Nutritional effects of delivered bicarbonate dose in maintenance hemodialysis patients

Oral sodium bicarbonate in people on haemodialysis: a randomised controlled trial

Background

Adverse events and mortality tend to cluster around dialysis sessions, potentially due to the impact of the saw-toothed profile of uraemic toxins such as potassium, peaking pre-dialysis and rapidly dropping during dialysis. Acidosis could be contributing to this harm by exacerbating a rise in potassium. The objectives of this study were to investigate the effects of oral bicarbonate treatment on reducing inter-dialytic potassium gain as well as other clinical consequences of preserving muscle mass and function and reducing intradialytic arrhythmia risk in people on haemodialysis.

Methods

Open-label randomised controlled trial in a single-centre (London, UK). Forty-three clinically stable adults on haemodialysis were recruited, with a 6 month average pre-dialysis serum bicarbonate level < 22 mmol/l and potassium > 4 mmol/l. Thirty-three participants completed the study. Oral sodium bicarbonate tablets titrated up to a maximum of 3 g bd (6 g total) in intervention group for 12 weeks versus no treatment in the control group. Outcomes compared intervention versus non-intervention phases in the treated group and equivalent time points in the control group: pre- and post-dialysis serum potassium; nutritional assessments: muscle mass and handgrip strength and electrocardiograms (ECGs) pre and post dialysis.

Results

Participants took an average of 3.7 ± 0.5 g sodium bicarbonate a day. In the intervention group, inter-dialytic potassium gain was reduced from 1.90 ± 0.60 to 1.69 ± 0.49 mmol/l (p = 0.032) and pre-dialysis potassium was reduced from 4.96 ± 0.62 to 4.79 ± 0.49 mmol/l without dietary change. Pre-dialysis bicarbonate increased from 18.15 ± 1.35 to 20.27 ± 1.88 mmol/l, however with an increase in blood pressure. Nutritionally, lean tissue mass was reduced in the controls suggesting less catabolism in the intervention group. There was no change in ECGs. Limitations are small sample size and unblinded study design lacking a placebo, with several participants failing to achieve the target of 22 mmol/l serum bicarbonate levels due mainly to tablet burden.

Conclusion

Oral sodium bicarbonate reduced bicarbonate loss and potassium gain in the inter-dialytic period, and may also preserve lean tissue mass.

Trial registration

The study was registered prospectively on 06/08/2015 with EU Clinical Trials Register EudraCT number 2015-001439-20.

Hemodialysis Modality, Percentage of Body Fat, and Patient Survival

Background

A number of studies have reported lower mortality of overweight hemodialysis patients. This post hoc analysis of an observational prospective single-center study was aimed at elucidating whether both being overweight and surviving longer could result from changes in the hemodialysis modality.

Methods

The study included a cohort of 242 patients who were gradually switched from cuprophane membrane and acetate dialysis to polysulfone (including high-flux) membranes and bicarbonate dialysis. The analysis involved 12 months of baseline data obtained during the first calendar year after the patients entered the study (1994–2001) and repeated measurements for up to 132 months of follow-up (until 2004). Anthropometric measurements were made during the winter season and the percentage of body fat (%fat) was calculated from triceps, biceps, subscapular, and suprailiac skinfolds (K/DOQI guidelines). Kt/V, normalized protein catabolic rate, and cardiovascular comorbidity were also determined and laboratory analyses undertaken.

Results

Significant correlations were found between %fat and bicarbonate dialysate as well as polysulfone membrane and high-flux membrane. The linear mixed model showed dependence of %fat on polysulfone and high-flux membrane (p<0.01) Multivariate Cox regression (time-dependent covariates) found %fat to be an independent factor for longer survival, in addition to polysulfone and high-flux membranes.

Conclusion

Changes in hemodialysis modality were followed by both higher body fat percentage and patient survival. The reverse epidemiology of overweight patients might be at least partially the result of the influence of nonnutritional factors, such as a change in hemodialysis modality (introducing biocompatible high-flux and low-flux membranes and bicarbonate dialysis).

Challenges of Providing Nutrition Support in the Outpatient Dialysis Setting

Malnutrition is prevalent in maintenance hemodialysis (MHD) patients and has been strongly associated with increased morbidity and mortality. There are numerous contributors to the development, occurrence, and persistence of malnutrition in the MHD patient. Intensive diet counseling and use of enteral supplements may not be effective interventions for patients exhibiting high nutrition risk. More aggressive nutrition options such as enteral and parenteral support are less often used and have associated risks. Intradialytic parenteral nutrition (IDPN) as a form of PN delivered during the dialysis procedure is a convenient and attractive convention that is underused because of its history and controversy. There is a lack of randomized controlled trials demonstrating improved morbidity and mortality with all nutrition support interventions in MHD patients. This research is particularly crucial for IDPN in order to render change in Medicare reimbursement. Qualification of patients for this therapy is difficult because of the very strict coverage criteria. For those patients who do qualify for IDPN, clinician nutrition support knowledge is essential for safe administration of solutions and effective physical, metabolic, and nutrition management of the patient. Attention to other factors that contribute to malnutrition in MHD such as treatment adequacy and comorbid conditions is important; however, the early detection of malnutrition in the MHD patient with appropriate level of nutrition intervention is critical. Future improved understanding of the malnutrition of uremia will allow for development and investigation of other strategies that are anti-catabolic or anabolic.

Correction of metabolic acidosis on serum albumin and protein catabolism in hemodialysis patients

BACKGROUND

The effect of the correction of metabolic acidosis (MA) on serum albumin concentrations (sAlbs) in hemodialysis (HD) patients is controversial. This study evaluated the role of the correction of MA on sAlb concentrations, normalized protein catabolic rate (nPCR), and the effect of the concomitant inflammatory status, in a group of acidotic HD patients.

