**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 and Hemodialysis 57

Given that both the Acid and Bicarbonate concentrates contain significant sodium (sodium chloride in Acid and sodium bicarbonate in the Bicarbonate). The sodium can therefore varied by adjusting the dilution of the Acid, Bicarbonate or both. The mechanism of this variation is determined by the design and software of the dialysis machine. Each manufacturer may have slightly different approach. All models of the Fresenius 2008® series (2008H, 2008K, 2008K2, 2008T) have an explicit mechanism behind sodium variation: the amount of Acid concentrate is varied to change the sodium concentration to the target value. The other electrolytes in the Acid component will vary in proportion to the sodium change, while the electrolytes in the Bicarbonate solution will remain unchanged (Fresenius Medical Care, 2001, 2009a, 2009b, 2010). Other manufactures advertise the ability to vary sodium across a wide range. The Gambro Artis® System can vary sodium concentration from 130- 160mEq/L - much wider than the Bicarbonate variability (24-38mEq/L). Therefore the majority, if not all, of the variation in sodium is produced from variation in the Acid concentrate (Gambro, 2008). Similar ranges apply to the Gambro AK96 Advance® and Bio® models: Sodium varies 130-160mEq/L and Bicarbonate 20-40mEq/L (Gambro, 2009). B.Braun's Dialog+® has a conductivity range from 12-17mS/cm, indicating a wide range of sodium variation, however, the relative contribution of Acid and Bicarbonate portions are not readily accessible (B.Braun Medical Inc., 2009). The capability and mechanism of sodium variation for the Baxter TINA® and ARENA® systems are not easily obtainable in an "open access" format. However, given the wide use if sodium modeling over the past two decades, any modern dialysis machine probably has the capability to generate individualized sodium

Systems like the Fresenius 2008® Series, which hold the Bicarbonate constant and vary the Acid in order to alter the sodium, will show the greatest variation in the other electrolytes in the acid component. As will be demonstrated below, however, these changes are minute and clinically irrelevant. If any of the other systems utilize a combination of Acid and Bicarbonate variations to alter sodium concentration, the changes in Acid electrolytes will be even less effected (the bicarbonate concentration would vary somewhat, however, the

The question arises, will there be a change in other electrolyte components during the sodium variation? Clinically these variations are insignificant and should not hinder the use of tailored sodium. Dialysis staff needs to be reassured of this, as many of the newer generation dialysis machines will display the changes to all electrolytes when one is changed. Some staff may see a small change in the potassium and undo the change because the potassium level does not match the prescription. Dialysis unit policy and dialysis orders should be written to accept small variation in other electrolytes during adjustment of sodium. Of note, during sodium profiling, all the acid electrolytes in the same way, resulting

Here is an example of the nature of electrolyte variation with individualized sodium. A clinician determines that a particular patient's individualized dialysate sodium should be 133mEq/L. Some adjustment of the dialysis machine is required as none of the available base solutions result in this a sodium of 133mEq/L. A Fresenius 2008T®, for example, manipulates the final dialysate sodium by varying concentration of the Acid component

in wider, yet still clinically insignificant, fluctuations in the other components.

**5.3 Dialysate proportioning systems** 

concentrations.

change would also be minimal).

**5.4 Electrolyte variability during sodium individualization** 

the 'ideal' sodium level as eventually an "Individualized" approach should be introduced. Staff awareness, training and 'buy in' are the only way to deliver individualized sodium.
