Automated peritoneal dialysis: a Spanish multicentre study

Background: A prospective sequential study on continuous ambulatory peritoneal dialysis (CAPD) and three techniques of automated peritoneal dialysis (APD) was conducted to assess peritoneal clearances, the influence of peritoneal permeability on nocturnal APD clearances and the suitability of the peritoneal equilibration test (PET) for predicting clearances on APD. Methods: After performing a PET, a series of clinical, biochemical and dialysis adequacy markers were evaluated after 2 months on CAPD, continuous cycling peritoneal dialysis (CCPD) and tidal volume peritoneal dialysis (TPD) with 50% and 25% tidal volumes. Forty five patients participated and 33 completed the study. Results: Serum urea and creatinine decreased significantly whereas haemoglobin and glucose increased. Mean peritoneal urea clearance (1/week) was 55.40±8.76 on CAPD, 74.82±12.62 on CCPD, 69.20±14.63 on TPD (tidal 50%) and 66.89±13.23 on TPD (tidal 25%); mean creatinine clearance (1/week/1.73 m²) was 42.80±9.95, 52.19±11.11, 51.31±13.3 and 49.17±11.83 respectively. Both clearances were significantly lower on CAPD than on APD (<0.001). CCPD was the automated technique that provided the best nocturnal urea clearance (P<0.01). Nocturnal creatinine clearance did not show significant differences between CCPD and TPD (tidal 50%), being better with both techniques than with TPD (tidal 25%). There were statistically significant differences between nocturnal dialysate to plasma (D/P) ratios and those corresponding to the nearest times in the PET. The urea D/P ratio at 180 min and the creatinine D/P ratio at 240 min of the PET were the parameters that better estimated nocturnal clearances on APD. Conclusions: 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. Key words: automated peritoneal dialysis; CAPD; clearances; PET