Vital capacity breath technique for rapid anaesthetic induction: comparison of sevoflurane and isoflurane

This study compares vital capacity rapid inhalational induction of anaesthesia with sevoflurane and isoflurane. Forty-six volunteers undergoing the procedure had one of the two agents: 25 had sevoflurane and 21 isoflurane. Subjects were unpremedicated and breathed approximately 1.7 MAC equivalents of either vapour. There were no significant differences in the patients' monitored cardiovascular, respiratory, and electrocardiographic variables. The mean time for induction of anaesthesia with sevoflurane (120 s) was significantly shorter than with isoflurane (145 s), reflecting its higher blood-gas solubility. There were fewer induction complications in the sevoflurane group. Subjects in the sevoflurane group found the induction of anaesthesia more pleasant and were more willing to undergo it again compared to subjects in the isoflurane group. We conclude that sevoflurane is superior to isoflurane in vital capacity rapid inhalational induction of anaesthesia, particularly in instances where premedication should be avoided.