CONTINOUS MONITORING OF DELIVERED DIALYSIS DOSE OBTAINED WITH EFFECTIVE IONIC DIALYSANCE

The most useful and widely applied index of dialysis dose is the Kt/V formula which represents the plasma volume cleared of urea. Kt/V recei ved by patients can be measured by several invasive and/or expensive m ethods requiring either blood samples or on-line sensing devices. In o rder to quantify Kt/V easily, we describe the clinical results obtaine d by a conductivity based method which measures on-line effective ioni c dialysance. The study was performed during three consecutive dialysi s sesions in 20 regular hemodialysis patients. We determined Kt/V by m easuring plasma urea and post rebound (30 min. after the end). The sec ond generation model of Gotch and Daugirdas were used to calculate Kt/ V. Urea clearance was also calculate at the end of the first hour. Ion ic dialysance and plasma water conductivity were recorded by the monit or. Total volume cleared was also recorded and Kt/V estimated assuming that urea distribution volume corresponded to a percentage of body we ight. The mean Kt/V determined was 1.27 +/- 0.26 (effective ionic dial ysance), 1.38 +/- 0.26 (Daugirdas) and 1.16 +/- 0.22 (Gotch). In spite of these significant differences, the Kt/V obtained with ionic dialys ance and the Kt/V obtained with Daugirdas and Gotch proved to be close ly correlated (r = 0.79 and r = 0.73, respectively; p < 0.001). Ionic dialysance and urea clearance were also correlated significantively (r = 0,81, p < 0,001). We could not find differences related to dialyser membrane. In conclusion, though effective ionic dialysance and effect ive urea clearance are not the same, the close correlation obtained in our study may make it easy to derive effective urea clearance from io nic dialysance (kurea = 68.7 + 0.87 x Dl). The Kt/V obtained by this m ethod also correlates with the Kt/V calculated with blood samples afte r rebound. This non-invasive monitoring of dialysis dose delivered to the hemodilysis patients seemes to be esasy, inexpensive and practical for monitoring every patient at every sesion.