Revisiting the Dialysate Sodium Prescription as a Tool for Better Blood Pressure and Interdialytic Weight Gain Management in Hemodialysis Patients

Abstract

Hypertension and chronic volume overload are complications often seen in hemodialysis patients. Current hemodialysis practices adopt a standard dialysate sodium prescription that is typically higher than the plasma sodium concentration of most patients. As a general rule, hemodialysis patients have stable predialysis plasma sodium concentrations, and each patient has a fixed "osmolar set point." Hypertonic dialysate sodium prescriptions, including sodium modeling, predispose to positive sodium balance and lead to higher blood pressure and increased interdialytic weight gain. Conversely, lowering or individualizing dialysate sodium reduces thirst, interdialytic weight gain, and blood pressure in non-hypotension prone dialysis patients. Optimization of the dialysate sodium prescription is an important step in achieving sodium balance and improving blood pressure control in hypertensive hemodialysis patients.

The interdialytic weight gain: a simple marker of left ventricular hypertrophy in children on chronic haemodialysis

“…The online intradialytic relative plasma volume curve is the net result of the plasma refilling rate compared to the ultrafiltration rate, and allows for early detection and prevention of intradialytic hypotension [9,13]. Patients who are fluid overloaded will show a flat relative plasma volume slope over the entire dialysis session.…”

“…If the curve shows a plateau after an initial drop [9], the plasma refilling rate has fully compensated for the ultrafiltration rate. In fact, the blood volume curve directly reflects one of the most important factors determining the plasma refilling rate, namely, the diffusive gradient of sodium between dialysate and plasma [13]. If a hypertonic dialysate sodium prescription is used (i.e.…”

“…content of sodium in the dialysate sodium is higher than plasma sodium content), there is better preservation of intravascular volume due to an increased plasma refilling rate. A positive dialysate-to-plasma sodium gradient reduces the risk of intradialytic hypotension, but it can potentially leave the patient in a positive sodium balance, a risk factor for higher blood pressure and increased IDWG [13]. Conversely, a dialysate sodium concentration that is lower than the plasma sodium concentration is a risk factor for more frequent intradialytic hypotensive episodes, but it does reduce postdialytic thirst and, therefore, should limit the IDWG.…”

“…Nonetheless, even a well-tolerated high ultrafiltration rate, such as >1.24 % body weight loss per hour in adults, is associated with greater mortality [19]. Thus, although a relationship between IDWG and left ventricular mass index is shown by Paglialonga et al [1], the dialysis prescription used to reach the target dry weight should consider the risk of a high ultrafiltration rate, especially if tolerance is induced by a positive dialysate-to-plasma sodium gradient [3,8,13]. Clinical practice guidelines based on expert opinion have proposed limiting the ultrafiltration rate to 1.5 % of body weight loss per hour in children [6], but in the light of recent studies, simply targeting a dry weight at the expense of high ultrafiltration rates is also harmful.…”

“…a diffusive gradient transfer). The dialysate sodium prescription should be adjusted to determine the dialysate-to-plasma sodium diffusive gradient [3,13]. Besides restricting interdialytic dietary salt intake, restricting dialysate sodium can reduce thirst, limit IDWG, assist in the achievement of dry weight and optimize blood pressure control [23].…”