Severe bradycardia and asystole with low dose sufentanil during induction with sevoflurane: a report of three cases

In a randomized double blind clinical study using low doses of fentanyl or sufentanil during sevoflurane induction, we observed three cases of severe bradycardia, forcing us to discontinue the study. We wish to describe these three cases. Anesthesia was induced in the three patients, using a single breath technique consisting of a mixture of sevoflurane 8% with a nitrous oxide flow of 3 L x min(-1) and an oxygen flow of 3 L x min(-1). After the patients had lost consciousness, low dose sufentanil was administered (0.025 microg x kg(-1) for the first patient and 0.1 microg x kg(-1) for the other two patients). Heart rate fell to 38, 40 and 42 beats x min(-1) respectively two minutes after the sufentanil injection in these three patients, and progressed to asystole in the third. All the patients responded to atropine 0.6 mg i.v. The addition of sufentanil, even at very low doses, during anesthesia induction with sevoflurane using a single breath technique, may be dangerous because of possible bradycardia and even asystole.