In vivo verification of an automatic noninvasive system for real time Kt evaluation

It is generally accepted that morbidity and mortality of hemodialysis patients is related to dialysis quantitation. Currently available methods for the quantitation of dialysis require blood sampling or a continuous measurement of changes in urea concentration during treatment. These maneuvers are time consuming and expensive, and are generally performed, at most, once per month. The authors introduce an on-line, automated method for measurement of dialyzer electrolyte clearance comparable to urea clearance by using dialysate conductivity sensors placed pre and post dialyzer, and measuring conductivity at three different pre dialyzer levels. Conditions that reduce clearance, such as recirculation or fiber clotting, are automatically taken into account so that the method measures effective clearance rather than dialyzer clearance. In vitro and in vivo studies validate the method. Results are immediately available and can be used to address problems such as improper needle placement and access recirculation. In addition, repetitive electrolyte clearance data can serve to enhance quality assurance programs with respect to verifying the function of reused or new dialyzers. Appropriate algorithms can be used to calculate delivered Kt/V.