Bicarbonate Dialysis Research Articles

Are Target Serum Bicarbonate Levels Achieved in Maintenance Hemodialysis Patients: A Single Centre Experience

Majority of the maintenance hemodialysis patients donot achieve the target predialysisserum bicarbonate levels. Routine monitoring of serum bicarbonate in diaysis patients is not universally done.We aimed to assess whether our dialysis population attained the predialysis serum bicarbonate target of >22 mEq/L as recommended by the NKF-KDOQI. Correlation between predialysis bicarbonate and clinical and biochemical parameters was also assessed. Fifty patients undergoing maintenance hemodialysis in Government Medical College, Thiruvananthapuram were included in the study.All patients received fixed non-individualizeddialysate bicarbonate concentrations. The mean predialysis bicarbonate obtained was 19 ± 4.2 mEq/L. Thirty six patients(72%) had bicarbonate levels less than 22 mEq/L. Nineteen patients (38%) had bicarbonate level less than 17mEq/L and 5 patients (10%) had level greater than 25 mEq/L. Majority of the patients failed to achieve the target serum bicarbonate. A negative correlation was obtained for predialysis bicarbonate levels with BMI, total protein, serum uric acid, serum phosphorus and serum ferritin. Better nutritional status may be associated with reduction in bicarbonate level because of increased acid generation. In conclusion this study emphasizes the importance of regular monitoring of serum bicarbonate levels in our dialysis patients and the need for adjusting the dialysate bicarbonate concentrations accordingly.

The effect of isohydric hemodialysis on the binding and removal of uremic retention solutes.

BackgroundThere is growing evidence that the accumulation of protein- bound uremic retention solutes, such as indoxyl sulfate, p-cresyl sulfate and kynurenic acid, play a role in the accelerated cardiovascular disease seen in patients undergoing chronic hemodialysis. Protein-binding, presumably to albumin, renders these solutes poor-dialyzable.We previously observed that the free fraction of indoxyl sulfate was markedly reduced at the end of hemodialysis. We hypothesized that solute binding might be pH-dependent and attributed the changes in free solute concentration to the higher serum pH observed at the end of standard hemodialysis with dialysis buffer bicarbonate concentration greater than 35 mmol/L. We observed that acidification of uremic plasma to pH 6 in vitro greatly increased the proportion of freeIS.MethodsWe tested our hypothesis by reducing the dialysate bicarbonate buffer concentration to 25 mmol/L for the initial half of the hemodialysis treatment (“isohydric dialysis”). Eight stable hemodialysis patients underwent “isohydric dialysis” for 90 minutes and then were switched to standard buffer (bicarbonate = 37mmol/L). A second dialysis, 2 days later, employed standard buffer throughout.ResultsWe found a clearcut separation of blood pH and bicarbonate concentrations after 90 minutes of “isohydric dialysis” (pH = 7.37, bicarbonate = 22.4 mmol/L) and standard dialysis (pH = 7.49, bicarbonate = 29.0 mmol/L). Binding affinity varied widely among the 10 uremic retention solutes analyzed. Kynurenic acid (0.05 free), p-cresyl sulfate (0.12 free) and indoxyl sulfate (0.13 free) demonstrated the greatest degree of binding. Three solutes (indoxyl glucuronide, p-cresyl glucuronide, and phenyl glucuronide) were virtually unbound. Analysis of free and bound concentrations of uremic retention solutes confirmed our prediction that binding of solute is affected by pH. However, in a mixed models analysis, we found that the reduction in total uremic solute concentration during dialysis accounted for a greater proportion of the variation in free concentration, presumably an effect of saturation binding to albumin, than did the relatively small change in pH produced by isohydric dialysis. The effect of pH on binding appeared to be restricted to those solutes most highly protein-bound.The solutes most tightly bound exhibited the lowest dialyzer clearances. An increase in dialyzer clearance during isohydric and standard dialyses was statistically significant only for kynurenic acid.ConclusionThese findings provide evidence that the binding of uremic retention solutes is influenced by pH. The effect of reducing buffer bicarbonate concentration (“isohydric dialysis:”), though significant, was small but may be taken to suggest that further modification of dialysis technique that would expose blood to a greater decrease in pH would lead to a greater increase the free fraction of solute and enhance the efficacy of hemodialysis in the removal of highly protein-bound uremic retention solutes.

