Intermittent Peritoneal Dialysis: Urea Kinetic Modeling and Implications of Residual Kidney Function

Abstract

♦Background Intermittent peritoneal dialysis (IPD) is an old strategy that has generally been eclipsed, in the home setting, by daily peritoneal therapies. However, for a select group of patients with exhausted vascular access or inability to receive PD at home, in-center IPD may remain an option or may serve as an incremental strategy before initiation of full-dose PD. We investigated the residual kidney clearance requirements necessary to allow thrice-weekly IPD regimens to meet current adequacy targets. ♦Methods The 3-pore model of peritoneal transport was used to examine 2 thrice-weekly IPD dialysis modalities: 5 – 6 dwells with 10 – 12 L total volume (low-dose IPD), and 50% tidal with 20 – 24 L total volume (high-dose IPD). We assumed an 8-hour dialysis duration and 1.5% dextrose solution, with a 2-L fill volume, except in tidal mode. The PD Adequest application (version 2.0: Baxter Healthcare Corporation, Deerfield, IL, USA) and typical patient kinetic parameters derived from a large dataset [data on file from Treatment Adequacy Review for Gaining Enhanced Therapy (Baxter Healthcare Corporation)] were used to model urea clearances. The minimum glomerular filtration rate (GFR) required to achieve a total weekly urea Kt/V of 1.7 was calculated. ♦Results In the absence of any dialysis, the minimum residual GFR necessary to achieve a weekly urea Kt/V of 1.7 was 9.7 mL/min/1.73 m2. Depending on membrane transport type, the low-dose IPD modality met urea clearance targets for patients with a GFR between 6.0 mL/min/1.73 m2 and 7.6 mL/min/1.73 m2. Similarly, the high-dose IPD modality met the urea clearance target for patients with a GFR between 4.7 mL/min/1.73 m2 and 6.5 mL/min/1.73 m2. ♦Conclusions In patients with residual GFR of at least 7.6 mL/min/1.73 m2, thrice-weekly low-dose IPD (10 L) achieved a Kt/V urea of 1.7 across all transport types. Increasing the IPD volume resulted in a decreased residual GFR requirement of 4.7 mL/min/1.73 m2 (24 L, 50% tidal). In patients with residual kidney function and dietary compliance, IPD may be a viable strategy in certain clinical situations.