Study on the safety and efficacy of different doses of remimazolam during anesthesia induction in elderly patients undergoing off-pump coronary artery bypass grafting

INTERVENTION: Low‐dose remimazolam group (Group L):Induction was performed with intravenous remimazolam at a dose of 0.15 mg/kg;Medium‐dose remimazolam group (Group M):Induction was performed with intravenous remimazolam at a dose of 0.2 mg/kg;High‐dose remimazolam group (Group H):Induction was performed with intravenous remimazolam at a dose of 0.25 mg/kg; CONDITION: Coronary Atherosclerotic Heart Disease PRIMARY OUTCOME: Changes in mean arterial pressure; SECONDARY OUTCOME: Changes in heart rate;Changes in mean arterial pressure;Changes in cardiac inde X(CI);Changes in stroke volume inde X(SVI);Time to loss of consciousness;Time to BIS<=60;Frequency of administration of rescue sedation;Incidence of hypotension at 5 minutes after endotracheal intubation;Incidence of hypertension at 5 minutes after endotracheal intubation;Incidence of bradycardia at 5 minutes after endotracheal intubation;Incidence of tachycardia at 5 minutes after endotracheal intubation;Incidence of malignant arrhythmias at 5 minutes after endotracheal intubation;Incidence of hypoxemia at 5 minutes after endotracheal intubation;Incidence of myocardial ischemia at 5 minutes after endotracheal intubation;Incidence of coughing;Incidence of injection pain; INCLUSION CRITERIA: 1. Patients diagnosed with coronary heart disease who are scheduled for elective off‐pump coronary artery bypass grafting; 2. Elderly patients aged 60 to 75 years old; 3. Body mass inde X(BMI) ranging from 18.5 to 23.9 kg/m^2; 4. American Society of Anesthesiologists (ASA) physical status classification II to III.