Evaluation of LMA Insertion with Sevoflurane 8% and N2O after Midazolam Administration

Abstract

Background: Sevoflurane is characterized by the lack of an unpleasant odorairway irritation and its low blood/gas partition coefficient (0.68), which provides rapid and smooth induction. Inhaled induction with sevoflurane is commonly used in pediare patients, but not in adult patients. This study was designed d investigate the time to completion of LMA insertion and end-irlal sevoflurane concentration during induction with sevoflurane 8%and N0 50%, after midazolam administration, in adults. Methods: Twenty eight patients, aged 20-60 years, were administered intravenous midazolam 30g/kg and after one minute, sevoflurane 8% and NO 50% were inhaled with tidal-volume breathing. One minute afu loss of consciousness, jaw thrust and mouth opening were checked and an LMA was inserted. The end-rial concentration of sevoflurane, and the times to loss of consciousness and completion of insertion were recorded. The man arterial pressure and heart rate were also recorded. Results: From initiation of sevoflurane and NO inhalation, it took 48 14 seconds until loss of consciousness, and 143 19 seconds until the completion of LMA insertion. The end-tidh sevoflurane concentration was 4.1 0.6% at loss of consciousness, 5.0 0.7% at one min after loss of consciousness, and 4.1 0.5% after LMA insertion. In all patients LMA insertion was successful and satisfactory. After LMA insertion compared to baseline, the mean arterial pressure was reduced and the heart rate increased. Conclusions: After small-dose of midazolam, inhaled induction with sevoflmne 8% and N0 50% allowed successful and satisfactory LMA insertion in adults.