Intradialytic changes of serum magnesium and their relation to hypotensive episodes in hemodialysis patients on different dialysates

Magnesium is a crucial mineral, involved in many important physiological processes. Magnesium plays a role of maintaining myocardial electrical stability in hemodialysis patients. Intradialytic hypotension is a common complication of dialysis and it is more common with acetate dialysate. The significance of the intradialytic changes of magnesium and their relation to parathyroid hormone (PTH) level and calcium changes during dialysis, and their relation to hypotensive episodes during dialysis are interesting. The aim of this work is to investigate the intradialytic changes of serum magnesium in chronic hemodialysis patients with different hemodialysis modalities and the relation to other electrolytes and to PTH, and also the relation to intradialytic hypotension. The present study was conducted on 20 chronic renal failure patients. All patients were on regular hemodialysis thrice weekly 4 hr each using acetate dialysate (group I). To study the effect of an acetate-based dialysate vs. a bicarbonate-based dialysate on acute changes of magnesium, calcium, phosphorus, and PTH during a hemodialysis session, the same patients were shifted to bicarbonate dialysis (group II). All patients were subjected to full history and clinical examination, predialysis laboratory assessment of blood urea nitrogen (BUN), serum creatinine, albumin, and hemoglobin, serial assessment of magnesium, calcium, phosphorus, and parathyroid hormone at the start of the hemodialysis session, 2 hr later, and at the end of the session, blood pH, and electrocardiogram (ECG) presession and postsession. All patients were urged to fix their dry weight, diet, and current medications. None of the patients had diabetes, neoplasia, liver disease, or cachexia, nor had they been recently on magnesium-containing drugs or previously parathyroidectomized. Hemodialysis sessions were performed by volumetric dialysis machines using the same electrolyte composition. Magnesium level significantly increased in the bicarbonate group at the end of dialysis (0 hr: 2.73+/-0.87, 2 hr: 3.21+/-1.1, and at 4 hr: 5.73+/-1.45 mg/dL, p value <0.01), while it significantly decreased in the acetate group (0 hr: 3.00+/-0.58, 2 hr: 2.26+/-0.39, 4 hr: 1.97+/-0.33 mg/dL, p value <0.01). Calcium level significantly increased in the bicarbonate group (p=0.024) but not in the acetate group. Phosphorus level significantly decreased in both acetate and bicarbonate groups. PTH level did not significantly change in either group, p value > or =0.05. Blood pH significantly increased, changing from acidic to alkaline pH, with both modalities of hemodialysis. ECG showed no significant changes during sessions with either type of dialysate. Hypotension was significantly higher in group I compared with group II (p=0.01), and this hypotension was positively correlated with a decrease in serum magnesium level in group I. Intradialytic changes in serum magnesium have no correlation with intradialytic changes in serum calcium or with PTH level. However, it was significantly correlated with hypotension during the dialysis session, especially with acetate dialysate. Further investigations are needed to determine whether or not this is true in patients using bicarbonate dialysis.     

Reducing the risk of intradialytic hypotension by altering the composition of the dialysate

Hypotension is the most common complication of outpatient hemodialysis sessions, with a reported prevalence of 4% to 31%, depending on which definition has been used and whether patients are symptomatic and nursing interventions were required. Dialysis centers which mix the dialysate in the dialysis machine have the opportunity to individualize the composition of the dialysate for patients. This permits a choice of dialysate sodium, potassium, calcium, magnesium, bicarbonate, acetate, and citrate concentrations and temperature. Studies have reported a higher intradialytic systolic blood pressure and fewer episodes of intradialytic hypotension when using a higher dialysate sodium, calcium, magnesium concentrations and lower temperature, but no clinical advantage for changing the potassium, bicarbonate, or citrate for acetate concentrations. The introduction of newer technology allowing real time measurements of plasma electrolyte concentrations will potentially allow changing the dialysate composition to reduce the risk of intradialytic hypotension without increasing the risk of positive electrolyte balances.     

