Intraoperative hypotension is common during major noncardiac surgery and is associated with adverse postoperative outcomes. Propofol, the most commonly used intravenous anesthetic agent worldwide, is associated with hypotension on induction and maintenance of general anesthesia. Remimazolam is a newly developed short-acting benzodiazepine drug and has been approved for use in procedural sedation and general anesthesia. It was associated with a lower incidence of hypotension during procedural sedation in previous studies. The aim of this study is to tested the primary hypothesis that total intravenous anesthesia with remimazolam reduces the duration and severity of hypotension during major noncardiac surgery compared with total intravenous anesthesia with propofol.

Inclusion Criteria:

• Age ≥45 years;

• Undergoing elective major surgery under general anesthesia (expected surgery time >2 h, expected length of postoperative stay >2 d);

• Need for intraoperative invasive blood pressure monitoring via arterial line;

• Fulfilling ≥1 of the following criteria (a-k):

  1. history of coronary artery disease;
  2. history of stroke;
  3. history of congestive heart failure;
  4. preoperative NT-proBNP >200 pg/mL;
  5. preoperative high sensitivity troponin T > 14 ng/L;
  6. age ≥70 years;
  7. diabetes requiring medical treatment;
  8. ASA status 3 or 4;
  9. history of chronic kidney disease (preoperative sCr >133μmol/L or 1.5 mg/dL);
  10. preoperative serum albumin <30 g/L;
  11. preoperative hemoglobin <100 g/L.

Exclusion Criteria:

• Undergoing organ transplantation, cardiac, neurological, or adrenal gland surgery;
• Planned intraoperative MAP higher or lower than 65 mmHg;
• Severe untreated or uncontrolled hypertension (preoperative SBP >180 mmHg and/or DBP >110 mmHg);
• End-stage renal disease requiring renal-replacement therapy;
• ASA score ≥5;
• Preoperative requirement of vasopressor infusion;
• Unable to receive bispectral index monitoring;
• Known allergy to benzodiazepines, propofol, opioids or cisatracurium;
• Current participation in another interventional study;
• Previous participation in this study;
• Pregnant or breastfeeding women.

The deidentified IPD will be shared upon reasonable request after study completion.