Continuous flow-through peritoneal dialysis (CFPD): Comparison of efficiency to IPD, TPD, and CAPD in an animal model

Abstract

Objective: To determine whether continuous flow-through peritoneal dialysis (CFPD), a treatment schedule in which peritoneal dialysate is infused continuously into one part of the abdomen (over the liver) and is drained from a distant part of the abdomen (the pelvis), can provide greater clearance than continuous ambulatory peritoneal dialysis (CAPD), tidal peritoneal dialysis (TPD), or intermittent peritoneal dialysis (IPD). Design: A prospective study comparing four schedules of peritoneal dialysis in the awake, normal dog, using glucose clearance as a substitute for urea clearance. Methods: We placed two chronic dialysis catheters into the abdomen of anesthetized dogs (with intraperitoneal portions of fluted or miniature column-disc design). On successive days, with the dogs awake and prone, we performed peritoneal dialysis for 4 hours with 1.5% dialysate according to one of four schedules, each with 2 L maximum intraperitoneal volume: CFPD (unidirectional flow at an average of 3.6 L/hr), IPD (2 L/hr), TPD (average of 3.6 L/hr, 1 L residual volume), and CAPD (2 L/4 hr). Glucose and urea clearances were calculated from blood and peritoneal concentrations and dialysate flow rates. Results: Stabilized glucose clearances (from 60 to 240 minutes) averaged 11 ± 5 mL/min for IPD, TPD, and CFPD, and 5 ± 2 mL/min for CAPD. However, glucose clearances of CFPD were 13 ± 6 mL/min when the intraperitoneal volume was maintained at 800-1000 mL, and 16.5 ± 6 mL/min when flow rate was 6 L/hr. Urea clearances were twice the measured glucose clearances. Conclusion: When CFPD is performed with an appropriate intraperitoneal volume and flow, it is the most chemically effective method of peritoneal dialysis in removing small molecules like urea.