Mortality associated with difficult airway in anesthesia is up to 30%. So, it is urgent to find a safe and effective method for intubation. Awake tracheal intubation which is used to retain spontaneous breathing is one of the important measures to ensure the safety of the patients with difficult airway in anesthesia.

Sufentanil is used to provide good analgesia and can effectively inhibit the reaction of awake tracheal intubation, however, the outstanding problem is serious respiratory depression after intravenous sufentanil injection. Few study showed that dezocine is a kappa opioid antagonist related to mild respiratory depression and can prevents sufentanil-induced cough during general anesthesia induction.It is necessary to carry out large-scale, multi-center, randomized, controlled clinical study to determine whether dezocine prevents sufentanil-induced respiratory depression and whether dezocine combined sufentanil is a safe and effective method for awake tracheal intubation.

Inclusion Criteria:

1. Written informed consent；
2. Selective surgery and general anesthesia patients；
3. Age 18-65 yrs；
4. Anesthesia Society of American (ASA) Scale I~II；

Exclusion Criteria:

1. Mallampatis Ⅲ-Ⅳ；
2. Heat rate < 50 beats/minutes；
3. II-III Atrioventricular block；
4. Use of alpha agonist or antagonist within two weeks；
5. Use of opioid within 24 hours；
6. Serious heart, liver, kidney disease and cerebrovascular disease；
7. Allergic to the trial drug and other anesthesia drug contraindication；
8. Factors existed that affect language communication；
9. Any respiratory disease；
10. Unsuccessful intubation for 3 times or drop out during intubation.