Nephrol Dial Transplant (1994) 9: 749-752
© 1994 European Renal Association-European Dialysis and Transplant Association
research-article
Maintaining adequacy in CAPD by individualizing the dialysis prescription
Lister Renal Unit, Stevenage Hertfordshire, UK
Correspondence and offprint requests to: Correspondence and offprint requests to. I E Tattersall, Lister Renal Unit, Stevenage, Herts SG 4AB, UK
Urea kinetic modelling (UKM) has been proposed as a tool for auditing the adequacy of CAPD and a total fractional daily urea cleared volume (Kt/V) of 0.25 suggested as the minimum adequate level. At the start of CAPD the kidneys contribute significantly to the total clearance and Kt/V often falls below 0.25 as renal function declines. We performed 3-monthly UKM measurements in 56 CAPD patients. These results were used to individualize exchange volume and frequency in an attempt to achieve a Kt/V>0.25 and compensate for declining renal function in all patients over a study period of 1 year.
The mean Kt/V was maintained over 0.29 over the study period. During this time the residual renal component of Kt/V fell significantly from 0.09 (SD ±0.07) to 0.06±0.08 (P < 0.001) while the dialysis component increased significantly from 0.20±0.05 to 0.24±0.05 (P<0.005). This was achieved by increasing the mean daily exchange volume from 8.12± 1.22 to 10.39 ±2.68 litres (P<0 001). After a year, 15 patients had Kt/V
0.25 despite maximum practical exchange volumes. Twelve patients dropped out of the study due to death (4), transplantation (2), and transfer to haemodialysis (6 patients, of whom 4 had frank uraemic toxicity).
In most CAPD patients it is possible to compensate for declining renal function by increasing exchange volume, at least over 1 year. However, CAPD was unable to provide Kt/V>0.25 in 40% of patients, despite individualization of the dialysis prescnption.
Keywords: CAPD; clearance; urea kinetic model; residual renal function; adequacy