Relationship between ionic dialysance and urea blood water clearance

Introduction: ionic dialysance is a method of continuous on-line monitoring of delivered dialysis without blood sampling. To compare the results obtai ned by ionic dialysance and those obtained by the traditional measurements of the dialysis dose, it is necessary to know the relationship between the ionic dialysance and urea clearance. Material and methods: Ionic dialysance and the urea clearance were determin ed in 18 patients (13 dialyzed with cuprophan and 5 patients with AN69). Ur ea clearance was measured by 6 different methods: urea clearance in whole b lood calculated with the arteriovenous difference in the urea concentration rates and the arterial flow measured by the rolling pump (KBAVb) or by ult rasounds (KBAVu); urea clearance in whole blood measured by the urea concen tration in the dialysate (KBD); urea blood water clearance measured by the arteriovenous difference in the concentration rates using the arterial flow measured by the roller pump (KwBAVb) or by ultrasounds (KwBAVu) and urea b lood water clearance measured by the urea concentration in dialysate (KwBD) . Results: The mean arterial flow measured by the roller pump was 314.4 +/- 1 6.2 ml/inin and 275.1 +/- 13.8 ml/min when measured by ultrasounds (p < 0.0 01). The data of ionic dialysance and urea clearances were as follow (ml/mi n): ionic dialysance 185,6 +/- 17.7; KBAVb 245.7 +/- 15.7; KBAu 215.4 +/- 1 3.2; KBD 231.6 +/- 13.1; KwBAVb 218.1 +/- 14; KwBAVu 191.2 +/- 11.8; KwBD 1 83.1 +/- 11.7. The absolute difference of ionic dialysance with the KwBAVu was 8.4 +/- 6 ml/min (range between -17.8 and 11.5 mi) and with the KwBD wa s 7.6 +/- 5.4 mi (range between -12.9 and 21.4 ml). Conclusions: There was a relationship between ionic dialysance and urea blo od water clearance. The best concordance was obtained when the clearance wa s calculated with the urea concentration of dialysate, or with the arteriov enous difference of the urea concentration rates and the arterial blood flo w measured by ultrasounds.