Nocturnal but not short hours quotidian hemodialysis requires an elevated dialysate calcium concentration

Inflammatory syndrome in patients on hemodialysis

Mortality is markedly elevated in hemodialysis (HD) patients. Between 30 and 50% of prevalent patients have elevated serum levels of inflammatory markers such as C-reactive protein and IL-6. The presence of inflammation, chronic or episodic, has been found to be associated with increased mortality risk. The causes of inflammation are multifactorial and include patient-related factors, such as underlying disease, comorbidity, oxidative stress, infections, obesity, and genetic or immunologic factors, or on the other side, HD-related factors, mainly depending on the membrane biocompatibility and dialysate quality. The adequate knowledge of these causes and their prevention or treatment if possible may contribute to improving the inflammatory state of patients who are on HD and possibly their mortality.

Left ventricular hypertrophy: is hyperphosphatemia among dialysis patients a risk factor?

Cardiovascular disease occurs in ESRD patients at rates that are far higher than is seen in the general population, and cardiovascular deaths account for the majority of deaths among dialysis patients. Abnormal mineral metabolism is a novel cardiovascular risk factor among dialysis patients. Recently published results demonstrated that even with good control of BP and anemia, conventional hemodialysis is associated with significant left ventricular hypertrophy (LVH); however, daily hemodialysis was associated with a significant reduction in LV mass index (LVMI). Furthermore, it was shown that control of serum phosphorus correlates with the reduction in LVMI. These data suggest a novel mechanism for the deleterious effect of elevated serum phosphorus on cardiovascular outcomes among hemodialysis patients: LVH. Other investigators have noted an association of hyperphosphatemia and LVH; however, this study was the first to demonstrate that improvement in serum phosphorus is associated with reduction in LVM. In addition, it is shown that daily hemodialysis is an effective modality in improving serum phosphorus through significantly improved phosphorus removal. Elevated serum phosphorus leads to vascular calcification, which can lead to LVH by decreasing vascular compliance. However, our study showed an improvement in LVMI during a 12-mo period. Because vascular calcification is unlikely to remit over this time period, it is proposed that serum phosphorus has a reversible, cardiotoxic effect that leads to LVH that can be reversed successfully with good control of serum phosphorus.

More frequent hemodialysis: back to the future?

An increase in the length of the standard in-center hemodialysis treatment by 30 to 45 minutes per session was not associated with an improvement in mortality in long-term hemodialysis patients enrolled in the HEMO study. Testing the possibility that delivering still higher doses of hemodialysis may have a beneficial effect on patient outcomes will require the use of more frequent hemodialysis or a much longer duration for each dialysis session. "Short-daily hemodialysis," actually 6 times per week hemodialysis for 1.5 to 3 hours per session, can provide some increase in small molecule clearance as measured by urea kinetics. "Long nocturnal daily hemodialysis," actually 6 times per week hemodialysis for 6 to 8 hours per session, provides a significant increase in both small-molecular-weight and large-molecular-weight clearance and often alleviates the need to take phosphate binders. The National Institutes of Health is sponsoring 2 clinical trials via the Frequent Hemodialysis Network to determine the impact of these 2 modalities on intermediate outcomes, compared with standard 3-times-per-week hemodialysis.

Conversion from conventional to nocturnal hemodialysis improves vitamin D levels

Patients on conventional hemodialysis have low levels of 25-hydroxy-vitamin D probably due to diet and decreased cutaneous synthesis. As 1,25 dihydroxy-vitamin D synthesis is substrate-dependent in end-stage renal disease, this could be a contributing factor to low 1,25 dihydroxy-vitamin D levels in patients undergoing conventional hemodialysis. We converted 35 patients historically on conventional hemodialysis to nocturnal hemodialysis for a minimum of 6 months thereby significantly increasing sessional equilibrated Kt/V from an average of 1.30 to an average of 2.01. Dietary restrictions were also removed. Serum phosphorus significantly fell, whereas the serum calcium, parathyroid hormone, and the mean dose of calcitriol did not change after the conversion. Significant increases in both 25-hydroxy and 1,25-dihydroxy-vitamin D levels were seen after hemodialysis mode conversion. A significant correlation was found between the dialysis dose and the levels of both hydroxylated forms of vitamin D. We suggest that improving uremia by nocturnal hemodialysis in the absence of exogenous supplementation is associated with increased 25 and 1,25-hydroxy-vitamin D levels. Additionally, normalization of serum phosphorus may improve 1alpha-hydroxylation thereby enhancing substrate-dependent generation of 1,25-dihydroxy-vitamin D in chronic dialysis patients.

