RESUMEN
Urea kinetic-modelling was performed on 109 patients undergoing hemodialysis (518 urea kinetic studies). Then, the theoretic times for a target TAC = 50 mg/dl (TTAC) and a Kt/V = 1 (TKTV) were estimated. The differences and correlations of both times were calculated. Also the correlation of PCR and Kt/V was analyzed in relation to the range of Kt/V. For all cases no differences were found in dialysis session length (TTAC 221.4 +/- 42.6 min.; TKTV 222.9 +/- 48.9 min.). Mean Kt/V was 1.00 +/- 0.15 and mean TAC was 55.2 +/- 13.2. 313 studies (60.4%) have a TAC > 50 mg/dl. For Kt/V < 0.80, 15.6% have a TAC < 50 mg/dl, when Kt/V > 0.80 41.2% of cases have a TAC < 50 mg/dl (p < 0.01). A linear correlation of Kt/V and PCR was found (r = 0.36, p < 0.01). This correlation was stronger for Kt/V < 0.8 (r = 0.54, p < 0.01, n = 47). When TTAC was compared to TKTV a great variability was found: 20.1% have differences lesser than 15 minutes; and this difference was more than 30 minutes in 58.5%. In 107 cases (20.7%) the TTAC produced a Kt/V < 0.8. In all cases a significant (p < 0.01) linear correlation between TKTV and TTAC was found (r = 0.46). TKTV was greater than TTAC for real Kt/V < 1, and lesser than TTAC cuando the effective Kt/V was > 1. It is concluded that in patients treated by dialysis prescription of dialysis session length by TAC or by Kt/V produce rather different times for an unique patient. These differences are related to the PCR, which have a significant correlation with Kt/V. TAC tends toward under value dialysis session length in patients with inadequate dialysis.