COMPARISON OF HIGH-EFFICIENCY AND STANDARD HEMODIALYSIS PROVIDING EQUAL UREA CLEARANCES BY PARTIAL AND TOTAL DIALYSATE QUANTIFICATION

Background. Short-duration high-efficiency haemodialysis has been util ized, increasingly in recent years to deliver adequate blood urea clea rances per dialysis session, However, high-efficiency and standard-dur ation haemodialysis schedules, which achieve equal patient urea cleara nces, may not represent equivalent dialytic therapy due to solute diff erences in intercompartmental dysequilibrium during dialysis and diffe rences in dialysis mechanics. Methods. To circumvent the effects of in tercompartmental dysequilibrium and postdialysis rebound solute cleara nces were measured by direct dialysis quantification (total and partia l dialysate collections) rather than blood clearances. High-efficiency haemodialysis (dialyser blood flow rate=400 ml/min; dialysis time=170 .67 min) was compared with standard haemodialysis (dialyser blood now rate=200 ml/min; dialysis time=240 min) performed in random order in s ix anuric patients using Fresenius FS dialysers and the same haemodial ysis machine. Such haemodialysis schedules were prescribed to provide equivalent urea clearances. Results. Patient plasma water urea clearan ces measured by direct dialysis quantification were equivalent, wherea s high efficiency haemodialysis achieved significantly lower phosphate clearances (P= 0.01), less net bicarbonate absorption (P=0.01), and l ower beta(2) microglobulin removal (P<0.0001) than standard haemodialy sis, Estimated total dialysate effluent volumes with partial dialysate collection and total dialysate collection correlated closely (r=0.95) and there were no differences between patient urea, creatinine and ph osphate clearances measured by partial and fetal dialysate quantificat ion. Conclusions, The data indicate that even if high-efficiency and s tandard haemodialysis provide equal whole-body urea clearances, delive red dialysis therapy is not equivalent. The partial dialysate collecti on method is as accurate as the cumbersome total dialysate collection approach and may be applied to assess delivered dialysis dose by minor modification of current haemodialysis machines.