[Kt/V as a measure of hemodialysis adequacy]

Dialysis efficacy and single hemodialysis urea removal is expressed as Kt/V value (normalized treatment ratio). All formulae for delivered Kt/V calculation are based on Gotch-Sargent's urea kinetic model solution for single dialysis. Error in calculation Kt/V results from falsely low postdialysis blood urea concentration in respect to real body urea concentration. Reasons for the low blood urea postdialysis value are recirculation (in blood access and cardiopulmonary) and postdialysis urea rebound. The Kt/V value is important for the outcome of the patients undergoing chronic hemodialysis therapy. There is a strong correlation between higher Kt/V value and lower mortality. This value must be precisely estimated. Novel methods for urea concentration measurement from spent dialysate with on-line monitors provide precise Kt/V calculation. These methods circumvent mistakes of postdialysis blood urea concentration estimation.