The purpose of this study is to determine whether nasal tracheal intubation using Blind Intubation Device is safe and effective in anesthetized patients with Mallampati class 3

The Blind Intubation Device (BID,Anhui Xiao Shan Hygienic Material Co.Ltd,Jixi County,China) is newly introduced for awake nasal intubation using a transillumination principle. For oral and maxillofacial surgery patients with anticipated difficult airways, the BID has a high rate of successful awake nasal intubation.Since the BID is more readily accessible,disposable and considerably less expensive,these advantages speak well for its use in China.However,to date,there is no study on its usage in anesthetized patients.The investigators hypothesized that a BID would be effective for nasal intubation in anesthetized patients with high Mallampati class and would result in fewer hemodynamic responses. To examine our hypothesis, the investigators would like to perform a prospective,randomized,controlled study to compare the effectiveness of the BID technique with a direct laryngoscope for nasal intubation in anesthetized patients with Mallampati class 3. The primary outcome measures are the hemodynamic changes during intubation. The investigators also would like to compare the intubation time required and associated airway complications in both groups as our second outcome.

Inclusion Criteria:

• ASA physical status 1-2
• Scheduled for oral and maxillofacial surgery under general anesthesia with nasotracheal intubation
• mallampati score 3

Exclusion Criteria:

• ASA physical status 3-4
• Patients with a history of intraoral,upper airway and neck surgeries
• Patients with a history of chronic respiratory, cardiovascular or any other systemic diseases
• morbid obesity
• neck scars
• mallampati score 4,inter-incisor distance<3cm, thyromental distance<6cm
• unstable cervical spine
• relevant drug allergy