- The delivered Kt/V often tends to be lower than the prescribed Kt/V which is why we target a spKt/V of 1.4 to achieve a minimum goal spKt/v of 1.2.
- When calculating treatment time using manufacturer’s provided in vitro K and KoA values (as we did in this case), it is important to remember that these values tend to be about 20% higher than actual in vivo values. This is one of the reasons why delivered Kt/V may be lower than prescribed Kt/V.
- In smaller patients, determining treatment time using goal spKt/V of 1.4 may lead you to under dose dialysis since a low ‘V’, mathematically increases the ratio spKt/V, gives a false sense of reassurance and may prompt you to decrease dialysis time. Smaller patients have higher post dialysis urea rebound, so their eKt/V may be significantly lower than spKt/V. In addition, short dialysis treatments may not be adequate to remove middle molecules and other uremic solutes as well as may result in higher ultrafiltration rates and intra-dialytic hypotension. Therefore before reducing dialysis time, other variables such as BP, phosphorus and potassium control, ultrafiltration goals etc. need to be considered. US KDOQI 2006 recommends a minimum session length of 3 hours irrespective of Kt/V.