Daily versus standard hemodialysis: one year experience

Update on Pediatric Hemodialysis Adequacy

The use of high reflux dialyzers to achieve a Kt/V_urea above 1.2 did not improve patient survival in most literature reports. After an electronic search in many sites, guidelines, systematic reviews, and review articles (cited references): We recommend (1) using the equilibrated double-pool, weekly rather than per session, Kt/V_urea, (2) Use of UF-dry weight to avoid V changes, (3) consider protein catabolic Rate (4) Use of double pool to avoid urea generation rebound effect. Beyond the urea model, other recommended parameters include the middle molecule clearance and patient clinical data as blood pressure control, normal ventricular morphology, and function, absence of anemia, bone mineral disease, vascular calcifications, good nutrition and growth, long-lasting vascular access, less intra-dialysis hypotension, fewer hospitalizations related to complications as infection, long-term patient survival with better life quality. All mentioned parameters are the good markers for adequate dialysis. Since (1) frequent short and (or) slow long dialysis sessions show better solute clearance and hemodynamic stability associated with better control of cardiovascular and bone disease, anemia, nutrition, and growth with better quality of life and survival. (2) The spare in the cost of the antihypertensive medications, erythroid-stimulating drugs, phosphate binders, and frequent hospitalization, compensates for the high dialysis cost. (3) The use of some advisable techniques can minimize access trauma; therefore, HD Model can be changeable according to each patient's clinical and biochemical follow-up dialysis adequacy progress pattern.

Hyperphosphatemia in Dialysis Patients: Beyond Nonadherence to Diet and Binders

Hyperphosphatemia in dialysis patients is routinely attributed to nonadherence to diet, prescribed phosphate binders, or both. The role of individual patient variability in other determinants of phosphate control is not widely recognized. In a manner that cannot be explained by dialysis parameters or serum phosphate levels, dialytic removal of phosphate may vary by >400mg per treatment. Similarly, enteral phosphate absorption, unexplained by diet or vitamin D intake, may differ by ≥250mg/d among patients. Binder efficacy also varies among patients, with 2-fold differences reported. One or more elements of this triple threat-varying dialytic removal, phosphate absorption, and phosphate binding-may account for hyperphosphatemia in dialysis patients rather than nonadherence to therapy. Just as the cause(s) of hyperphosphatemia may vary, so too may an individual patient's response to different therapeutic interventions.

Effect of frequent or extended hemodialysis on cardiovascular parameters: a meta-analysis

BACKGROUND

Increased left ventricular (LV) mass is a risk factor for cardiovascular mortality in patients with chronic kidney failure. More frequent or extended hemodialysis (HD) has been hypothesized to have a beneficial effect on LV mass.

STUDY DESIGN

Meta-analysis.

SETTING & POPULATION

MEDLINE literature search (inception to April 2011), Cochrane Central Register of Controlled Trials and ClinicalTrials.gov using the search terms "short daily HD," "daily HD," "quotidian HD," "frequent HD," "intensive HD," "nocturnal HD," and "home HD."

SELECTION CRITERIA FOR STUDIES

Single-arm cohort studies (with pre- and post-study evaluations) and trials examining the effect of frequent or extended HD on cardiac morphology and function and blood pressure parameters. Studies of hemofiltration, hemodiafiltration, and peritoneal dialysis were excluded.

INTERVENTION

Frequent (2-8 hours, >3 times weekly) or extended (>4 hours, 3 times weekly) HD compared with conventional (≤4 hours, 3 times weekly) HD.

OUTCOMES

Absolute changes in cardiac morphology and function, including LV mass index (LVMI; primary) and blood pressure parameters (secondary).

RESULTS

We identified 38 single-arm studies, 5 crossover trials, and 3 randomized controlled trials. By meta-analysis of 23 study arms, frequent or extended HD significantly reduced LVMI from baseline (-31.2 g/m(2), 95% CI, -39.8 to -22.5; P < 0.001). The 3 randomized trials found a less pronounced net reduction in LVMI (-7.0 g/m(2); 95% CI, -10.2 to -3.7; P < 0.001). LV ejection fraction improved by 6.7% (95% CI, 1.6% to 11.9%; P = 0.01). Other cardiac morphologic parameters showed similar improvements. There also were significant decreases in systolic, diastolic, and mean blood pressure and mean number of antihypertensive medications.

LIMITATIONS

Paucity of randomized controlled trials.

