Age

18–65

Sex

ALL

Healthy volunteers

Not accepted

\>18 years old,\<65 years old
Signed informed consent
Undergoing selective operation （ time of operation is over two hours）
ASA classification I-II
Mallampati classification 3-4
suspicious difficult airway, but the anesthetists decide to try to rapid induction

Patients with several dysfunctions of liver, kidney or heart)
Patients with a full stomach or have other risk factors of reflux aspiration
Any medicine was taken before surgery, which might enhance or mitigate the effects of muscle relaxant
Infection of the mouth or nose
Allergy history of any medicine which would be used in this study
Pregnant and lactating women
Patients with neuromuscular disease

Safety and Feasibility of Reversible Induction Strategy