Weight Limitations for Weekly Urea Clearances Using Various Exchange Volumes in Continuous Ambulatory Peritoneal Dialysis

Abstract

Objective To calculate the relationships of weekly KT/V urea to standard body weight with different exchange volumes (2, 2.5, or 3 L) for continuous ambulatory peritoneal dialysis (CAPD) in functionally a nephric patients and to display the results in graphic form. Design Theoretical calculations using previously measured 24-hour dialysate/plasma urea values in 77 CAPD patients and other defined components of weekly KT/V urea. Setting Measurements and calculations in theoretical patients doing standard CAPD with four daily exchanges. Patients Theoretical functionally anephric patients on standard CAPD as above. Interventions Theoretical calculations based on instillation of 2-, 2.5-, and 3-L exchange volumes. Main Outcome Measures Weekly urea clearances normalized to total body water (weekly KT/V urea). The values using different exchange volumes were related to standard body weight. Results Although a minimum recommended weekly KT/V urea target is arbitrary, the results illustrate the range of flexibility of CAPD relative to KT/V urea values with variations in exchange volume. The standard weights above which anephric patients on CAPD using four exchanges per day with 2-, 2.5-, and 3-L exchanges cannot reach a weekly KT/V urea target of 1.7, have been identified. The range of weekly KT/V urea levels possible with different exchange-volume programs has been graphically illustrated. Conclusions Weights above which a weekly KT/V urea of 1.7 cannot be reached in functionally anephric patients are 64, 77.6, and 91 kg for CAPD using 2-, 2.5-, and 3- L exchanges, respectively.