Dialysate Flow Rate and Delivered Kt/Vurea for Dialyzers with Enhanced Dialysate Flow Distribution

Previous in vitro and clinical studies showed that the urea mass transfer-area coefficient (K(o)A) increased with increasing dialysate flow rate. This observation led to increased dialysate flow rates in an attempt to maximize the delivered dose of dialysis (Kt/V(urea)). Recently, we showed that ure...

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Bibliographic Details
Published in:Clinical journal of the American Society of Nephrology 2011-09, Vol.6 (9), p.2235-2239
Main Authors: Ward, Richard A, Idoux, John W, Hamdan, Hiba, Ouseph, Rosemary, Depner, Thomas A, Golper, Thomas A
Format: Article
Language:English
Subjects:
Adult
Aged
Aged, 80 and over
Cross-Over Studies
Dialysis Solutions
Female
Humans
Male
Middle Aged
Original
Renal Dialysis - instrumentation
Urea - blood
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Summary:Previous in vitro and clinical studies showed that the urea mass transfer-area coefficient (K(o)A) increased with increasing dialysate flow rate. This observation led to increased dialysate flow rates in an attempt to maximize the delivered dose of dialysis (Kt/V(urea)). Recently, we showed that urea K(o)A was independent of dialysate flow rate in the range 500 to 800 ml/min for dialyzers incorporating features to enhance dialysate flow distribution, suggesting that increasing the dialysate flow rate with such dialyzers would not significantly increase delivered Kt/V(urea). We performed a multi-center randomized clinical trial to compare delivered Kt/V(urea) at dialysate flow rates of 600 and 800 ml/min in 42 patients. All other aspects of the dialysis prescription, including treatment time, blood flow rate, and dialyzer, were kept constant for a given patient. Delivered single-pool and equilibrated Kt/V(urea) were calculated from pre- and postdialysis plasma urea concentrations, and ionic Kt/V was determined from serial measurements of ionic dialysance made throughout each treatment. Delivered Kt/V(urea) differed between centers; however, the difference in Kt/V(urea) between dialysate flow rates of 800 and 600 ml/min was NS by any measure (95% confidence intervals of -0.064 to 0.024 for single-pool Kt/V(urea), -0.051 to 0.023 for equilibrated Kt/V(urea), and -0.029 to 0.099 for ionic Kt/V). These data suggest that increasing the dialysate flow rate beyond 600 ml/min for these dialyzers offers no benefit in terms of delivered Kt/V(urea).
ISSN:1555-9041
1555-905X
DOI:10.2215/CJN.02630311