NONINVASIVE MONITORING OF EFFECTIVE DIALYSIS DOSE DELIVERED TO THE HEMODIALYSIS PATIENT

Assessment of normalized dialysis dose Kt/V actually delivered to the patient carries the drawback of requiring several blood or dialysate s amplings and urea concentration measurements. In order to easily quant ify Kt/V, we validate here the routine implementation of an original t echnique for the noninvasive, on-line, and fully automatic estimation of total mean urea clearance. This estimation is obtained from the mea surement by a conductivity method of the effective ionic dialysance D- R, which is the dialysance of electrolytes taking into account ultrafi ltration and recirculation. The observed increase in D-R with ultrafil tration rate and decrease in D-R with elevation of access recirculatio n ratio show that the estimation of D-R is affected by ultrafiltration and recirculation in a consistant manner. The mean value K-eff of ion ic dialysance D-R was compared with the value K-dc of effective urea c learance obtained by dialysate collection during 12 haemodialysis sess ions. The similarity (magnitude of variation 5%) between the ionic dia lysance K-eff and the effective urea clearance K-de supports the valid ity of the equivalence between the transfer characteristics of electro lytes and urea through the dialyser membrane. Given an estimate of the urea distribution volume V, this estimation of effective urea clearan ce by ionic dialysance measurement allows an on-line estimation of the normalized dialysis dose Kt/V actually delivered to the patient.