PARAMETER-ESTIMATION IN 6 NUMERICAL-MODELS OF TRANSPERITONEAL TRANSPORT OF POTASSIUM IN PATIENTS UNDERGOING PERITONEAL-DIALYSIS

The mechanisms of transperitoneal potassium transport during peritonea l dialysis were evaluated by validation of different mathematical mode ls. The models were designed to elucidate the presence or absence of d iffusive, non-lymphatic convective and lymphatic convective solute tra nsport. Experimental results were obtained from 26 non-diabetic patien ts undergoing peritoneal dialysis. The validation procedure demonstrat ed that models including both diffusive and non-lymphatic convective s olute transport were superior to the other models. Lymphatic convectiv e solute transport was not identifiable. Furthermore, it was demonstra ted experimentally that the equilibrium distribution of potassium betw een plasma water and dialysate did not differ from a Donnan equilibriu m, although the precondition of the Donnan equilibrium was not fulfill ed, i.e. the volumes on each side of the membrane were not constant an d dialysate was not an ultrafiltrate of plasma.