Systems of membranes involved in peritoneal dialysis

To evaluate whether the viscera contribute to the system of membranes used in peritoneal dialysis, dialysis rate studies were performed comparing control rats (n = 9, mean peritoneal area 509 +/- 38 cm2) with eviscerated rats (n = 12, mean peritoneal area 200 +/- 123 cm2). The mass transfer coefficient (MTC) and absorption from the peritoneal cavity were calculated for urea, creatinine, and inulin, which had been added to commercially available 1.5% hydrous dextrose dialysate. Rates of peritoneal blood flow to the peritoneal membranes remaining after evisceration were similar for both groups. Urea, creatinine, glucose, and inulin were used as markers to compare control and eviscerated animals. The MTC results were (in milliliters per minute, mean +/- SEM): urea 3.0 +/- 0.3, 4.1 +/- 0.5 (P less than 0.01); creatinine 1.4 +/- 0.2, 2.0 +/- 0.2 (P less than 0.05); glucose 1.2 +/- 0.3, 1.7 +/- 0.2 (P less than 0.09); inulin 0.3 +/- 0.02, 0.6 +/- 0.1 (P less than 0.01); and MTC inulin/MTC urea 0.16 +/- 0.01, 0.14 +/- 0.01. Absorption of urea, creatinine, glucose, and inulin from the peritoneal cavity was only 10% to 23% greater among control animals. Whether the results were caused by nonparticipation of the intestinal viscera or other mechanisms, such as improved contact between dialysate and membrane, awaits further study.