Most of the major spinal surgeries are performed in the supine position, which causes a decrease in stroke volume and cardiac index, which leads to the occurrence of hypotension during surgery. Postoperative hypotension causes an imbalance in the supply and demand of oxygen, leading to postoperative myocardial infarction or acute renal damage, and may increase mortality one year after surgery. Propofol, which is most commonly used for total intravenous anesthesia, can further increase the incidence of hypotension during surgery. Therefore, there is a continuing demand for an anesthetic agent that is more hemodynamically stable. Remimazolam, an ultra-short acting benzodiazepine that has a similar structure to midazolam, but whose activity is terminated by esterase hydrolysis, is expected to have less hemodynamic effects than propofol. Therefore, the purpose of this study is to investigate the effect of general anesthesia using remimazolam and general anesthesia using propofol on hemodynamic safety during surgery in patients undergoing major spinal surgery in the supine position.

Inclusion Criteria:

• ASA physical status: 1-3
• age: 19-80 years
• patients who are scheduled to undergo a major spine surgery in the prone position

Exclusion Criteria:

• patients who refuse to participate
• body mass index: <15kg/m2 or >35kg/m2
• patients with uncontrolled hypertension, hyperthyroidism, severe cardiac disease
• patients who are contraindicated to the use of remimazolam including severe hepatic disease, acute glaucoma, shock, acute alcohol intoxication
• allergic to propofol and midazolam
• patients who are judged unsuitable to participate in the study for other reasons by medical staffs