Acute continuous hemofiltration with dialysis: effect on insulin concentrations and glycemic control in critically ill patients.

OBJECTIVES

To quantitate insulin losses and glucose absorption during acute continuous hemofiltration with dialysis and to assess the clinical importance of these changes.

DESIGN

Prospective collection of serum and ultradiafiltrate fluid in patients receiving acute continuous hemofiltration with dialysis. Measurements of serum and ultradiafiltrate insulin and glucose concentrations. Calculations of insulin excretion and glucose absorption. Correlation of findings with patient outcome.

SETTING

University medical center.

PATIENTS

Sixteen ICU patients with acute renal failure.

MEASUREMENTS AND MAIN RESULTS

The mean serum glucose concentration before acute continuous hemofiltration with dialysis was 178 mg/dL (9.9 mmol/L) (95% confidence interval 112 to 244 mg/dL [6.2 to 13.6 mmol/L]), increasing to 257 mg/dL (14.3 mmol/L) (95% confidence interval 167 to 347 mg/dL [9.3 to 19.3 mmol/L]) after 4 hrs of acute continuous hemofiltration with dialysis, and stabilizing at 207 mg/dL (11.5 mmol/L) (95% confidence interval 160 to 254 mg/dL [8.9 to 14.1 mmol/L]) at 24 hrs. Mean plasma insulin concentration before acute continuous hemofiltration with dialysis was 34.4 mU/L (95% confidence interval 8.6 to 60.2 mU/L), increasing to 54.4 mU/L at 4 hrs (95% confidence interval 25 to 83.8 mU/L; NS). There was no significant decrease in mean insulin concentration across the filter (51.8 mU/L before filtration vs. 51.9 mU/L after filtration). Insulin was detected in the ultradiafiltrate but its overall mean clearance rate was only 6.2 mL/min, with mean daily losses of 689 mU/day (95% confidence interval 325 to 1053 mU/day). During acute continuous hemofiltration with dialysis, glucose absorption through the filter averaged 134 g/day (95% confidence interval 96.2 to 171.8 g/day). Plasma insulin concentrations were significantly (p < .05) lower in survivors than nonsurvivors (51.7 vs. 123.6 mU/L).

CONCLUSIONS

Significant glucose absorption occurs during acute continuous hemofiltration with dialysis and is coupled with minor insulin losses (< 1 U/day) through the filter. These events do not appear to have major clinical impact. A low plasma insulin concentration is associated with diminished mortality rates in this group of patients.