[Does method of anesthesia modify postoperative ischemia incidence? A study of patients after aortocoronary bypass...

In the postoperative period after coronary artery bypass graft surgery, the physician's enhanced attention should be focused on the incidence of myocardial ischaemia. The increased stress in the awakening patient as well as the return of autonomous reflexes can be the cause of imbalances in myocardial oxygen supply and uptake. Therefore, a probable influence of the pharmacologic profile of the intraoperatively applied anaesthetics on the incidence of postoperative myocardial ischaemia is of importance for adapting therapy on ICU to minimize any ischaemic risk. After approval by the ethics committee, a prospective randomized study was performed in 40 male patients who underwent coronary artery bypass graft surgery. The aim of the study was to compare balanced anaesthetic techniques performed with fentanyl and halothane, isoflurane and enflurane, respectively, with total intravenous anaesthesia performed with fentanyl and midazolam. An index to classify detection of ischaemia into three categories (ischaemia, probable ischaemia, no ischaemia) was established, based on measurements of myocardial lactate extraction and ST-segment analysis. Simultaneously, measurements of haemodynamic parameters and serum concentrations of catecholamines and intraoperatively applied anaesthetics were taken. In 8% of all measurements (30% of all patients) ischaemia was detected in the observation period and in 37% of all measurements (72.5% of all patients) probable ischaemia was detected. No significant difference was found concerning the incidence of myocardial ischaemia between all groups. The results of this investigation indicate that the application of inhalational anaesthetics for maintaining anaesthesia in coronary artery bypass graft surgery does not increase the risk of postoperative myocardial ischaemia.