DIFFUSIVE AND CONVECTIVE SOLUTE TRANSPORT IN PERITONEAL-DIALYSIS WITHGLUCOSE AS AN OSMOTIC AGENT

To investigate possible effects of glucose concentration, dwell time, and peritoneal reabsorption on the combined diffusive and convective p eritoneal solute transport, dialysate to plasma concentration ratios ( D/P) and solute clearances were evaluated for 6-h peritoneal dwell stu dies with 1.36, 2.27, and 3.86% glucose solutions. The diffusive mass transport coefficient, K-BD, and sieving coefficient, S, were estimate d using the Babb-Randerson-Farrell model of peritoneal transport. Dial ysate volumes over time and peritoneal reabsorption rates, K-E, were a ssessed using radiolabeled iodinated serum albumin (RISA). The transpo rt parameters were estimated with and without peritoneal reabsorption of solutes taken into account. To test the stability of the transport parameters throughout a single peritoneal dwell, K-BD and S values wer e estimated for the initial 3-120 min, the final 120-360 min, and the entire 3-360 min dwell period for dialysis with 3.86% glucose solution . The transport parameters did not differ between the three dialysis f luids although clearances of small solutes were higher with the 3.86% solution. Values of K-BD, but not S, were dependent on the correction for peritoneal reabsorption of solutes. Computer simulations showed th at S could be estimated even with the 1.36% glucose solution. A signif icant change of the transport parameters, with increased values of K-B D during the initial period of the dwell, was found for urea, potassiu m, sodium, and total protein during dialysis with the 3.86% solution. S values for urea and potassium were close to 1 during the initial per iod whereas unphysical (higher than 1) S values were found for the who le dwell period. The transient increase of K-BD during the initial par t of the dwell may reflect changes in the peritoneal barrier possibly induced by fresh dialysis fluid. In conclusion, the transport paramete rs K-BD and S are not influenced by the concentration of glucose in th e dialysis fluid. Moreover, the estimation of K-BD but not of S is dep endent on the assumed rate of peritoneal reabsorption. Finally, the cu rrent results challenge the assumption that K-BD and S are constant th roughout a peritoneal dialysis exchange.