Phosphate and Calcium Control in Short Frequent Hemodialysis with the NxStage System One Cycler: Mass Balance Studies and Comparison with Standard Thrice-Weekly Bicarbonate Dialysis

Background: Short frequent dialysis with NxStage System One cycler (NSO) has become increasingly popular as home hemodialysis prescription. Short dialysis sessions with NSO might not allow adequate phosphate (P) removal. Methods: Single-session and weekly balances of P and calcium (Ca) were compared in 14 patients treated with NSO (6 sessions/week) and in 14 patients on standard bicarbonate dialysis (BHD). Results: NSO and BHD showed similar plasma P fall, with end-dialysis plasma P slightly lower in BHD (2.2 ± 0.5 vs. 2.7 ± 0.8 mg/dL, p < 0.02). Single-session P removal was lower in NSO, but weekly removal was higher (3,488 ± 1,181 mg vs. 2,634 ± 878, p < 0.003). Plasma Ca increase was lower in NSO, with similar PTH fall. Ca balance varied according to start plasma Ca, dialysate to blood Ca gradient and net ultrafiltration. Conclusions: short, frequent home hemodialysis with NSO, on a 6/week-based prescription, allows higher weekly P removal than BHD. With the dialysate Ca concentration in use (6 mg/dL), total plasma Ca and iCa concentration increase is lower in NSO.

A case in which an allergy was suspected to have been caused by a bicarbonate dialysate containing acetate

A case in which an allergy was suspected to have been caused by a bicarbonate dialysate containing acetate

The dynamics of the metabolism of acetate and bicarbonate associated with use of hemodialysates in the ABChD trial: a phase IV, prospective, single center, single blind, randomized, cross-over, two week investigation

BackgroundIn the United States, hemodialysis (HD) is generally performed via a bicarbonate dialysate. It is not known if small amounts of acid used in dialysate to buffer the bicarbonate can meaningfully contribute to overall buffering administered during HD. We aimed to investigate the metabolism of acetate with use of two different acid buffer concentrates and determine if it effects blood bicarbonate concentrations in HD patients.MethodsThe Acid-Base Composition with use of hemoDialysates (ABChD) trial was a Phase IV, prospective, single blind, randomized, cross-over, 2 week investigation of peridialytic dynamics of acetate and bicarbonate associated with use of acid buffer concentrates. Eleven prevalent HD patients participated from November 2014 to February 2015. Patients received two HD treatments, with NaturaLyte® and GranuFlo® acid concentrates containing 4 and 8 mEq/L of acetate, respectively. Dialysate order was chosen in a random fashion. The endpoint was to characterize the dynamics of acetate received and metabolized during hemodialysis, and how it effects overall bicarbonate concentrations in the blood and dialysate. Acetate and bicarbonate concentrations were assessed before, at 8 time points during, and 6 time points after the completion of HD.ResultsData from 20 HD treatments for 11 patients (10 NaturaLyte® and 10 GranuFlo®) was analyzed. Cumulative trajectories of arterialized acetate were unique between NaturaLyte® and GranuFlo® (p = 0.003), yet individual time points demonstrated overlap without remarkable differences. Arterialized and venous blood bicarbonate concentrations were similar at HD initiation, but by 240 min into dialysis, mean arterialized bicarbonate concentrations were 30.2 (SD ± 4.16) mEq/L in GranuFlo® and 28.8 (SD ± 4.26) mEq/L in NaturaLyte®. Regardless of acid buffer concentrate, arterial blood bicarbonate was primarily dictated by the prescribed bicarbonate level. Subjects tolerated HD with both acid buffer concentrates without experiencing any related adverse events.ConclusionsA small fraction of acetate was delivered to HD patients with use of NaturaLyte® and GranuFlo® acid buffers; the majority of acetate received was observed to be rapidly metabolized and cleared from the circulation. Blood bicarbonate concentrations appear to be determined mainly by the prescribed concentration of bicarbonate.Trial registrationThis trial was registered on ClinicalTrials.gov on 11 Dec 2014 (NCT02334267).