Comparison between different dialysate calcium concentrations in nocturnal hemodialysis

Benefits of dialysate with greater calcium (Ca) concentration are reported in nocturnal hemodialysis (NHD) to prevent Ca depletion and subsequent hyperparathyroidism. Studies with patients dialyzing against 1.25 mmol/L Ca baths demonstrate increases in alkaline phosphatase (ALP) and parathyroid hormone (PTH) and increasing dialysate Ca subsequently corrects this problem. However, whether 1.5 or 1.75 mmol/L dialysate Ca is most appropriate for NHD is yet to be determined, and differences in the effect on mineral metabolism of daily vs. alternate daily NHD have also not been well defined. We retrospectively analyzed mineral metabolism in 48 patients, from 2 institutions (30 at Monash and 18 at Geelong), undergoing home NHD (8 hr/night, 3.5-6 nights/week) for a minimum of 6 months. Thirty-seven patients were dialyzed against 1.5 mmol/L Ca bath and 11 patients against 1.75 mmol/L. We divided patients into 4 groups, based on dialysate Ca and also on the hours per week of dialysis, <40 (1.5 mmol/L, n=29 and 1.75 mmol/L, n=8) or > or =40 (n=4 and 7). We compared predialysis and postdialysis serum markers, time-averaged over a 6-month period, and the administration of calcitriol and Ca-based phosphate binders between 1.5 and 1.75 mmol/L Ca dialysate groups. Baseline characteristics between all groups were similar, with a slightly longer, but nonsignificant, duration of NHD in both 1.75 mmol/L dialysate groups compared with 1.5 mmol/L. The mean predialysis Ca, phosphate, and Ca x P were similar between the 1.5 and 1.75 mmol/L groups, regardless of NHD hr/week. Postdialysis Ca was significantly greater, with 1.75 vs. 1.5 mmol/L in those dialyzing <40 hr/week (2.64+/-0.19 vs. 2.50+/-0.12 mmol/L, p=0.046), but postdialysis Ca x P were similar (2.25+/-0.44 vs. 2.16+/-0.29 mmol(2)/L(2), p=0.60). Parathyroid hormone was also lower with 1.75 vs. 1.5 mmol/L baths in the <40 hr/week groups (31.99+/-26.99 vs. 14.47+/-16.36 pmol/L, p=0.03), although this difference was not seen in those undertaking NHD > or =40 hr/week. Hemoglobin, ALP, and albumin were all similar between groups. There was also no difference in vitamin D requirement when using 1.75 mmol/L compared with the 1.5 mmol/L dialysate. Multivariate analysis to determine independent predictors of postdialysis serum Ca showed a statistically significant positive association with predialysis Ca, dialysate Ca, and total NHD hr/week. An elevated dialysate Ca concentration is required in NHD to prevent osteopenia but differences in serum markers of mineral metabolism between 1.5 and 1.75 mmol/L Ca dialysate in NHD in our study were few. This was similar for patients undertaking NHD <40 or > or =40 hr/week, although differences in the frequency of NHD may also be as important as dialysate Ca with regard to serum Ca levels. With concerns that prolonged higher Ca levels contribute to increased cardiovascular mortality, the optimal Ca dialysate bath is still unknown and further studies addressing bone metabolism with larger NHD numbers are required.

