45 mL/min/1.73 m2 [<0.75 mL/s]) creatinine clearances in 15,314 subjects participating in the Third National Health and Nutrition Examination Survey. RESULTS: Adjusted for demographics, smoking, history of myocardial infarction or stroke, exercise level, and use of cholesterol medications, the presence of metabolic syndrome was associated with greater odds for inflammation in the groups with high (odds ratio, 2.55; 95% confidence interval [CI], 1.99 to 3.27), moderate (odds ratio, 2.17; 95% CI, 1.81 to 2.60), and low (odds ratio, 1.87; 95% CI, 1.36 to 2.56) creatinine clearances. When all 5 components of metabolic syndrome were included in the same model, only hypertension, abdominal obesity, and low high-density lipoprotein level were associated significantly with inflammation in all 3 groups. There also was a graded association between number of component conditions of metabolic syndrome and inflammation within each creatinine-clearance group. CONCLUSION: Metabolic syndrome is associated with inflammation in patients with varying levels of kidney function. Future studies are warranted to determine in patients with chronic kidney disease whether there is a synergistic effect of metabolic syndrome and inflammation on the incidence of atherosclerotic events and whether interventions targeted toward metabolic syndrome might modulate inflammation.

Adult↗
PubMed2005

Patient preferences for in-center intense hemodialysis.

There is a lack of data on patient preferences for intense hemodialysis (IHD). In this study, we conducted a cross-sectional survey to identify patient preferences and patient-centered barriers for IHD. A questionnaire on preferences and anticipated barriers, anticipated benefits, and quality of life for three in-center IHD schedules (daytime 2 hr six times/week [DHD], nocturnal 8 hr three times/week [ND3], and nocturnal 8 hr six times/week [ND6]) was administered to 100 chronic hemodialysis patients. A majority of patients (68%) were willing to undergo DHD for symptomatic benefits or increase in survival. An increase in energy level (94%) and improvement in sleep (57%) were the most common potential benefits that would justify DHD, but only 19% would undergo DHD for an increase in survival of < or =3 years. Only 20% and 7% would consider ND3 and ND6, respectively. The most common reported barriers were inadequate time for self (50%) and family (53%), followed by transportation difficulties (53%). Most patients would undergo DHD for symptomatic or survival benefits, but not ND3 or ND6. Disruption of personal time, however, is an important consideration. Success of DHD program would depend on arrangements for transportation to dialysis unit.

Adult↗
PubMed2005

Different responses by cultured aortic and venous smooth muscle cells to gamma radiation.

BACKGROUND: Stenosis of hemodialysis arteriovenous grafts is usually focal and caused by the proliferation of vascular smooth muscle cells (SMCs). External radiation of the graft is a potential strategy to prevent stenosis; however, the relative responsiveness of arterial and venous SMCs to radiation is unknown. METHODS: Human aortic and saphenous vein SMCs were cultured in a medium containing growth factors and serum and treated with 0 to 50 Gy in a gamma irradiator. At 2 to 20 days post-irradiation, cell counting, methylthiazoletetrazolium dye reduction, [(3)H]-thymidine uptake, and bromodeoxyuridine (BrdU) incorporation assays were performed. RESULTS: All assays showed that 1 to 50 Gy inhibited the proliferation of both aortic and venous SMCs in a dose-dependent manner. Importantly, venous cells were less susceptible to radiation in all assays, compared to aortic cells. At day 10, 1 to 50 Gy of radiation inhibited the increase in the number of aortic cells by 24% to 66% and venous cells by 8% to 25% (P < 0.01) (aortic vs. venous). The differences between aortic and venous cells varied among different assays and were most pronounced in the BrdU assay. CONCLUSION: Inasmuch as myointimal hyperplasia occurs at both arterial and venous anastomoses, future strategies using radiation to prevent hemodialysis vascular access stenosis should take these differences into consideration.

