Patient inclusion and exclusion criteria
obesity, bronchiectasis, upper respiratory tract infection, fracture, allergy, pulmonary diseases, cardiovascular or cerebrovascular diseases
OBESITY, UPPER RESPIRATORY TRACT INFECTIONS, NEUROMUSCULAR DISORDERS, BRONCHIECTASIS, AIRWAY OBSTRUCTION, ALLERGY, PULMONARY DISEASES, GASTROESOPHAGEAL REFLUX DISEASE
All patients were aged 18–60 years, had an ASA physical status 1–2, and were scheduled for elective microlaryngeal vocal cord polypectomy with anticipated surgery time less than 20 min. Exclusion criteria are: severe upper airway obstruction, known difficult mask ventilation or difficult intubation, skull base fracture or other defects, severe cardiovascular or cerebrovascular diseases, upper respiratory tract infection within two weeks, bronchiectasis or other pulmonary diseases, neuromuscular disorders, obesity with body mass index (BMI) above 35, severe or poorly controlled gastroesophageal reflux disease, pregnancy, allergy to any agent used in the study.