Insulin dose versus rate of potassium decrease in the treatment of hyperkalemia with iv insulin during extracorporeal circulation: An observational study

Abstract

Background: Glucose-insulin infusion can be used in the treatment of hyperkalemia occurring during extracorporeal circulation (ECC) in patients undergoing cardiac surgery. Objective: The purpose of this observational study was to investigate the effects of 2 different insulin doses administered during ECC on the rate of decrease in serum potassium level and the incidences of hypokalemia and hypoglycemia in hyperkalemic patients. Methods: Hyperkalemic patients in whom continuous retrograde warmblood cardioplegia was used were enrolled. Patients were assigned to 1 of 2 groups based on serum potassium level (⩾7 mmol/ L, group 1; 6–6.9 mmol/ L, group 2). Fifty international units of crystallized human insulin was given IV as a bolus dose to group 1 and 25 IU to group 2. The rate of decrease in serum potassium level was recorded, the time required for the level to decrease to 5.5 mmol/L after insulin injection was recorded, and patients were monitored for hypokalemia and hypoglycemia. Results: Thirty-six patients (24 males, 12 females; mean age, 52.5 years) were enrolled. The mean time required for the serum potassium level to decrease to 5.5 mmol/L after insulin injection was 22.7 ± 1.9 minutes in group 1 and 15.7 ± 0.8 minutes in group 2. During this interval, the mean decreases and the mean rate of decrease in serum potassium level were as follows: group 1, 1.78 mmol/L and 0.078 mmol/L per minute, respectively; group 2, 0.076 mmol/L and 0.0048 mmol/L per minute, respectively. The incidences of hypokalemia and hypoglycemia were significantly higher in group 1 than in group 2. Conclusions: In this study population, the serum potassium level needed for discontinuation of ECC was achieved more rapidly with insulin 50 IU than with insulin 25 IU, but with higher incidences of hypokalemia and hypoglycemia.