Intraoperative muscle and fat metabolism in diabetic patients during coronary artery bypass grafting surgery: a parallel microdialysis and organ balance study.

BACKGROUND Surgical trauma causes stress and inflammatory reactions with elevated serum free fatty acids (FFA) and glucose levels characteristic of intraoperative insulin resistance. Our aim was to compare microdialysis findings with those using the classical organ balance technique and to test the clinical feasibility of microdialysis during cardiac surgery. METHODS Nine diabetic and nine non-diabetic patients, undergoing routine coronary artery bypass grafting surgery, were studied using both microdialysis and the organ balance technique in the brachio-radial muscle of the forearm, and microdialysis in the pre-pectoral fat tissue. Glucose, lactate, and glycerol were measured in arterial and venous plasma and in the microdialysate before administration of heparin, at the release of the aortic cross-clamp, and before transfer to the intensive care unit. RESULTS Glucose release from the diabetic muscle at the last sampling time was detected. This was confirmed by a negative glucose A-I (arterial-interstitial difference) in the muscle. No differences were observed regarding lipolysis in the fat tissue in terms of A-I of glycerol. Intergroup differences were detected at the first sampling time, where arterial plasma glucose and plasma insulin levels were higher and muscle interstitial glucose lower in the diabetic patients. Plasma insulin was higher in the diabetic patients even at the final measurement time. CONCLUSIONS In terms of lipolysis in the fat tissue and glucose transport in the muscle, the non-diabetic patients were metabolically 'diabetics' during surgery. Despite strict blood glucose control, disturbances in glucose homeostasis in the diabetic muscle persist. Microdialysis was easy to use during cardiac surgery.