• C Y Li, C T Wu, C S Wong, C A Sun, C C Yeh, and S T Ho.
• Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
• Acta Anaesthesiol. Sin. 1998 Mar 1;36(1):37-41.

BackgroundThe present study was to determine the effective concentration of halothane for insertion of laryngeal mask airway (LMA) and for intubation of endotracheal tube (ETT) in pediatric patients.MethodsForty-eight ASA class 1 patients, aged from 10 months to 6 years, scheduled for minor elective surgery were randomly assigned to two groups i.e., LMA and ETT. The concentration of halothane effective in fifty percent of patients (EC50) was determined by the up-and-down method (with 0.5% as a step size). After the predetermined concentration of halothane delivered from a calibrated vaporizer was established and maintained for 20 min, LMA insertion or ETT intubation was attempted without the patient being curarized. The response of patient to LMA or ETT was reported either as "movement" or "non-movement". The effective concentration and associated 95% confidence limits were determined in each group.ResultsAn effective concentration of halothane for LMA insertion was 1.5 +/- 0.4% (95% confidence limits 1.4-1.7%), whereas that for ETT intubation was 2.3 +/- 0.5% (95% confidence limits 2.1-2.5%). The difference between these two values was statistically significant (p < 0.01). Airway reflexes after LMA insertion were minimal.ConclusionsThe insertion of LMA could be performed at a significantly less halothane concentration in comparison with ETT intubation in children.

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