Antimetabolites↗
PubMed2004

Duration of end-stage renal disease and kidney transplant outcome.

BACKGROUND: Patients nearing end-stage renal disease (ESRD) increasingly choose pre-emptive renal transplant (PRT) to avoid pre-transplant dialysis and to minimize ESRD. Compared with long-term dialysis, PRT has been shown to increase allograft survival. However, the merit of short-term dialysis is not well characterized, and it may be the better medical choice in some patients. The goal of the study was to characterize the relationship between the duration of dialysis vs allograft and patient survival. METHODS: We performed a retrospective nationwide cohort study of all kidney transplants (Tx) between January 1, 1990 and December 31, 1999, with a follow-up period through December 31, 2000. Participants were identified using the United States Renal Data System (USRDS), which tracks all ESRD cases in the nation including patients on dialysis and with kidney Tx. Patients with the history of more than one kidney Tx were excluded. Allograft survival and recipient survival were the primary outcomes of this study. Duration of ESRD as a continuous variable as well as divided into categories (14 days, 15-60 days, 61-180 days, 181-365 days, 1-2 years, 2-3 years, 3-5 years and >5 years) was the primary risk factor of interest. Models were adjusted for multiple donor and recipient factors, including demographics and co-morbidities, as well as for Tx procedure characteristics. RESULTS: A total of 81,130 patient records were used for analysis (age 44.1+/-14.3 years, 61% males, 24% black, 29% diabetic, pre-transplant ESRD duration 27.1+/-26.4 months, 26% living donors). ESRD duration, as a continuous variable, is associated with a modest increase in the risk of graft failure over time [hazard ratio (HR) 1.02 per year of ESRD duration, P<0.001]. When ESRD is studied as a categorical variable (duration of 0-14 days vs longer durations), the increased risk of allograft failure reached statistical significance only when the time on dialysis was > or =181 days. The duration of ESRD was a significant risk for recipient death (HR 1.04 per year, P<0.001); however, mortality risk reached statistical significance only when the patient had been on dialysis for > or =1 year. CONCLUSIONS: This study of USRDS records suggests that a short (<6 months) dialysis course has no detrimental effect on graft and patient survival, and should not be deferred if medically indicated.

Adult↗
PubMed2004

Arterial and venous smooth-muscle cells differ in their responses to antiproliferative drugs.

Arteriovenous polytetrafluoroethylene (PTFE) grafts used for hemodialysis often fail as the result of myointimal hyperplasia with vascular smooth-muscle-cell (SMC) proliferation. The stenotic lesions occur primarily at the graft-vein anastomosis and less frequently at the graft-artery anastomosis. To explore the potentials of pharmacologic agents in preventing hemodialysis-graft stenosis, we first examined the susceptibility of venous and aortic SMCs to 3 antiproliferative drugs. Human aortic and saphenous-vein SMCs were cultured in a medium containing insulin, epidermal growth factor, fibroblast growth factor, and fetal bovine serum. Various concentrations of dipyridamole (0-100 microg/mL), paclitaxel (0-100 microg/mL), and tranilast (0-300 microg/mL) were added. After 72 hours, we subjected the cells to a mitochondrial enzymatic (methylthiazoletetrazolium; MTT) assay and a bromodeoxyuridine (BrdU)-incorporation assay as a means of assessing their proliferation. Dipyridamole, paclitaxel, and tranilast each inhibited the proliferation of aortic and venous SMCs in a dose-dependent manner ( P <.0001). Approximately 90% inhibition was achieved at dipyridamole concentrations of 75 microg/mL and greater in both MTT and BrdU assays; paclitaxel and tranilast were less effective. The venous SMCs were substantially more susceptible to inhibition by all 3 drugs than were the aortic SMCs in the MTT assay. The concentrations required to produce 50% inhibition (IC 50 ) in the venous cells were 5.8 microg/mL (11.5 micromol/L), 9.1 microg/mL (10.7 micromol/L), and 37.4 microg/mL (114.3 micromol/L), respectively, for dipyridamole, paclitaxel, and tranilast. These concentrations were approximately 4.2, 5.3, and 3.0 times lower, respectively, than the corresponding IC 50 values for the aortic cells. The differences in IC 50 between the aortic and venous cells for the 3 drugs were less pronounced in the BrdU assay. The results of this study suggest that strategies for the prevention of stenosis should take into account the fact that lesions at venous anastomoses of arteriovenous grafts may respond differently to drugs than do those at arterial anastomoses.

