Sufentanil and nitrous oxide anaesthesia for cardiac surgery

We have investigated the use of sufentanil 3.75-15 micrograms kg-1 by supplementing anaesthesia with nitrous oxide and midazolam. Thirty patients with ejection fractions exceeding 30% were studied while undergoing scheduled coronary artery vein graft surgery. Even in the lowest dose group (3.75 micrograms kg-1), haemodynamic responses to surgical and anaesthetic stimuli were sufficiently obtunded that no patient exhibited an increase in heart rate or systolic arterial pressure greater than 20% of the control value. Marked hypotension occurred in some patients during unstimulated periods. Such periods of hypotension were associated with equally marked decreases in systemic vascular resistance. The mean recovery times to spontaneous ventilation after the end of surgery ranged from 6 to 12 h. This is longer than would be expected from other studies using a similar dose of sufentanil. This may be related to the use of benzodiazepines during anaesthesia and to their use after surgery in those patients who became restless.