BIS monitored day‐case cardioversion: a comparison of sevoflurane with propofol

Abstract

This study compared haemodynamic parameters and Bispectral Index System (BIS) values during day-case DC cardioversion of atrial fibrillation with either propofol or sevoflurane anaesthesia. After Research Ethics Committee approval and written informed consent, 60 patients scheduled for elective day-case cardioversion were randomly assigned to two groups. Both groups had a BIS electrode applied before induction of anaesthesia. Patients in one group were given intravenous propofol 2% at 67 mg.min−1 via infusion pump and the other inhaled sevoflurane 8% in 10 l.min−1 oxygen. The patients were asked to tap continuously with their index finger on their chest during induction. The induction-time endpoint was taken when the patient stopped tapping and then either the infusion of propofol was stopped or the inspired sevoflurane was reduced to 6%. One minute later, a DC shock was delivered. Eye opening to verbal command was then taken as the point of awakening. Before hospital discharge, patients completed a questionnaire that included scoring of pain on induction, postoperative nausea and vomiting and overall satisfaction. There was no difference between the mean (SD) age and weight of the propofol and sevoflurane group (respectively 70.0 (9.1) vs 70.1 (10.1) years and 80.4 (16.8) vs 86.4 (14.6) kg). The mean (SD) time taken for induction was significantly lower in the sevoflurane group (93.1 (45.0) vs 124.0 (29.6) s; p < 0.05). Mean arterial pressure was significantly lower in the propofol group after cardioversion (86.7 (15.5) vs 106.3 (21.1) mmHg; p < 0.01) and at eye opening to verbal command (83.1 (13.3) vs 104.2 (15.9) mmHg; p < 0.01). The propofol group also had correspondingly lower median (IQR) BIS values (47 (40–57) vs 65 (47–73) and 73 (69–82) vs 83 (79–87); p < 0.05). None of the patients reported awareness and satisfaction scores were similar in both groups. A previous study suggested that sevoflurane induction provided better cardiovascular stability than a target-controlled infusion of propofol for anaesthesia for cardioversions [1]. In our study, despite using less propofol (1.7 mg.kg−1 vs 2.9 mg.kg−1), patients also had significantly lower blood pressure and BIS values compared with sevoflurane. The time taken for induction in elderly patients may be longer with propofol infusion [2]. In our study, induction with propofol also appeared to take longer patients with atrial fibrillation compared with sevoflurane. A slow circulation time should speed induction with inhaled sevoflurane due to the more rapid rise in alveolar concentration compared with a normal circulation. Sevoflurane-induction anaesthesia for patients with atrial fibrillation undergoing DC cardioversion offers appropriate anaesthetic depth with less haemodynamic depression and more rapid recovery when compared with propofol. Future studies using BIS monitoring may help to refine anaesthetic administration to these patients.