Haemodynamics and Myocardial Oxygenation during Anaesthesia for Coronary Artery Surgery: Comparison between Enflurane and High‐Dose Fentanyl Anaesthesia

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Abstract
Changes in central and coronary hemodynamics and myocardial oxygenation during anesthesia induction, intubation, skin incision and sternotomy were studied in 24 patients undergoing a coronary artery bypass grafting operation under either high-dose fentanyl or enflurane anesthesia. The anesthesia induction caused no changes in the coronary hemodynamics in either group, in spite of a marked decrease in the coronary perfusion pressure during enflurane induction. In both groups a decrease in the coronary sinus blood flow and an increase in the coronary vascular resistance was observed after the intubation. At this stage, 2 patients in both groups had a low level of myocardial lactate extraction, indicating possible myocardial ischemia; mean myocardial lactate extraction had decreased significantly from the awake level in both groups. A circulatory response to surgical stimulation was seen in both groups, although it could be somewhat better controlled during enflurane anesthesia. In the enflurane patients the increase in myocardial O2 demand was accompanied by increased coronary flow, while in the fentanyl group the increase in coronary flow was not in proportion to the increased O2 demand, and an increase in myocardial O2 extraction was also seen. During surgery, 3 fentanyl patients and 1 enflurane patient had a low level of myocardial lactate extraction.