This randomized, double-blind, controlled clinical study will evaluate the effects of different dose combinations of intravenous metoprolol and sufentanil on cardiovascular responses during oral endotracheal intubation under general anesthesia.

Endotracheal intubation may cause transient increases in heart rate and blood pressure due to sympathetic stimulation. This study aims to determine whether metoprolol, in combination with different doses of sufentanil, can improve hemodynamic stability during and after intubation.

A total of 900 adult patients aged 18 to 65 years with American Society of Anesthesiologists physical status I or II who are scheduled for elective non-cardiac surgery under general anesthesia with endotracheal intubation will be enrolled. Participants will be randomly assigned to one of 30 groups according to the combination of metoprolol dose and sufentanil dose. Metoprolol doses include 0, 0.1, 0.2, 0.3, 0.4, and 0.5 mg/kg, and sufentanil doses include 0.1, 0.2, 0.3, 0.4, and 0.5 mcg/kg.

All participants will receive standardized anesthetic induction and maintenance. Hemodynamic changes will be observed for 10 minutes after intubation. The main outcome is the success rate of hemodynamic stability within 0 to 10 minutes after intubation. Secondary outcomes include the incidence of hypotension, hypertension, bradycardia, and tachycardia.

Inclusion Criteria:

• Age 18 to 65 years.
• American Society of Anesthesiologists physical status I or II.
• Scheduled for elective non-cardiac surgery.
• Planned general anaesthesia with endotracheal intubation.

Exclusion Criteria:

• Cardiovascular or respiratory diseases, such as uncontrolled hypertension or bronchial asthma.
• Current use of β-blockers.
• History of chronic drug use or alcohol abuse.
• Hepatic or renal impairment.
• Known allergy to any study drug.
• Anticipated difficult airway.
• Any other condition that may affect the conduct of the study.