Dexmedetomidine reduces end-tidal sevoflurane median effective concentration value for Ambu AuraOnce laryngeal mask insertion in children

Objective Investigation the effect of dexmedetomidine(Dex) on the end-tidal concentration of sevoflurane at which 50%[median effective concentration (EC50)] of the attempts to insert the Ambu AuraOnce(Ambu) laryngeal mask would be successful. Methods 50 patients of ASA physical statusⅠ, aged 4-10 years, undergoing plastic surgery with general anesthesia were randomly divided to the group Dex(group D) and the controlled group(group C). Anesthesia was induced with sevoflurane 8% in a mixture of nitrous oxide(N2O) 50% and oxygen 50%. After intravenous cannula was placed, N2O was discontinued and inhalation concentration of sevoflurane was modified to reach predetermined end-tidal concentration of sevoflurane. In group D, Dex 1 μg/kg was infused for 10 min. In group C, 0.9% sodium chloride solution was infused. 10 min later, Ambu laryngeal mask was inserted in both groups. For the first patient in group D and in group C, the end-tidal concentration of sevoflurane was designed at 1.8%. Using modified Dixon′s up-down method, the target end-tidal concentration of sevoflurane for the next patient was determined with increment size of 0.2%. Results The values of sevoflurane required for successful insertions of Ambu laryngeal mask in group D and in group C were 1.44%(1.17%, 1.60%) and 1.77%(1.52%, 2.01%) respectively. Conclusions Dex 1 μg/kg reduces the value of EC50 of sevoflurane for insertion of Ambu AuraOnce laryngeal mask airway in children. Key words: Ambu laryngeal mask; Children; Sevoflurane; Dexmedetomidine