• Jun Li, Li-Sha Ye, Ping Gao, Xu-Tong Zhang, Jian Xu, Er-Zhan Su, and Qing-Quan Lian.
• Department of Anesthesiology, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou 325027, China.
• Zhonghua Yi Xue Za Zhi. 2009 Apr 21;89(15):1012-5.

ObjectiveTo investigate the optimal concentrations of sevoflurane and propofol for laryngeal mask airway (LMA) insertion in Chinese boys of different ages.Methods200 boys with ASA status I weighting 7 - 53 kg undergoing inguinal operation were divided into 4 groups (n = 50) according to age: Group A (aged 7 m-1 yr), Group B (1 - 3 yrs), Group C (4 - 6 yrs), and Group D (7 - 11 yrs). No premedication was given. General anesthesia was induced with propofol intravenous infusion at target effect-site concentration by target controlled infusion (TCI) using children Marsh model (Subgroups As, Bs, Cs, and Ds, 25 cases for each subgroup) or sevoflurane inhalation combined with 50% N2O (Subgroups Ap, Bp, Cp, and Dp, 25 cases for each subgroup) the optimal concentration was predetermined according to the modification of Dixon's up-and-down method. The size of LMA was determined according to the boy's weight and reverse technique was used to place LMA. The insertion conditions were noted as satisfactory when the jaw was relaxed, lash reflex disappeared, no coughing, gagging, swallowing, and laryngospasm was seen, and limb movement was minimal.ResultsThe levels of ED(50) of P(ET)-sevoflurane for LMA insertion in Subgroups As, Bs, Cs, and Ds were 2.96% (95% CI 2.58% - 3.44%), 2.62% (95% CI 2.31% - 2.90%), 2.16% (95% CI 1.97% - 2.33%), and 1.89% (95% CI 1.66% - 2.24%) respectively. The levels of ED(50) of target effect site concentration with propofol for LMA insertion in Subgroups Ap, Bp, Cp, and Dp were 4.74 microg/ml (95% CI 4.49 - 5.13 microg/ml), 4.33 microg/ml (95% CI 4.07 - 4.62 microg/ml), 4.10 microg/ml (95% CI 3.90 - 4.31 microg/ml), and 3.65 microg/ml (95% CI 3.24 - 3.98 microg/ml) respectively.ConclusionThe ED(50) level of P(ET)-sevoflurane or target effect site concentration with propofol for LMA insertion in Chinese boys decreases gradually along with the increase of age.

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