Hemodynamic Changes according to the Remifentanil Effect Site Concentration for Patients under Total Intravenous Anesthesia during Laryngeal Microscopic Surgery

Background: Laryngeal microscopic surgery directly stimulates an airway via endotracheal intubation and insertion of a suspension laryngoscope, and this can result in acute elevation of the blood pressure and heart rate.Therefore, an anesthesia that can maintain a sufficient depth of anesthesia and simultaneously makes awakening and recovery possible in a short period is required.We wanted to present the effect site concentration of remifentanil for achieving the best anesthesia by observing the hemodynamic changes according to the effect site concentration of remifentanil.Methods: 36 patients, who corresponded with the ASA physical status classification 1 and 2 and who were from 20 to 70 years old, were the subjects of this study.They were randomly classified into three groups according to the effect site concentration of remifentanil.Propofol 4μg/ml was infused continuously, and remifentanil was continuously infused for each group to achieve an effect site concentration of 4 ng/ml, 6 ng/ml, and 8 ng/ml, respectively.Rocuronium 0.5 mg/kg was used.The arterial blood pressures and heart rates were measured before induction of anesthesia, before endotracheal intubation, after endotracheal intubation and after insertion of a suspension laryngoscope.Results: In comparison with the other groups, the 4 ng/ml remifentanil group was able to prevent acute elevation of blood pressure and heart rate.Conclusions: For total intravenous anesthesia using propofol and remifentanil, 4 ng/ml of remifentanil is proposed to be the effect site concentration that is able to stably maintain blood pressure and heart rate during laryngeal microscopic surgery.(Korean J Anesthesiol 2007; 52: 9∼15)