The optimal clinical dose of alfentanil for tracheal intubation during inhalation induction with sevoflurane after sedation with ketamine in children

Background: The purpose of this study was to determine the clinical effective dose of alfentanil required for successful tracheal intubation during inhalation induction using 5% sevoflurane without neuromuscular blockade in children sedated with ketamine. Methods: Twenty-one children, aged 3 − 10 years, undergoing surgeries under general anesthesia were enrolled into the study. All patients were premedicated with 0.004 mg/kg glycopyrrolate intramuscularly 30 min before anesthesia. To facilitate separation of the child from the parents, intravenous 1 mg/kg ketamine was given prior to transfer into the operating room. After inhalation induction with 5% sevoflurane and 100% oxygen, pre-determined dose of alfentanil was injected over 20 sec. The dose of alfentanil was determined by modified Dixon's up-and-down method (2 μ g/kg as a step size starting from 12 μ g/kg). The study ended when six independent pairs of patients, who manifested cross over from ‘failure’ to ‘success’ for tracheal intubation, were recruited. Results: In 50% of children, the effective bolus dose (ED 50 ) (95% confidence intervals) of alfentanil for successful tracheal intubation was 7.2 μ g/kg (6.3 − 8.1 μ g/kg) during sevoflurane inhalation induction. From isotonic regression, 95% effective dose (ED 95 ) (95% confidence intervals) of alfentanil was 9.9 μ g/kg (2.2 − 16.0 μ g/kg). Conclusions: During inhalation induction using 5% sevoflurane without neuromuscular blockade after ketamine sedation, the ED 50 and ED 95 of alfentanil for successful tracheal intubation were 7.2 μ g/kg and 9.9 μ g/kg in children, respectively. (Anesth Pain Med 2010; 5: 82 ∼ 86)