Results of improvement in adequacy of intermittent hemodialysis (IHD) in uremic patients

Sodium modeling is a strategy to decrease the incidence of hypotension during hemodialysis. Side effects include increased interdialytic weight gain. By default, all patients at our dialysis center are started on HD with sodium modeling. Purpose: To compare weight gain and blood pressure after discontinuation of sodium modeling. Methods: Ten patients using sodium modeling were changed to a standard sodium bath after a change in attending physician. After IRB approval, we collected and retrospectively reviewed the change in interdialytic weight gains, episodes of hypotension (defined as an episode of hypotension requiring staff intervention), and starting and ending blood pressure. Data from one week prior to Na change (PRE) was compared to one week after Na change (POST) using a paired samples t‐test. Results: Data from 4 men and 6 women with a mean age of 65.2 ± 13.7 years was reviewed. ESRD diagnoses included diabetes (n = 4) and hypertension (n = 6). Interdialytic weight gain significantly decreased after discontinuation of sodium modeling (PRE 3.86 kg, POST 3.11 kg, p = 0.004). No significant change in blood pressure at the start (PRE 154/82 POST 156/83, p = 0.745) or end of HD (PRE 123/69, POST 130/67, p = 0.201) was observed. However, the frequency of symptomatic hypotension increased after change to standard sodium bath (PRE = 6%, POST = 27%, p = 0.031). All episodes of hypotension occurred in 3 of the 10 study patients. No patient required cessation of HD or transfer to the emergency department. The degree of weight gain was not correlated with the likelihood of intradialytic hypotension. Conclusion: A change from sodium modeling to standard sodium dialysate lowers interdialytic weight gain but increases the incidence of mild symptomatic hypotension. Further study is needed to determine whether mild hypotension is preferable to increased interdialytic weight gain and to determine the relationship of increased weight gain to complications of volume overload such as LVH and CHF.     

Is there an association between intradialytic hypotension and serum magnesium changes?

Intradialytic hypotension (IDH) is the most common complication of hemodialysis (HD). The aim of this study was to investigate the significance of intradialytic changes of serum magnesium (sMg) and its relation to IDH. We considered 58 patients undergoing HD. Serum magnesium was measured at start, after 2 hours, and at the end of the HD sessions. Total sMg concentration corrected for albumin was according to Krolles proposed formula. Blood pressure was measured every 30 min. Data were analyzed by SPSS.15. A P value of less than 0.05 was considered as significant. Occurrence of IDH among HD patients was 27.6% (16/58). Serum magnesium decreased significantly during HD session (P<0.05). Comparing corrected sMg in IDH group with non-IDH group showed that: corrected sMg was 0.66 ± 0.14 mmol/L vs. 0.84 ± 0.26 mmol/L at the start of dialysis (P=0.43), 0.62 ± 0.17 mmol/L vs. 0.74 ± 0.23 mmol/L (P=0.04) at 2 hours, and 0.61 ± 0.12 mmol/L vs. 0.72 ± 0.22 mmol/L (P=0.03) at the end of dialysis. Intradialytic hypotension episodes were significantly related to a decrease in sMg during dialysis (P=0.02). There was a significant decrease in sMg levels during dialysis. Intradialytic hypotension was significantly related to lowered sMg levels during dialysis.     

Pre to post‐dialysis plasma sodium change better predicts clinical outcomes than dialysate to plasma sodium gradient in quotidian hemodialysis

Sodium balance across a hemodialysis treatment influences interdialytic weight gain (IDWG), pre‐dialysis blood pressure, and the occurrence of intradialytic hypotension, which associate with patient morbidity and mortality. In thrice weekly conventional hemodialysis patients, the dialysate sodium minus pre‐dialysis plasma sodium concentration (δDPNa+) and the post‐dialysis minus pre‐dialysis plasma sodium (δPNa+) are surrogates of sodium balance, and are associated with both cardiovascular and all‐cause mortality. However, whether δDPNa+ or δPNa+ better predicts clinical outcomes in quotidian dialysis is unknown. We performed a retrospective analysis of clinical and demographic data from the Southwestern Ontario Regional Home Hemodialysis program, of all patients since 1985. In frequent nocturnal hemodialysis, δPNa+ was superior to δDPNa+ in predicting IDWG (R² = 0.223 vs. 0.020, P = 0.002 vs. 0.76), intradialytic change in systolic (R² = 0.100 vs. 0.002, P = 0.02 vs. 0.16) and diastolic (R² = 0.066 vs. 0.019, P = 0.02 vs. 0.06) blood pressure, and ultrafiltration rate (R² = 0.296 vs. 0.036, P = 0.001 vs. 0.52). In short hours daily hemodialysis, δDPNa+ was better than δPNa+ in predicting intradialytic change in diastolic blood pressure (R² = 0.101 vs. 0.003, P = 0.02 vs. 0.13). However, δPNa+ was better than δDPNa+ in predicting IDWG (R² = 0.105 vs. 0.019, P = 0.04 vs. 0.68) and pre‐dialysis systolic blood pressure (R² = 0.103 vs. 0.007, P = 0.02 vs. 0.82). We also found that the intradialytic blood pressure fall was greater in frequent nocturnal hemodialysis patients than in short hours daily patients, when exposed to a dialysate to plasma sodium gradient. These results provide a basis for design of prospective trials in quotidian dialysis modalities, to determine the effect of sodium balance on cardiovascular outcome.     