Shortcoming and Gravity of the usual Prescription for Bicarbonate Dialysis Fluid (&gt; Problem of Calcification by Acidification with 3 mmol/l Acetate)

Shortcoming and Gravity of the usual Prescription for Bicarbonate Dialysis Fluid (&gt; Problem of Calcification by Acidification with 3 mmol/l Acetate)

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach.

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients’ lives. In the early years of dialysis, potassium was identified as “the killer”, and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the “third era” finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the “magic numbers” of nutritional requirements (calories: 30–35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on “conventional” thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of “vascular healthy” food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

Extracorporeal CO2 removal by hemodialysis: in vitro model and feasibility

BackgroundCritically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO2 from the blood, mainly as bicarbonate. In this study, Stewart’s approach to acid-base chemistry was used to create a dialysate that would maintain blood pH while removing CO2 as well as determine the blood and dialysate flow rates necessary to remove clinically relevant CO2 volumes.MethodsBench studies were performed using a scaled down respiratory hemodialyzer in bovine or porcine blood. The scaling factor for the bench top experiments was 22.5. In vitro dialysate flow rates ranged from 2.2 to 24 mL/min (49.5–540 mL/min scaled up) and blood flow rates were set at 11 and 18.7 mL/min (248–421 mL/min scaled up). Blood inlet CO2 concentrations were set at 50 and 100 mmHg.ResultsResults are reported as scaled up values. The CO2 removal rate was highest at intermittent hemodialysis blood and dialysate flow rates. At an inlet pCO2 of 50 mmHg, the CO2 removal rate increased from 62.6 ± 4.8 to 77.7 ± 3 mL/min when the blood flow rate increased from 248 to 421 mL/min. At an inlet pCO2 of 100 mmHg, the device was able to remove up to 117.8 ± 3.8 mL/min of CO2. None of the test conditions caused the blood pH to decrease, and increases were ≤0.08.ConclusionsWhen the bench top data is scaled up, the system removes a therapeutic amount of CO2 standard intermittent hemodialysis flow rates. The zero bicarbonate dialysate did not cause acidosis in the post-dialyzer blood. These results demonstrate that, with further development, respiratory hemodialysis can be a minimally invasive extracorporeal carbon dioxide removal treatment option.

A randomized cross-over study comparing the performance of HD integra\u2122 central concentrate system versus pre-produced concentrate in hemodialysis

BackgroundPre-produced bicarbonate concentrates (PPC) are still widely used in developing countries despite its cost and risk but Central Concentrate System (CCS) is lacking in data to support its wider adoption.MethodsWe conducted an 8-week randomized crossover study on 16 Hemodialysis machines to compare CCS versus PPC. Performance is assessed by solute concentrations while safety is assessed by microbial count, endotoxin level and adverse event reporting.ResultsMicrobial counts and endotoxin levels were monitored on 48 occasions during the 8-week study for the CCS arm of the study. The levels were all below the action limit during the study. No patient reported any adverse events. Dialysate Sodium, Chloride and Bicarbonate concentrations were measured on a total of 128 occasions for each arm of the study. The relative deviations of Sodium, Chloride and Bicarbonate concentration were within ±5% of their nominal values for both. The 95% Confidence Intervals for the ratio of the mean solute concentrations on the CCS to PPC lie within the tolerance limit of ±5%.ConclusionModern CCS is bacteriologically safe and its performance statistically equivalent to PPC.

Changes in Serum Bicarbonate Levels Caused by Acetate‐Containing Bicarbonate‐Buffered Hemodialysis Solution: An Observational Prospective Cohort Study

