Background: Cardiac surgery is a stress that causes insulin resistance, which leads to an increase in insulin requirement. The aim of the present study was to evaluate the effect of a pre-operative oral carbohydrate drink vs. overnight fasting on perioperative insulin requirements in non-diabetic patients undergoing elective coronary artery bypass grafting (CABG) surgery.
Methods: One hundred and one patients scheduled for CABG were enrolled in the study. After fasting overnight, the patients were randomised into two groups. In the control group (C), no drink was given in the morning. In the treatment group (T), the patients ingested 400 ml of carbohydrate fluid 2 h before induction of anaesthesia. Blood glucose and insulin requirement was recorded. Gastric drainage was measured. Post-operative nausea and vomiting was recorded.
Results: Neither the number of patients requiring insulin nor the amount of insulin required to maintain normoglycaemia differed between the study groups. More patients in the treatment group experienced nausea post-operatively (26 vs. 16, P=0.044), but vomiting was equally common in the study groups (10 vs. 7). Intra-operative gastric drainage was 26.8+/-57.9 ml in the treatment group vs. 16+/-37.9 ml in the control group (NS).
Conclusion: In this study patient population, a pre-operative oral carbohydrate drink did not reduce post-operative insulin resistance or post-operative nausea and vomiting. According to our findings, it is safe to allow cardiac surgery patients to drink clear fluids up to 2 h before induction of anaesthesia, because gastric emptying of the drink was almost total and no aspiration occurred.