CONCLUSIONS

Conversion from conventional to frequent or extended HD is associated with improvements in cardiac morphology and function, including LVMI and LV ejection fraction, respectively, and several blood pressure parameters, which collectively might confer long-term cardiovascular benefit. Trials with long-term clinical outcomes are needed.

Modification of cardiovascular risk in hemodialysis patients: An evidence-based review

Cardiovascular disease accounts for 40% to 50% of deaths in dialysis populations. Overall, the risk of cardiac mortality is 10-fold to 20-fold greater in dialysis patients than in age and sex-matched controls without chronic kidney disease. The aim of this paper is to review critically the evidence that cardiac outcomes in dialysis patients are modified by cardiovascular risk factor interventions. There is limited, but as yet inconclusive controlled trial evidence that cardiovascular outcomes in dialysis populations may be improved by antioxidants (vitamin E or acetylcysteine), ensuring that hemoglobin levels do not exceed 120 g/L (especially in the setting of known cardiovascular disease), prescribing carvedilol in the setting of dilated cardiomyopathy, and by using cinacalcet in uncontrolled secondary hyperparathyroidism. Similarly, there are a number of negative controlled trials, which have demonstrated that statins, high-dose folic acid, angiotensin-converting enzyme inhibitors, multiple risk factor intervention via multidisciplinary clinics, and high-dose or high-flux dialysis are ineffective in preventing cardiovascular disease. Although none of these studies could be considered conclusive, the negative trials to date should raise significant concerns about the heavy reliance of current clinical practice guidelines on extrapolation of findings from cardiovascular intervention trials in the general population. It may be that cardiovascular disease in dialysis populations is less amenable to intervention, either because of the advanced stage of chronic kidney disease or because the pathogenesis of cardiovascular disease in dialysis patients is different from that in the general population. Large, well-conducted, multicenter randomized-controlled trials in this area are urgently required.

Daily Hemodialysis: A Systematic Review

Several studies have reported improved outcomes with daily hemodialysis (DHD), but the strength of this evidence has not been evaluated. The published evidence on DHD was synthesized and its quality rated to inform need and sample size calculations for a randomized trial. Citations were identified in MEDLINE and EMBASE using validated search strategies. Dialysis journals that were not indexed and bibliographies of relevant articles were hand-searched. Two authors reviewed all citations. Articles that reported original data on five or more adults who were receiving DHD (1.5 to 3 h, 5 to 7 d/wk) for > or = 3 mo were included. Twenty-five articles reporting 14 unique populations with 268 patients (five to 72 per study) met inclusion criteria. Of the 14 cohorts, 13 were studied with an observational design, 10 were studied prospectively, and four had parallel control groups. Mean age ranged form 41 to 64 yr, mean time on dialysis was 2 to 11 yr, 0 to 28% of patients had diabetes, > 90% had arteriovenous fistulae, and > 50% were dialyzed at home. Most data were described at < or = 12 mo of follow-up. Outcomes included quality of life, cardiovascular disease, erythropoiesis, nutritional status, hospitalizations, and vascular access failures. Reporting was too heterogeneous to allow pooling of data. Ten of 11 studies suggested improvements in blood pressure; findings for other outcomes varied. Discontinuation of DHD occurred in 0 to 57% in-center and 0 to 15% home patients. Studies of DHD are limited by small sample size, nonideal control groups, selection and dropout biases, and paucity of data on potential risks. Randomized trials with adequate statistical power are required to establish the efficacy and the safety of DHD.

Prolonged protective effect of short daily hemodialysis against dialysis-induced hypotension

BACKGROUND/AIMS

Short daily hemodialysis (HD) has a protective effect against dialysis-induced hypotension (DIH). We examined whether this effect extends beyond the treatment period.

METHODS

We analyzed clinical variables in 6 patients (5 with diabetes mellitus) who underwent conventional hemodialysis (CHD) for 4 h three times weekly for 12 weeks; then short daily HD for 2 h six times weekly for 12 weeks, and then 12 more weeks of CHD. All patients had been given vasopressors for severe DIH.