Fresenius Medical Care's NaturaLyte dialysate has been associated with increased risk of sudden cardiac death by causing metabolic alkalosis from its acetate content based on retrospective data using pre-dialysis bicarbonate levels only. The study objective was to measure inter/intra-dialytic changes in serum bicarbonate and degree of alkalosis conferred by varying concentrations of NaturaLyte bicarbonate dialysate. Thirty-nine hemodialysis patients were divided into four groups based on prescribed bicarbonate dialysate concentrations; Group 1 (N=9): 30-32mEq/L, Group 2 (N=5): 33-34mEq/L, Group 3 (N=10): 35-36mEq/L, Group 4 (N=15): 37-40mEq/L. Serial (pre-dialysis, immediate post-dialysis, 2h post-dialysis, and 68h post-dialysis) bicarbonate levels were measured. Mean pre-dialysis serum bicarbonate levels (representing 44h post-dialysis levels) in all four groups were not statistically different. Pre-dialysis and 68h post-dialysis bicarbonate levels in each group were also not significantly different. However, immediate post-dialysis and 2h post-dialysis bicarbonate levels were significantly increased in all four groups proportional to dialysate dose. There was statistically significant inter-group bicarbonate level difference (P<0.05) except between the first and second (P=0.43) and second and third (P=0.07) groups in the immediate post-dialysis period. Similar results were obtained for the 2h post-dialysis period. High bicarbonate dialysate causes large and rapid fluctuations in serum bicarbonate levels during the intra/inter-dialytic period, which returns to baseline within 44 to 68h after dialysis. This refutes the necessity to correct pre-dialysis acidosis with high bicarbonate dialysate since rapid equilibration is likely to occur and unnecessarily exposes patients to large shifts in their acid base balance.

Effects of two different dialytic treatments on inflammatory markers in people with end-stage renal disease with and without type 2 diabetes mellitus

This study was aimed to evaluate the effects on some inflammatory markers of two dialytic treatments [bicarbonate dialysis (BHD) and hemodiafiltration (HDF)] in patients with severe chronic kidney disease.We evaluated: blood glucose, homeostasis model assessment insulin resistance index, homocistein (Hcs), high sensitivity C-reactive protein (hs-CRP), fibrinogen, lipoprotein (a) [Lp(a)], metalloproteinases-2, and -9 (MMP-2 and MMP-9), and soluble receptor for advanced glycation end products (sRAGE).Considering the all sample, we observed a decrease of sRAGE with BHD, but not with HDF. Fibrinogen, MMP-2, and -9, Hs-CRP decreased after HDF, but not after BHD. In diabetics, blood glucose decreased after HDF dialysis, but not after BHD. Soluble receptor for advanced glycation end products obtained with HDF were higher compared to BHD. Fibrinogen, MMP-2, MMP-9, Hcs, Hs-CRP decreased, and ADN increased after HDF, these changes did not happen after BHD. Furthermore, sRAGE, and ADN were higher, and MMP-2 lower after HDF. In euglycemic patients, instead, MMP-2, MMP-9, and Hs-CRP decreased, and ADN increased with HDF, but not with BHD.We can conclude that hemodiafiltration seems to greater reduce inflammatory markers, and it could be more suitable for people with type 2 diabetes.Registration number: ClinicalTrials.gov NCT01049152.

Correlations of serum magnesium with dyslipidemia in patients on maintenance hemodialysis

Correlations of serum magnesium with dyslipidemia in patients on maintenance hemodialysis

RBP4: A Culprit for Insulin Resistance in End Stage Renal Disease That Can Be Cleared by Hemodiafiltration

Introduction Retinol Binding Protein 4 (RBP4) is mainly excreted by the kidney and plays a pivotal role in insulin resistance (IR). In our study, we evaluated the association between RBP4 and IR in hemodialysis subjects (HD). We also assessed how circulating RBP4 could be influenced by kidney transplant or different dialytic techniques. Methods RBP4 serum levels were evaluated in HD (n = 16) and matched healthy controls (C; n = 16). RBP4 and glucose transporter type 4 (GLUT4) mRNA expressions were also determined in adipose tissue. Circulating RBP4 was evaluated after kidney transplant (n = 7) and in hemodialysis patients (n = 10) enrolled in a cross-over study treated with standard bicarbonate dialysis (BD) or hemodiafiltration (HDF). Results HOMA index (P < 0.05) and serum RBP4 (P < 0.005) were higher in HD compared to C. RBP4 levels positively correlated with fasting serum glucose (P < 0.05). RBP4 mRNA was lower in HD compared to C (P < 0.05) and positively correlated with kidney function (P < 0.05) and GLUT4 mRNA (P < 0.001). Transplant or HDF reduced circulating RBP4 (P < 0.01 and P < 0.05, resp.). Our results demonstrate that IR is associated with high circulating RBP4 and that suppressed RBP4 adipose tissue expression is accompanied by reduced GLUT4 expression in HD. Renal transplantation or HDF are effective in lowering serum RBP4 levels.

