Perioperative hyperinsulinaemic normoglycaemic clamp causes hypolipidaemia after coronary artery surgery

Background. Glucose - insulin - potassium (GIK) administration is advocated on the premise of preventing hyperglycaemia and hyperlipidaemia during reperfusion after cardiac interventions. Current research has focused on hyperglycaemia, largely ignoring lipids, or other substrates. The present study examines lipids and other substrates during and after on-pump coronary artery bypass grafting and how they are affected by a hyperinsulinaemic normoglycaemic clamp. Methods. Forty-four patients were randomized to a control group (n = 21) or to a GIK group ( n 23) receiving a hyperinsulinaemic normoglycaemic clamp during 26 h. Plasma levels of free fatty acid (FFA), total and lipoprotein (VLDL, HDL, and LDL)-triglycerides (TG), ketone bodies, and lactate were determined. Results. In the control group, mean FFA peaked at 0.76 (SEM 0.05) mmol litre 21 at early reperfusion and decreased to 0.3 - 0.5 mmol litre 21 during the remaining part of the study. GIK decreased FFA levels to 0.38 (0.05) mmol litre 21 at early reperfusion, and to low concentrations of 0.10 (0.01) mmol litre 21 during the hyperinsulinaemic clamp. GIK reduced the area under the curve (AUC) for FFA by 75% and for TG by 53%. The reduction in total TG was reflected by a reduction in the VLDL (-54% AUC) and HDL (-42% AUC) fraction, but not in the LDL fraction. GIK prevented the increase in ketone bodies after reperfusion ( 244 to -47% AUC), but was without effect on lactate levels. Conclusions. Mild hyperlipidaemia was only observed during early reperfusion ( before heparin reversal) and the hyperinsulinaemic normoglycaemic clamp actually resulted in hypolipidaemia during the largest part of reperfusion after cardiac surgery.