A comparison of peritoneal dialysance (D) during CAPD, intermittent peritoneal dialysis (IPD) and tidal PD (TPD) in awake normal dogs.

The important variables which determine peritoneal clearances include: residual volume, cycle volume, and cycle frequency. Various combinations of these variables result in CAPD, IPD, and TPD schedules. We decided to develop an animal model in which the clearances of these modes could be compared, performing dialysis on awake dogs with normal kidney function. In five successive experiments, two silicone catheters were placed in the abdomen of anesthetized dogs, one in the lower abdomen and one between the liver and diaphragm. On successive days, with the dogs awake but lying down, CAPD, IPD, and TPD schedules were performed for 4 hours, using 1.5% Inpersol (Abbott Laboratories, IL.). For CAPD the infused volume was 2 liters, drained at 4 hours. For IPD, 2 liters were infused and drained each hour. For TPD, one liter residual was infused, and another liter infused and drained each 20 minutes, to result in a 3 liter/hour flow-through-rate. The dialysance of glucose (Dglu) was calculated from changes in dialysate and blood glucose concentration. Dglu reproducibly predicted the Durea, with Dglu = 0.6 Durea. Our experiments demonstrated that without efforts to optimize TPD, its dialysance is similar to that of standard TPD. The higher average TP volume of TPD offsets the higher fluid flow rate of TPD schedules. Both IPD and TPD have higher dialysance than CAPD.