Arteries↗
PubMed2004

Cardiac diseases in maintenance hemodialysis patients: results of the HEMO Study.

BACKGROUND: Cardiac disease is a common cause of death in chronic hemodialysis patients. A subanalysis of the data on cardiac diseases in the Hemodialysis (HEMO) Study was performed. The specific objectives were: (1) to analyze the prevalence of cardiac disease at baseline; (2) to characterize the incidence of various types of cardiac events during follow-up; (3) to examine the association of cardiac events during follow-up with baseline cardiac diseases; and (4) to examine the effect of dose and flux interventions on various types of cardiac events. METHODS: The HEMO Study is a randomized multi-center trial on 1846 chronic hemodialysis patients at 15 clinical centers comprising 72 dialysis units. The scheduled maximum follow-up duration was 0.9 to 6.6 years, with the mean actual follow-up of 2.84 years. The interventions were standard-dose versus high-dose and low-flux versus high-flux hemodialysis in a 2 x 2 factorial design. RESULTS: At baseline, 80% of patients had cardiac diseases, including ischemic heart disease (IHD) (39%), congestive heart failure (40%), arrhythmia (31%), and other heart diseases (63%). There were a total of 1685 cardiac hospitalizations, with angina and acute myocardial infarction accounting for 42.7% of these hospitalizations. There were 343 cardiac deaths during follow-up, accounting for 39.4% of all deaths. IHD was implicated in 61.5% of the cardiac deaths. Any cardiac disease at baseline was highly predictive of cardiac death during follow-up [relative risk (RR) 2.57; 95% CI 1.73-3.83]. There were no significant effects of dose or flux assignments on the primary outcome of all-cause mortality or the main secondary cardiac composite outcome of first cardiac hospitalization or all-cause mortality. Assignment to high-flux dialysis was, however, associated with decreased cardiac mortality and the composite outcome of first cardiac hospitalization or death from cardiac causes. CONCLUSION: The HEMO Study identified IHD to be a major cause of cardiac hospitalizations and cardiac deaths. Future strategies for the prevention of cardiac diseases in the maintenance hemodialysis population should focus on this entity. Although high-flux dialysis did not reduce all-cause mortality, it might improve cardiac outcomes. This hypothesis needs to be further examined.

Adult↗
PubMed2004

Kinetics of urea and beta-microglobulin during and after short hemodialysis treatments.

