Acid-base profile and predictors of metabolic acidosis in patients undergoing peritoneal dialysis with lactate- and bicarbonate-buffered peritoneal dialysis solutions.

Metabolic acidosis correction is one of the goals of renal replacement therapy. Correction of acidosis in peritoneal dialysis (PD) may be affected by PD modalities such as automated PD (APD) or by new solutions containing a combination of bicarbonate and lactate as a buffer [bicarbonate continuous ambulatory PD (CAPD)]. The aim of the present study was to examine the acid-base status of our PD population and to compare the effects of APD, lactate CAPD, and bicarbonate CAPD on serum bicarbonate levels. We studied 35 stable patients undergoing APD (n = 15), lactate-buffered (35 mEq/L) CAPD (n = 14), and bicarbonate/lactate-buffered CAPD (n = 6) for 48.5 +/- 38.1 months. Most of our patients had serum bicarbonate levels in the normal range. In 3 patients (8%), HCO3 was below 22 mEq/L, and in 8 patients (22%; APD = 2, lactate CAPD = 2, bicarbonate CAPD = 4), HCO3 was above 28 mEq/L. We found no statistically significant correlations between HCO3 serum levels and PD prescription, peritoneal membrane characteristics, or intake of calcium carbonate and sevelamer hydrochloride. Patients on bicarbonate CAPD had higher HCO3 serum levels, but this difference disappeared when corrections for duration of dialysis, residual urine volume, and PD adequacy indices were applied. In the studied PD population, adequate correction of metabolic acidosis was achieved, as reflected in serum bicarbonate levels. We observed no difference in serum bicarbonate levels between APD and lactate CAPD patients. The new bicarbonate-buffered PD solutions are more biocompatible and can result in higher serum bicarbonate levels. However, a significant number of PD patients on bicarbonate-buffered solutions may become alkalotic. The clinical significance of these results needs further examination in prospective studies.