Less dialysis-induced morbidity and vascular instability with bicarbonate in dialysate.

We devised three protocols to test the postulate that increased morbidity during high-efficiency dialysis with large-surface-area units (LS) might be due in part to the increased flux of bicarbonate out and acetate into the patient inherent is LS dialysis. The first protocol showed that with LS-acetate dialysis there was a marked fall in plasma bicarbonate and Pco2 during the first 3 to 4 h, followed by a rapid rise in bicarbonate above normal and return to control in Pco2. With LS-bicarbonate dialysis, these oscillations were largely eliminated. A second double-blind protocol showed that central nervous system-type symptoms noted during and after LS-acetate dialysis were reduced significantly by switching to LS-bicarbonate dialysis. The third protocol showed that with LS-carbonate the tolerable rate of ultrafiltration could be increased 67% compared with LS-acetate dialysis.