Kinetic Modeling of Incremental Ambulatory Peritoneal Dialysis Exchanges

♦ BACKGROUND: Incremental peritoneal dialysis (PD), the gradual introduction of dialysate exchanges at less than full-dose therapy, has been infrequently described in clinical reports. One concern with less than full-dose dialysis is whether urea clearance targets are achievable with an incremental regimen. In this report, we used a large database of PD patients, across all membrane transport types, and performed urea kinetic modeling determinations of possible incremental regimens for an individual membrane type. ♦ METHODS: Using a modified 3-pore model of peritoneal transport, various incremental manual continuous ambulatory PD (CAPD) exchanges employing glucose and/or icodextrin were evaluated. Peritoneal urea clearances from those simulations were added to residual kidney urea clearance for patients with various glomerular filtration rates (GFRs), and the total weekly urea clearance was then compared to the total weekly urea Kt/V target of 1.7. All 4 peritoneal membrane types were modeled. For each simulated prescription, net ultrafiltration and carbohydrate absorption were also calculated. ♦ RESULTS: Incremental CAPD regimens of 2 exchanges a day met adequacy targets if the GFR was 6 mL/min/1.73 m² in all membrane types. For regimens employing 3 exchanges a day, Kt/V targets were achieved at GFR levels of 4 to 5 mL/min/1.73 m² in high transporters to low transporters but higher tonicity 2.5% glucose solutions or icodextrin were required in some regimens. ♦ CONCLUSIONS: This work demonstrates that with incremental CAPD regimens, urea kinetic targets are achievable in most new starts to PD with residual kidney function. Incremental PD may be a less intrusive, better accepted initial treatment regime and a cost-effective way to initiate chronic dialysis in the incident patient. The key role of intrinsic kidney function in incremental regimens is highlighted in this analysis and would warrant conscientious monitoring.