Sodium and ultrafiltration profiling in hemodialysis: A long-forgotten issue revisited

Sodium and ultrafiltration profiling are method of dialysis in which dialysate sodium concentration and ultrafiltration rate are altered during the course of the dialysis session. Sodium and ultrafiltration profiling have been used, commonly simultaneously, to improve hemodynamic stability during hemodialysis. Sodium profiling is particularly effective in decreasing the incidence of intradialytic hypotension, while ultrafiltration profiling is suggested to decrease subclinical repeated end organ ischemia during dialysis. However, complications such as increased interdialytic weight gain and thirst due to sodium excess have prevented widespread use of sodium profiling. Evidence suggest that different sodium profiling techniques may lead to different clinical results, and preferring sodium balance neutral sodium profiling may mitigate adverse effects related to sodium overload. However, evidence is lacking on the long-term clinical outcomes of different sodium profiling methods. Optimal method of sodium profiling as well as the utility of sodium/ultrafiltration profiling in routine practice await further clinical investigation.     

Determinants of metabolic acidosis among hemodialysis patients

Metabolic acidosis is frequently present, poorly controlled, and associated with adverse effects among hemodialysis patients. Potential determinants of metabolic acidosis include endogenous acid production, administration of alkali, neutralization of acid by buffers, dilution of serum bicarbonate by interdialytic fluid gain, and loss of bicarbonate in stool. Understanding the relative importance of these determinants may help guide efforts to manage metabolic acidosis. We used chart abstraction, patient interviews, and laboratory testing to assess variables related to acid production (protein breakdown), alkali administration (dialysis dose, missed treatments, dialysate bicarbonate concentration, oral bicarbonate supplements), acid buffering (phosphorus binders), dilution of bicarbonate (interdialytic weight gain), and loss of bicarbonate in stool (diarrhea) for 190 randomly selected patients from 44 hemodialysis facilities. We used multivariate analyses to determine which potential determinants were independently associated with predialysis serum bicarbonate levels. Of all patients, 30% had metabolic acidosis (serum bicarbonate level <22 mEq/L). On multivariate analysis, metabolic acidosis was more likely with increased protein nitrogen appearance (odds ratio [OR] 1.60 per 0.2 g/kg/day, p=0.001) and less likely with increased Kt/V (OR 0.61 per 0.20 increase in Kt/V, p<0.001) and with increased calcium carbonate use (OR 0.38 per 2 g/day, p=0.003). Key determinants of metabolic acidosis among hemodialysis patients are protein breakdown, dialysis dose, and specific phosphorus binders. Further work is needed to develop interventions to address these determinants.     

Using dialysis machine technology to reduce intradialytic hypotension

Intradialytic hypotension remains the most frequent complication associated with routine outpatient hemodialysis. Although increasing dialysis frequency and also lengthening dialysis session duration can reduce the risk of intradialytic hypotension, in practice, these options are limited to a small minority of dialysis patients. To help reduce intradialytic hypotension, a number of technological developments have been incorporated into the hemodialysis machine, based around relative blood volume monitoring, an indirect assessment of plasma volume. Further developments based on so called "fuzzy" logic feedback systems designed to adjust either or both the ultrafiltration rate and dialyzate sodium concentration according to relative changes in plasma volume. In addition, cooling and dissipation of the heat generated during dialysis also reduces the risk of intradialytic hypotension, and this can be regulated by cooling of the dialyzate using thermal control systems. In addition, convective therapies, such as online hemodialfiltration, have also been reported to reduce the frequency of intradialytic hypotension; whether this effect is simply due to increased cooling remains to be determined. Although all these developments have been reported to reduce the frequency of serious intradialytic hypotensive episodes, they have not been able to totally abolish hypotension, as they can not alone compensate for excessive weight gains and consequent excessive ultrafiltration requirements. Thus, in addition to the advances in hemodialysis machine technology designed to reduce intradialytic hypotension, attention also needs to be focused on reducing interdialytic weight gains, so reducing ultrafiltration requirement.     

