SOLUTE CLEARANCES WITH HIGH DIALYSATE FLOW-RATES AND GLUCOSE-ABSORPTION FROM THE DIALYSATE IN CONTINUOUS ARTERIOVENOUS HEMODIALYSIS

The purpose of this study was to determine the effects of high inlet dialysate flow rates (IDFR) on the clearances of urea and creatinine and to measure the absorption of glucose through the dialyzer in continuous arteriovenous hemodialysis (CAVHD). Ten anuric acute renal failure patients in the intensive care unit were studied. Increasing the IDFR from 0 to 33.3 mL/min (0 to 2 L/h) produced linear increments in the clearances of urea and creatinine, whereas further increases in the IDFR from 33.3 to 66.7 mL/min (2 to 4 L/h) produced less important, but still significant, increases in the clearances. At 66.7 mL/min, the clearances for urea and creatinine were 48.5 ± 3.4 and 42.2 ± 2.5 mL/min, respectively. Using a dialysate with a glucose concentration of 25.3 mmol/L (0.5 g/dL), the net transfer of glucose through the dialyzer did not change significantly, from 16.7 to 66.7 mL/min of IDFR. Increasing the inlet dialysate glucose concentration from 25.3 to 75.8, 126.3, and 214.6 mmol/L (0.5 to 1.5, 2.5, and 4.25 g/dL) at a fixed IDFR of 16.7 mL/min produced linear increments in the net glucose transferred to the patient, from 0.12 ± 0.02 to 0.67 ± 0.05, 1.25 ± 0.06 and 2.30 ± 0.14 mmol/min, respectively (21.4, 121.0, 225.7, and 414.5 mg/min). No significant changes in the ultrafiltration and plasma flow rates through the dialyzer were recorded at these different IDFR or inlet dialysate glucose concentrations. Ten patients were treated for 4 days or more with 16.7 mL/min (1 L/h) IDFR CAVHD with excellent control over kidney function parameters. We conclude that CAVHD with an IDFR of 16.7 mL/min is generally sufficient to control uremia, as it yields urea clearances of 35 L/d, equivalent to 4 hours of conventional hemodialysis. Since 60% of the glucose is absorbed through the dialyzer, intradialytic parenteral nutrition can be achieved with dialysate solutions containing glucose concentrations of 75.8 and 126.3 mmol/L (1.5 and 2.5 g/dL) yielding 2,900 to 5,500 kJ/d (700 to 1,300 kcal/24 h). High IDFR of 66.7 mL/min provide daily urea clearances of 70 L, equivalent to 8 hours of daily conventional hemodialysis. Potential new applications of such high IDFR CAVHD include lithium and methanol intoxications, as well as hyperkalemia, hyperuricemia, hyperphosphatemia, and hypercalcemia. © 1992, National Kidney Foundation, Inc.. All rights reserved.