Small and Middle Molecular Weight Solute Clearance in Nocturnal Intermittent Peritoneal Dialysis

Abstract

Objectives

To determine the dialysate-to-plasma (D/P) concentration ratios and peritoneal dialytic clearance (Cl_D) of substances with a wide range of molecular weights in subjects receiving a simulated nocturnal intermittent peritoneal dialysis (NIPD) session.

Design

Open-label single-dose study.

Subjects

Six end-stage renal disease patients undergoing peritoneal dialysis (PD).

Setting

Clinical research center of a university-affiliated hospital.

Interventions

Subjects received intravenous gentamicin and vancomycin on the first day of the study. Subjects received no PD until their return on the following day, when subjects underwent a simulated NIPD session utilizing four 2- to 2.5-L peritoneal dialysate dwells of 2 hours. Blood and dialysate samples were collected immediately before the session and after each dialysate dwell for determination of urea, creatinine, gentamicin, vancomycin, and β₂-microglobulin (β2M) concentrations. Each solute's D/P concentration ratio and peritoneal Cl_D were calculated.

Measurements and Main Results

The (mean ±SD) 2-hour D/P concentration ratios were 0.78 ± 0.05 (urea), 0.49 ± 0.11 (creatinine), 0.38 ± 0.08 (gentamicin), 0.11 ± 0.06 (vancomycin), and 0.07 ± 0.03 (β2M). Peritoneal Cl_D values (mL/min of dialysis) were 19.0 ± 2.8 (urea), 12.1 ± 3.5 (creatinine), 8.4 ± 2.8 (gentamicin), 2.7 ± 1.5 (vancomycin), and 1.7 ± 0.8 (β2M). The D/P concentration ratios and peritoneal Cl_D values for urea, creatinine, and gentamicin were significantly different from vancomycin and β2M (repeated measures ANOVA, p < 0.05). β₂-Micro-globulin peritoneal Cl_D was strongly related to gentamicin peritoneal Cl_D (r = 0.96, p < 0.05).

Conclusion

Small molecular weight solutes have significantly greater D/P and peritoneal Cl_D than middle molecular weight solutes in NIPD. In NIPD, daily peritoneal Cl_D of β2M is lower than that reported in continuous ambulatory PD. NIPD also results in lower drug Cl_D than that reported in continuous ambulatory PD studies.