Continuous Flow through Peritoneal Dialysis (Cfpd): Comparison of Efficiency to Ipd, Tpd, and Capd in An Animal Model

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 mU minfor 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.