A MODEL FOR NONINVASIVE ESTIMATION OF IN-VIVO DIALYZER PERFORMANCES AND PATIENTS CONDUCTIVITY DURING HEMODIALYSIS

On-line monitoring of hemodialysis sessions requires a non-invasive es timation of the parameters concerning the patient's status and the dia lyzer performances. We describe here a model based on a new method for non-invasive dialysance and patient conductivity measurements. In thi s technique the same probe measures alternately the conductivity at th e dialysate inlet and outlet for two different dialysate conductivity values. From these data, an appropriate model allows to determine the patient's conductivity as well as the effective dialysance of ionised solutes, that is to say the dialysance corrected for recirculation. A strong correlation is evidenced between the effective dialysance measu red by this method and the urea clearance measured by conventional met hods (r=0.98 for in vitro solutions; r=0.82 in in vivo situations).