Effect of glucose-insulin-potassium on hyperlactataemia in patients undergoing valvular heart surgery

Hyperlactataemia represents oxygen imbalance in the tissues and its occurrence during cardiac surgery is associated with adverse outcomes. Glucose-insulin-potassium (GIK) infusion confers myocardial protection against ischaemia-reperfusion injury and has the potential to reduce lactate release while improving its clearance. OBJECTIVES The objective of this study is to compare the effect of GIK on the incidence of hyperlactataemia in patients undergoing valvular heart surgery. DESIGN A randomised controlled study. SETTING Single university teaching hospital. PATIENTS One hundred and six patients scheduled for elective valvular heart surgery with at least two of the known risk factors for hyperlactataemia. INTERVENTION Patients were randomly allocated to receive either GIK solution (insulin 0.1IUkg^-1 h^-1 and an infusion of 30% dextrose and 80mmoll^-1 potassium at 0.5mlkg^-1 h^-1) or 0.9% saline (control) throughout surgery. MAIN OUTCOME MEASURES The primary outcome was the incidence of hyperlactataemia (lactate ≥4mmoll^-1) during the operation and until 24h after the operation. Secondary outcomes included haemodynamic parameters, use of vasopressor or inotropic drugs, and fluid balance until 24h postoperatively. Postoperative morbidity endpoints were also assessed. RESULTS The incidences of hyperlactataemia were similar in the groups (32/53 patients in each of the control and GIK groups, P>0.999). There were no intergroup differences in haemodynamic parameters, use of vasopressor and inotropic drugs, or fluid balance. The incidences of postoperative morbidity endpoints were similar in both groups. CONCLUSION Despite its theoretical advantage, GIK did not provide beneficial effects in terms of the incidence of hyperlactataemia or outcome in patients undergoing valvular heart surgery.