RESULTS

The severe DIH disappeared during the short daily HD. There were significant decreases in body weight (BW), cardiothoracic ratio (CTR), blood pressure (BP), normal saline solution (NSS) amount (62.8 +/- 26.4 vs. 9.8 +/- 7.4 ml/session, p < 0.05), frequency (0.60 +/- 0.26 vs. 0.10 +/- 0.07 infusions/session, p < 0.05) and postdialysis atrial natriuretic peptide (ANP) (176.8 +/- 56.4 vs. 104.8 +/- 42.3 pg/ml, p < 0.05). Weekly ultrafiltration volume (6.3 +/- 0.9 vs. 7.9 +/- 0.7 l, p < 0.05) was significantly higher during the short daily HD period than during the first CHD period. The vasopressor treatment was therefore stopped or reduced in all patients during the short daily HD period. Because DIH recurred in the second CHD period despite a significant increase in BP, the vasopressor treatment was resumed in 5 patients. BW, CTR, NSS infusion amount and frequency, or postdialysis ANP did not differ significantly between the short daily HD and second CHD periods.

CONCLUSIONS

The protective effect of short daily HD against DIH lasted more than 12 weeks after the treatment ended. We therefore conclude that temporary short daily HD is useful for preventing DIH.

Hypertension control with daily dialysis

Hypertension is present in 60-90% of patients on maintenance hemodialysis (HD) and it is an important cause of cardiovascular (CV) mortality and morbidity. Frequent and prolonged HD has been uniformly shown to control hypertension in end-stage renal disease (ESRD) patients more effectively than conventional HD. The etiology of hypertension is predominantly volume dependent, but in a subset of patients increased renin, sympathetic overactivity, and endothelial dysfunction may play a role. Intradialytic hypotension precludes attainment of dry weight and hence optimal control of hypertension in conventional HD is challenging. Frequent and prolonged dialysis with gentle and persistent ultrafiltration allows time for refilling of the intravascular compartment and permits normalization of extracellular volume. It is also possible that intensive dialysis enables removal of pressor molecules and improves endothelial function. Improved blood pressure control translates into regression of left ventricular hypertrophy in patients on daily HD. Thus prolonged and frequent dialysis permits better control of hypertension via volume and volume-independent mechanisms and also improves cardiac geometry.

Vascular access survival and morbidity on daily dialysis: a comparative analysis of home and limited care haemodialysis

BACKGROUND

Concerns about vascular access failure may have limited the widespread use of daily haemodialysis (DHD). We assessed the incidence and type of vascular access complications during DHD and other schedules, both at home and on limited care haemodialysis.

METHODS

All patients were treated in a limited care and home haemodialysis unit with a stable caregiver team (November 1998-November 2002). Vascular access failure, surgical treatment, angioplasty and declotting were studied alone or in combination by univariate and multivariate models. We analysed the effects of age, sex, comorbidity, previous vascular events, schedule, setting of treatment (home, limited care), dialysis follow-up, vascular access (native vs prosthetic, first vs subsequent) and setting of vascular access creation. 'Intention to treat' and 'per protocol' analyses were performed.

RESULTS

In 2160 patient-months (home dialysis: DHD 400 months, non-DHD 655 months; limited care: DHD 208 months; non-DHD 897 months), 57 adverse events occurred (27 failures), in which 30 were at home (nine DHD) and 27 were in limited care (five DHD). The probability of remaining free from adverse events at 6 and 12 months was 89% and 80% on DHD and 79% and 76% on other schedules ('intention to treat'). Univariate analyses revealed a significant difference for the setting of the vascular access creation (lower risk of vascular access complications in our centre) and sex (male sex was protective). Logistic regression and Cox analyses confirmed the role for the setting of the vascular access creation.

CONCLUSIONS

Although DHD did not appear as a risk factor for vascular access morbidity or failure at home or in a limited care centre setting, the setting of vascular access creation may influence its success.

DAILY HEMODIALYSIS-SELECTED TOPICS: Short Daily Hemodialysis and Nutritional Status in Patients with Chronic Renal Failure