BACKGROUND: Daily short hemodialysis (HD) is often prescribed by simply doubling treatment frequency and halving treatment time; however, the effect of this prescription approach on the equilibrated HD dose (urea eKt/V) and whole body clearance for beta(2)-microglobulin has not been established. METHODS: We compared urea and beta(2)-microglobulin kinetics during and 60 minutes after a short HD treatment and a conventional HD treatment in a crossover study on 22 maintenance HD patients: 16 male and 6 female, 61 +/- 18 (mean +/- standard deviation) years of age. One patient in each treatment modality was excluded from certain analyses because of missing data. Short and conventional HD treatments were essentially identical, except for treatment times, which were 116 +/- 14 and 241 +/- 27 minutes, respectively. Blood samples were collected at regular intervals during and after treatments, and additional blood and dialysate samples were collected at 60 minutes of treatment to evaluate dialyzer clearances. RESULTS: Plasma water urea clearances measured directly across the dialyzer during short and conventional HD treatments were not different (255 +/- 23 mL/min and 255 +/- 28 mL/min, respectively). The 60-minute postdialysis blood urea nitrogen concentration rebounded more (P < 0.01) after short HD than conventional HD (5.9 +/- 3.1 vs. 4.0 +/- 1.5 mg/dL, respectively). Calculated urea eKt/V values using the Daugirdas-Schneditz rate equation were not different from those measured during conventional HD using the 60-minute postdialysis concentration but significantly overestimated measured urea eKt/V values during short HD. Postdialysis rebound of beta(2)-microglobulin concentrations was variable but similar after short and conventional HD treatments (0.1 +/- 3.4 vs. 0.7 +/- 1.8 mg/L, respectively). Whole body clearances of beta(2)-microglobulin calculated from predialysis and immediate (10-second) postdialysis serum concentrations during short and conventional HD treatments were not different from each other (42.9 +/- 24.1 vs. 41.9 +/- 22.4 mL/min, respectively). CONCLUSION: These observations show that the Daugirdas-Schneditz rate equation is accurate in predicting urea eKt/V during conventional, but not during short, HD. In contrast, whole body clearances of beta(2)-microglobulin during short and conventional HD treatments were similar. We conclude that calculation of accurate estimates of urea eKt/V, but not clearances of beta(2)-microglobulin, differ during short and conventional HD treatments.

Blood Urea Nitrogen↗
PubMed2004

Inhibition of neointimal hyperplasia in vascular grafts by sustained perivascular delivery of paclitaxel.

BACKGROUND: Neointimal hyperplasia occurs commonly at the anastomoses of arteriovenous grafts for chronic hemodialysis, causing stenosis and occlusion. Antiproliferative drugs may be effective in inhibiting hyperplasia, but local drug delivery would be required to minimize systemic side effects. We examined the feasibility of local drug delivery to inhibit neointimal hyperplasia at dialysis grafts in a canine model. METHODS: Bilateral polytetrafluoroethylene loop grafts (10-cm length and 6-mm internal diameter) were placed between the femoral artery and ipsilateral femoral vein of five mongrel dogs. At the time of surgery or 1 to 5 weeks later, 2 mL of a thermosensitive biodegradable copolymer (ReGel) mixed with 0.26 mg or 0.65 mg paclitaxel were applied to the external surface of one graft around the anastomoses to provide a depot for sustained release of the drug. ReGel alone without paclitaxel was applied to the contralateral graft as a control. The grafts and the connecting vessels were explanted at eight or nine weeks, and the cross-sections were examined histologically. The degree of hyperplasia at the anastomoses was graded by five blinded independent reviewers, with scores ranging from 0 to 5. RESULTS: The median (25th-75th percentile) hyperplasia score of both arterial and venous anastomoses was 1.80 (0.90-3.05) in the grafts treated with ReGel alone, and 0.95 (0.70-1.50) in the grafts treated with ReGel/paclitaxel (N= 8; P < 0.05 by Wilcoxon signed rank test). There were no noticeable localized or systemic complications attributed to the treatments in these animals. Paclitaxel levels in the plasma obtained from forelimb veins were undetectable (<10 ng/mL). CONCLUSION: These results suggest that the local delivery of antiproliferative agents using a thermosensitive, injectable biodegradable copolymer (ReGel) for sustained delivery is a promising strategy to inhibit neointimal hyperplasia of arteriovenous hemodialysis grafts.

Animals↗
PubMed2004

In vitro pharmacological inhibition of human vascular smooth muscle cell proliferation for the prevention of hemodialysis vascular access stenosis.

