The Effect-Site Concentration of Remifentanil Blunting Cardiovascular Responses to Tracheal Intubation and Skin Incision During Bispectral Index-Guided Propofol Anesthesia

In Brief We sought to determine the effect-site concentration of remifentanil blunting sympathetic responses to tracheal intubation and skin incision during bispectral index (BIS)-guided propofol anesthesia. Forty-one ASA physical status I–II patients, aged 20–65 yr and undergoing major abdominal surgery, were randomly assigned to one of two groups: tracheal intubation (group TI, n = 20) or skin incision (group SI, n = 21). All patients received a target-controlled infusion of propofol of 4 μg/mL, which was then adjusted to maintain a BIS value ranging between 40 and 50. The effect-site concentration of remifentanil blocking the sympathetic responses to tracheal intubation and skin incision in 50% of cases (Ce50) was determined using an up-and-down sequential allocation method. The mean (95% confidence interval [CI]) Ce50 of remifentanil was 5.0 ng/mL for TI (95% CI, 4.7–5.4 ng/mL) and 2.1 ng/mL for SI (95% CI, 1.4–2.8 ng/mL). This study shows that effect-site concentrations of remifentanil of 5 ng/mL and 2 ng/mL are effective in blunting sympathetic responses to tracheal intubation and skin incision in 50% of patients when combined with a BIS-guided target controlled infusion of propofol. IMPLICATIONS: We determined the effect-site concentration of remifentanil blocking the sympathetic responses to tracheal intubation and skin incision in 50% of patients. We found that during a bispectral index-guided target controlled infusion of propofol, effect-site concentrations of remifentanil of 5 ng/mL and 2 ng/mL are required to blunt sympathetic responses to tracheal intubation and skin incision in 50% of patients, respectively.