THE RELATIONSHIP BETWEEN URINE VOLUME AND DRAIN VOLUME AS DETERMINANTS OF FRACTIONAL UREA CLEARANCE IN CONTINUOUS PERITONEAL-DIALYSIS

A logistic regression model developed and validated in Albuquerque ide ntified 24 hr urine volume (UV) and 24 hr drain volume/(body water) (D V/V) as predictors of fractional urea clearance (KT/V) in continuous p eritoneal dialysis (CPD). Solution of this model provided DV/V values consistent with KT/V at least equal to a target KT/V for a given UV. T he predictive accuracy of these unique DV/V values was tested in urea kinetic studies performed in 108 CPD patients in Thessaloniki and Athe ns with UV varying between 0 and 2 L/24 h. Two target weekly KT/V valu es, 1.70 and 1.90, were investigated. The equation DV/V = (5.2811 - 3. 6996UV)/17.554, derived by solving the logistic regression model, dete cted weekly KT/V > 1.70 (69/108, or 63.9% of the studies) with a sensi tivity of 87.3% and a specificity of 60.4%. According to the same equa tion, the maximal UV consistent with weekly KT/V less than or equal to 1.70 is 1.427 L/24 hr. The equation DV/V = (5.4994 - 2.6007UV)/17.007 detected weekly KT/V > 1.90 (44/108, or 40.7% of the studies) with a sensitivity of 90.3% and a specificity of 79.2%. According to this equ ation, the maximal UV consistent with weekly KT/V less than or equal t o 1.90 is 2.115 L/24 hr. Determination of the lowest daily DV consiste nt with a target KT/V at any daily UV (within a wide range) is feasibl e in CPD.