Estimating EC95 of Remifentanil for Cough Prevention During Emergence From Total Intravenous Anesthesia With Propofol and Remifentanil in Patients Undergoing Transsphenoidal Hypophysectomy

A given effect site concentration of remifentanil would be administered to subjects using TCI system. According to biased coin design, the given concentration of remifentanil is determined according to success or failure of just previously enrolled patient. If the former patient did not cough during anesthetic emergence at a given concentration (success), the next patient will be randomly allocated into the same concentration of remifentanil with 18/19 of probability or the lower concentration of remifentanil by 0.4 ng/ml with 1/19 of probability. If the former patient coughed during anesthetic emergence (failure), the next will be automatically allocated into the higher concentration of remifentanil by 0.4 ng/ml.