Frequent Hemodialysis Network (FHN) randomized trials: Study design

Observational studies suggest improvements with frequent hemodialysis (HD), but its true efficacy and safety remain uncertain. The Frequent Hemodialysis Network Trials Group is conducting two multicenter randomized trials of 250 subjects each, comparing conventional three times weekly HD with (1) in-center daily HD and (2) home nocturnal HD. Daily HD will be delivered for 1.5-2.75 h, 6 days/week, with target eK(t)/V(n) > or = 0.9/session, whereas nocturnal HD will be delivered for > or = 6 h, 6 nights/week, with target stdK(t)/V of > or = 4.0/week. Subjects will be followed for 1 year. The composite of mortality with the 12-month change in (i) left ventricular mass index (LVMI) by magnetic resonance imaging, and (ii) SF-36 RAND Physical Health Composite (PHC) are specified as co-primary outcomes. The seven main secondary outcomes are between group comparisons of: change in LVMI, change in PHC, change in Beck Depression Inventory score, change in Trail Making Test B score, change in pre-HD serum albumin, change in pre-HD serum phosphorus, and rates of non-access hospitalization or death. Changes in blood pressure and erythropoiesis will also be assessed. Safety outcomes will focus on vascular access complications and burden of treatment. Data will be obtained on the cost of delivering frequent HD compared to conventional HD. Efforts will be made to reduce bias, including blinding assessment of subjective outcomes. Because no large-scale randomized trials of frequent HD have been previously conducted, the first year has been designated a Vanguard Phase, during which feasibility of randomization, ability to deliver the interventions, and adherence will be evaluated.

Comparison of biochemical, haematological and volume parameters in two treatment schedules of nocturnal home haemodialysis

BACKGROUND

The biochemical, haemodynamic, clinical and nutritional benefits of nocturnal home haemodialysis (NHHD) compared with 4 h, three times per week conventional haemodialysis are well known and accrue by increasing dialysis time and frequency either for 8 h alternate night per week (NHHD3.5) or for 8 h six nights per week (NHHD6). However, there are little data comparing NHHD3.5 with NHHD6.

METHOD AND RESULTS

Thirteen patients on NHHD6 were compared with 21 patients on NHHD3.5, all with similar demographic profiles. Pre- and post-dialysis phosphate (PO4) control was ideal between the groups. However, all NHHD6 needed PO4 supplementation compared with 4/21 (19%) NHHD3.5. In the present study, 8/21 (38%) NHHD3.5 needed PO4 binders whereas none was required with NHHD6. The pre-haemoglobin (Hb) 122.8 g/L (NHHD6) versus 124.9 g/L (NHHD3.5) and the pre-albumin 38.31 g/L (NHHD6) versus 37.71 g/L (NHHD3.5) were not significantly different. NHHD6 had significantly lower pre-blood urea and creatinine (10.16 vs 19.54 mmol/L and 437.0 vs 812.3 micromol/L, respectively). Less interdialytic urea and creatinine fluctuation were also noted in NHHD6. Of major significance was the significantly lower ultra filtration rate and intradialytic weight gains (mean +/- SEM) of NHHD6 (249 +/- 76 mL/h and 2.0 +/- 0.65 kg) versus NHHD3.5 (425 +/- 168 mL/h and 2.9 +/- 1.2 kg).

CONCLUSION

The authors conclude that NHHD6 offers the optimum biochemical, volume and clinical outcome, but NHHD3.5 has additional appeal to providers seeking home-based therapy cost advantages and consumable expenditure control. A flexible dialysis programme should offer all the time and frequency options of NHHD but in particular, should support NHHD at a frequency sympathetic to the clinical rehabilitation and lifestyle aspirations of individual patients.

Phosphorus balance and mineral metabolism with 3 h daily hemodialysis

Poor control of mineral metabolism is independently associated with mortality in patients receiving hemodialysis. We analyzed data from a 12-month, prospective, non-randomized, controlled study of daily hemodialysis (DHD) (six sessions/week 3 h each) (n=26) vs conventional hemodialysis (CHD) (three sessions/week 4 h each) (n=51) for achievement of mineral metabolism goals and we performed a substudy of weekly dialytic phosphorus removal in DHD vs CHD. Phosphorus control was superior in the DHD group (% change from baseline to end-of-study -27+/-30% vs +7%+/-35% in the CHD group, P=0.0001). Percentage of patients using phosphate binders decreased from 77 to 40% among subjects on DHD, whereas these parameters did not change (76 vs 77%) in the CHD group (P=0.03 by Breslow-Day test for homogeneity of the odds ratios). Weekly mean phosphorus removal was higher in the DHD group (2452+/-720 mg/week vs 1572+/-366 mg/week, P=0.04). Mean normalized protein catabolic rate increased (0.90+/-0.43-1.22+/-0.26 g/kg/day, P=0.0013). DHD was also associated with an increase in the percent of subjects achieving three or more mineral metabolism goals (for phosphorus, calcium x phosphorus and parathyroid hormone) (15 vs 46%, P=0.046). In conclusion, DHD improves phosphorus control by increasing dialytic phosphorus removal while maintaining nutritional status and reducing the use of phosphate binders. The net effect allows for improved achievement of mineral metabolism goals.