The efficiency of potassium removal during bicarbonate hemodialysis

Patients on chronic hemodialysis often portray high serum [K+]. Although dietary excesses are evident in many cases, in others, the cause of hyperkalemia cannot be identified. In such cases, hyperkalemia could result from decreased potassium removal during dialysis. This situation could occur if alkalinization of body fluids during dialysis would drive potassium into the cell, thus decreasing the potassium gradient across the dialysis membrane. In 35 chronic hemodialysis patients, we compared two dialysis sessions performed 7 days apart. Bicarbonate or acetate as dialysate buffers were randomly assigned for the first dialysis. The buffer was switched for the second dialysis. Serum [K+], [HCO3-], and pH were measured in samples drawn before dialysis; 60, 120, 180, and 240 min into dialysis; and 60 and 90 min after dialysis. The potassium removed was measured in the dialysate. During the first 2 hr, serum [K+] decreased equally with both types of dialysates but declined more during the last 2 hr with bicarbonate dialysis. After dialysis, the serum [K+] rebounded higher with bicarbonate bringing the serum [K+] up to par with acetate. The lower serum [K+] through the second half of bicarbonate dialysis did not impair potassium removal (295.9 +/- 9.6 mmol with bicarbonate and 299.0 +/- 14.4 mmol with acetate). The measured serum K+ concentrations correlated with serum [HCO3-] and blood pH during bicarbonate dialysis but not during acetate dialysis. Alkalinization induced by bicarbonate administration may cause redistribution of K during bicarbonate dialysis but this does not impair its removal. The more marked lowering of potassium during bicarbonate dialysis occurs late in dialysis, when exchange is negligible because of a low gradient.     

Effects of citrate‐enriched bicarbonate based dialysate on anticoagulation and dialyzer reuse in maintenance hemodialysis patients

Systemic anticoagulation with unfractionated heparin is commonly used in maintenance hemodialysis (HD), but it increases the risk of bleeding complications. We investigated whether the use of citrate‐enriched bicarbonate based dialysate (CD) would reduce systemic anticoagulation without compromising the efficacy of reprocessed dialyzers. This is a crossover study in which half of a total of 30 patients initially underwent HD with acetate‐enriched bicarbonate based dialysate and a standard heparin dose of ～100 IU/kg (Treatment A), whereas the remaining patients were treated with CD and a 30% reduced heparin dose (Treatment B). After 12 consecutive HD sessions in each treatment, the dialysate and heparin doses were reversed, then followed for another period of 12 HD sessions. The two treatment phases were split by a washout period of six HD sessions using acetate‐enriched bicarbonate based dialysate and standard heparin dose. Systemic anticoagulation was higher in Treatment A. The activated partial thromboplastin time at the end of HD session was 68 ± 36 seconds in Treatment A and 47 ± 16 seconds in Treatment B (P = 0.005). Sixty‐eight percent of the dialyzers remained adequate until the 12th use in Treatment A and 61% did so in Treatment B (P = 0.63). Patients had three and 24 cramps episodes during Treatment A and B, respectively (P < 0.001). Nine and 26 symptomatic intradialytic hypotension episodes were seen in Treatment A and B, respectively, (P = 0.003). In conclusion, the use of CD had a favorable effect on anticoagulation in the extracorporeal circuit in patients on maintenance HD, but it was also associated with more hypotension and cramps.     

Changes in biochemical,hemodynamic, and dialysis adherence parameters in hemodialysis patients during Ramadan

This paper aimed to study the effect of Ramadan fasting on biochemical and clinical parameters and compliance for dialysis. A prospective multicenter observational cross‐sectional study comparing fasting with a non‐fasting stable adult hemodialysis patients for demographic and biochemical parameters, compliance with dialysis, inter‐dialytic weight gain, pre‐ and post‐blood pressure, and frequency of intradialytic hypotensive episodes was carried out. Six hundred thirty‐five patients, of whom 64.1% fasted, were studied. The fasters were younger (53.3 ± 16.2 vs. 58.4 ± 16.1 years; P = 0.001) but had similar duration on dialysis (P = 0.35). More fasters worked (22.0% vs. 14.6%; P = 0.001) and missed dialysis sessions during Ramadan. No differences were noted between groups in sex, diabetic status, or dialysis shift or day. There were no differences in the pre‐ and post‐dialysis blood pressure; serum potassium, albumin or weight gain; diabetic status; sex; and dialysis shift time or days. However, serum phosphorous was significantly higher in the fasting group (2.78 ± 1.8 vs. 2.45 ± 1.6 mmol/L; P = 0.045). There were no intragroup differences in any of the parameters studied when comparing the findings during Ramadan with those in the month before Ramadan. Fasters were significantly younger and more likely to be working, to miss dialysis sessions, and to have higher serum phosphorous levels. No other differences were observed.     