Malnutrition is a frequent complication in hemodialysis patients and is associated with increased mortality and morbidity. Interventions such as oral or intravenous nutritional supplements have often failed to improve nutritional status. We report here the effect that daily dialysis, practiced in our center since 1997, has had on nutritional parameters. Seventeen patients treated with conventional hemodialysis (4-5 hours, three times per week, for 9.6 +/- 8.4 years) were converted to short daily hemodialysis (2-2.5 hours, six times per week, for a mean of 39.1 +/- 23.5 months). Dietary, anthropometric, and biochemical evaluations were performed during conventional hemodialysis, after 1 year on short daily hemodialysis (sDHD(year)), and at the end of follow-up (sDHD(end)). Daily protein intake increased from 1.21 +/- 0.27 g/kg/day with conventional hemodialysis to 1.51 +/- 0.47 g/kg/day at sDHD(year) and 1.51 +/- 0.37 g/kg/day at sDHD(end). Energy intake increased from 33.6 +/- 9.5 kcal/kg/day to 38.3 +/- 10.9 kcal/kg/day at sDHD(year) and 39.4 +/- 9.4 kcal/kg/day at sDHD(end). The normalized protein equivalent nitrogen appearance (nPNA) increased from 1.19 +/- 0.34 g/kg/day with conventional hemodialysis to 1.34 +/- 0.43 g/kg/day sDHD(year) and 1.37 +/- 0.37 g/kg/day sDHD(end). Biochemical indicators also increased: serum albumin increased from 40.2 +/- 3.3 g/L to 44.5 +/- 4.6 g/L and 45.1 +/- 4.1 g/L, and prealbumin increased from 0.32 +/- 0.06 g/L to 0.38 +/- 0.09 g/L and 0.36 +/- 0.09 g/L, respectively. These improvements were accompanied by an increase in body weight from 62.0 +/- 10.6 kg on conventional hemodialysis to 64.3 +/- 10.2 kg at sDHD(year) and 65.5 +/- 9.7 kg at sDHD(end). All the changes between conventional hemodialysis and short daily hemodialysis were statistically significant. Increased frequency is more important than increased dialysis dose. Short daily hemodialysis appears to be a suitable method to improve nutritional status in dialysis patients.

Willingness of dialysis patients to participate in a randomized controlled trial of daily dialysis

BACKGROUND

The National Institutes of Health (NIH) has proposed conducting randomized controlled trials comparing short, daily, in-center hemodialysis with conventional hemodialysis. However, there is concern that difficulties recruiting patients may prevent the successful completion of such trials if patients believe the inconveniences of daily dialysis outweigh any potential health benefits.

METHODS

To gauge willingness to participate in a daily dialysis trial, we described a hypothetical, randomized controlled trial comparing conventional to daily hemodialysis to 209 chronic hemodialysis patients, and assessed their motivations for and concerns about participating.

RESULTS

We found that 85 patients (41%) of 209 patients who agreed to be interviewed expressed some willingness to participate in the hypothetical trial. Patients who expressed greater willingness to participate were younger (OR for participating = 0.96 per year, 95% CI = 0.94 to 0.98, P= 0.001), less likely to smoke (OR = 0.38, 95% CI = 0.17 to 0.84, P= 0.017), more likely to have been hospitalized during the last 12 months (OR = 2.8, 95% CI = 1.5 to 5.5, P= 0.002), less likely to have reactive airway disease (OR = 0.21, 95% CI = 0.06 to 0.69, P= 0.01) or coronary artery disease (OR = 0.20, 95% CI = 0.08 to 0.53, P= 0.001), and less likely to be on the waiting list for a kidney transplant (OR = 0.23, 95% CI = 0.10 to 0.50, P < 0.0001).

CONCLUSION

The study suggests that less than half of eligible patients would be willing to participate in the randomized controlled trial. Differing willingness to participate across patient subgroups suggests that certain subgroups (i.e., older patients and those with coronary artery disease) will need to be targeted to ensure that results are generalizable to most hemodialysis patients.

Hyperphosphatemia in end-stage renal disease

Hyperphosphatemia occurs universally in end-stage renal disease (ESRD) unless efforts are made to prevent positive phosphate balance. Positive phosphate balance results from the loss of renal elimination of phosphate and continued obligatory intestinal absorption of dietary phosphate. Increased efflux of phosphate from bone because of excess parathyroid hormone-mediated bone resorption can also contribute to increased serum phosphate concentrations in the setting of severe hyperparathyroidism. It is important to treat hyperphosphatemia because it contributes to the pathogenesis of hyperparathyroidism, vascular calcifications, and increased cardiovascular mortality in ESRD patients. Attaining a neutral phosphate balance, which is the key to the management of hyperphosphatemia in ESRD, is a challenge. Control of phosphorus depends on its removal during dialysis and the limitation of gastrointestinal absorption by dietary phosphate restriction and chelation of phosphate. Knowledge of the quantitative aspects of phosphate balance is useful in optimizing our use of phosphate binders, dialysis frequency, and vitamin D sterols. The development of new phosphate binders and efforts to find new ways to inhibit gastrointestinal absorption of phosphate will lead to improvements in the control of serum phosphate levels in ESRD.

