As reported, about 0.43% patients can not be intubated unevenly because of difficult airway and 30% of the total death of anesthesia due to failed intubation. The difficult airway will disturb the clinical treatment and even threaten the patients' life. But the present methods for tracheal intubation during awake intubation can not provided ideal intubation condition. In this study, the investigators will perform topical anesthesia with the nebulized 2% lidocaine at 10L/min oxygen flow rate, and the observer's assessment of alert and sedation (OAA/S) scale was controlled to 3-4 points by intravenous midazolam,propofol, and remifentanil. Tracheal intubation was performed after topical anesthesia. The arterial pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO2) were recorded and blood samples were taken to measure stress factor during intubation period.Intubation condition score was assessed and the complications like local anesthetic toxicity, mucosa injury, respiration depress were also recorded. Patients were asked whether they could recall the events during intubation 24 hr after operation. The investigators aim is to evaluate the effect of topical anesthesia with lidocaine nebulized by 10L/min oxygen flow rate during awake tracheal intubation.

90 adult patients for elective surgery under general anesthesia, aged 18-60 years old, Mallampti Ⅰ-Ⅱ class, , were randomly allocated to receive topical anesthesia with pressure nebulized 2% lidocaine for glottis either two times or three times or four times(each group n=30). Before topical anesthesia, the observer's assessment of alert and sedation (OAA/S) scale was controlled to 3-4 points by intravenous midazolam (0.03mg/kg), propofol (2mg/kg/h) and remifentanil (0.05μg/kg/min). Ten minutes after sedation, topical anesthesia was performed with the nebulized 2% lidocaine at 10L/min oxygen flow rate, meantime patients were told to breathe deeply. Tracheal intubation was performed after topical anesthesia. The arterial pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO2) were recorded and blood samples were taken to measure the serum cortisol and insulin concentration during intubation period. Intubation condition score was assessed and the complications like local anesthetic toxicity, mucosa injury, respiration depress were also recorded. Patients were asked whether they could recall the events during intubation 24 hr after operation.

Inclusion Criteria:

• Adult patients aged 18-60 years old with Mallampti Ⅰ-Ⅱ class

Exclusion Criteria:

• Patients who have allergic reaction to the drugs used during anesthesia
• Patients who have a history of gastro-esophageal regurgitation, or with full stomach
• Patients with abnormality of cardiopulmonary function, renal and liver function
• Patients with abnormality of endocrine function
• Patients with increased intracranial pressure or epilepsy