An acute rise of plasma Na+ concentration associates with syndecan-1 shedding during hemodialysis

Dialysate Sodium Lowering in Maintenance Hemodialysis: A Randomized Clinical Trial

Key Points

Treatment to dialysate sodium 135 versus 138 mEq/L led to no difference in the rate of change in intradialytic hypotension, but symptoms were greater in the low arm. Use of a dialysate sodium concentration of 135 versus 138 mEq/L led to a small reduction in interdialytic weight gain, but had no effect on predialysis BP. Raising dialysate sodium concentration from 135 to 140 mEq/L reduced intradialytic hypotension and was associated with a marked increase in BP.

Background

Lowering dialysate sodium concentration may improve volume and BP control in patients on maintenance hemodialysis.

Methods

We randomized 42 participants 2:1 to dialysate sodium 135 versus 138 mEq/L for 6 months. This was followed by a 12-week extension phase in which sodium was increased to 140 mEq/L in low-arm participants. The primary outcome was intradialytic hypotension (IDH). Secondary outcomes included dialysis disequilibrium symptoms, emergency room visits/hospitalizations, interdialytic weight gain, and BP. Longitudinal changes across arms were analyzed using linear mixed regression.

Results

Treatment to dialysate sodium 135 versus 138 mEq/L was not associated with a difference in a change in the rate of IDH (mean change [95% confidence interval], 2.8 [0.8 to 9.5] versus 2.7 [1.1 to 6.2] events per 100 treatments per month); ratio of slopes 0.96 (0.26 to 3.61) or emergency room visits/hospitalizations (7.3 [2.3 to 12.4] versus 6.7 [2.9 to 10.6] events per 100 patient-months); difference 0.6 (−6.9 to 5.8). Symptom score was unchanged in the 135 mEq/L arm (0.7 [−1.4 to 2.7]) and decreased in the 138 mEq/L arm ([5.0 to 8.5 to 2.0]; difference 6.0 [2.1 to 9.8]). Interdialytic weight gain declined in the 135 mEq/L arm and was unchanged in the 138 mEq/L arm (−0.3 [−0.5 to 0.0] versus 0.3 [0.0 to 0.6] kg over 6 months; difference [−0.6 (−0.1 to −1.0)] kg). In the extension phase, raising dialysate sodium concentration from 135 to 140 mEq/L was associated with an increase in interdialytic weight gain (0.2 [0.1 to 0.3] kg) and predialysis BP (7.0 [4.8 to 9.2]/3.9 [2.6 to 5.1] mm Hg) and a reduction in IDH (odds ratio, 0.66 [0.45 to 0.97]).

Conclusions

Use of a dialysate sodium concentration of 135 as compared with 138 mEq/L was associated with a small reduction in interdialytic weight gain without affecting IDH or predialysis BP, but with an increase in symptoms. Raising dialysate sodium concentration from 135 to 140 mEq/L was associated with a reduction in IDH, small increase in interdialytic weight gain, and marked increase in predialysis BP.

Clinical Trial registration number

NCT03144817 .

Update on Hemodialysis-Induced Multiorgan Ischemia: Brains and Beyond

Hemodialysis is a life-saving treatment for patients with kidney failure. However, patients requiring hemodialysis have a 10-20 times higher risk of cardiovascular morbidity and mortality than that of the general population. Patients encounter complications such as episodic intradialytic hypotension, abnormal perfusion to critical organs (heart, brain, liver, and kidney), and damage to vulnerable vascular beds. Recurrent conventional hemodialysis exposes patients to multiple episodes of circulatory stress, exacerbating and being aggravated by microvascular endothelial dysfunction. This promulgates progressive injury that leads to irreversible multiorgan injury and the well-documented higher incidence of cardiovascular disease and premature death. This review aims to examine the underlying pathophysiology of hemodialysis-related vascular injury and consider a range of therapeutic approaches to improving outcomes set within this evolved rubric.‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬.

