The evils of intradialytic sodium loading

Abstract

Increased salt intake is related to extracellular fluid expansion and a rise in blood pressure, and has been linked to cardiovascular disease. Several studies have also suggested that sodium can exert detrimental effects via blood pressure-independent mechanisms. Chronic kidney disease patients are particularly susceptible to the negative consequences of sodium loading. While individuals with normal kidney function are able to regulate their sodium balance, hemodialysis patients have to rely virtually entirely on the dialysis procedure for sodium elimination. Tragically, the dialysis procedure has, in many instances, turned into a de facto source of sodium loading rather than a means for sodium removal. The main sources of sodium related to the dialysis procedure are (1) diffusive influx from the dialysate, including inappropriate use of sodium profiling; (2) the use of saline solution for priming and rinsing; and (3) the treatment of intradialytic hypotension and cramps with saline solution. Creating a positive intradialytic sodium balance is effective in acutely reducing the incidence of intradialytic symptoms, but it also sustains a vicious cycle hampering the attainment of dry weight and predisposes the patient to an increased risk of intradialytic complications during the following dialysis session. Avoiding sodium loading in hemodialysis patients is a cornerstone of blood pressure and fluid status management and, therefore, deserves a conscious effort, bearing in mind not only short-term effects but also long-term goals. In the absence of routine means of quantifying sodium balance, sodium profiling should be viewed critically, as it has been shown to induce a positive sodium balance in the majority of cases. A preferred approach under these circumstances may be simple sodium alignment. In combination with the abdication of saline solution for priming, rinsing, and intradialytic infusions, these measures would go a long way to help reduce sodium overload and achieve a more physiologic sodium balance in this patient population.