Rapid inhalation induction with high concentration of sevoflurane using a new vaporizer

Sevoflurane allows a moderately rapid induction with only slight problems of induction. However, it has not been possible to conduct tests with more than 2.6 minimum alveolar concentration (MAC) of sevoflurane (4.5%) because of the limitations in the performance of the currently available vaporizer. We tested the performance of a new vaporizer and tried it with single breath induction. The new vaporizer could deliver a 4.3 MAC (7.5%) sevoflurane through oxygen of 8 liter/min. Twenty-one unpremedicated volunteers breathed 7.5% sevoflurane in oxygen. The mean time for induction of anesthesia was 48 +/- 16 seconds, reflecting its high concentration and low blood/gas solubility. Although coughing was observed in two subjects, laryngospasm, breath holding, and secretions did not occur during induction by this method. All subjects except one would be willing to undergo similar induction again. This study demonstrate that the new vaporizer can be used to administer 7.5% concentration of sevoflurane and to adequately perform smooth and rapid inhalation induction of anesthesia in young volunteers without premedication.