Effect of increasing exchange volume or frequency on CAPD efficiency

We evaluated the effect of increasing the volume of all exchanges (group A), increasing exchange frequency (group B), or increasing nocturnal exchange volume alone (group C) on dialysis urea and creatinine clearances (DUrCl and DCrCl, respectively) and on KT/V in 20 continuous ambulatory peritoneal dialysis (CAPD) patients (25 maneuvers in 20 patients). The average duration of the maneuver was 4.5 +/- 2.1 months. In group A, a significant increase occurred in DCrCl and DUrCl. Residual renal function (RRF) decreased by an average of 0.5 mL/min (not significant, NS). In group B, DUrCl increased by 19% (NS). RRF decreased significantly from 2.5 +/- 1.0 mL/min to 1.0 +/- 0.6 mL/min. In group C no changes were noted in dialysate clearances or RRF. In all groups KT/V was maintained regardless of the maneuver employed and despite the changes in dialysis clearance observed in groups A and B. This stability is probably related to the significant decline in RRF for the group as a whole during the observation period. KT/V can be maintained as RRF declines with either increases in dialysate volume or exchange frequency. However, efforts to increase KT/V to higher mandated values will probably require changes in both dialysate volume and frequency.