Figure 24

The current utilization of a bicarbonate dialysate requires a specially designed system that mixes a bicarbonate and an acid concentrate with purified water. The acid concentrate contains a small amount of lactic or acetic acid and all the calcium and magnesium. The exclusion of these cations from the bicarbonate concentrate prevents the precipitation of magnesium and calcium carbonate that would otherwise occur in the setting of a high bicarbonate concentration. During the mixing procedure the acid in the acid concentrate reacts with an equimolar amount of bicarbonate to generate carbonic acid and carbon dioxide. The generation of carbon dioxide causes the pH of the final solution to fall to approximately 7.0-7.4. The acidic pH and the lower concentrations in the final mixture allow the calcium and magnesium to remain in solution. The final concentration of bicarbonate in the dialysate is approximately 33-38 mmol/L.

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