Sevoflurane: a comparison between vital capacity and tidal breathing techniques for the induction of anaesthesia and laryngeal mask airway placement.

Sixty unpremedicated adult day-case patients were randomly assigned to either vital capacity or tidal breathing inhalational induction techniques. End points assessed included loss of eyelash reflex, time to drop a weighted syringe, time to jaw relaxation and time to the end of laryngeal mask airway insertion. Complications occurring during the induction of anaesthesia were recorded. The data show that there is no statistical or clinical difference between the two induction techniques. Patient acceptance of both techniques was similarly high. When the time taken to prime the anaesthetic breathing system is taken into consideration, the vital capacity technique is more expensive for induction of anaesthesia. These results therefore question the need for the vital capacity induction technique with sevoflurane 8%.