Regression of left ventricular hypertrophy after conversion to nocturnal hemodialysis

BACKGROUND

Left ventricular hypertrophy (LVH) is an independent risk factor for mortality in the dialysis population. LVH has been attributed to several factors, including hypertension, excess extracellular fluid (ECF) volume, anemia and uremia. Nocturnal hemodialysis is a novel renal replacement therapy that appears to improve blood pressure control.

METHODS

This observational cohort study assessed the impact on LVH of conversion from conventional hemodialysis (CHD) to nocturnal hemodialysis (NHD). In 28 patients (mean age 44 +/- 7 years) receiving NHD for at least two years (mean duration 3.4 +/- 1.2 years), blood pressure (BP), hemoglobin (Hb), ECF volume (single-frequency bioelectrical impedance) and left ventricular mass index (LVMI) were determined before and after conversion. For comparison, 13 control patients (mean age 52 +/- 15 years) who remained on self-care home CHD for one year or more (mean duration 2.8 +/- 1.8 years) were studied also. Serial measurements of BP, Hb and LVMI were also obtained in this control group.

RESULTS

There were no significant differences between the two cohorts with respect to age, use of antihypertensive medications, Hb, BP or LVMI at baseline. After transfer from CHD to NHD, there were significant reductions in systolic, diastolic and pulse pressure (from 145 +/- 20 to 122 +/- 13 mm Hg, P < 0.001; from 84 +/- 15 to 74 +/- 12 mm Hg, P = 0.02; from 61 +/- 12 to 49 +/- 12 mm Hg, P = 0.002, respectively) and LVMI (from 147 +/- 42 to 114 +/- 40 g/m2, P = 0.004). There was also a significant reduction in the number of prescribed antihypertensive medications (from 1.8 to 0.3, P < 0.001) and an increase in Hb in the NHD cohort. Post-dialysis ECF volume did not change. LVMI correlated with systolic blood pressure (r = 0.6, P = 0.001) during nocturnal hemodialysis. There was no relationship between changes in LVMI and changes in BP or Hb. In contrast, there were no changes in BP, Hb or LVMI in the CHD cohort over the same time period.

CONCLUSIONS

Reductions in BP with NHD are accompanied by regression of LVH.

Hemodialysis-associated hypertension: pathophysiology and therapy

The majority of end-stage renal disease (ESRD) patients are hypertensive. Hypertension in the hemodialysis patient population is multifactorial. Further, hypertension is associated with an increased risk for left ventricular hypertrophy, coronary artery disease, congestive heart failure, cerebrovascular complications, and mortality. Antihypertensive medications alone do not adequately control blood pressure (BP) in hemodialysis patients. There are, however, several therapeutic options available to normalize BP in these patients, often without the need for additional drug therapy (eg, long, slow hemodialysis; short, daily hemodialysis; nocturnal hemodialysis; or, most effectively, dietary salt and fluid restriction in combination with reduction of dialysate sodium concentration). Optimal BP in dialysis patients is not different from recommendations for the general population, even though definite evidence is not yet available. Predialysis systolic and diastolic BPs are of particular importance. Left ventricular mass correlates with predialysis systolic BP. Survival is better in hemodialysis patients with a mean arterial pressure below 99 mm Hg as compared with those with higher BP. Low predialysis systolic BP (<110 mm Hg) and low predialysis diastolic BP (<70 mm Hg) are associated with increased mortality, primarily because of severe congestive heart failure or coronary artery disease. Patients that experience repeated intradialytic hypotensive episodes should also be viewed with caution, and predialytic BP values should be reevaluated. A possible treatment option for these patients may be slow, long hemodialysis; short, daily hemodialysis; or nocturnal hemodialysis. Among the antihypertensive agents currently available, angiotensin-converting enzyme (ACE) inhibitors appear to have the greatest ability to reduce left ventricular mass. Pressure load can be satisfactorily determined by using the average value of predialysis BP measurements over 1 month. In selected hemodialysis patients, interdialytic ambulatory blood pressure monitoring (ABPM) may help to determine if the patient is in fact hypertensive. In addition, ABPM provides important information about the change in BP between day and night. Regular home BP monitoring, yearly echocardiography, and treatment of traditional risk factors for cardiovascular disease are recommended.

