Effects of Remimazolam on the Intraoperative Hemodynamics in Bypass Surgery

Inclusion Criteria: * Patients who undergo elective extracranial-intracranial bypass surgery * American Society of Anesthesiologists grade 1,2,3 * Age \> 18 years old Exclusion Criteria: * Refuse to participate to the study * American Society of Anesthesiologists grade 4 * Body Mass Index \< 18.5 kg/m2 or \> 35 kg/m2 * Allergic history of benzodiazepine * Pregnant * Acute narrow-angle glaucoma * Shock or Coma * Acute alcohol addicted * Obstructive sleep apnea * dependency on alcohol or drug * Severe acute respiratory insufficiency * Hypersensitivity to Dextran 40