A comparison of center-based vs. home-based daily hemodialysis for patients with end-stage renal disease

Home hemodialysis has been a therapeutic option for almost 4 decades. The complexity of dialysis equipment has been a factor-limiting adoption of this modality. We performed a feasibility study to demonstrate the safety of center-based vs. home-based daily hemodialysis with the NxStage System One portable hemodialysis device. We also performed a retrospective analysis to determine if clinical effects previously associated with short-daily dialysis were also seen using this novel device. We conducted a prospective, 2-treatment, 2-period, open-label, crossover study of in-center hemodialysis vs. home hemodialysis in 32 patients treated at 6 U.S. centers. The 8-week In-Center Phase (6 days/week) was followed by a 2-week transition period and then followed by the 8-week Home Phase (6 days/week). We retrospectively collected data on hemodialysis treatment parameters immediately preceding the study in a subset of patients. Twenty-six out of 32 patients (81%) successfully completed the study. Successful delivery of at least 90% of prescribed fluid volume (primary endpoint) was achieved in 98.5% of treatments in-center and 97.3% at home. Total effluent volume as a percentage of prescribed volume was between 94% and 100% for all study weeks. The composite rate of intradialytic and interdialytic adverse events per 100 treatments was significantly higher for the In-Center Phase (5.30) compared with the Home Phase (2.10; p=0.007). Compared with the period immediately preceding the study, there were reductions in blood pressure, antihypertensive medications, and interdialytic weight gain. Daily home hemodialysis with a small, easy-to-use hemodialysis device is a viable dialysis option for end-stage renal disease patients capable of self/partner-administered dialysis.     

Predictors of post‐hospitalization recovery of renal function among patients with acute kidney injury requiring dialysis

Introduction: Acute kidney injury (AKI) requiring dialysis complicates 1% of all hospital admissions, and up to 30% of survivors will still require dialysis at hospital discharge. There is a paucity of data to describe the postdischarge outcomes or to guide evidence‐based dialysis management of this vulnerable population. Methods: Single‐center, retrospective analysis of 100 consecutive patients with AKI who survived to hospital discharge and required outpatient dialysis. Data collection included baseline characteristics, hospitalization characteristics, and outpatient dialysis treatment variables. Primary outcome was dialysis independence 90 days after discharge. Findings: Overall, 43% of patients recovered adequate renal function to discontinue dialysis, with the majority recovering within 30 days post discharge. Worse baseline renal function was associated with lower likelihood of renal recovery. In the first week postdischarge, patients with subsequent nonrecovery of renal function had greater net fluid removal (5.3 vs. 4.1 L, P = 0.037), higher ultrafiltration rates (6.0 vs. 4.7 mL/kg/h, P = 0.041) and more frequent intradialytic hypotension (24.6% vs. 9.3% with 3 or more episodes, P = 0.049) compared to patients that later recovered. Discussion: A significant proportion of AKI survivors will recover renal function following discharge. Outpatient intradialytic factors may influence subsequent renal function recovery.     

Calcium‐phosphate and parathyroid intradialytic profiles: A potential aid for tailoring the dialysate calcium content of patients on different hemodialysis schedules

Severe hyperparathyroidism is a challenge on hemodialysis. The definition of dialysate calcium (Ca) is a pending issue with renewed importance in cases of individualized dialysis schedules and of portable home dialysis machines with low‐flow dialysate. Direct measurement of calcium mass transfer is complex and is imprecisely reflected by differences in start‐to‐end of dialysis Ca levels. The study was performed in a dialysis unit dedicated to home hemodialysis and to critical patients with wide use of daily and tailored schedules. The Ca‐phosphate (P)‐parathyroid hormone (PTH) profile includes creatinine, urea, total and ionized Ca, albumin, sodium, potassium, P, PTH levels at start, mid, and end of dialysis. “Severe” secondary hyperparathyroidism was defined as PTH > 300 pg/mL for ≥3 months. Four schedules were tested: conventional dialysis (polysulfone dialyzer 1.8–2.1 m²), with dialysate Ca 1.5 or 1.75 mmol/L, NxStage (Ca 1.5 mmol/L), and NxStage plus intradialytic Ca infusion. Dosages of vitamin D, calcium, phosphate binders, and Ca mimetic agents were adjusted monthly. Eighty Ca‐P‐PTH profiles were collected in 12 patients. Serum phosphate was efficiently reduced by all techniques. No differences in start‐to‐end PTH and Ca levels on dialysis were observed in patients with PTH levels < 300 pg/mL. Conversely, Ca levels in “severe” secondary hyperparathyroid patients significantly increased and PTH decreased during dialysis on all schedules except on Nxstage (P < 0.05). Our data support the need for tailored dialysate Ca content, even on “low‐flow” daily home dialysis, in “severe” secondary hyperparathyroid patients in order to increase the therapeutic potentials of the new dialysis techniques.     

