Adequate Combination of Target Effect-site Concentration of Propofol and Remifentanil for Tracheal Intubation

Background: We wanted to determine an adequate combination of target effect-site concentrations of remifentanil and propofol during anesthetic induction with target controlled infusion (TCI).We also determined whether increasing remifentanil concentrations might reduce propofol consumption at loss of consciousness (LOC).Methods: Sixty ASA 1 or 2 patients were randomly allocated according to the target effect-site concentration of remifentanil and propofol (R7P3: remifentanil 7 ng/ml + propofol 3μg/ml, R5P4: remifentanil 5 ng/ml + propofol 4μg/ml, R3P5: remifentanil 3 ng/ml + propofol 5μg/ml).After the target effect-site concentration of remifentanil had been reached, the TCI of propofol was started.The effect-site concentration of propofol at LOC was recorded.When the target effect-site concentration of propofol was reached, 0.6 mg/kg of rocuronium was administered.Tracheal intubation was performed after 2 minutes.The noninvasive blood pressure, heart rate (HR), bispectral index (BIS), and infused dose of remifentanil and propofol were recorded.Results: R3P5 groupd showed a significant increase in mean blood pressure after intubation (104 ± 31.9 mmHg, P ＜ 0.05) compared to R7P3 and R5P4.BIS at the time when propofol reached its target effect-site concentration was significantly higher in the R7P3 group (71.6 ± 9.9, P ＜ 0.05 compared to R5P4 and R3P5).There was a significant relationship between the effect-site concentration of remifentanil and propofol at LOC (Y = 2.032 -0.351X, R 2 = 0.551, P ＜ 0.0001). Conclusions: The R5P4 target effect-site concentrations are adequate dosing combinations during TCI induction based on hemodynamic responses and BIS values. (Korean J Anesthesiol 2008; 54: 37∼42)