Improved solutions for peritoneal dialysis: physiological calcium solutions, osmotic agents and buffers

Theoretical and clinical studies suggest that reduction of PD fluid calcium to 1.25 mmol/liter allows administration of larger doses of calcium carbonate, improves phosphate control and obviates the need for aluminum gels in most CAPD patients, without increasing hypercalcemia or hyperparathyroidism. Hypermagnesemia can also be avoided by reducing PD fluid magnesium concentration to 0.25 mmol/liter. Although glucose is a safe, effective an cheap osmotic agent, it provides a short duration of ultrafiltration, and contributes to significant metabolic abnormalities. Amino acids and glucose polymer are potential alternatives to glucose, and early clinical studies are encouraging. The unphysiological concentration of lactate in PD fluids has been shown to have pathological consequences, and undoubtedly bicarbonate would be a preferable buffer. Manufacturing techniques are being developed to produce such a fluid. A fluid containing bicarbonate and the peptide glycylglycine (30:10 mmol/liter) gives a stable buffer with a pH of 7.35, but has only undergone animal studies so far. Glucose solutions have deleterious effects on the peritoneal membrane, particularly during episodes of severe peritonitis, and the high osmolality is toxic to peritoneal host defense cells. Prompt treatment of peritonitis, early removal of the catheter where necessary, and minimization of glucose exposure, may do much to lengthen the dialysis life of the peritoneum.