Adequacy of CAPD: a quantitative approach

In prescribing CAPD, general clinical practice is to use the standard regimen of 2L x 4 exchanges/day without regard to patient size, nutritional status, or residual kidney function. The standard regimen is usually adjusted in a trial and error manner reacting to clinical symptoms, life style issues, and patient compliance. The purpose of this paper is to recommend an alternative, quantitative approach based on urea kinetics that is prospective rather than reactive, and objective rather than subjective. The value of urea kinetic-based hemodialysis therapy prescription is well established and applying this knowledge to CAPD is a good starting point. The importance of small solute clearances for CAPD adequacy can be established on both theoretical and clinical grounds. The value of the KT/V urea index, its calculation, scaling factors for CAPD-hemodialysis comparisons, and the correlation between KT/V and weekly creatinine clearances are examined. Residual renal function has a significant impact on small solute clearances, and failure to adjust the therapy prescription to compensate for declining residual kidney function will have a detrimental impact on KT/V and the protein catabolic rate.