[Coronary circulation, myocardial oxygen consumption and myocardial metabolism during enflurane-nitrous oxide anesthesia in coronary patients].

The effects of enflurane on myocardial oxygen consumption, metabolism and coronary blood flow (argon washin) were studied in 10 patients with 2- or 3-vessel coronary artery disease undergoing coronary artery bypass surgery. All patients were men with stable angina and normal left ventricular function and were on maintenance doses of beta-receptor- or calcium-antagonists. Anaesthesia consisted of enflurane and 50% nitrous oxide in oxygen. Measurements were performed and blood samples were taken with the patient awake, 30 min after induction of anaesthesia without any surgical stimulation and during sternotomy. End-tidal enflurane concentrations averaged 0.9% after induction and 2.5% during sternotomy. Enflurane decreased coronary blood flow significantly by 36% after induction, while sternotomy increased coronary blood flow by 29%. Myocardial oxygen uptake was decreased by 33% and was increased by 37% during sternotomy. Coronary vascular resistance did not change significantly during the entire observation period, while coronary sinus oxygen saturation significantly increased after induction by 20% followed by a decrease to preinduction levels during sternotomy. Myocardial glucose, free fatty acids, lactate and pyruvate uptake were significantly reduced after induction and increased to preinduction levels during sternotomy. Myocardial lactate production could not be demonstrated at any time during the observation period.