Metabolic acidosis in hemodialysis patients: a review

Metabolic acidosis is highly prevalent in hemodialysis patients. The disorder is associated with increased mortality and its deleterious effects are already present in the predialysis phase of chronic kidney disease. Metabolic acidosis has been linked to progression of chronic kidney disease, changes in protein and glucose metabolism, bone and muscle disorders and cardiovascular disease. At present, the control of metabolic acidosis in hemodialysis is mainly focused on the supply of bicarbonate during dialysis session, but further studies are needed to set the optimum target serum bicarbonate and the best concentration of the bicarbonate dialysate. The present study reviews pathophysiological and epidemiological aspects of metabolic acidosis in hemodialysis patients and also addresses its adverse effects and treatment.

Dialysate bicarbonate variation in maintenance hemodiafiltration patients: Impact on serum bicarbonate, intradialytic hypotension and interdialytic weight gain.

The dialysate bicarbonate (DB) influences the acid-base balance in dialysis patients. Very low and high serum bicarbonate (SB) have been related with a higher mortality. Acid-base balance also has been associated with hemodynamic effects in these patients. The trial aim was to compare the effect of DB concentration variation on SB levels in maintenance hemodiafiltration (HDF) patients and the effect on intradialytic hypotension and interdialytic weight gain. A prospective study, with 9 months of follow-up, involving 93 patients, divided in two groups: group 1 and group 2 with a DB of 34 mmol/L and 30 mmol/L, respectively, with monitoring of pre and post HDF SB, intradialytic hypotension, and interdialytic weight gain. Pre dialysis SB was higher in group 1: median concentration of 22.7 mmol/L vs. 21.1 mmol/L (P < 0.001). Post dialysis SB levels were higher in group 1: median concentration of 28.0 mmol/L vs. 25.3 mmol/L (P < 0.001). Post dialysis SB in alkalotic range was only detected in group 1 (51.2% of the patients). No significant differences were detected in intradialytic hypotension rate [28.0 vs. 27.4 episodes per 1000 sessions in group 1 and 2, respectively, (P = 0.906)] or in average interdialytic weight gain [2.9% vs. 3.0% in group 1 and 2, respectively, (P = 0.710)]. DB of 30 mmol/L appears to be associated with SB levels closer to physiological levels than 34 mmol/L. The bicarbonate dialysate, in the tested concentrations, did not appear to have a significant impact on intradialytic hypotension and interdialytic weight gain in maintenance HDF patients.

36th International Symposium on Intensive Care and Emergency Medicine : Brussels, Belgium. 15-18 March 2016.

36th International Symposium on Intensive Care and Emergency Medicine : Brussels, Belgium. 15-18 March 2016.

Mistakes and bioethics in nephrology

“Acetate intolerance” was one of the first negative signs of acetate hemodialysis registered in the history of the treatment of chronic renal failure. Now we consider an error such an approach to kidney disease. But it was an “institutional” error according to the classification of the Italian historian of Medicine, Ettore De Benedetti, to distinguish it from the “personal” error, committed after the revision of acetate treatment and the introduction of bicarbonate dialysis. The same difference could be considered in the “short hemodialysis” technique for the adverse cardiovascular outcome. Many examples of “institutional” and “personal” errors in nephrology are reported. Errors need to be recorded and to be analysed if we want to discover why they occur and how they must be prevented. If we want to eliminate errors, it is mandatory to overcome certain attitudes, deeply rooted in the profession. Medical attitudes are often determined by medical bioethics and by the principles that determine whether ideas or actions are considered right or wrong. Errors by doctors are common. In order to reduce errors many authorities tried to reduce them giving some methodological advices. Very important are the proposals of a clinician, Neil McIntyre, and a philosopher, Karl Popper, for a “new” professional ethics summarized in ten theses, reported in this article.&nbsp;(Bioethics)

Correlation of bioelectrical impedance analysis phase angle with changes in oxidative stress on end-stage renal disease patients, before, during, and after dialysis

