Macintosh direct laryngoscope has been mostly widely used for anesthesiologists in operation rooms or emergency situations all over the world. With rapidly development of technical devices, nowadays videolaryngoscope has become more and more popular in hospitals, for it could improve first intubation success rate and it is easier for beginners to learn. And there are many different types of videolaryngoscope for different purpose, like with or without a channel, different curvature, and so go. In this study, our aim is to study whether the videolaryngoscope which can be adjustable or not costs less intubation time and causes fewer injury in expected non-difficult airway patients by experienced anesthesiologists, compared with the classic Macintosh direct laryngoscope.

Inclusion Criteria:

• age between18 and 65 years
• ASA(American Society of anesthesiologists) I-II
• BMI 18-30 kg/m2
• scheduled to receive elective surgery under general anesthesia with expected non-difficult airway in operation rooms.

Exclusion Criteria:

• expected difficult airway
• allergy to anesthesia induction drugs
• scheduled to receive surgeries affecting vocalisation
• with high reflux aspiration risk
• with acute and chronic cardiac or respiratory failure
• with glucocorticoids medication history
• with mental disorder or transferred to SICU(Surgical Intensive Care Unit) or ICU after surgery who can not cooperate well with others
• refused or have participated in other clinical trials that may have effects on the outcomes of this study

Not decided yet. We plan to share the above information from the article has been published to six months after publication.

Access Criteria has not been decided.