Effect-site concentration of remifentanil for blunting hemodynamic responses to tracheal intubation using light wand during target controlled infusion-total intravenous anesthesia

BACKGROUND Transillumination using a light wand is an alternative type of laryngoscope used for tracheal intubation. There is little information available on the effect-site concentration of remifentanil required to control hemodynamic changes induced by tracheal intubation using the transillumination method during total IV anesthesia. We therefore conducted this study to determine the effect-site concentration of remifentanil blunting hemodynamic responses after tracheal intubation in patients receiving propofol anesthesia. METHODS We enrolled 26 healthy adult patients (ASA physical status I-II), aged 16-67 scheduled for surgery within 2 hours. All patients received a target-controlled infusion of 4 µg/ml propofol. The effect-site target-concentration of remifentanil of 5.0 ng/ml was chosen for the first patient. We used the Dixon's up-and-down sequential allocation method for determining the next remifentanil concentration. The time required for tracheal intubation was measured as the level of intubation stimulation. RESULTS The average intubation time was 13.9 ± 9.1 seconds. From the Dixon's method, the EC(50) of remifentanil blunting the hemodynamic response to tracheal intubation was 2.94 ng/ml. CONCLUSIONS This study shows that effect-site concentrations of remifentanil of 2.94 ng/ml is effective in blunting sympathetic responses to tracheal intubation in 50% of patients with normal airway anatomy when combined with a target controlled infusion of propofol (4 µg/ml).