Anaesthesia for myocardial revascularisation

We studied the effects on myocardial performance and metabolism of fentanyl/propofol and fentanyl/enflurane anaesthesia in 20 patients before coronary artery bypass grafting. Anaesthesia was induced with fentanyl 20 micrograms.kg-1 and pancuronium 0.15 mg.kg-1. Patients received, by random allocation, either propofol by infusion, 6 mg.kg-1.h-1 reduced by half after 10 min then adjusted as necessary (mean rate 2.8 mg.kg-1.h-1), or enflurane 0.8% inspired concentration for 10 min reduced to 0.6% and adjusted as required (mean 0.7%). Measurements were made before induction, after tracheal intubation, after skin incision and after sternotomy. There were no significant differences between the groups in any haemodynamic variables during the study. Following intubation both groups showed a rise in heart rate (p < 0.01) and cardiac index (p < 0.05). Systemic vascular resistance decreased after intubation (p < 0.05) then returned to baseline during surgery; stroke index was unchanged after intubation but was reduced during surgery (p < 0.01) as systemic vascular resistance increased. Regional and global coronary blood flow were maintained in both groups, as were myocardial oxygen consumption and lactate extraction ratio. However, lactate production did occur in one patient receiving enflurane and Holter monitoring confirmed ischaemia. One patient receiving propofol showed lactate production not accompanied by any ECG changes. This study suggests that propofol may be a suitable alternative to enflurane as an adjunct to opioids in anaesthesia for coronary artery bypass grafting.