A load volume suitable for reaching dialysis adequacy targets in anuric patients on 4-exchange CAPD.

Introduction: Continuous ambulatory peritoneal dialysis (CAPD) depuration indexes are targeted to get a minimum total weekly peritoneal urea clearance (Kt/V) of 1.70 and creatinine clearance/1.73 m(2) (pCrCL) of 50 l. In anuric patients these targets are difficult to achieve. Since dialysis volumes (load, VOL(in); drain, VOL(out)) are the main determinants of peritoneal clearances (pCLs), we aimed to estimate the minimum volumes required to fulfill these targets in anuric patients.

Methods: Sixty-nine CAPD anuric patients from eight dialysis units were observed retrospectively. Demographic data, dialysis schedule, VOLs and depuration indexes were recorded. The relationship between normalized VOLs and pCLs was estimated by linear regression analysis as a whole (95 % confidence interval of the fit) and stratified by tertiles of body weight (BW) and surface area (BSA).

Results: Mean weekly pKt/V was 1.89 ± 0.29, pCrCL 52.9 ± 8.0, VOL(in) 32.9 ± 5.3 ml/kg and VOL(out) 37.4 ± 6.7 ml/kg exchange. VOL(in) and VOL(out) correlated with depuration indexes only if normalized. A VOL(in) of 28.5 ml/kg exchange (27.0-30.0) was associated with a pKt/V of 1.70, and a VOL(in) of 29.5 (26.5-31.5) with a pCrCL of 50 l, with a VOL(out) of 31.7 ml/kg (29.5-33.5) and 32.4 (27.2-35.5), respectively. Smaller patients needed a lower normalized VOL(in)/exchange to obtain pKt/V = 1.70 (1st vs. 2nd vs. 3rd BW tertiles: 28.3 vs. 28.9 vs. 29.0 ml/kg; BSA tertiles: 1,696 vs. 1,935 vs. 2,086 ml/1.73).

Conclusions: In CAPD anuric patients VOL(in) prescription could be tailored to body mass to reach the minimum depuration target. Normalized VOL(in) might be prescribed in slightly higher doses (from 27 to 30 ml/kg exchange) for patients with higher body mass.