BACKGROUND: Vascular access for chronic hemodialysis often fails as a result of stenosis caused primarily by the proliferation of vascular smooth muscle cells (VSMC). Various drugs have been shown to inhibit the proliferation of VSMC under different conditions. METHODS: In this study, we compared the inhibitory effect of ten drugs on the proliferation of human aortic smooth muscle cells (SMC) in culture. Quiescent cells were cultured in the presence of growth factors, fetal bovine serum and incremental concentrations of the test drug. Cell proliferation was assessed by the MTT reduction assay. RESULTS: Aspirin, enalaprilat, heparin, hydroxyurea, indomethacin and tirofiban were ineffective. While dipyridamole, paclitaxel, tranilast and verapamil inhibited cell proliferation, the concentrations required were significantly higher than the clinical plasma levels achieved after systemic administration. CONCLUSION: Local delivery of these drugs to the target site may therefore be a more effective and appropriate strategy for the prevention of hemodialysis vascular access stenosis.

Antineoplastic Agents↗
PubMed2004

Association of obesity with inflammation in chronic kidney disease: a cross-sectional study.

OBJECTIVE: As adipose tissue releases inflammatory cytokines, obesity is associated with elevated C-reactive protein (CRP) levels in the general population. We examined the cross-sectional association of body mass index (BMI) with CRP in patients with chronic kidney disease (CKD). DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: Ninety-four CKD patients with varying levels of renal function seen at the University of Utah outpatient renal clinic were studied. METHODS: Data on demographics (age, gender, race), comorbidity (diabetes mellitus, hypertension, myocardial infarction/angina, cerebrovascular disease, peripheral vascular disease, and smoking) and anthropometry (height and weight) were obtained by patient interview and chart reviews. High-sensitivity CRP was measured by the N-latex assay on a BN II nephelometer. MAIN OUTCOME MEASURE: Risk factors of high CRP. RESULTS: In a multivariable logistic regression model, when compared with patients with a BMI < 25, the odds of CRP > 3.0 mg/L were 2.5-fold (95% CI, 1.02 to 5.99) higher in patients with BMI > or = 30. In a stepwise multiple linear regression model, BMI (regression coefficient [beta] = 0.06; 95% CI, 0.03 to 0.1; P < .01), serum creatinine (beta = 0.16; 95% CI, 0.04 to 0.3; P = .01) and age (beta = 0.01; 95% CI, -0.001 to 0.03; P = .05) were significantly associated with log transformed CRP. CONCLUSION: These data suggest that as in the general population, in CKD patients, obesity, a traditional risk factor for atherosclerosis, is associated with inflammation, a novel risk factor for atherosclerosis.

Adult↗
PubMed2003

Creatinine production, nutrition, and glomerular filtration rate estimation.

This study examined the validity and clinical implications of the assumption of the Modification of Diet in Renal Disease Study (MDRD) formula that age, gender, race, and BUN account for creatinine production (CP). The relationships of MDRD GFR, CP, and nutrition were examined in 1074 Dialysis Morbidity and Mortality Study Wave II patients with reported measured creatinine clearances at initiation of dialysis. Age, gender, race, BUN, and serum creatinine (Scr) were used to calculate MDRD GFR. The measured 24-h urinary creatinine was used to estimate CP. In linear regression, Scr positively correlated with CP independent of age, gender, race, and BUN. Compared with the highest CP quartile, the lowest CP quartile had lower creatinine clearance (5.8 +/- 2.9 versus 11.3 +/- 3.4 ml/min, P <.01) despite lower Scr (5.8 +/- 2.6 versus 8.6 +/- 3.1 mg%, P <.01). There was an excellent correlation between the reciprocal of Scr and the MDRD GFR (r = 0.90). As a result, the MDRD GFR was higher in the lowest CP quartile (10.9 +/- 4.6 versus 7.6 +/- 2.4 ml/min, P <.01). Malnutrition (48% versus 26%, P <.01) was more common in the lowest CP quartile. Each 5-ml/min increase in MDRD GFR was associated with 21% higher odds of malnutrition (P = 0.046) in a multivariable logistic regression, which was abolished by controlling for CP. The fundamental assumption of the MDRD formula is invalid in patients with advanced renal failure, and the use of this formula in these patients might introduce biases.

