Minimum Alveolar Concentration of Sevoflurane for Laryngeal Mask Airway Removal in Anesthetized Children

BACKGROUND: In children, it is preferable to remove the laryngeal mask airway (LMA) when the patient is still anesthetized. We sought to determine the optimal minimum alveolar concentration of sevoflurane that would allow removal of the LMA in children without airway complications. METHODS: We studied 25 unpremedicated children between 7 mo and 10 yr of age, ASA Status I, undergoing urologic or plastic surgery. General anesthesia was induced with sevoflurane and oxygen given via mask. The LMA was inserted and anesthesia was maintained with sevoflurane in oxygen. The LMA was removed at the end of surgery when the end-tidal sevoflurane concentration had reduced to a predetermined level, determined by the up-and-down method, with 0.2% as a step size. A removal accomplished without coughing, teeth clenching, gross purposeful movement, breath holding or laryngospasm, during or within 1 min after removal, was considered to be successful. RESULTS: The minimum alveolar concentration of sevoflurane at which 50% of LMA removals were successful was 1.84% (95% confidence limits, 1.45%-1.96%), and the 95% effective dose for successful removal was 2.17% (95% confidence limits, 2.02%-3.48%). CONCLUSIONS: LMA removal may be accomplished without coughing, moving, or any other airway complication at 1.84% end-tidal sevoflurane concentration in 50% of anesthetized children.