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

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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.