The goal of this prospective observational study is to investigate minimum cuff pressure to prevent gas leakage during mechanical ventilation in laryngomicrosurgery.

It has been well known that cuff pressure should be adequately limited to prevent ischemic injury of tracheal mucosa, which is about 20-30 mmHg. However, higher cuff pressure that 20-30 mmHg might be required to prevent gas leakage during general anesthesia for laryngomicrosurgery.

The hypothesis of this study is that the required cuff pressure to prevent gas leakage from mechanical ventilation during general anesthesia for laryngomicrosurgery, and there will be no damage from the required cuff pressure because of short time of surgery.

Inclusion Criteria:

• patients who is scheduled for laryngomicrosurgery due to simple vocal cord cyst or nodule

Exclusion Criteria:

• Who doesn't agree to enroll
• do not use a reinforced tracheal tube of internal diameter of 5.5 mm for male patient
• do not use a reinforced tracheal tube of internal diameter of 5.0 mm for female patient

Adult patient who is scheduled for laryngomicrosurgery due to simple vocal cord cyst or nodule