The Endothelial Glycocalyx: A Possible Therapeutic Target in Cardiovascular Disorders

The physiological, anti-inflammatory, and anti-coagulant properties of endothelial cells (ECs) rely on a complex carbohydrate-rich layer covering the luminal surface of ECs, called the glycocalyx. In a range of cardiovascular disorders, glycocalyx shedding causes endothelial dysfunction and inflammation, underscoring the importance of glycocalyx preservation to avoid disease initiation and progression. In this review we discuss the physiological functions of the glycocalyx with particular focus on how loss of endothelial glycocalyx integrity is linked to cardiovascular risk factors, like hypertension, aging, diabetes and obesity, and contributes to the development of thrombo-inflammatory conditions. Finally, we consider the role of glycocalyx components in regulating inflammatory responses and discuss possible therapeutic interventions aiming at preserving or restoring the endothelial glycocalyx and therefore protecting against cardiovascular disease.

Measuring the Concentration of Serum Syndecan-1 to Assess Vascular Endothelial Glycocalyx Injury During Hemodialysis

Glycocalyx is present on the surface of healthy endothelium, and the concentration of serum syndecan-1 can serve as an injury marker. This study aimed to assess endothelial injury using serum syndecan-1 as a marker of endothelial glycocalyx injury in patients who underwent hemodialysis. In this single-center, retrospective, observational study, 145 patients who underwent hemodialysis at the Gifu University Hospital between March 2017 and December 2019 were enrolled. The median dialysis period and time were 63 months and 3.7 h, respectively. The serum syndecan-1 concentration significantly increased from 124.6 ± 107.8 ng/ml before hemodialysis to 229.0 ± 138.1 ng/ml after hemodialysis (P < 0.001). Treatment with anticoagulant nafamostat mesylate inhibited hemodialysis-induced increase in the levels of serum syndecan-1 in comparison to unfractionated heparin. Dialysis time and the change in the syndecan-1 concentration were positively correlated. Conversely, the amount of body fluid removed and the changes in the syndecan-1 concentration were not significantly correlated. The reduction in the amount of body fluid removed and dialysis time inhibited the change in the syndecan-1 levels before and after hemodialysis. In conclusion, quantitative assessment of the endothelial glycocalyx injury during hemodialysis can be performed by measuring the serum syndecan-1 concentration, which may aid in the selection of appropriate anticoagulants, reduction of hemodialysis time, and the amount of body fluid removed.

Human glycocalyx shedding: Systematic review and critical appraisal

BACKGROUND

The number of studies measuring breakdown products of the glycocalyx in plasma has increased rapidly during the past decade. The purpose of the present systematic review was to assess the current knowledge concerning the association between plasma concentrations of glycocalyx components and structural assessment of the endothelium.

METHODS

We performed a literature review of Pubmed to determine which glycocalyx components change in a wide variety of human diseases and conditions. We also searched for evidence of a relationship between plasma concentrations and the thickness of the endothelial glycocalyx layer as obtained by imaging methods.

RESULTS

Out of 3,454 publications, we identified 228 that met our inclusion criteria. The vast majority demonstrate an increase in plasma glycocalyx products. Sepsis and trauma are most frequently studied, and comprise approximately 40 publications. They usually report 3-4-foldt increased levels of glycocalyx degradation products, most commonly of syndecan-1. Surgery shows a variable picture. Cardiac surgery and transplantations are most likely to involve elevations of glycocalyx degradation products. Structural assessment using imaging methods show thinning of the endothelial glycocalyx layer in cardiovascular conditions and during major surgery, but thinning does not always correlate with the plasma concentrations of glycocalyx products. The few structural assessments performed do not currently support that capillary permeability is increased when the plasma levels of glycocalyx fragments in plasma are increased.

CONCLUSIONS

Shedding of glycocalyx components is a ubiquitous process that occurs during both acute and chronic inflammation with no sensitivity or specificity for a specific disease or condition.