The effective bolus dose of remifentanil to facilitate laryngeal mask airway insertion during inhalation induction of sevoflurane in children.

Objective: The additional administration of remifentanil during inhalation induction with sevoflurane could provide better conditions for laryngeal mask airway (LMA) insertion than sevoflurane alone. This study was designed to evaluate the 50 % effective bolus dose (ED50) and 95 % effective bolus dose (ED95) of remifentanil required for LMA insertion in children during inhalation induction with sevoflurane.

Methods: Pediatric patients aged 3-12 years requiring general anesthesia were recruited. A predetermined dose of remifentanil was injected over 30 s after the induction of general anesthesia with sevoflurane. LMA insertion was attempted 60 s after remifentanil injection. The dose of remifentanil was determined using the Dixon's up-and-down method, starting from 0.5 μg/kg (step size of 0.05 μg/kg).

Results: The study was conducted until seven cross-over points and 29 children were collected. The ED50 of remifentanil for successful LMA insertion during sevoflurane inhalation induction in children was 0.168 ± 0.035 μg/kg using Dixon's method. In addition, the ED50 and ED95 of remifentanil from the probit analysis were 0.176 μg/kg (95 % confidence limits, 0.102-0.216 μg/kg) and 0.268 μg/kg (95 % confidence limits, 0.223-0.659 μg/kg), respectively.

Conclusions: The ED50 and ED95 of remifentanil for successful LMA insertion in children were estimated to be 0.176 (0.168) and 0.268 μg/kg during inhalation induction with 2.1 % sevoflurane.