Chronic kidney disease is a condition that promotes oxidative stress. There are conflicting evidence about the role of hemodialysis on oxidative stress, that are mostly related with the various types of membrane materials used, the quality and type of dialysate, the method used, etc. The phase angle (PhA), which is determined with bioelectrical impedance analysis (BIA), measures the functionality of cell membranes. In this study, the correlation of the PhA with parameters of oxidative stress is attempted for the first time. We evaluated parameters of oxidative status as total antioxidant capacity (TAC) in erythrocytes (RBCs) and plasma of patients with ESRD undergoing hemodialysis with low flux synthetic polysulfone membranes. Measurements were recorded from 30 patients (16 men and 14 women) aged 64 ± 14 years before, during, and after dialysis, and in 15 healthy volunteers aged 56 ± 12 years The PhA was obtained by BIA. The plasma TAC increased significantly (41%, p < 0.05). Intracellular TAC noted a non-significant increase. Total antioxidant capacity of the patients before and after hemodialysis was significantly lower from the healthy volunteers (p < 0.05) showing that ESRD patients are at the state of increased oxidative stress. The PhA increased in significantly positive correlation with plasma TAC at the end of hemodialysis. The process of hemodialysis with biocompatible synthetic membranes and bicarbonate dialysate improved plasma TAC. The positive correlation of PhA with extracellular TAC could evolve to a method of oxidative stress estimation by BIA but further research is needed.

Variability in monthly serum bicarbonate measures in hemodialysis patients: a cohort study.

BackgroundSome nephrologists have advocated an individualized approach to the prescription of bicarbonate hemodialysis. However, the utility of monthly serum bicarbonate levels for guiding and evaluating such treatment decisions has not been evaluated. We sought to define the variability of these measurements and to determine factors that are associated with month-to-month variability in pre-dialysis serum bicarbonate.MethodsWe examined the monthly variability in serum bicarbonate measurements among 181 hemodialysis patients admitted to a free-standing dialysis unit in the Bronx, NY from 1/1/2008-6/30/2012. All patients were treated with a uniform bicarbonate dialysis prescription (bicarbonate 35 mEq/L, acetate 8 mEq/L). Pre-dialysis serum bicarbonate values were obtained from monthly laboratory reports. Month-to-month variability was defined using a rolling measurement for each time point.ResultsOnly 34 % of high serum bicarbonate values (>26 mEq/L) remained high in the subsequent month, whereas 60 % converted to normal (22–26 mEq/L). Of all low values (<22 mEq/L), 41 % were normal the following month, while 58 % remained low. Using the mean 3-month bicarbonate, only 29 % of high values remained high in the next 3-month period. In multivariable-adjusted longitudinal models, both low and high serum bicarbonate values were associated with greater variability than were normal values (β = 0.12 (95 % CI 0.09–0.15) and 0.24 (0.18 to 0.29) respectively). Variability decreased with time, and was significantly associated with age, phosphate binder use, serum creatinine, potassium, and normalized protein catabolic rate.ConclusionsMonthly pre-dialysis serum bicarbonate levels are highly variable. Even if a clinician takes no action, approximately 50 % of bicarbonate values outside a normal range of 22–26 mEq/L will return to normal in the subsequent month. The decision to change the bicarbonate dialysis prescription should not be based on a single bicarbonate value, and even a 3-month mean may be insufficient.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0206-2) contains supplementary material, which is available to authorized users.

Correcting Acidosis during Hemodialysis: Current Limitations and a Potential Solution.

The deleterious catabolic and pro-inflammatory effects of acidosis in hemodialysis (HD) patients and the importance of its correction for limiting mineral bone disease (MBD) are well known. Although oral base therapy could be a solution for correcting acidosis in HD patients, it increases their already enormous medication load and sodium intake; this approach is not used commonly. Therefore, we need to rely more on correcting acidosis during the HD procedure, which is difficult to achieve, in part, because HD is an intermittent therapy. The currently used fixed dialysate bicarbonate concentrations are associated with pre-HD acidosis and intra-dialytic alkalosis. We suggest that a decreasing dialysate bicarbonate concentration from an initially high concentration be considered as a means of correcting acidosis with limited intra-dialytic alkalosis. Some evidence, as well as theoretical considerations, supports such an approach.