Kinetic Modeling of Continuous Flow Peritoneal Dialysis

Kinetic models have been derived for analysis of the effects on peritoneal urea clearance (Kp) of continuous single-pass flow of fresh peritoneal dialysate and continuous flow of peritoneal dialysate recirculating through an external dialyzer. Generalized solution of the models shows that both predict Kp to be a well-defined function of the peritoneal mass transfer coefficient (MTC) and the dialysance (D) of the external dialyzer, while the MTC is a function of the rate and distribution of dialysate flow. Thus the models should be useful to guide studies to optimize CFPD. Analysis of reported in vivo data indicate that with dialysate flow rate and D both in the range of 200 ml/min, MTC levels of 60-70 ml/min and Kp levels of 50 ml/min can be achieved. If the model predictions are verified in vivo, 8-hour overnight CFPD 6 nights/week could provide the average-size anephric patient a weekly stdKt/V of 3.2 which is competitive with daily hemodialysis. Kinetic modeling of ultrafiltration indicated ultrafiltration rates 0.2-0.3 L/hr should be achieved with 1.0-1.25% dextrose dialysate. The model shows average rates of glucose absorption can theoretically be reduced by 33% compared to CAPD with the same amount of fluid removal.