PERITONEAL-DIALYSIS PRESCRIPTION - THE CLEARANCE PEAK MODEL

Creatinine clearance (GRCL) was studied in 20 patients on CAPD in rela tion to the dwell times (DT), in order to establish a personalised dia lysis schedule with the best clearance (CL) results, while respecting the patient's life-style. By calculating the CRCL from the two exchang es with dwell-times of 4 and 8 hours (2 1, 2.27%), curves (2nd degree polynomial regression) were plotted with three points (0h, 4h, 8h) for CRCL and the ultrafiltration rate (UF) as a function of the DT. The D T corresponding to the CRCL peak (CLPeak-time) was calculated for each subject with the first derivative of the function. On the basis of th e CRCL obtained with the three most common DT (4h, 6h, 8h), we divided the patients into three categories (CLPeak;time <5h: ''fast'': 5-7h: ''normal''; >7h: ''slow'') for the best CRCL correspondence of the 4h, 6h or 8h exchanges respectively. Also the 8h/4h ratio was used to det ermine CLPeak-time. For each of the three categories there is a corres ponding dialysis schedule for the best CRCL and UF results of the exch anges with DT of 4, 6 and 8 hours, plus the theoretical calculation of the daily CRCL obtainable (''fast'': APD; ''normal''' CAPD 4 exchange s/DAPD 4 exchanges; ''slow'': CAPD 4 exchanges). The ''CLPeak'' dialys is prescription model therefore identifies the most advantageous DT fo r each patient by using the CRCL values of two 2.27% exchanges of 4 an d 8h respectively. Functional classification into three categories may give a rational orientation to dialysis prescription in order to reac h the maximum CRCL possible with the individual peritoneal transport r ates.