Daily hemodialysis: a dialysis provider perspective

Regardless of size, ownership or corporate structure, the goal of the dialysis provider is to deliver the best renal substitution therapy in the safest and most convenient manner, at a cost commensurate with reimbursement. This paper reviews the available data on daily hemodialysis, focusing on its ability to satisfy this goal. In addition, it examines the potential influence of frequency, time, and dose of dialysis on clinical outcomes of various series over the last 3 decades. The available data strongly suggest the clinical benefits of daily hemodialysis, but are not sufficient to show statistically better outcomes. Under the present reimbursement system, daily hemodialysis is not economically feasible in the United States. Prospective clinical trials designed to prove the benefits of these therapies and justify their reimbursement are needed.

Daily hemodialysis: challenges and opportunities in the delivery and financing of end-stage renal disease patient care

Daily/home hemodialysis is the latest technologic advance in the care of end-stage renal disease (ESRD) patients, and promises improved clinical outcomes and quality of life. Should these benefits prove to be true, an increasing number of patients will be interested in this modality of care, raising challenges and opportunities for providers of care and payers, as well as patients themselves. For patients to have access to this and other new forms of technology to treat ESRD, it will be necessary to re-examine the current care delivery and financing systems and reconfigure these so that the incentives of best clinical practice and outcomes are properly aligned with appropriate and sensible cost constraint.

Effect of therapy time and frequency on effective solute removal

Increasing dialysis frequency or time increases the removal of the molecules diffusing slowly across the intercompartmental barriers. By offering frequent dialysis the time on dialysis can be decreased, possibly without worsening the outcome. Increasing dialysis time increases large molecule removal. Increasing in both frequency and time on dialysis increases the removal of solutes of all molecular sizes. Increasing frequency and/or time of dialysis may have many other beneficial effects that are not traditionally quantitated and which can affect outcomes.

The case for daily dialysis: its impact on costs and quality of life

Research suggests daily hemodialysis may improve clinical outcomes. To date, a comprehensive review of its implications on quality of life has not been performed, and little is known about its economic impact. We conducted an economic evaluation comparing short daily or nocturnal hemodialysis with thrice-weekly conventional in-center dialysis. Data on the quality of life and clinical effects of daily dialysis were obtained from more than 60 reports from 13 daily dialysis programs around the world (n = 197). Cost data were derived principally from the US Renal Data System, Centers for Disease Control, and Medicare Payment Advisory Commission. Resource use during daily hemodialysis was modeled after two ongoing programs in the United States. Results suggest that patients feel better and direct treatment costs could be reduced with daily dialysis. Costs are sensitive to assumptions about the effect of daily dialysis on hospital days. Reductions of at least 8% in hospital days are required for these modalities to be cost saving compared with documented reductions of 30% to 100%. Larger well-controlled studies of daily versus conventional dialysis would be helpful to determine whether daily dialysis fulfills these promises. Medicare policy, which limits payment for most patients to three dialysis treatments weekly, poses a disincentive to more widespread adoption among dialysis centers. Given this constraint to broader acceptance, we address several policy options to gain a better understanding of the potential risks and benefits of daily dialysis.

Phosphate removal and hemodialysis conditions

Hyperphosphatemia is frequently found in hemodialysis patients, and the association with an increased risk of mortality has been demonstrated. Other authors have linked hyperphosphatemia to increased cardiovascular mortality. The normalization of phosphate plasma levels is therefore an important goal in the treatment of end-stage renal disease patients. Absorption of phosphate from the food exceeds the elimination through a hemodialysis treatment, and this leads to a chronic phosphate load for the majority of hemodialysis patients. This imbalance should be improved by either a reduction of phosphate absorption or an increased removal of phosphate. A reduction of phosphate absorption can be achieved by reducing the amount of phosphate in the diet or by the administration of phosphate binders. Unfortunately, these measures imply practical difficulties, for example, a lack of patient compliance or other side effects. When considering modifications of the hemodialysis treatment, an essential understanding of the kinetics of dialytic phosphate removal is mandatory. Phosphate is unevenly distributed in different compartments of the body. Only a very small amount of phosphate is present in the easily accessible plasma compartment. The major part of phosphate removed during hemodialysis originates from the cytoplasm of cells. A transfer from intracellular space to the plasma and further from the plasma to the dialysate is necessary. However, if we consider improvement to phosphate removal by dialysis procedures, full dialyzer clearance is effective in only the initial phase of the dialysis treatment. After this initial phase, the transfer rate for phosphate from the intracellular space to the plasma becomes the rate-limiting step for phosphate transport. Attempts to improve this transfer rate have recently been investigated by acidosis correction, but turned out not to be consistently successful. Furthermore, modifications of the treatment schedule have been described in the literature as measures to influence the phosphate balance consistently. Successful improvements of the phosphate balance can be achieved specifically through increasing the frequency of the dialysis treatments.

