Convective Characteristics of Pediatric Peritoneal Dialysis

The convective aspects of pediatric peritoneal dialysis (PD) -fluid transfer with its attendant solvent drag -were evaluated in vivo in 8 children on maintenance PD. The evaluation was performed according to the mass transport model of pyle. Reflection coefficients were calculated for urea, creatinine, uric acid, glucose and idealized total protein. These values were compared to adult means. There were no differences in reflection coefficients, except for total protein, which had a lower value. Maximum ultrafiltration rates were also calculated for the three commercially avail able dialysate glucose concentrations (1.5%, 2.5%, 4.25%). These values were scaled for body surface area to allow comparison with adult means. All values were lower than the adult means, but were not outside two standard deviations. Convective transport in PD in children over 1 Vl years of age, does not appear to be significantly different than that in adults. There are two components to solute removal in peritoneal dialysis: diffusion and convection. Convective transport, the passive movement of solute in a solvent stream across a semipernleable membrane, is directly related to the rate of ultrafiltration. The convective component of solute removal in peritoneal dialysis may be responsible for a significant per cent of transport of larger molecular weight solutes (I). Little infornlation is currently available concerning this aspect of pediatric peritoneal dialysis. Kohaut and Alexander have reported that it is more difficult to achieve ultrafiltration in infants than in older children, adolescents, and adults (2). The convective component of peritoneal dialysis in infants may therefore contribute less to overall solute removal than in older children and adults.