Cardiovascular response of a continuous variable rate alfentanil infusion for abdominal aortic surgery

A prospective study was undertaken to determine the cardiovascular response of a continuous alfentanil infusion during abdominal aortic surgery (AAS). Each subject (n = 20) received a beta-blocking drug preoperatively, and was premedicated with oral lorazepam. Anaesthesia was induced with alfentanil 50 micrograms.kg-1 and thiopentone 3 mg.kg-1, and was maintained with a variable rate infusion of alfentanil and 66 per cent nitrous oxide in oxygen. During the infusion, boluses of alfentanil, 7.5 micrograms.kg-1, were administered to maintain heart rate and blood pressure within 20 per cent of awake baseline values. Haemodynamic stability during surgery was achieved with infusion rates varying between 0.5 and 2.5 micrograms.kg-1, which resulted in mean alfentanil serum concentrations ranging from 186 +/- 53 to 315 +/- 98 ng.ml-1. The mean cumulative alfentanil dose was 15.4 +/- 6.2 mg.patient-1 for surgery which lasted an average of 141 +/- 41 min. Throughout surgery, no patient required inhalational anaesthetic agents or vasoactive drugs. Fifteen of the 20 patients had perioperative Holter monitoring. No myocardial ischaemia was detected during the intraoperative period. However, there was a 33 per cent incidence of myocardial ischaemia on the first postoperative day. There were no myocardial infarcts and no deaths. We conclude that in beta-blocked patients undergoing aortic reconstructive surgery, a variable rate alfentanil infusion administered with 66 per cent nitrous oxide provides anaesthesia characterized by good haemodynamic control without the need for supplemental agents or vasoactive drugs.