The laryngeal mask airway (LMA) is a simple and safe method for airway control in children. We therefore determined, with meaningful confidence intervals, the time required for successful insertion of LMA in 95% of children with 8 vol% inspired sevoflurane and no muscle relaxant.

Forty-six patients, ASA physical status I or II, aged 12-108 months old who were scheduled to undergo elective surgery were included. Patients received 5 mg/kg of thiopental and 0.02 mg/kg of atropine intravenously. After loss of the eye lid reflex, we applied an anesthesia circuit prefilled with 8 vol% dialed sevoflurane in 100% O₂. A classic LMA (# 2) insertion was attempted after a predetermined induction time. A probit analysis was used to determine the induction time required to achieve 50% and 95% success rates during LMA insertion.

A probit model of induction time was predictive of successful intubation (P = 0.155). The induction times needed to achieve 50% and 95% successful LMA insertion were 125 s (95% confidence interval, 52-146 s) and 208 s (178-382 s), respectively.

Ninety five percent success can be obtained with approximately 208 s for ages one to 9 years with classic LMA (# 2). The induction time can vary by LMA size and induction methods. Therefore further studies using different sizes of LMA and induction methods are needed.