It has been reported that target-controlled infusion of remifentanil can reduce cough against endotracheal tube during emergence from general anesthesia. We hypothesized that effective concentration of remifentanil for preventing cough during anesthetic emergence varies depending on the type of main anesthetic agents which is administered with remifentanil during general anesthesia. The purpose of this study is to evaluate the effective concentrations of remifentanil to prevent coughing during emergence from general anesthesia according to main anesthetic agent (sevoflurane, desflurane, and propofol).

Inclusion Criteria:

• aged 20-60
• ASA classification I~II
• female patients
• patients who undergoing thyroidectomy

Exclusion Criteria:

• Patients with acute or chronic respiratory disease
• patient who has smoking history
• patient who has hypertension
• patient who has esophageal reflux
• patient who having an expectorant or cough remedy