This study confirms that TPD does not improve the results of CCPD. Significant differences between D/P ratios during actual nocturnal cycles and PETs were observed.

Objectives To compare the peritoneal clearances of urea and creatinine in continuous ambulatory peritoneal dialysis (CAPD) with three types of automated peritoneal dialysis (APD): continuous cycling peritoneal dialysis (CCPD), 50% tidal peritoneal dialysis (TPD), and 25% TPD and to assess the usefulness of the peritoneal equilibration test (PET) in predicting peritoneal clearances in overnight APD. Patients Eleven uremic patients (mean age 44.5 ± 15.45 years with a mean time on dialysis of 42.63 ± 25.62 months) were included in the study. Measurements PET for urea and creatinine following Twardowski's method. Peritoneal clearances for urea and creatinine CAPD: samples of blood and dialysate within 24 hours. APD: blood mean levels of urea and creatinine before and after nighttime dialysis. Dialysate: urea and creatinine in nocturnal and daytime dialysate. Results Peritoneal clearance of creatinine was 38.14 ± 9.99 L/week/1.73 m2 in CAPD, 44.28 ± 12.4 L/week/1.73 m2 in CCPD, 50.07 ± 17.86 L/week/1.73 m2 in 50% TPD (p < 0.05) and 40.18 ± 6.65 L/week/1.73 m2 in 25% TPD. Peritoneal clearance of urea improved significantly in the three modalities of APD: 51.91 ± 12.58 L/week/1.73 m2 in CAPD; 66.7 ± 9.9 L/week/1. 73 m2 in CCPD (p < 0.05); 76.3 ± 14.5 L/week/1. 73 m2 in 50% TPD (p < 0.001) and 64.3 ± 11.4 L/week/1.73 m2 in 25% TPD (p < 0.05). The dialysatel plasma (DIP) ratio of creatinine at 30,60, 120,180, and 240 minutes showed significant correlation with nighttime APD clearance. Nevertheless, only the DIP ratio of urea at 30, 60, and 120 minutes correlated with overnight APD clearance. Conclusions A remarkable improvement was observed with APD regarding the clearance of urea mainly when 50% tidal peritoneal dialysis was used, whereas it was less noticeable in the clearance of creatinine. The PET is a helpful tool in predicting overnight peritoneal clearances of creatinine but it is less useful in predicting urea clearance.