Inclusion Criteria:  18-65 years; Elective endoscopic transsphenoidal resection of pituitary adenomas; ASA status I-III; Informed consent signed by patients.  Exclusion Criteria:  Complicated with cerebrovascular disease; Complicated with lung disease, the SpO2 is less than 95% without oxygen inhalation; It is expected to retain endotracheal intubation after operation; The disturbance of consciousness can not cooperate with the evaluation before operation; Complicated with hypothyroidism; The previous history of neck surgery, burns, radiotherapy; Invasive pituitary adenomas with Knosp grade 4.