The optimum dose of intranasal remifentanil for laryngeal mask airway insertion during sevoflurane induction in children: a randomized controlled trial.

Objective: The purpose of this study was to determine the optimum dose of intranasal remifentanil required to produce satisfactory laryngeal mask airway (LMA) insertion conditions during inhalation induction of anesthesia using 5% sevoflurane in children.

Methods: Seven-five American Society of Anesthesiologists physical status (ASA) I subjects, aged 2-5 years, scheduled for minor elective surgery were randomly allocated to receive one of five doses of intranasal remifentanil (nil, 0.25, 0.5, 0.75 and 1.0 μg·kg(-1)) during 5% sevoflurane induction. Laryngeal mask insertion was attempted 120 s after intranasal remifentanil administration and the response of subjects was classified as either 'Failure' or 'Success'. "Success" was defined as a relaxed mandible without coughing, gapping, swallowing, laryngospasm or gross purposeful movement. Secondary outcomes included the duration of apnea, hemodynamic changes and complications.

Results: For each groups (nil, 0.25, 0.5, 0.75 or 1.0 μg·kg(-1) remifentanil), the incidence of satisfactory LMA insertion conditions was 0, 33.3%, 60%, 86.7% and 100% respectively. None of subjects suffered from any serious complications such as laryngospasm,or hypotension and bradycardia.

Conclusions: The ED50 and ED95 of intranasal remifentanil for successful LMA insertion in children were estimated to be 0.36 and 0.998 μg·kg(-1) during 5% sevoflurane inhalation induction for 3 min.