SBP≥180 mmHg or \<90 mmHg, DBP≥110 mmHg or \<60 mmHg.

Serious heart, brain, liver, kidney, lung, endocrine diseases or serious infections.

Hematopoietic dysfunction or bleeding tendency and hemorrhagic disease.

A neuromuscular system disease.

Airway and lung surgery.

Predict possible or happened difficult airway.

Immune function defect.

Sure/suspected abuse of narcotic analgesics or drugs or alcohol dependence.

The test drug allergy or have other contraindications in patients.

Childbearing age women not to take appropriate contraception, pregnancy or lactation.

Participated in other clinical drug research in the last 30 days.

Effect of Dexmedetomidine on Levels of Plasma Inflammatory Factor in Asthma Patients Undergoing General Anesthesia