**4.2 Individualized approach**

Several questions must be answered when formulating an individualized dialysate sodium. Will changing dialysate sodium cause long-term changes in serum osmolality? Are serum

Sodium and Hemodialysis 55

therefore do not participate in Gibbs-Donnan. Thus diffusible serum sodium is higher than expected in proportion to the lipid content of serum. In patients with relatively normal lipids, however, this difference is small enough to be ignored. In summary, dialysate

The default sodium prescription should be equal the serum sodium. Dialysate with identical sodium concentration to serum keeps sodium diffusion neutral; this approach relies exclusively on ultrafiltration for mass transfer of sodium/volume. If attempting to minimize variables, an isotonic dialysate is preferred; in this way ultrafiltration is responsible for the net sodium transfer while not being silently counteracted by dialysate sodium diffusing into

Dialysate with higher sodium concentration than the patient's serum sodium will provide a net sodium transfer into the patient. Hypertonic dialysate is only indicated chronically for non-hypertensive patients with significant, recurrent intradialytic hypotension or acutely for

Dialysate with lower sodium concentration than the patient's serum sodium will accept a net sodium transfer out of the patient. If attempting to maximize methods for BP control and IDWG management, the utilization of hypotonic dialysate is preferred, insofar as is

**5. Technical & systems requirements for adjustment of dialysate sodium** 

As with any prescription, benefits are never greater than the level of compliance. In the case of dialysate sodium, several technical and systems issues must be understood in order to modify a dialysate sodium level. Given the many daily problems that dialysis unit staff must face, awareness of the prescribed sodium can easily be overlooked. Further, both doctors and staff may not be aware of the mechanisms required to change dialysate sodium. Depending on each unit's equipment and dialysate formulation, changing dialysate sodium may cause changes in the other electrolytes; this can cause consternation or confusion. Staff awareness of the importance and compliance and Medical director interventions: In our experience, despite excellent and capable dialysis staff, modifications to the sodium prescription can easily be overlooked. In our unit, dialysate is delivered from a central system. The sodium concentration "out of the wall" is determined by the concentrate formula ordered by the unit – or even determined by a corporate purchasing office. There are several points of intervention. First, medical directors, need to be aware of the level of sodium in their concentrates. There are several manufactures of dialysate concentrate each with its unique formulation. Further, some manufacturers offer a variety of sodium levels within their own product lines. One intervention could be for the medical director to select the formulation that delivers the desired default sodium – based on our recommendation this would be 137mEq/L (see Paragraph 4.1). Changing the base solution is not the only method to vary the sodium in a unit and may not be economical or practical. Even if the central supply of dialysate does not match the "Facility-Wide" prescription, the staff can change to sodium concentration at each individual dialysis machine. Dialysis unit staff should be educated regarding the importance and technique of making changes to match the prescription. This education should be done even if the central supply of dialysate has

sodium set to serum sodium can be considered functionally isonatric.

**4.2.3 Final individualized guidelines** 

prevention of disequilibrium syndrome.

tolerated by interdialytic symptoms.

the patient.

and dialysate sodium estimations equivalent concepts? As will be demonstrated below, predialysis serum sodium tends to be relatively constant over time, eliminating the need to measure the sodium every treatment. Further, conventions in laboratory reporting and the Gibbs-Donnan effect influence the direction of diffusive mass transfer between serum and dialysate.
