Ultrafiltration with an isosmotic solution during long peritoneal dialysis exchanges.

The potential of a starch-derived glucose polymer (molecular weight 16,800) as an osmotic agent for peritoneal dialysis was evaluated. A dialysate isosmotic to uraemic serum (302 [SEM 1.3] mOsm/kg) containing 5% glucose polymer (9.4 mmol/l) was compared with hypertonic (332 [1.0] mOsm/kg) 1.36% glucose (76 mmol/l) solution for ultrafiltration, solute transport, and carbohydrate absorption over 6 h and 12 h peritoneal dialysis exchanges. Glucose polymer solution produced substantially greater net ultrafiltration than glucose, while maintaining stable dialysate osmolality throughout the exchanges. At 6 h and 12 h, 14.4% and 28.1% of glucose polymer had been absorbed, compared with 61.5% and 83.0% of glucose; thus, glucose polymer provided less than 50% of the calorie load of the glucose dialysate per unit volume of ultrafiltrate. There was a 7-9-fold increase in serum maltose with glucose polymer. This high-molecular-weight glucose polymer produced sustained ultrafiltration even when dialysate osmolality remained within the physiological range, by a mechanism resembling "colloid" osmosis. It is a safe and effective osmotic agent but its long-term effects need further study.