Adult↗
PubMed2003

Impact of timing of initiation of dialysis on mortality.

Previous studies showed that sicker patients were initiated on dialysis at higher GFR as estimated by the Modification of Diet in Renal Disease (MDRD) formula. It was previously shown that patients with low creatinine production were malnourished and had low serum creatinine levels and creatinine clearances (CrCl) but high MDRD GFR at initiation of dialysis. Therefore, a propensity score approach was used to examine the associations of MDRD GFR and measured CrCl at the initiation of dialysis with subsequent mortality. Baseline data and outcomes were obtained from the Dialysis Morbidity Mortality Study Wave II. Propensity scores for early initiation derived by logistic regression were used in Cox models to examine mortality. Each 5-ml/min increase in MDRD GFR at initiation of dialysis in the entire cohort was associated with increased hazard of death in multivariable Cox model (hazard ratio [HR] 1.14; P = 0.002). In the subgroup of patients with reported CrCl, higher MDRD GFR was associated with increased risk of death (for each 5-ml/min increase, HR 1.27; P < 0.001) but not CrCl (for each 5-ml/min increase, HR 0.98; P = 0.81). These divergent results might reflect erroneous GFR estimation by the MDRD formula. Furthermore, these data do not support earlier initiation of dialysis. Therefore, for patients without clinical indications for initiation of dialysis, the appropriate GFR level for initiation of dialysis is unknown.

Adult↗
PubMed2003

Effects of high-flux hemodialysis on clinical outcomes: results of the HEMO study.

Among the 1846 patients in the HEMO Study, chronic high-flux dialysis did not significantly affect the primary outcome of the all-cause mortality (ACM) rate or the main secondary composite outcomes, including the rates of first cardiac hospitalization or ACM, first infectious hospitalization or ACM, first 15% decrease in serum albumin levels or ACM, or all non-vascular access-related hospitalizations. The high-flux intervention, however, seemed to be associated with reduced risks of specific cardiac-related events. The relative risks (RR) for the high-flux arm, compared with the low-flux arm, were 0.80 [95% confidence interval (CI), 0.65 to 0.99] for cardiac death and 0.87 (95% CI, 0.76 to 1.00) for the composite of first cardiac hospitalization or cardiac death. Also, the effect of high-flux dialysis on ACM seemed to vary, depending on the duration of prior dialysis. This report presents secondary analyses to further explore the relationship between the flux intervention and the duration of dialysis with respect to various outcomes. The patients were stratified into a short-duration group and a long-duration group, on the basis of the mean duration of dialysis of 3.7 yr before randomization. In the subgroup that had been on dialysis for >3.7 yr, randomization to high-flux dialysis was associated with lower risks of ACM (RR, 0.68; 95% CI, 0.53 to 0.86; P = 0.001), the composite of first albumin level decrease or ACM (RR, 0.74; 95% CI, 0.60 to 0.91; P = 0.005), and cardiac deaths (RR, 0.63; 95% CI, 0.43 to 0.92; P = 0.016), compared with low-flux dialysis. No significant differences were observed in outcomes related to infection for either duration subgroup, however, and the trends for beneficial effects of high-flux dialysis on ACM rates were considerably weakened when the years of dialysis during the follow-up phase were combined with the prestudy years of dialysis in the analysis. For the subgroup of patients with <3.7 yr of dialysis before the study, assignment to high-flux dialysis had no significant effect on any of the examined clinical outcomes. These data suggest that high-flux dialysis might have a beneficial effect on cardiac outcomes. Because these results are derived from multiple statistical comparisons, however, they must be interpreted with caution. The subgroup results that demonstrate that patients with different durations of dialysis are affected differently by high-flux dialysis are interesting and require further study for confirmation.

Female↗
PubMed2002

Effect of dialysis dose and membrane flux in maintenance hemodialysis.

