Effect of alternative osmotic agents on peritoneal transport

To investigate the impact of osmotic agents on solute transport in continuous ambulatory peritoneal dialysis single 6-hour dwell studies were performed in nondiabetic patients using different osmotic agents: glucose 3.86%, amino acids 2.70, and glycerol 2.50%. Diffusive mass transport coefficient (KBD) and sieving coefficient (S) were assessed for urea, creatinine, glucose, glycerol, potassium, sodium, and total protein using the Babb-Randerson-Farrell model. The estimated KBD values for small solutes were higher in peritoneal dialysis fluid based on amino acids than in both glucose- and glycerol-based dialysis solutions. S values for small solutes were higher in glucose-based peritoneal dialysis fluid than in dialysis solutions based on amino acids and glycerol. Moreover, nonphysical, i.e., out of the range 0-1, S values were obtained for urea and potassium in glucose-based peritoneal dialysis fluid and for glucose and glycerol applied as osmotic agents. No difference in the transport parameters for total protein was found between the three investigated dialysis fluids. We conclude that the composition of dialysis fluid (osmotic agent, buffer solute, pH) can change the transport characteristics of the peritoneum. Furthermore, other physiological processes besides the diffusive and convective transport can contribute to the net peritoneal transport of some solutes.