When using nitrous oxide for general anesthesia, nitrous oxide diffusion induces intracuff hyperinflation of the endotracheal tube. Furthermore the difference among various types of cuffed endotracheal tubes in cuff pressure behavior during nitrous oxide exposure.

TaperGuard(TM) tube has been newly introduced and has tapered-shape cuff. In vitro study, the intracuff pressure of TaperGuard(TM) tube was lower than that of conventional tube with cylindrical-shaped cuff of the conventional tube(Hi-Lo(TM) tube). Therefore, this clinical study is needed to evaluate the intracuff pressure during general anesthesia with nitrous oxide exposure.

During 60 minutes after routine anesthetic induction and intubation of the endotracheal tubes, intracuff pressures will be measured every 10 minutes with a manometer (VBM, Sulz, Germany).

60% nitrous oxide will be added at time 0. For 60 minutes from the beginning of general anesthesia, intracuff pressures will be measured every 10 minutes.

After 60 minutes, Intracuff pressures will be maintained around 20 cm H2O during the remaining period of the surgery.

The questionnaire for a sore throat, hoarseness, and dysphagia will be questioned at about 1, 6, and 24 hours after the surgery and the general anesthesia.

Inclusion Criteria:

• Patients who will undergo general anesthesia in a supine position with a neutral position of the head (hand and forearm sugery)
• 18~70 years old
• American society of anesthesiologists physical status 1-2
• Body mass index < 30 kg/m2

Exclusion Criteria:

• Contraindication for nitrous oxide
• Difficult intubation
• Cormack-Lehane grade > 3
• Airway-related or pulmonary diseases
• Short or long operation time (< 1 hour or > 3 hours)