Transnasal humidified rapid-insufflation ventilatory exchange(THRIVE), or also termed high flow nasal oxygenation (HFNO) is a method of supplying heated, humidified high concentrations of oxygen via nasal cavity. This study hypothesizes that in general anesthesia for laryngeal microsurgery, high-flow nasal oxygen without endotracheal intubation reduces cough during the emergence period compared to endotracheal intubation.

Laryngeal microsurgery is mainly performed by a conventional method of general anesthesia with endotracheal intubation (ET), which may have difficulty accessing the lesion behind the larynx, and may be limited in securing space for surgical manipulation. To compensate for these shortcomings, a method of maintaining general anesthesia without using an endotracheal tube has been introduced, and high-flow nasal oxygen(HFNO) and transnasal humidified rapid insufflation ventilatory exchange(THRIVE) enable tubeless anesthesia due to apnea oxygenation and apnea ventilation effect during laryngeal microsurgery. Coughing and straining can be accompanied by emergence after general anesthesia. Forceful vocal cord adduction especially after upper respiratory surgery such as laryngeal microsurgery can cause damage and bleeding of surgical tissue, delaying wound healing. If a small amount of remifentanil is continuously injected during emergence after total intravenous anesthesia(TIVA), airway complications such as coughing can be reduced during emergence without delay in recovery time, and hemodynamic stability can be promoted. In this study, the effect of endotracheal intubation and high-flow nasal oxygen on the emergence cough and postoperative sore throat is compared when total intravenous anesthesia(TIVA) using propofol and remifentanil is performed in patients undergoing laryngeal microsurgery. This study hypothesizes that in general anesthesia for laryngeal microsurgery, high-flow nasal oxygen without endotracheal intubation reduces cough during the emergence period compared to endotracheal intubation.

Inclusion Criteria:

• Patients with American Society of Anesthesiologists classification 1 or 2 who receive general anesthesia for laryngeal microsurgery

Exclusion Criteria:

• Patients with major cardiovascular, pulmonary, and cerebrovascular disease
• Laser laryngeal surgery
• Morbid obesity (BMI>35 kg/m2)