Volume-Based Peritoneal Dialysis Prescription Guide to Achieve Adequacy Targets

Abstract

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Background: The use of automated and continuous ambulatory peritoneal dialysis (APD and CAPD) prescriptions (Rxs) to achieve adequate uremic toxin and fluid removal targets is important for attaining optimal patient outcomes. One approach for predicting such Rxs is the use of kinetic modeling. ♦

Methods: Demographic data and peritoneal membrane characteristics derived from a peritoneal equilibration test (PET) were available from 1,005 patients in North American centers who participated in a national adequacy initiative in 1999. Twelve patient subgroups were identified according to peritoneal membrane transport type and tertiles of total body water, assumed equal to urea distribution volume (Vurea). Each patient was then modeled using PD Adequest 2.0 to be treated by 12 CAPD and 34 APD Rxs using both glucose and icodextrin solutions to achieve adequacy targets of weekly urea Kt/V of 1.7 and 1 L of daily ultrafiltration (UF). Residual kidney function (RKF) was assumed to be 0, 2, 4, and 6 mL/min. Feasible peritoneal dialysis (PD) Rxs were identified where: 1) the 95% confidence limit achieved the goal of meeting the targets for urea Kt/V, daily UF, and both in 85%, 75%, and 70% of patients, respectively; 2) average PD solution dextrose concentration was < 2.5%; and 3) the number of daytime exchanges was minimized. ♦

Results: Feasible PD Rxs were similar when RKF was ≥ 2 mL/min, allowing condensed recommendations based on RKF ≥ 2 mL/min or < 2 mL/min. Individuals with lower or slower membrane transport required relatively greater 24-h solution volumes to achieve adequacy targets when RKF fell below 2 mL/min. With increasing Vurea, there was disproportionately greater dependence on RKF to achieve targets. While multiple Rxs achieving urea Kt/V and daily UF goals were identified for all membrane transport types, use of icodextrin in the long dwell reduced the need for a midday exchange in APD, glucose exposure, required fill and 24-h dwell volumes, irrespective of RKF and Vurea. While these benefits were most notable in high and high-average transporters, similar results were also seen in low and low-average transporters. ♦

Conclusions: Kinetic modeling identified multiple APD and CAPD Rxs that achieved adequate uremic solute and fluid removal for patients, irrespective of RKF and Vurea. Use of icodextrin rather than glucose in the long dwell reduced the complexity of the PD regimen, total glucose exposure, and 24-h total treatment solution volumes. Irrespective of modeling, adequacy of any PD prescription should be based upon individual clinical evaluation both for volume and solute removal.

Keywords: Glucose; icodextrin; kinetic modeling; peritoneal dialysis; prescription; total body water; ultrafiltration; urea Kt/V.

Figure 1 —

Summary of the modeled patient groups. Only a subgroup of modeled patients are shown for simplicity. RKF = residual kidney function; V_urea = urea distribution volume; H= high; HA = high-average; LA = low-average; L = low.

Figure 2 —

CAPD and APD prescriptions considered in the modeling. CAPD = continuous ambulatory peritoneal dialysis; APD = automated peritoneal dialysis.

Figure 3 —

Patient distribution in the modeled membrane transport type and V_urea groups. Y axis represents the percentage of patients in the cohort falling into each of four specific membrane transport characteristics and V_urea tertiles. The table illustrates specific numerical percentages for each specific Transport-V_urea subcategory. L = low; LA = low-average; HA = high-average; H= high; V_urea = urea distribution volume.

Figure 4 —

Prescriptions for patients with residual urea clearance less than 2 mL/min. APD = automated peritoneal dialysis; CAPD = continuous ambulatory peritoneal dialysis.

Figure 5 —

Prescriptions for patients with residual urea clearance greater than or equal to 2 mL/min. APD = automated peritoneal dialysis; CAPD = continuous ambulatory peritoneal dialysis.