Influence of sodium profile in preventing complications during hemodialysis

Although a safe procedure, hemodialysis (HD) can cause numerous complications. The objective of this study was to evaluate the incidence of complications during dialysis, interdialytic weight gain, and the predialysis and postdialysis blood pressure in HD patients with and without variable sodium. Patients were observed during 12 HD sessions and those presenting with recurrent hypotension were selected for a step-wise model of variable sodium profiling. A total of 53 patients were evaluated; the mean-SD age was 53.7+/-16.3 years and 22 (41.5%) were male. Of these, 18 (34.0%) were selected to receive variable sodium profiling: the mean (SD) age was 59.9+/-12.6 years, and 10 (55.6%) were female. A significant decline in the occurrence of cramps (p<0.027), in the mean interdialytic weight gain (p<0.009), and a tendency to reduce the number of hypotensive episodes were detected in patients using variable sodium profiling. On the other hand, predialysis systolic blood pressure presented a significant increase (p<0.048). Using variable sodium, there was a statistically significant reduction in cramps and in the mean interdialytic weight gain. There was a significant increase in predialysis systolic pressure. Regarding hypotension episodes, only a tendency toward a reduction in the frequency of hypotension episodes could be detected.     

Online hemodiafiltration: 4 years of clinical experience

Online hemodiafiltration (online HDF) is a new hemodialysis technique combining convection and diffusion and thus also enabling the purification of large molecules. As yet, only a small number of clinical experiences have been published about the effectiveness and safety of online HDF. We present a prospective and observational study conducted on 31 patients treated with online HDF in our center in the last 4 years. The purpose of the study is to compare the evolution of the following aspects before and after starting online HDF: dose of dialysis, purification of medium-sized/large molecules, inflammation, nutrition, Ca-P metabolism, anemia, and intradialytic complications. Online HDF increased Kt/V to 31.0% (p > 0.001) and reduced postdialysis beta(2)-M to 66.4% (p > 0.001). The rest of the parameters analyzed did not vary significantly. During online HDF, episodes of symptomatic hypotension fell by 45% in relation to conventional hemodialysis, and no relevant complication occurred. Online HDF is very useful in patients in whom we need to increase replacement therapy, such as patients with a large body surface, those in whom we suspect a residual syndrome or those who have been receiving dialysis for a long time and for whom we wish to prevent amyloidosis. Online HDF is safe and better tolerated than conventional hemodialysis.     

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.     

Overview of clinical studies in hemodiafiltration: What do we need now ?

Despite several technical advances in dialysis treatment modalities and a better patient care management including correction of anemia, suppression of secondary hyperparathyroidism, lipid and oxidative stress profiles improvement, the morbidity and the mortality of dialysis patients still remain still elevated. Recent prospective interventional trials in hemodialysis (HEMO study and 4D study) were not very conclusive in showing any significant improvement in dialysis patient outcomes. High-efficiency convective therapies, such as online hemodiafiltration (HDF), are claimed to be superior to conventional diffusive hemodialysis (HD) in improving the dialysis efficacy and in reducing intradialytic morbidity and all-cause and cardiovascular mortality in dialysis patients. The aim of this report was, first, to review the evidence-based facts tending to prove the superiority of HDF vs. HD in terms of efficacy and tolerance, and, second, to analyze the needs to prove the clinical superiority of HDF in terms of reducing morbidity and all-cause mortality of dialysis patients. A systematic review of studies comparing HDF and HD has been performed in the microbiological safety of online production, the solute removal capacity of small and medium-size uremic toxins, and its implication in the reduction of the bioactive dialysis system vs. patient interaction. Major planned randomized international studies comparing HDF and HD in terms of morbidity and mortality have been reviewed. To conclude, it is thought that these long-term prospective randomized trials will clarify on a scientific evidence-based level the putative beneficial role of high-efficiency HDF modalities on dialysis patient outcomes.