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      Comparison of toxin removal outcomes in online hemodiafiltration and intra-dialytic exercise in high-flux hemodialysis: A prospective randomized open-label clinical study protocol

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          Maintenance hemodialysis (HD) patients universally suffer from excess toxin load. Hemodiafiltration (HDF) has shown its potential in better removal of small as well as large sized toxins, but its efficacy is restricted by inter-compartmental clearance. Intra-dialytic exercise on the other hand is also found to be effective for removal of toxins; the augmented removal is apparently obtained by better perfusion of skeletal muscles and decreased inter-compartmental resistance. The aim of this trial is to compare the toxin removal outcome associated with intra-dialytic exercise in HD and with post-dilution HDF.


          The main hypothesis of this study is that intra-dialytic exercise enhances toxin removal by decreasing the inter-compartmental resistance, a major impediment for toxin removal. To compare the HDF and HD with exercise, the toxin rebound for urea, creatinine, phosphate, and β 2-microglobulin will be calculated after 2 hours of dialysis. Spent dialysate will also be collected to calculate the removed toxin mass. To quantify the decrease in inter-compartmental resistance, the recently developed regional blood flow model will be employed. The study will be single center, randomized, self-control, open-label prospective clinical research where 15 study subjects will undergo three dialysis protocols (a) high flux HD, (b) post-dilution HDF, (c) high flux HD with exercise. Multiple blood samples during each study session will be collected to estimate the unknown model parameters.


          This will be the first study to investigate the exercise induced physiological change(s) responsible for enhanced toxin removal, and compare the toxin removal outcome both for small and middle sized toxins in HD with exercise and HDF. Successful completion of this clinical research will give important insights into exercise effect on factors responsible for enhanced toxin removal. The knowledge will give confidence for implementing, sustaining, and optimizing the exercise in routine dialysis care. We anticipate that toxin removal outcomes from intra-dialytic exercise session will be comparable to that obtained by standalone HDF. These results will encourage clinicians to combine HDF with intra-dialytic exercise for significantly enhanced toxin removal.

          Trial registration

          ClinicalTrials.gov number, NCT01674153

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          Most cited references 32

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          Serum beta2-microglobulin level is a significant predictor of mortality in maintenance haemodialysis patients.

          Beta(2)-microglobulin (beta(2)-M) is recognized as a surrogate marker of middle-molecule uraemic toxins and is a key component in the genesis of dialysis-associated amyloidosis. Few studies have evaluated the association of beta(2)-M levels with clinical outcome in dialyzed patients. The prognostic implication of serum beta(2)-M levels for the survival of haemodialysis patients was examined in 490 prevalent haemodialysis patients (60.1 +/- 11.8 years, haemodialysis duration of 87.4 +/- 75.7 months, 288 males and 202 females; 24% diabetics). The patients were divided into two groups according to their serum beta(2)-M levels: lower beta(2)-M group (n = 245) with serum beta(2)-M or=32.2 mg/L. During the follow-up period of 40 +/- 15 months, there were 91 all-cause deaths, and out of them, 36 were from cardiovascular diseases. Kaplan-Meier analysis revealed that all-cause mortality in the higher beta(2)-M group was significantly higher compared to that in the lower beta(2)-M group (P < 0.001). Multivariate Cox proportional hazards analyses showed that serum beta(2)-M level was a significant predictor for all-cause mortality (hazard ratio, 1.05; 95% CI, 1.01-1.08; P = 0.005), and for non-cardiovascular mortality (hazard ratio, 1.06; 95% CI, 1.02-1.10; P = 0.006), after adjustment for age, gender, haemodialysis duration, the presence of diabetes, serum albumin and serum C-reactive protein. These results demonstrate that the serum beta(2)-M level is a significant predictor of mortality in haemodialysis patients, independent of haemodialysis duration, diabetes, malnutrition and chronic inflammation, suggesting the clinical importance of lowering serum beta(2)-M in these patients.
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            Exercise training during hemodialysis improves dialysis efficacy and physical performance.