Emerging strategies for lowering serum phosphorous in patients with end-stage renal disease

Hyperphosphataemia is a major problem in patients with chronic kidney disease as it has been associated with increased morbidity and mortality. Over the last four decades, different modalities have been applied to treat hyperphosphataemia with varying degrees of success. Unfortunately, treatment strategies have led to unforeseen complications. These have prompted the development of new classes of medications with potentially better efficacy and few short-term and long-term side effects. This article reviews the causes, mechanism and management of hyperphosphataemia.

Review of dialysate calcium concentration in hemodialysis

The dialysate calcium (Ca) concentration for hemodialysis (HD) patients can be adjusted to manage more optimally the body's Ca and phosphate balance, and thus improve bone metabolism as well as reduce accelerated arteriosclerosis and cardiovascular mortality. The appropriate dialysate Ca concentration allowing this balance should be prescribed to each individual patient depending on a multitude of variable factors relating to Ca load. A lower dialysate Ca concentration of 1.25 to 1.3 mmol/L will permit the use of vitamin D supplements and Ca-based phosphate binders in clinical practice, with much less risk of Ca loading and resultant hypercalcemia and calcification. Low Ca baths are useful in the setting of adynamic bone disease where an increase in bone turnover is required. However, low Ca levels in the dialysate may also predispose to cardiac arrhythmias and hemodynamically unstable dialysis sessions with intradialytic hypotension. Higher Ca dialysate is useful to sustain normal serum Ca levels where patients are not taking Ca-based binders or if Ca supplements are not able to normalize serum levels. Suppression of hyperparathyroidism is also effective with dialysate Ca of 1.75 mmol/L, but hypercalcemia, metastatic calcification, and oversuppression of parathyroid hormone are risks. Dialysate Ca of 1.5 mmol/L may be a compromise between bone protection and reduction in cardiovascular risk for conventional HD and is a common concentration used throughout the world. The increase in longer, more frequent dialysis such as short-daily and nocturnal HD, however, provides another challenge with regard to optimal dialysate Ca levels and higher levels of 1.75 mmol/L are probably indicated in this setting. Difficulties in determining the ideal dialysate Ca occur because of the complex pathophysiology of bone and mineral metabolism in HD patients and there needs to be a balance between dialysis prescription and other treatment modalities. To optimize management of the abnormal Ca balance, other aspects of this disorder need to be more fully clarified and, with evolving medications for phosphate control and treatment of secondary hyperparathyroidism, as well as the emergence of a multitude of different HD regimes, further studies are required to make definitive recommendations. At present, we need to maintain flexibility with HD treatments and so dialysate Ca needs to be individualized to meet the specific requirements of patients by optimizing management of renal bone disease and simultaneously reducing metastatic calcification and cardiovascular disease.

Short-term effects of nocturnal haemodialysis on carnitine metabolism

BACKGROUND

Functional carnitine deficiency [as indicated by an abnormal acyl-carnitine/free-carnitine (AC:FC) ratio] is commonly seen in patients with end-stage renal disease (ESRD), resulting in significant clinical detriments including anaemia, cardiomyopathy and muscle weakness. Nocturnal haemodialysis (NHD) (5-6 sessions per week, 8 h per treatment) has been reported to reverse several surrogate markers of uraemia. Conversely, as a consequence of increased dialysis dose, NHD may have the potential to aggravate plasma nutrient deficiencies. Our objective was to determine the effects of NHD on plasma free-carnitine levels and carnitine metabolism.

