Dizocine (0.03 mg/kg) or saline followed by sufentanil 0.4ug/kg was administered, and induction was completed with 3 min of observation. Heart rate and mean arterial pressure (MAP) were recorded before induction of anesthesia, before and 1 min after intubation, and side effects during induction, such as vomiting, hypoxemia (SpO2 <90%), or other expected effects. The number of coughs was recorded in both groups, and the severity of cough was defined as follows: mild, 1-2 coughs; moderate, 3-4 coughs; severe, 5 or more coughs.

Inclusion Criteria:

• Patients admitted for elective valve surgery, artificial vessel replacement or coronary artery bypass graft surgery; Age 18~80 years old; Sex is not limited; ASA class II~III; NYHA Class II-III; Patients or their family members have signed the clinical trial informed consent form

Exclusion Criteria:

• Upper respiratory tract infection within the last two weeks; Long history of smoking; chronic obstructive pulmonary disease; Highly reactive airway diseases such as bronchitis and asthma; Presence of high cranial pressure, high eye pressure, pulmonary alveolus; Malignant tumor, hematological disease, severe liver and kidney dysfunction, recent serious infection, etc.