BACKGROUND: The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain. METHODS: We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer. RESULTS: In the standard-dose group, the mean (+/-SD) urea-reduction ratio was 66.3+/-2.5 percent, the single-pool Kt/V was 1.32+/-0.09, and the equilibrated Kt/V was 1.16+/-0.08; in the high-dose group, the values were 75.2+/-2.5 percent, 1.71+/-0.11, and 1.53+/-0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3+/-7 ml per minute in the low-flux group and 34+/-11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as compared with the standard-dose group was 0.96 (95 percent confidence interval, 0.84 to 1.10; P=0.53), and the relative risk of death in the high-flux group as compared with the low-flux group was 0.92 (95 percent confidence interval, 0.81 to 1.05; P=0.23). The main secondary outcomes (first hospitalization for cardiac causes or death from any cause, first hospitalization for infection or death from any cause, first 15 percent decrease in the serum albumin level or death from any cause, and all hospitalizations not related to vascular access) also did not differ significantly between either the dose groups or the flux groups. Possible benefits of the dose or flux interventions were suggested in two of seven prespecified subgroups of patients. CONCLUSIONS: Patients undergoing hemodialysis thrice weekly appear to have no major benefit from a higher dialysis dose than that recommended by current U.S. guidelines or from the use of a high-flux membrane.

Adult↗
PubMed2002

Relationship between volume status and blood pressure during chronic hemodialysis.

BACKGROUND: The relationship between volume status and blood pressure (BP) in chronic hemodialysis (HD) patients remains incompletely understood. Specifically, the effect of interdialytic fluid accumulation (or intradialytic fluid removal) on BP is controversial. METHODS: We determined the association of the intradialytic decrease in body weight (as an indicator of interdialytic fluid gain) and the intradialytic decrease in plasma volume (as an indicator of postdialysis volume status) with predialysis and postdialysis BP in a cross-sectional analysis of a subset of patients (N=468) from the Hemodialysis (HEMO) Study. Fifty-five percent of patients were female, 62% were black, 43% were diabetic and 72% were prescribed antihypertensive medications. Dry weight was defined as the postdialysis body weight below which the patient developed symptomatic hypotension or muscle cramps in the absence of edema. The intradialytic decrease in plasma volume was calculated from predialysis and postdialysis total plasma protein concentrations and was expressed as a percentage of the plasma volume at the beginning of HD. RESULTS: Predialysis systolic and diastolic BP values were 153.1 +/- 24.7 (mean +/- SD) and 81.7 +/- 14.8 mm Hg, respectively; postdialysis systolic and diastolic BP values were 136.6 +/- 22.7 and 73.9 +/- 13.6 mm Hg, respectively. As a result of HD, body weight was reduced by 3.1 +/- 1.3 kg and plasma volume was contracted by 10.1 +/- 9.5%. Multiple linear regression analyses showed that each kg reduction in body weight during HD was associated with a 2.95 mm Hg (P=0.004) and a 1.65 mm Hg (P=NS) higher predialysis and postdialysis systolic BP, respectively. In contrast, each 5% greater contraction of plasma volume during HD was associated with a 1.50 mm Hg (P=0.026) and a 2.56 mm Hg (P < 0.001) lower predialysis and postdialysis systolic BP, respectively. The effects of intradialytic decreases in body weight and plasma volume were greater on systolic BP than on diastolic BP. CONCLUSIONS: HD treatment generally reduces BP, and these reductions in BP are associated with intradialytic decreases in both body weight and plasma volume. The absolute predialysis and postdialysis BP levels are influenced differently by acute intradialytic decreases in body weight and acute intradialytic decreases in plasma volume; these parameters provide different information regarding volume status and may be dissociated from each other. Therefore, evaluation of volume status in chronic HD patients requires, at minimum, assessments of both interdialytic fluid accumulation (or the intradialytic decrease in body weight) and postdialysis volume overload.

Adult↗