Tidal peritoneal dialysis: Comparison of different tidal regimens and automated peritoneal dialysis

Background. The National Kidney Foundation Dialysis Outcomes Quality Initiative (DOQI) clinical practice guidelines have suggested minimal weekly Kt/V urea and creatinine clearance goals for peritoneal dialysis patients maintained on continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). Achieving these goals may present problems, particularly in larger patients whose residual renal function declines. Thus, modifications of the dialysis regimen, such as tidal peritoneal dialysis (TPD), have been developed. However, the ability of TPD to improve the efficiency of the dialysis procedure remains uncertain. Methods. Stable, cycling peritoneal dialysis patients were placed into two groups to study the effectiveness of different TPD prescriptions on peritoneal clearances of urea and creatinine. The volume of dialysis solution used and the duration of therapy were fixed in the two groups. Comparisons were made to conventional APD using multiple hourly cycles in which spent dialysis solution was completely drained with each cycle. Group I patients received a total of 15 L of PD solution over 9.5 hours in the dialysis unit. These patients received 10, 25, and 50% TPD and APD on four separate days. Group II patients received 24 L of PD solution over 9.5 hours. These patients received 25 and 50% APD on separate days in the dialysis unit. Peritoneal dialysis clearances for urea (pKt/V) and creatinine (pC(Cr)) levels were calculated for both groups. The results were then analyzed to determine whether there was any significant difference among the various prescriptions. Results. The data in the group I patients indicated a mean daily pKt/V of 0.22 +/- 0.03 with 10% TPD, 0.23 +/- 0.02 with 25% TPD, 0.25 +/- 0.02 with 50% TPD, and 0.26 +/- 0.02 with APD. Paired t-test analysis for pKt/V demonstrated that 10 and 25% TPD resulted in significantly lower values than 50% TPD and APD (P < 0.05). Mean daily pC(Cr) L/24 h/1.73 m(2) was 6.03 +/- 0.72 for 10% TPD, 6.34 +/- 0.83 for 25% TPD, 6.65 +/- 0.51 for 50% TPD, and 7.01 +/- 0.96 for APD; these differences were not significantly different. The data in the group II patients demonstrated a mean daily pKt/V of 0.28 +/- 0.03 with 25% TPD, 0.29 +/- 0.05 with 50% TPD, and 0.30 +/- 0.05 for APD. The mean daily pC(Cr) was 6.69 +/- 0.47 for 25% TPD, 8.09 +/- 1.30 for 50% TPD, and 7.63 +/- 1.13 for APD. There were no statistical differences for pKt/V and pC(Cr) within the 24 L group. Conclusion. When the duration of therapy and volume of dialysate volume are kept constant, TPD does not result in an improvement in clearances compared with conventional APD, at least with dialysate volumes up to 24 L.