Abstract
The effect of dialysate dwelling volume on peritoneal mass and fluid transfer was investigated in CAPD patients with various body sizes. Mass transfer area coefficient (MATC) of urea N, creatinine and glucose were studied in 6 stable CAPD patients with an average peritoneal permeability [body surface area (BSA)>1.6:3 patients BSAG<1.6:3 patients] using dialysate volume of 1.0, 1.5, 2.0 and 2.5L for 2 hours. Dialysate solute concentrations were monitored every 40 minutes. Modified Henderson equation was used to calculate MTAC for 3 solutes as a function of fill volume. Ultrafiltration rate (UFR), peritoneal net fluid absorptiom rate (PNFAR) and residual fluid volume in peritoneal cavity were calculated by the change of dialyaste dextran 70 concentration. MTAC of all 3 solutes increased in an almost linear fashion as infusion volume increased. The fill volume for peak MTAC was about 2L in patients with BSA less than 1.6m2. On the other hand, it was more than 2L in patients with BSA more than 1.6m2. PNFAR increased in a dose dependent fashion as fill volume increased. The fill volume for peak UFR was between 1.5 and 2.0L in patients with small body size and was 2-2.5L in large patients. In conclusion, MTAC of small molecular weight solute and PNFAR increased in a dose dependent fashion associated with increasing fill volume. The fill volume for their peak seems to depend on patients body sizes, indicating that each patient has his/her adequate fill volume. This should be taken into consideration when prescrbing the dialysate dose in CAPD/APD patients.
