Background and objective: A multicentre study was conducted to compare three methods of inhalation induction with sevoflurane in adult premedicated patients.
Methods: One-hundred-and-twenty-five adult patients of ASA I–II were scheduled for short elective surgical procedures (<90 min) under general anaesthesia with spontaneous ventilation of the lungs via a laryngeal mask airway. Patients were randomly assigned to one of three groups: conventional stepwise inhalation induction group (Group C) or vital capacity rapid inhalation induction groups at 4.5% (Group VC4.5) or at 8% sevoflurane (Group VC8). Before anaesthetic induction, fentanyl 1 μg kg−1 was given and the face mask applied with the anaesthetic breathing system primed with sevoflurane 4.5% or 8% in the respective vital capacity groups. Loss of eyelash reflex, time to cessation of finger tapping, laryngeal mask insertion, side-effects and adequacy of induction were recorded.
Results: The time to loss of eyelash reflex was significantly shorter in both vital capacity groups vs. the control group: VC8: 68 ± 7 s; and VC4.5: 94 ± 6.5 s vs. C: 118 ± 6.4 s (P < 0.0001). Significant differences were found in all pairwise comparisons for time to cessation of tapping: Group VC8 (62 ± 7 s), Group VC4.5 (85 ± 6 s) and Group C (116 ± 6 s; P < 0.0001). The time to laryngeal mask insertion was significantly shorter in the Group VC8 (176 ± 13 s) compared with the other two groups, Group VC4.5 (219 ± 13 s) and Group C (216 ± 9 s). There were no significant differences in the incidence of side-effects between the three groups.
Conclusions: Inhalation induction of anaesthesia with sevoflurane with the three techniques tested is safe, reliable and well accepted by the patients. The vital capacity rapid inhalation group primed with sevoflurane 8% was the fastest method with no relevant side-effects.