Conductivity: on-line monitoring of dialysis adequacy.

Cardiovascular disease and the inadequacy of delivered dialysis are the main factors determining morbidity and mortality in dialysis patients. We have already demonstrated that a conductivity kinetic model makes it possible to match interdialytic sodium loading and intradialytic sodium removal (the main factor determining cardiovascular morbidity) without the need for blood samples and, thus, in routine clinical practice. The aim of the present study was to test the possibility of using the conductivity method also to determine Kt/v without blood or dialysate sampling. In 18 steady-state patients, the urea distribution volume (V) was kinetically determined once using ionic dialysance (D) values instead of those of effective urea clearance. One month later, the Kt/V was determined by using the current D and T values and the predetermined V (Dt/V), then compared with the equilibrated Kt/V computed by means of the SPVV kinetic model (eqKt/V). The mean value of Dt/V was 1.18+/-0.15; while of eqKt/V it was 1.18+/-0.16, with a mean difference of 0.00+/-0.07. The conductivity method therefore seems to be very promising not only for monitoring the sodium balance, but also for quantifying delivered dialysis. Since its simplicity and low-cost make it suitable for use at each dialysis session, the conductivity method could therefore lead to significant progress in dialytic practice by contributing to the elimination of the two main causes of morbidity and mortality in dialysis patients.