METHODS

We conducted an observational cohort study with a before and after design. Nine ESRD patients (age: 47 +/- 3; mean +/- SEM) were studied. Routine biochemical, haemodynamic and carnitine metabolic products were analysed at baseline while on conventional haemodialysis and 2 months post-conversion to NHD. Free-carnitine and total-carnitine levels were generated by colorimetric assays. The difference between total- and free-carnitine concentrations was estimated to be the acyl-carnitine level. Paired t-test was used to ascertain statistical significance.

RESULTS

After conversion to NHD, there was a significant increase in urea clearance in all patients. Plasma free-carnitine levels fell from 26.54 +/- 2.99 to 15.6 +/- 2.34 micromol/l (P < 000.1). A similar reduction in plasma acyl-carnitine levels was observed (from 13.22 +/- 1.34 to 6.24 +/- 1.20 micromol/l (P < 0.001)). The AC:FC ratio improved from 0.51 +/- 0.03 to 0.39 +/- 0.03 (P < 0.005) (Normal < 0.25).

CONCLUSION

NHD is associated with an improvement in AC:FC ratio. Further research is needed to examine the longitudinal clinical impact of this metabolic correction and to examine whether this effect is sustained.

Calcium phosphate metabolism and bone mineral density with nocturnal hemodialysis

An elevated calcium x phosphate product (Ca x P) is an independent risk factor for vascular calcification and cardiovascular death in dialysis patients. More physiological dialysis in patients undergoing nocturnal hemodialysis (NHD) has been shown to produce biochemical advantages compared with conventional hemodialysis (CHD) including superior phosphate (P) control. Benefits of dialysate with greater calcium (Ca) concentration are also reported in NHD to prevent Ca depletion and subsequent hyperparathyroidism, but there are concerns that a higher dialysate Ca concentration may contribute to raised serum Ca levels and greater Ca x P and vascular disease. The NHD program at our unit has been established for 4 years, and we retrospectively analyzed Ca and P metabolism in patients undergoing NHD (8-9 h/night, 6 nights/week). Our cohort consists of 11 patients, mean age 49.3 years, who had been on NHD for a minimum of 12 months, mean 34.3 months. Commencement was with low-flux (LF) NHD and 1.5 mmol/L Ca dialysate concentration, with conversion to high-flux (HF) dialyzers after a period (mean duration 18.7 months). We compared predialysis serum albumin, intact parathyroid hormone, P, total corrected Ca, and Ca x P at baseline on CHD, after conversion to LF NHD and during HF NHD. We also prospectively measured bone mineral density (BMD) on all patients entering the NHD program. Bone densitometry (DEXA) scans were performed at baseline (on CHD) and yearly after commencement of NHD. With the introduction of HF dialyzers, the Ca dialysate concentration was concurrently raised to 1.75 mmol/L after demonstration on DEXA scans of worsening osteopenia. Analysis of BMD, for all parameters, revealed a decrease over the first 12 to 24 months (N = 11). When the dialysate Ca bath was increased, the median T and Z scores subsequently increased (data at 3 years, N = 6). The mean predialysis P levels were significantly lower on LF NHD vs. CHD (1.51 vs. 1.77 mmol/L, p = 0.014), while on HF NHD P was lower again (1.33 mmol/L, p = 0.001 vs. CHD). Predialysis Ca levels decreased with conversion from CHD to LF NHD (2.58 vs. 2.47 mmol/L, p = 0.018) using a 1.5 mmol/L dialysate Ca concentration. The mean Ca x P on CHD was 4.56 compared with a significant reduction of 3.74 on LF NHD (p = 0.006) and 3.28 on HF NHD (p = 0.001 vs. CHD), despite the higher dialysate Ca in the latter. We conclude that an elevated dialysate Ca concentration is required to prevent osteopenia. With concerns that prolonged higher Ca levels contribute to increased cardiovascular mortality, the optimal Ca dialysate bath is still unknown. Better P control on NHD, however, reduces the overall Ca x P, despite the increased Ca concentration, therefore reducing the risk of vascular calcification.

