Update and Perspectives in the Personalized Management of Sodium, Water, Volume and Hemodynamic Disorders of Dialysis Patients

Abstract

Sodium and water-related disorders are major components of chronic kidney disease (CKD) and contribute significantly to cardiovascular (CV) complications and mortality. Usually, they are marked by gradual accumulation of sodium, water and have hemodynamic consequences (i.e., fluid overload, hypertension and cardiac disorders) along with the progression of kidney failure culminating in end stage kidney disease. Renal replacement therapy which is then required to sustain life is intended to restore sodium, fluid and pressure disorders along with the objective of reducing the uremic toxin load. Unfortunately, the intermittent nature of conventional short hemodialysis relying on a so called ‘dry weight’ probing approach, only partially restores the sodium-water overload related disorders, thereby exposing patients to further multi-organ damage through the resultant dialysis-induced systemic stress (DISS). Fluid volume management in dialysis patients has emerged as a very challenging condition that requires further attention and more precise tools. Furthermore, recent findings indicate that the physiology of sodium is more complex than that previously summarized by the kidney-centric two-compartment model (volemia and Interstitium) linked to osmotically active sodium (water-bound sodium). A third tissue compartment (skin, muscle) of sodium has now been identified, taking the form of free-water sodium [glycosaminoglycans (GAGs) or gel-like component] with newly-identified pathophysiologic metabolic consequences. All these findings suggest that restoration of sodium homeostasis in dialysis-dependent chronic kidney disease patients should encompass a more holistic approach to improve cardiac health and reduce cardiovascular burden in this highly vulnerable population. In this context, new tools for monitoring and managing dialysis patients to ensure a more precise and personalized control of their sodium and water homeostasis, volemic and hemodynamic disorders are needed. Several monitoring and management tools (e.g., bioimpedance, lung ultrasound, blood volume control, thermal balance control) are already available with potential value. The conductivity measurement-based automated sodium control module represents the latest and very appealing addition to this list of innovative tools. Although establishing the clinical value of these tools requires further outcome-based studies, current clinical use of this new tools has shown promising indications towards the goal of reducing CV morbidity and mortality in kidney dialysis patients. A brief review of these new pathophysiologic findings as well as clinical interests of these new tools is provided in this narrative review.