METHODS

The correction of MA by oral supplementation with sodium bicarbonate, and the evaluation of its effect on sAlb, nPCR, and high-sensitivity C-reactive protein (hsCRP), were performed in 29 patients on bicarbonate dialysis for a median of 30 months. Other variables included pre-HD arterial pH, serum bicarbonate, serum creatinine, serum Na, body weight, interdialytic weight gain, pre-HD systolic and diastolic blood pressure, and Kt/V.

RESULTS

Serum bicarbonate and pH increased significantly (P < .0001), from 19.1 +/- 0.7 mmol/L to 24.6 +/- 1.1 mmol/L and from 7.33 +/- 0.03 to 7.39 +/- 0.02, respectively (all values with +/- are SD). The nPCR decreased from 1.13 +/- 0.14 g/kg/day to 1.05 +/- 0.14 g/kg/day (P < .0001). The other variables did not change significantly. In 17 patients with high-sensitivity C-reactive protein <10 mg/L, sAlb increased from 3.7 +/- 0.3 g/dL to 4.0 +/- 0.3 g/dL (P < .01), whereas in 12 with high-sensitivity C-reactive protein >or=10 mg/L, sAlb did not change (3.5 +/- 0.17 g/dL vs. 3.4 +/- 0.13 g/dL; P = NS).

CONCLUSIONS

Oral sodium bicarbonate supplementation is effective in correcting MA in HD patients and does not affect interdialytic weight gain, plasma Na, and blood pressure. The correction of MA is effective in reducing protein catabolism (nPCR) in both inflamed and less inflamed HD patients, but increases sAlb only in patients without inflammation. In inflamed patients, the correction of MA is not sufficient per se to improve sAlb concentrations.

Challenges of nutrition intervention for malnourished dialysis patients

Malnutrition, or protein energy wasting (PEW), is prevalent in patients with chronic kidney disease stage 5 dialysis (CKD-5). One criterion of PEW strongly associated with morbidity and mortality in CKD-5 dialysis patients is the serum albumin level. Serum albumin levels have not improved over the past 10 years. Typical intervention strategies need to be reevaluated. Intradialytic parenteral nutrition (IDPN) is a form of parenteral nutrition delivered during dialysis that is a convenient and assured route of nutrition alimentation for high-nutrition-risk PEW patients who cannot improve nutrition status by oral and enteral routes. Recent qualification criteria for IDPN changes in Medicare part D have made this therapy an available option for many more of these high-nutrition-risk PEW patients. Nutrition support knowledge in clinicians is essential to administer IDPN effectively and to optimize clinical response. An improved understanding of the milieu of uremia and PEW of CKD-5, as well as the study of nutrition interventions inclusive of IDPN, will allow for effective strategies toward improved outcomes in the future.

Long-term oral sodium bicarbonate supplementation does not improve serum albumin levels in hemodialysis patients

Metabolic acidosis, a frequent event in hemodialysis patients, has been implicated as a potential cause of protein-energy malnutrition. Unfortunately, correction of metabolic acidosis by means of high bicarbonate concentration in the dialysate does not seem to lead to significant changes in nutritional parameters. The project was a single-arm, open-label, 12-month pilot study at a university-based tertiary care center aimed at evaluating whether correction of metabolic acidosis through long-term oral sodium bicarbonate supplementation improves serum albumin levels and other nutritional parameters in patients undergoing maintenance hemodialysis. Twenty highly acidotic hemodialysis patients patients were invited to consume an oral supplementation of sodium bicarbonate (1 g, thrice daily), for 12 months. Patients were followed at baseline and every month, until month 12. At each follow-up visit, dry body weight, BMI, blood pressure, presence of edema, venous bicarbonate, and serum albumin were measured. Total lymphocyte count, fasting total cholesterol and C-reactive protein were assessed every 2 months. At baseline and at 12 months, the subjective global assessment of nutritional status and the protein equivalent of nitrogen appearance normalized to actual body weight were determined. Plasma bicarbonate level rose from 18.1 +/- 2.7 to 22.1 +/- 4.5 mmol/l after 10 months (p = 0.001). Mean serum albumin levels were 3.8 +/- 0.2 mg/dl at baseline and 3.9 +/- 0.2 at the end of the study. Repeated measure ANOVA showed that there was no significant effect of bicarbonate treatment on serum albumin levels (p = 0.29), dry weight (p = 0.1), serum total cholesterol (p = 0.97), total lymphocyte count (p = 0.69), or C-reactive protein (p = 0.85). Mean subjective global assessment score was 4.53 +/- 0.37 at baseline and 4.58 +/- 0.54 at 12 months (p = 0.1). Mean nPNA (g/kg/day) was 0.86 +/- 0.05 at baseline and 0.85 +/- 0.08 at month 12. The present study demonstrates that long-term oral sodium bicarbonate at the dose of 1 gram thrice daily has no significant effect on nutritional status of HD patients.

Malnutrition in Hemodialysis Patients: What Therapy?

Malnutrition is common in hemodialysis patients and is a powerful predictor of morbidity and mortality. Although much progress has been made in recent years in identifying the causes and pathogenesis of malnutrition in hemodialysis patients, as well as recognizing the link between malnutrition and morbidity and mortality, no consensus has been reached concerning its management. Along with such conventional interventions as nutritional counseling, oral nutritional supplements, and intradialytic parenteral nutrition, novel preventive and therapeutic strategies have been tested, such as appetite stimulants, growth hormone, androgenic anabolic steroids, and anti-inflammatory drugs, with contradictory and nonconclusive results. Malnutrition still remains a great challenge for nephrologists in the third millennium.