Composition and clinical use of hemodialysates

A thorough knowledge and understanding of the principles underlying the preparation and the clinical application of hemodialysates can help us provide exemplary patient care to individuals having end-stage renal disease. It is prudent to be conversant with the following: (a) how each ingredient in a dialysate works, (b) the clinical circumstances under which the concentration of an ingredient can be altered, and (c) the special situations in which unconventional ingredients can be introduced into a dialysate. The potential to enrich dialysates with appropriate ingredients (such as iron compounds) is limited only by the boundaries of our imagination.

Calcium and phosphate balance in adolescents on home nocturnal haemodialysis

Studies in adults show superior serum phosphate and parathyroid hormone (PTH) control on slow nocturnal haemodialysis (NHD) compared with conventional haemodialysis. We studied the progress of four children aged 12, 13, 14 and 16 years after they had been initiated on NHD. The follow-up period ranged from 6 months to 20 months. Biochemical indices of bone metabolism were collected prospectively. All four children were initially dialysed against a 1.5 mmol/l calcium bath. In two patients, owing to biochemical hypocalcaemic episodes, the dialysate calcium concentration was increased to 1.75 mmol/l. One patient became hypercalcaemic and received calcitonin for bone pain secondary to osteoporosis and was dialysed against a 1.0 mmol/l calcium bath. Including an evaluation of dietary intake, all four patients had a net positive calcium balance, ranging from 5.1 mmol/m2 body surface area (BSA) per day to 24.3 mmol/m2 BSA per day. A significant reduction in the pre-dialysis phosphate level was observed in all four patients, such that none required dietary restrictions or phosphate binders, and dialysate phosphate supplements of 0.8-2.03 mmol/l were employed to prevent hypophosphataemia. The (CaxPO4) dropped below 4.4 mmol(2) l(-2) in all four patients. Concurrently, significant reductions in intact PTH levels were seen in all four patients, but the level dropped to below normal range in two. In our cohort of patients, NHD rapidly lowered plasma phosphate and PTH levels, and additional dialysate phosphate and possibly calcium may be necessary to prevent bone demineralisation due to chronic losses and to prevent oversuppression of PTH.

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.

Control of Hyperphosphatemia among Patients with ESRD

Derangements of mineral metabolism occur during the early stages of chronic kidney disease (CKD). Hyperphosphatemia develops in the majority of patients with ESRD and has long been associated with progression of secondary hyperparathyroidism and renal osteodystrophy. More recent observational data have associated hyperphosphatemia with increased cardiovascular mortality among dialysis patients. Adequate control of serum phosphorus remains a cornerstone in the clinical management of patients with CKD not only to attenuate the progression of secondary hyperparathyroidism but also possibly to reduce the risk for vascular calcification and cardiovascular mortality. These measures include dietary phosphorus restriction, dialysis, and oral phosphate binders. Dietary restriction is limited in advanced stages of CKD. Phosphate binders are necessary to limit dietary absorption of phosphorus. Aluminum hydroxide is an efficient binder; however, its use has been nearly eliminated because of concerns of toxicity. Calcium salts are inexpensive and have been used effectively worldwide as an alternative to aluminum. Concerns of calcium overload have led to the investigation of alternatives. Currently, only two Food and Drug Administration-approved noncalcium, nonaluminum binders are available. Sevelamer hydrochloride is an exchange resin and was not as effective as calcium acetate in meeting new guideline recommendations in one double-blind clinical trial. Lanthanum carbonate is a rare earth element and has been studied less extensively. Concerns of long-term administration and toxicity exist. Furthermore, these agents are significantly more expensive than calcium salts, which may contribute to patient noncompliance.

Newer Paradigms in Renal Replacement Therapy: Will They Alter Cardiovascular Outcomes?

Cardiovascular disease remains the leading cause of morbidity and mortality for patients with end-stage renal disease. Conventional hemodialysis has had limited impact on cardiovascular risk factors and mortality. Increasing evidence suggests that nocturnal home hemodialysis has beneficial effects on cardiovascular parameter outcomes. This article reviews the documented effects of nocturnal home hemodialysis on blood pressure control, cardiac geometry and left ventricular systolic function, lipid profiles, calcium-phosphate metabolism, parathyroid hormone levels, homocysteine levels, sleep apnea, and autonomic modulation of heart rate. It discusses possible mechanisms to explain these observed changes.

