The dual blockade of the renin-angiotensin system in hemodialysis patients requires decreased dialysate sodium concentration

A potential link between AQP3 and SLC14A1 gene expression level and clinical parameters of maintenance hemodialysis patients

Background

The transport of water and urea through the erythrocyte membrane is facilitated by aquaporins such as aquaglyceroporin (AQP3), and type B urea transporters (UT-B). As they may play an important role in osmotic balance of maintenance hemodialysis (HD) patients, the aim of the present study was to determine whether any relationship exists between the expression of their genes and the biochemical / clinical parameters in HD patients.

Methods

AQP3 and UT-B (SLC14A1) gene expression was evaluated using RT-qPCR analysis in 76 HD patients and 35 participants with no kidney failure.

Results

The HD group demonstrated significantly higher median expression of AQP3 and UT-B (Z = 2.16; P = 0.03 and Z = 8.82; p < 0.0001, respectively) than controls. AQP3 negatively correlated with pre-dialysis urea serum concentration (R = -0.22; P = 0.049) and sodium gradient (R = -0.31; P = 0.04); however, no significant UT-B correlations were observed. Regarding the cause of end-stage kidney disease, AQP3 expression positively correlated with erythropoietin dosages in the chronic glomerulonephritis (GN) subgroup (R = 0.6; P = 0.003), but negatively in the diabetic nephropathy subgroup (R = -0.59; P = 0.004). UT-B positively correlated with inter-dialytic weight gain% in the GN subgroup (R = 0.47; P = 0.03).

Conclusion

Maintenance hemodialysis seems significantly modify AQP3 and UT-B expression but their link to clinical and biochemical parameters needs further large-scale evaluation.

Efficacy and safety of dual vs single renin-angiotensin-aldosterone system blockade in chronic kidney disease: An updated meta-analysis of randomized controlled trials

BACKGROUND

To lower albuminuria and to achieve blood pressure (BP) goals, dual renin-angiotensin-aldosterone system (RAAS) inhibitors are sometimes used in clinical practice for the treatment of CKD. However, the efficacy and safety of dual RAAS blockade therapy remains controversial.

METHODS

PubMed, EMBASE, and Cochrane Library were searched, and random effects model was used to calculate the effect sizes of eligible studies. Potential sources of heterogeneity were detected by meta-regression and subgroup analysis.

RESULTS

The present meta-analysis of 72 randomized controlled trials with 10,296 patients demonstrated that dual RAAS blockade therapy was superior to monotherapy in reducing the urine albumin excretion, urine protein excretion, and BP. These beneficial effects were related to the decrease of glomerular filtration rate, the increase of serum potassium level, and higher rates of hyperkalemia and hypotension. Meanwhile, these effects did not lead to improvements in short-term or long-term outcomes, including doubling of serum creatinine, acute kidney injury, end-stage renal disease, mortality, and hospitalization. Compared with the single therapy, angiotensin-converting enzyme inhibitor (ACEI) in combination with angiotensin-receptor blocker (ARB) was a better dual therapy than ACEI or ARB in combination with renin inhibitor or aldosterone receptor antagonist in decreasing urine albumin excretion, urine protein excretion and BP, and the combination was not associated with a lower glomerular filtration rate.

CONCLUSION

Compared with the single therapy, ACEI in combination with ARB was a better dual therapy than ACEI or ARB in combination with renin inhibitor or aldosterone receptor antagonist. Although ACEI in combination with ARB was associated with higher incidences of hyperkalemia and hypotension, careful individualized management and potassium binders may further expand its application (PROSPERO number CRD42020179398).

Efficacy and Safety of Angiotensin-Converting Enzyme Inhibitor in Combination with Angiotensin-Receptor Blocker in Chronic Kidney Disease Based on Dose: A Systematic Review and Meta-Analysis

Background: The purpose of this meta-analysis was to evaluate the controversy of angiotensin-converting enzyme inhibitor (ACEI) in combination with angiotensin-receptor blocker (ARB) in the treatment of chronic kidney disease (CKD) based on dose.

Methods: PubMed, EMBASE, and Cochrane Library were searched to identify randomized controlled trials (RCTs) from inception to March 2020. The random effects model was used to calculate the effect sizes. Potential sources of heterogeneity were detected using sensitivity analysis and meta-regression.

