Transperitoneal solute movement in children.

The transperitoneal movement of solute in children was examined by means of a theoretical consideration of the peritoneal clearance formula and by the performance of peritoneal solute diffusion curves and measurement of peritoneal clearances of multiple solutes. Theoretical considerations led to the conclusion that when dialysis mechanics are held constant, peritoneal clearances scaled for weight are similar in individuals of widely varying weight when the volume of infused dialysate is also scaled for weight if peritoneal permeability and surface area are constant. In one group of studies, solute diffusion curves and weight-scaled peritoneal clearances of urea, phosphate, creatinine, and urate were similar in 3 children ages 4 to 18 months compared to 4 children ages 2.5 to 18.5 years. In a second group of studies, weight-scaled peritoneal clearances of inulin but not urea were shown to be marginally lower in 4 children who had been dialyzed longer than 6 months compared with 4 children dialyzed less than 1 month. Hypertonic glucose dialysis in these children was shown to enhance urea clearance but not that of inulin. It is concluded that comparative studies of peritoneal clearances can characterize the transperitoneal movement of solute in children of widely varying body size. Such studies are of greatest value when systematically performed and similar ratios of dialysate volumes to body pools of solute are used.