Maximum ultrafiltration rates during peritoneal dialysis in rats

Maximum ultrafiltration rates during peritoneal dialysis in rats. It has been suggested that filtration pressure equilibrium could occur in peritoneal capillaries during peritoneal dialysis with very hypertonic exchanges. Rats were exposed to peritoneal dialysis solutions using 16ml instillations, 30 minute cycles, and dextrose concentrations from 1.4 to 20 g%. There was a plateau in ultrafiltration per exchange at mean osmotic gradients above 360 mOsm/kg H2O near 12.5 ml/ex (0.42 ml/min). The findings are also compatible with filtration pressure equilibrium predictions at an effective capillary plasma flow of 0.84ml/min and a filtration fraction near 50%. Studies with cardiovascular drugs (norepinephrine i.v., nitroprusside i.p., and dobutamine i.v.) showed no effects on the maximum ultrafiltration rates. This might indicate that flow is rather fixed because of known microcirculatory effects of solutions themselves