Sevoflurane anaesthesia with the Komesaroff vaporizer inside the circle system

This study assessed the safety of sevoflurane anaesthesia using two Komesaroff vaporizers inside the circle with both spontaneous and controlled ventilation. Sevoflurane concentrations were continuously monitored using a mass spectrometer and the anaesthetic depth was easily controlled. Involuntary movements occurred in eight patients and breath-holding occurred in five patients after inhalational induction. With continuous monitoring of sevoflurane concentrations, induction and maintenance of anaesthesia using a vaporizer inside the circle is safe during both controlled and spontaneous ventilation. However the high incidence of involuntary movements may limit the feasibility of induction in spontaneously breathing patients.