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. CONCLUSION 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.