            To determine the impact of a 20-week intradialytic exercise program, consisting of 60 minutes of cumulative duration, low-intensity exercise during the first 2 hours of dialysis, on dialysis efficacy, physical performance, and quality of life in self-care hemodialysis (HD) patients. One-group repeated measures. Satellite HD units affiliated with a Canadian teaching hospital. A convenience sample of 13 self-care HD patients who were stable on dialysis for a minimum of 6 months and were medically screened for significant cardiac, pulmonary, and/or musculoskeletal pathology that would preclude exercise. A 5-month intradialytic exercise program in which subjects exercised 3 times a week (cycle ergometer, mini-stepper) for 30 minutes in each of the first 2 hours of HD. Dialysis efficacy (in single-pool model of urea kinetics [spKt/V]) was assessed prior to and at the end of each month of the exercise program. Physical function (6-minute walk test [6MWT]), and quality of life. (Kidney Disease Quality of Life-Short Form [KDQOL]) were determined at baseline and at weeks 10 and 20 of the exercise program. SpKt/V increased 11% at the end of the first month of the program (P<.05) and remained elevated for the duration of the program (18%-19%). Distance walked on the 6MWT increased by 14% at both weeks 10 and 20 (P<.05). No changes were noted in KDQOL scores. A low-intensity intradialytic exercise program is a viable adjunctive therapy, which improves HD efficacy and physical function in HD patients.
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              Control of serum phosphate without any phosphate binders in patients treated with nocturnal hemodialysis.

              We compared the efficacy and the long-term effects of nocturnal hemodialysis (NHD) versus conventional hemodialysis (CHD) in controlling serum phosphate levels in patients with end-stage renal disease (ESRD). Patients underwent thrice weekly CHD and were subsequently switched to NHD six nights weekly. In the "acute" study serum and dialysate phosphate were measured during and after dialysis, and the total dialysate was collected to calculate mass solute removal. Although pre-dialysis (1.7 +/- 0.6 vs. 1.5 +/- 0.8 mM) serum phosphate levels were similar in CHD and NHD, respectively, post-dialysis levels were slightly lower with CHD (0.7 +/- 0.2 vs. 0.8 +/- 0.2 mM, P < 0.05). The measured phosphate removed per session of CHD or NHD was comparable, 25.3 +/- 7.5 versus 26.9 +/- 9.8 mumol/session, respectively. On the other hand, the cumulative weekly phosphate removal was significantly higher with NHD as compared to CHD, 75.8 +/- 22.5 versus 161.6 +/- 59.0 mumol/week (P < 0.01). In the "chronic" study serum phosphate levels were measured monthly for five months on CHD and for five months after the patients were switched to NHD. Dietary phosphate intake and the dosage of phosphate binders were tabulated. Serum phosphate levels fell during NHD: 2.1 +/- 0.5 mM at the beginning of the study and 1.3 +/- 0.2 mM five months after being switched to NHD (P < 0.001). At the same time dietary phosphate intake increased by 50%. By the fourth month of NHD therapy none of the patients was taking any phosphate binders. In conclusion, NHD is more effective in controlling serum phosphate levels than CHD, allowing patients to discontinue their phosphate binders completely and to ingest a more liberal diet.

                Author and article information

                BMC Nephrol
                BMC Nephrol
                BMC Nephrology
                BioMed Central
                23 November 2012
                : 13
                : 156
                [1 ]Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
                [2 ]Rehabilitation Medicine, National University Hospital, Singapore, Singapore
                [3 ]National University Heart Center, Singapore, Singapore
                [4 ]Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
                [5 ]Department of Laboratory Medicine, National University Hospital, Singapore, Singapore
                [6 ]Division of Nephrology, Department of Medicine, National University Hospital, Singapore, Singapore
                Copyright ©2012 Maheshwari et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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