Anaesthesia for coronary artery bypass grafting: opioid‐analgesia combined with either flunitrazepam, propofol or isoflurane

This is a prospective, open, randomized study comparing three different anaesthetic regimens with respect to haemodynamic stability (cardiac index and pressure measurements), ischaemia (ECG), and loss of awareness (midlatency auditory evoked potentials) in 58 patients undergoing coronary artery surgery. Anaesthesia was based on fentanyl 0.01 mg kg ‐1 bw for induction and 0.8‐2.0 mg h ‐1 in combination with nitrous oxide for maintenance before cardiopulmonary bypass and 0.2‐0.6 mg h ‐1 without nitrous oxide during and after cardiopulmonary bypass. Eighteen patients were anaesthetised with flunitrazepam 0.01 mg kg ‐1 bw for induction and received thereafter 1–2 mg h ‐1 for maintenance (group F). In 40 patients anaesthesia was induced with etomidate and maintained with either isoflurane 0.4‐1.2 vol% (group I) or propofol 4–10 mg kg ‐1 bw h ‐1 (group P). Vasodilators and inotropes were used for haemodynamic control when needed. Haemodynamic variables and ECG were studied at five timepoints (awake; after induction before surgery; after sternotomy; before cardiopulmonary bypass; and 20 min after separation from bypass). During surgical stimulation, vasodilators were needed significantly more frequently in group F, than in groups I and P. Surgery and sternotomy caused an increase in SVI and APs/SV in all groups. Differences between the groups were only found for systemic pressures, which after sternotomy were lowest in group I and before cardiopulmonary bypass were highest in group F. After termination of bypass all groups showed an increase in HR and a decrease in SVI, SVR, and LVSWI compared to the awake state, while CI remained unchanged. The only differences noted between the groups were a lower PCWP and a smaller reduction in SVR with propofol compared to the others and higher APs/SV with propofol compared to isoflurane. Concerning ST segment changes (> 0.1 mV, leads II and/or V5) at the five measurement times, significant differences were found comparing groups F and P after sternotomy ( P < 0.10) and comparing groups F and I after separation from CPB ( P <0.05), group F showing the highest incidences of ischaemic events. A blinded evaluation of auditory evoked potentials demonstrated more reduced midlatency auditory potentials after sternotomy during isoflurane and propofol anaesthesia than during flunitrazepam. The authors conclude that fentanyl supplemented with isoflurane or propofol was unequivocally superior to supplementation with flunitrazepam.