END-TIDAL SEVOFLURANE CONCENTRATIONS FOR LARYNGEAL MASK AIRWAY INSERTION AND FOR TRACHEAL INTUBATION IN CHILDREN

Background: Sevoflurane, a new inhalational anesthetic agent character ized by a low blood-gas partition coefficient and nonpungent odor, app ears suitable as an induction agent for children. The laryngeal mask a irway is a new device for maintaining airway patency during anesthesia . This study was conducted to determine the sevoflurane concentrations required for insertion of a laryngeal mask (MAC(LMI)) and for trachea l intubation (MAC(TI)) in children. Methods: Forty-two patients, aged 1-9 yr, scheduled for surgery during general anesthesia were randomly assigned into two groups: MAC(LMI) (n = 21) and MAC(TI) (n = 21). Afte r the predetermined end-tidal concentration had been established and m aintained for 20 min, laryngeal mask insertion or tracheal intubation was attempted without neuromuscular relaxants or other adjuvants. Each concentration at which laryngeal mask insertion or tracheal intubatio n was attempted was predetermined by the up-and-down method (with 0.5% as a step size). Results: Sevoflurane MAC(LMI) was 2.00 +/- 0.28%. Se voflurane MAC(TI) was 2.83 +/- 0.34%, significantly greater than MAC(L MI). Conclusions: Laryngeal mask insertion can be performed at a lesse r sevoflurane concentration than that required for tracheal intubation .