Does convective dialysis therapy applied daily approach renal blood purification?

Outcome studies in dialysis have generally failed to show an impact of changes in membrane flux or biocompatibility, and only dose increases up to a certain level have been shown to improve survival significantly. However, to see an effect of a potentially improved dialysis treatment, all available factors that make dialysis more physiological may need to be combined. A membrane that mimics the glomerular basement membrane in being hemocompatible, having a high hydraulic permeability and a generous sieving, yet not leading to albumin loss could be used. The dialysis fluid composition could be individualized, and the quality and volume appropriate for the selected application. The new system of online-prepared ultrapure dialysis fluid and sterile infusion solutions, as integral parts of the treatment, are cost effective and labor saving as well as biocompatible. Ideally, we should select a blood purification method that covers the same range of solutes as the kidney. Convection is equally effective for all solutes that can pass through the membrane, and the corresponding renal therapy is hemofiltration. For enhanced small solute removal, convection can be combined with diffusion as in hemodiafiltration, which has the potential to achieve the largest solute removal over a wide molecular weight spectrum among all forms of dialysis. Finally, the dialysis treatment should be applied as often as is practically possible-preferably daily-in order to reduce the peaks caused by uremic toxins, the exposure to acidosis and alkalosis, and the burden on the cardiovascular system by overhydration. While the designed therapy is already technically feasible today, a positive result from outcome studies will be needed to bring about the political and economic decisions required to change conventional dialysis into a treatment approaching true renal blood purification.

Short daily hemodialysis and nutritional status

Daily hemodialysis improves clinical outcomes in dialysis patients. This study shows the results of 10 patients who underwent short daily hemodialysis (SDHD) from 23.2 +/- 13 months and focuses on nutritional status under this strategy. With SDHD, patients had an increase in energy and protein intake confirmed by an increase in dry weight and lean body mass. Additional clinical improvement was obtained for blood pressure control, regression of left ventricular hypertrophy, correction of anemia, and better quality of life. These biological and clinical improvements are mainly the results of a higher frequency of dialysis sessions. The nutritional improvements with disappearance of anorexia are the consequence of general well being, less dietetic constraints, and less drugs prescribed. Short daily hemodialysis offers an adequate and more physiological strategy and may be considered for improving nutritional status in selected patients.

Clinical outcome of daily dialysis

Dialysis patients are prone to malnutrition, which may be counteracted by daily home hemodialysis (DHHD, 6 times a week) due to improved clinical outcome and quality of life. Eleven patients were treated with DHHD during 18 months, after a run-in period with three dialysis sessions a week. The total weekly dialysis dose was kept constant during the first 6 months of DHHD, whereupon it was allowed to increase. KT/V was 3.1 +/- 0.5 at baseline, 3.2 +/- 0.5 after 6 months and 4.0 +/- 0.8 at 18 months. Blood pressure decreased from 142 +/- 19/83 +/- 8 to 130 +/- 25/79 +/- 9 mmHg with a more than 50% reduction in antihypertensive medication. Potassium did not change, but potassium binding resins could be stopped almost completely. Bicarbonate increased from 20.6 +/- 3.3 to 23.1 +/- 2.6 mEq/L after 18 months. Patients with a protein intake of less than 1.0 g/kg/d showed a greater increase in body weight (62.3 +/- 6.0 to 65.5 +/- 3.7, P: < 0.05) and normalized protein catabolic rate (nPCR) (0.87 +/- 0.08 to 1.25 +/- 0.36, ns) than patients with acceptable protein intake (>/=1.0 g/kg/d). Phosphate decreased, though not significantly, especially in the latter group. Erythropoietin dose could be reduced from 6400 +/- 5400 U/L at baseline to 5100 +/- 4000 U/L at 18 months. Quality of life improved significantly, especially with to respect to physical condition and mental health. The DHHD markedly improves hemodynamic control and quality of life. Overall nutritional parameters did not change, except cholesterol. Patients with a low protein intake, however, showed a significant increase in body weight, and a greater rise in nPCR.