ANESTHESIA FOR CORONARY-ARTERY BYPASS-GRAFTING - OPIOID-ANALGESIA COMBINED WITH EITHER FLUNITRAZEPAM, PROPOFOL OR ISOFLURANE

This is a prospective, open, randomized study comparing three differen t anaesthetic regimens with respect to haemodynamic stability (cardiac index and pressure measurements), ischaemia (ECG), and loss of awaren ess (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 oxid e for maintenance before cardiopulmonary bypass and 0.2-0.6 mg h-1 wit hout nitrous oxide during and after cardiopulmonary bypass. Eighteen p atients were anaesthetised with flunitrazepam 0.01 mg kg-1 bw for indu ction and received thereafter 1-2 mg h-1 for maintenance (group F). In 40 patients anaesthesia was induced with etomidate and maintained wit h either isoflurane 0.4-1.2 vol% (group 1) 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 fi ve timepoints (awake; after induction before surgery; after sternotomy ; before cardiopulmonary bypass; and 20 min after separation from bypa ss). During surgical stimulation, vasodilators were needed significant ly more frequently in group F, than in groups I and P. Surgery and ste rnotomy caused an increase in SVI and APs/SV in all groups. Difference s between the groups were only found for systemic pressures, which aft er sternotomy were lowest in group I and before cardiopulmonary bypass were highest in group F. After termination of bypass all groups showe d an increase in HR and a decrease in SVI, SVR, and LVSWI compared to the awake state, while CI remained unchanged. The only differences not ed 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 comp aring groups F and I after separation from CPB (P<0.05), group F showi ng the highest incidences of ischaemic events. A blinded evaluation of auditory evoked potentials demonstrated more reduced midlatency audit ory potentials after sternotomy during isoflurane and propofol anaesth esia than during flunitrazepam. The authors conclude that fentanyl sup plemented with isoflurane or propofol was unequivocally superior to su pplementation with flunitrazepam.