Results: This meta-analysis of 53 RCTs with 6,375 patients demonstrated that in patients with CKD, ACEI in combination with ARB was superior to low-dose ACEI or ARB in reducing urine albumin excretion (SMD, −0.43; 95% CI, −0.67 to −0.19; p = 0.001), urine protein excretion (SMD, −0.22; 95% CI, −0.33 to −0.11; p < 0.001), and blood pressure (BP), including systolic BP (WMD, −2.89; 95% CI, −3.88 to −1.89; p < 0.001) and diastolic BP (WMD, −3.02; 95% CI, −4.46 to −1.58; p < 0.001). However, it was associated with decreased glomerular filtration rate (GFR) (SMD, −0.13; 95% CI, −0.24 to −0.02; p = 0.02) and increased rates of hyperkalemia (RR, 2.07; 95% CI, 1.55 to 2.76; p < 0.001) and hypotension (RR, 2.19; 95% CI, 1.35 to 3.54; p = 0.001). ACEI in combination with ARB was more effective than high-dose ACEI or ARB in reducing urine albumin excretion (SMD, −0.84; 95% CI, −1.26 to −0.43; p < 0.001) and urine protein excretion (SMD, −0.24; 95% CI, −0.39 to −0.09; p = 0.002), without decrease in GFR (SMD, 0.02; 95% CI, −0.12 to 0.15; p = 0.78) and increase in rate of hyperkalemia (RR, 0.94; 95% CI, 0.65 to 1.37; p = 0.76). Nonetheless, the combination did not decrease the BP and increased the rate of hypotension (RR, 3.95; 95% CI, 1.13 to 13.84; p = 0.03) compared with high-dose ACEI or ARB.

Conclusion: ACEI in combination with ARB is superior in reducing urine albumin excretion and urine protein excretion. The combination is more effective than high-dose ACEI or ARB without decreasing GFR and increasing the incidence of hyperkalemia. Despite the risk of hypotension, ACEI in combination with ARB is a better choice for CKD patients who need to increase the dose of ACEI or ARB (PROSPERO CRD42020179398).

Practice patterns in transitioning patients from chronic kidney disease to dialysis: a survey of United States nephrologists

Background

There are no guidelines for transitioning patients from chronic kidney disease stage 5 to hemodialysis. We conducted this study to determine if there are uniform patterns in how nephrologists transition patients to dialysis.

Methods

We designed an electronic survey with 39 questions and sent it to a database of practicing nephrologists at the National Kidney Foundation. Factors that were important for transitioning a patient to hemodialysis were evaluated, including medication changes on dialysis initiation, dry weight and dialysis prescription.

Results

160 US Nephrologists replied to the survey; 18% (29/160) of the responses were completed via social media sites. Prior to dialysis, 74% (118/160), prescribed furosemide and 67% (107/160) used furosemide with metolazone. Once dialysis started, only 46% (74/160) of the responders continued patients on diuretics daily. Hypertension medications prescribed in dialysis were calcium channel blockers 69% (112/160), beta blockers 36% (58/160), angiotensin converting enzyme inhibitor 32% (53/160), angiotensin receptor blocker 29% (46/160) and diuretics 25% (42/160). Once dialysis started, 68% (109/160) routinely changed medications. Most, 67% (107/160) ordered patients to avoid anti-hypertensive medications on dialysis days to allow for ultrafiltration. Dry weight was determined in the first week by 29% (46/160) and in the first month by 53% (85/160). Most, 59% (94/160) felt that multiple causes lead to hypertension. Most nephrologists would prescribe small dialyzers and a shorter period of time for the first dialysis session.

Conclusion

The transition period to chronic hemodialysis has variations in practice patterns and may benefit from further studies to optimize clinical practice.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0943-0) contains supplementary material, which is available to authorized users.

Determinants of thirst distress in patients on hemodialysis

PURPOSE

Thirst sensation can induce nonadherence with fluid restriction in patients on hemodialysis (HD) and may lead to large interdialytic weight gain (IWG). This study aimed to evaluate thirst distress and its determinants and to explore fluid management strategies used by patients on HD.

METHODS

A cross-sectional study was conducted in a sample of 203 patients who were followed in three HD centers in Turkey, from January 2015 to June 2015. Data were collected by a personal information form, the Thirst Distress Scale (TDS) and the Visual Analogue Scale (VAS) for thirst and xerostomia. Data analysis was performed using descriptive statistics, Student's t test, the one-way analysis of variance, Pearson's correlation coefficients, and linear regression analysis.

RESULTS

The mean TDS score was 20.71 ± 8.34, which is a higher than moderate level of thirst distress. The significant determinants of thirst distress of the patients were the VAS thirst score (unstandardized β = 1.73, p < 0.001), the VAS xerostomia score (unstandardized β = 0.42, p < 0.001), and the IWG values (unstandardized β = 1.20, p = 0.003), after controlling for specific variables. The most common strategies used to reduce fluid intake or relieve thirst were avoiding salty foods (70.9 %), limiting salt on food (70.9 %), and spacing liquids over the entire day (57.6 %).

CONCLUSIONS

Patients with higher levels of thirst and xerostomia and those with a high IWG were more likely to have higher thirst distress. A greater understanding of thirst distress and its related factors could contribute to more effective interventions that improve health and well-being in patients on HD.

Validity and reliability of the Turkish version of the thirst distress scale in patients on hemodialysis

PURPOSE

Thirst has been reported as an important source of distress for patients on hemodialysis. However, there is no instrument available that assesses thirst distress of Turkish patients on hemodialysis. Therefore, the aim of this study was to examine the psychometric properties of the Turkish version of the Thirst Distress Scale (TDS-T) for patients on hemodialysis.

