Biocompatibility studies with bicarbonate-based solutions

During long-term peritoneal dialysis (PD) treatment, the biocompatibility of the dialysis fluid is one of the factors that determine the functional integrity of the peritoneal mesothelium and stroma, and the alertness and functional capacity of the peritoneal host defense system. In vitro studies show that conventional acidic lactate-based PD solutions (LB fluids) are detrimental to some of the more important functions of the peritoneal cell system including mesothelial and white blood cells. The main toxic components of the fluids are the high hydrogen ion content (pH = 5-5.6), high lactate concentration, and osmolality. Some toxic side effects can be omitted using bicarbonate-based fluids (BB fluids), in which lactate has been replaced by bicarbonate and the pH has been normalized (7.2-7.4). The present paper is an overview of the biocompatibility tests and studies performed using bicarbonate-based continuous ambulatory peritoneal dialysis (CAPD) fluids. While the final long-term clinical evaluation of the BB fluids is still missing, biocompatibility tests indicate that these fluids are less toxic to many cell systems than the conventional acidic LB fluids. BB fluids with a high glucose content remain cytotoxic. The BB fluids are well tolerated in animal studies. Some BB fluids increase the ultrafiltration in short-term animal studies when compared with LB fluids. The few animal studies failed to demonstrate a better preservation of the peritoneal membrane integrity by BB fluids. The difference in cell toxicity between LB and BB fluids as measured in vitro also seems detectable during the first 30 min of intraperitoneal dwell in man.