Nocturnal haemodialysis in Australia and New Zealand (Review Article)

Although early experience in Australia and New Zealand confirmed home haemodialysis to be well tolerated, effective and with lower morbidity and mortality compared with centre-based haemodialysis, the advent of ambulatory peritoneal dialysis and 'satellite' haemodialysis has led to a steadily declining home haemodialysis population. However, the emergence of nocturnal haemodialysis, as a safe and highly effective therapy, has added to the modality choices now available and offers a new, highly attractive home-based option with many advantages over centre-based dialysis. For the patient, nocturnal haemodialysis means fluid and dietary freedom, less antihypertensive medication, the abolition of phosphate binders, the return of daytime freedom and the capacity for full-time employment. Potential biochemical benefits include normalization of the blood urea, serum creatinine, albumin, beta(2) microglobulin, homocysteine and triglyceride levels and other nutritional markers. Improved quality of life and sleep patterns and a resolution of sleep apnoea have been shown. Left ventricular function has also shown marked improvement. For the provider, nocturnal home haemodialysis offers clear cost advantages by avoiding high-cost nursing and infrastructure expenditure. Although consumable and equipment costs are higher, the savings on wage and infrastructure far outweigh this added expenditure. These combined factors make nocturnal haemodialysis an irresistible addition to comprehensive dialysis services, both from a clinical outcome and fiscal perspective.

Quotidian dialysis – update 2005

PURPOSE OF REVIEW

The interest in quotidian hemodialysis has increased further after the HEMO study reported that high-dose thrice-weekly hemodialysis failed to improve clinical outcomes. This, in combination with a significant volume of newly published data, made a review of the topic of quotidian hemodialysis timely.

RECENT FINDINGS

The published research has revealed further evidence of cardiovascular and quality-of-life improvements as well as financial benefits with quotidian hemodialysis. Accrued worldwide experience has confirmed the previously published benefits of quotidian hemodialysis. There has been a significant effort by industry to produce patient-friendly machines for home hemodialysis. Reports on the use of daily hemodialysis and hemodiafiltration in children have appeared. An international registry of patients on quotidian hemodialysis has been created. The need for modification of the funding mechanisms and the lack of prospective randomized controlled studies on quotidian hemodialysis led to the funding of such studies by the National Institutes of Health in collaboration with Centers for Medicare and Medicaid services to be completed by 2008. The proper funding for daily home hemodialysis was secured in the province of British Columbia, Canada, and is under consideration elsewhere.

SUMMARY

There is increasing evidence confirming that quotidian hemodialysis improves clinical outcomes in a cost-efficient manner. Provided that the reimbursement issues are resolved these modalities may be utilized extensively at home as well as in the in-center facilities. The revitalization of home hemodialysis will compensate for the decline in utilization of continuous ambulatory peritoneal dialysis and the nursing shortage encountered in most countries.

Dialysis dose and frequency

BACKGROUND

From the beginning of the dialysis era, the issue of optimal dialysis dose and frequency has been a central topic in the delivery of dialysis treatment.

METHODS

We undertook a discussion to achieve a consensus on key points relating to dialysis dose and frequency, focusing on the relationships with clinical and patient outcomes.

