Small and middle molecular weight solute clearance in nocturnal intermittent peritoneal dialysis

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 dialys is (PD). Setting: Clinical research center of a university-affiliated hospital. Interventions: Subjects received intravenous gentamicin and vancomycin on t he first day of the study. Subjects received no PD until their return on th e following day, when subjects underwent a simulated NIPD session utilizing four 2- to 2.5-L peritoneal dialysate dwells of 2 hours. Blood and dialysa te samples were collected immediately before the session and after each dia lysate dwell for determination of urea, creatinine, gentamicin, vancomycin, and beta(2)-microglobulin (beta 2M) concentrations. Each solute's D/P conc entration ratio and peritoneal Cl-D were calculated. Measurements and Main Results: The (mean +/-SD) a-hour D/P concentration ra tios 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 (beta 2M). Perit oneal CI, 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 (beta 2M). The D/P concentration ratios and peritoneal Cl-D values for urea, creatinine, and gentamicin were significantly different from van comycin and beta 2M (repeated measures ANOVA, p < 0.05). beta(2)-Microglobu lin 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 a nd peritoneal Cl-D than middle molecular weight solutes in NIPD. In NIPD, d aily peritoneal Cl-D of beta 2M is lower than that reported in continuous a mbulatory PD. NIPD also results in lower drug Cl-D than that reported in co ntinuous ambulatory PD studies.