PH Equilibration with Acetate and Lactate Solutions during Peritoneal Dialysis

Abstract

Commercial dialysis solutions contain acetate or lactate and have pH values usually below 6.5. Losses of ultrafiltration in CAPD have been more frequent with acetate than with lactate solutions. It has been suggested that a slower increase of pH following intraperitoneal instillation of acetate solutions may produce alterations in membrane function. We compared intraperitoneal equilibration of pH in rats with acetate and lactate solutions. In our rat model pH equilibration rates were similar for acetate and lactate solutions. Commercial peritoneal dialysis solutions contain glucose as an osmotic agent and acetate or lactate as a buffer (1,2). The pH is adjusted to below 6.0 to prevent glucose caramelization during heat sterilization (3). Acetate and lactate are absorbed during peritoneal dialysis and, when metabolized generate bicarbonate (2). Bicarbonate itself is not used in commercial solutions because these solutions also contain calcium and calcium bicarbonate is unstable in solution on storage. Many workers (4–8) have observed that patients on continuous ambulatory peritoneal dialysis (CAPD) with solutions containing acetate suffer losses of ultrafiltration over time. Also encapsulating sclerosing peritonitis is seen more often in association with acetate solutions (9–11). Pedersen et al (12) fear that prolonged exposure to a low pH may irritate the peritoneal membrane and that, during peritoneal dialysis cycles with acetate as the buffer, the pH in the intraperitoneal solution increases more slowly. These studies were undertaken to determine whether, during peritoneal dialysis exchanges, acetate and lactate solutions had the same rate of change of pH.