METHODS

This study was conducted methodologically. A convenience sample of 142 Turkish patients on hemodialysis participated in this study. Data were collected by using a questionnaire, the TDS-T and a visual analogue scale for thirst intensity. The analysis of data included descriptive statistics, the one-sample Kolmogorov-Smirnov test, Kruskal-Wallis test, Mann-Whitney U test, correlation coefficients and psychometric tests.

RESULTS

The TDS-T demonstrated acceptable internal consistency (Cronbach's alpha coefficient = .81), good test-retest reliability (intraclass correlation coefficient = .88), and correlations with interdialytic weight gain values and thirst intensity scores (measured by visual analogue scale) indicating concurrent and convergent validity, respectively. Construct validity was supported by known-group comparisons. The results revealed a one-component structure of the instrument.

CONCLUSIONS

The psychometric properties of the TDS-T were consistent with those reported in the original study. The TDS-T was found to be a valid and reliable tool for evaluating thirst distress in patients on hemodialysis.

Sodium gradient, xerostomia, thirst and inter-dialytic excessive weight gain: a possible relationship with hyposalivation in patients on maintenance hemodialysis

Purpose

The aim of the study was to assess whether hyposalivation is linked with increased thirst sensation and weight gain in hemodialysis (HD) patients and whether there is any connection between hyposalivation and sodium balance.

Methods

One hundred and eleven participants (64 males and 47 females) receiving maintenance hemodialysis, mean age 59.1 ± 13.6 years old, were involved in the study. All participants completed a survey evaluating thirst intensity (DTI) and xerostomia inventory (XI). In addition, pre-dialysis sodium concentration and inter-dialytic weight gain (IWG) were assessed. The division into no-hyposalivation and hyposalivation groups was based on an unstimulated whole saliva (UWS) flow rate.

Results

Hyposalivation, UWS below 0.1 mL/min, was reported in 28.8 % of HD patients. In these participants, IWG was higher than in patients with UWS > 0.1 mL/min (3.65 ± 1.78 vs 3.0 ± 1.4; p = 0.042), as well as the pre-dialysis sodium gradient (3.22 ± 2.1 vs 1.6 ± 2.8; p = 0.031). The mean XI and DTI scores did not differ between study groups. In the hyposalivation group, pre-dialysis sodium serum gradient negatively correlated with saliva outflow (ρ = −0.61, p = 0.019) and positively with IWG (ρ = 0.49, p = 0.022). IWG correlated with XI (ρ = 0.622, p = 0.016) in hyposalivation group and with DTI in no-hyposalivation group (ρ = 0.386, p = 0.033).

Conclusions

Hyposalivation significantly correlates with IWG; however, its influence on thirst and self-reported mouth dryness seems to be weaker than expected. Additionally, hyposalivation was found to be associated with an elevated pre-dialysis sodium gradient.

Rationale and design of the Sodium Lowering In Dialysate (SoLID) trial: a randomised controlled trial of low versus standard dialysate sodium concentration during hemodialysis for regression of left ventricular mass

BACKGROUND

The current literature recognises that left ventricular hypertrophy makes a key contribution to the high rate of premature cardiovascular mortality in dialysis patients. Determining how we might intervene to ameliorate left ventricular hypertrophy in dialysis populations has become a research priority. Reducing sodium exposure through lower dialysate sodium may be a promising intervention in this regard. However there is clinical equipoise around this intervention because the benefit has not yet been demonstrated in a robust prospective clinical trial, and several observational studies have suggested sodium lowering interventions may be deleterious in some dialysis patients.

METHODS/DESIGN

The Sodium Lowering in Dialysate (SoLID) study is funded by the Health Research Council of New Zealand. It is a multi-centre, prospective, randomised, single-blind (outcomes assessor), controlled parallel assignment 3-year clinical trial. The SoLID study is designed to study what impact low dialysate sodium has upon cardiovascular risk in dialysis patients. The study intends to enrol 118 home hemodialysis patients from 6 sites in New Zealand over 24 months and follow up each participant over 12 months. Key exclusion criteria are: patients who dialyse more frequently than 3.5 times per week, pre-dialysis serum sodium of <135 mM, and maintenance hemodiafiltration. In addition, some medical conditions, treatments or participation in other dialysis trials, which contraindicate the SoLID study intervention or confound its effects, will be exclusion criteria. The intervention and control groups will be dialysed using dialysate sodium 135 mM and 140 mM respectively, for 12 months. The primary outcome measure is left ventricular mass index, as measured by cardiac magnetic resonance imaging, after 12 months of intervention. Eleven or more secondary outcomes will be studied in an attempt to better understand the physiologic and clinical mechanisms by which lower dialysate sodium alters the primary end point.

DISCUSSION

The SoLID study is designed to clarify the effect of low dialysate sodium upon the cardiovascular outcomes of dialysis patients. The study results will provide much needed information about the efficacy of a cost effective, economically sustainable solution to a condition which is curtailing the lives of so many dialysis patients.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry number: ACTRN12611000975998.