RESULTS

Traditionally, dialysis adequacy has been quantified referring to the kinetics of urea, taken as a paradigm of all uraemic toxins, and applying the principles of pharmacokinetics using either single- or double-pool variable volume models. An index of dialysis dose is the fractional clearance of urea, which is commonly expressed as Kt/V. It can be calculated from blood urea concentration and haemodialysis (HD) parameters, according to the respective urea kinetic model or by means of simplified formulas. Similar principles are applicable to peritoneal dialysis (PD), where weekly Kt/V and creatinine clearance are used. Recommended minimal targets for dialysis adequacy have been defined by both American and European guidelines (DOQI and European Best Practice Guidelines, respectively). The question of how to improve the severe outcome of dialysis patients has recently come back to the fore, since the results of two recent randomized controlled trials led to the conclusion that, in thrice weekly HD and in PD, increasing the dialysis dose well above the minimum requirements of current American guidelines did not improve patient outcome. Daily HD (defined as a minimum of six HD sessions per week), in the form of either short daytime HD or long slow nocturnal HD, is regarded as a possibility to improve dialysis patient outcome. The results of the studies published so far indicate excellent results with respect to all outcomes analysed: optimal blood pressure control, regression of left ventricular hypertrophy and amelioration of left ventricular performance, improvement of renal anaemia, optimal hyperphosphataemia control, improvement of nutritional status, reduction in oxidative stress indices and improvement in quality of life. The basis for these beneficial effects is thought to be a more physiological clearance of solutes and water, with reduced pre- and post-HD solute concentrations and interdialytic oscillation, compared with traditional HD. Apart from concerns regarding reimbursement and organizational issues, no serious adverse effects have been described with daily HD. However, the evidence accumulated is limited mainly to retrospective cohorts, with small patient numbers and no adequate controls in most instances. Therefore, large prospective studies with adequate controls are required to make daily HD accepted by reimbursing authorities and patients.

CONCLUSIONS

Given the available observational and interventional body of evidence, there is no reason to reduce arbitrarily dialysis dose, particularly dialysis treatment time in HD patients treated three times weekly. Daily HD represents a very promising tool for improving dialysis outcomes and quality of life, although its impact on patient survival has not yet been proven definitively.

Is more frequent hemodialysis beneficial and what is the evidence?

PURPOSE OF REVIEW

The HEMO study results have shown that increasing dialysis dose in conventional thrice weekly hemodialysis does not improve patient outcomes. Interest has therefore turned to more frequent (daily) hemodialysis treatments. This review covers the rationale for such an approach together with a current review of the published study data.

RECENT FINDINGS

Recent studies have suggested improvements in a number of intermediate patient outcomes such as cardiovascular (blood pressure control, left ventricular hypertrophy), anemia, phosphate control, nutritional status and quality of life. Some of these outcomes are associated with increased survival in the dialysis population.

SUMMARY

The inference from these studies is that more frequent hemodialysis will indeed reduce mortality and morbidity. To date, however, the studies have all been small and underpowered to detect such primary outcomes. No randomized controlled trials are yet reported. The US National Institutes of Health have sponsored larger scale North American based studies and an International Registry of Daily Dialysis patients has been created to attain further information of the possible benefits of such therapy. In spite of the paucity of hard evidence the studies to date have been enough to convince some jurisdictions to recognize and fund daily hemodialysis treatments.

DAILY HEMODIALYSIS-SELECTED TOPICS: The London, Ontario, Daily/Nocturnal Hemodialysis Study

The London Daily/Nocturnal Hemodialysis Study, a prospective, comparative, nonrandomized study, directly compared outcomes of quotidian (daily) hemodialysis patients with conventional thrice-weekly hemodialysis patients. Patients were assigned to either daily (short-hours) hemodialysis (n = 11) or nocturnal hemodialysis (n = 12) and followed up for 5-36 months; all data were directly compared with matched control patients receiving conventional hemodialysis (n = 22). Outcomes evaluated were adequacy (urea kinetics), nutrition, anemia management, blood pressure and volume control, calcium/phosphorus control, and patient quality of life. In addition, a detailed economic analysis was undertaken. The study showed that both quotidian hemodialysis regimens are more effective than conventional hemodialysis in improving weekly urea clearance. Significant clinical improvements were seen with quotidian therapy in the areas of nutrition (short-hours daily), blood pressure (both), volume control (short-hours daily), calcium/phosphorus control (nocturnal), and quality of life (both). A nonsignificant trend for improvement in anemia management was suggested. The economic analysis showed substantial savings in annualized cost per quality-adjusted life-year in changing from conventional hemodialysis (carried out in-center, in satellite units, or at home) to home quotidian hemodialysis. The substantial clinical benefits of home quotidian hemodialysis, combined with the economic advantage shown by this study, clearly justify its expansion. (The details of this study have recently been published in 11 articles in the American Journal of Kidney Diseases[2003;42(suppl 1)].