Kt/V is a commonly used measure of treatment adequacy.

• Human studies suggest that a Kt/V > 1.4 may be associated with better outcomes

• K= Urea clearance (ml/min)
• t = time on CRRT / day (min)
• V = volume of distribution (ml)

K - a measurement of instantaneous urea clearance (removal rate/concentration)

Calculation of K based on patient factors. K can be estimated before treatment begin. This is called Kcalc. Once CRRT is begun, delivered K can be determined (Kdel). The formula used to determine Kt/V is dependant on the mode of CRRT utilized (CVVH, CVVHD, CVVHDF) . Formulas available here

Common assumptions:

• t – Not really 24 hours / day (there is always down time) we assume 22 hours or 1,320 min

• V – urea is equally distributed in all body water compartments and because CRRT removes uria in a slow, gradual manner, the entire body can be treated as one compartment.

– Therefore, V = 60% of body weight in Kg

An example is avaliable here