The prevention of intraoperative hypotension could reduce postoperative organ injury and mortality, particularly in elderly patients receiving long-term renin-angiotensin system inhibitors. Previous meta-analyses suggest that ciprofol, a novel intravenous anesthetic agent, may provide improved hemodynamic stability compared to propofol; however, its precise effects on perioperative hemodynamics remain unclear. The study will assess whether ciprofol improves perioperative hemodynamic stability in elderly patients receiving renin-angiotensin system inhibitors.

Elderly patients receiving long-term renin-angiotensin system inhibitors commonly exhibit reduced vascular elasticity, impaired cardiovascular reserve, and diminished compensatory mechanisms. Regular use of renin-angiotensin system inhibitors has thus emerged as a significant risk factor for intraoperative hypotension, increasing the potential for end-organ injury and closely correlating with postoperative complications such as myocardial injury, acute kidney injury, and increased mortality.

Ciprofol (HSK3486) is a novel intravenous anesthetic agent that has demonstrated efficacy non-inferior to propofol for induction and maintenance of general anesthesia, with an improved safety profile and fewer adverse effects. Recent meta-analyses indicate that ciprofol administration is associated with a significantly reduced incidence of intraoperative hypotension compared with propofol; however, robust evidence from randomized controlled trials (RCTs) remains limited. The present study aims to evaluate the impact of ciprofol on perioperative hemodynamics in elderly patients receiving renin-angiotensin system inhibitors. Given the increased risk of intraoperative hypotension in this patient cohort, the investigation of hemodynamic stability with ciprofol holds substantial clinical significance and may inform anesthetic management strategies for this vulnerable population.

Inclusion Criteria:

1. Patients undergoing elective abdominal surgery under general anesthesia
2. Duration of surgery exceeding 2 hours
3. Patients receiving long-term renin-angiotensin system inhibitor therapy (>3 months prior to surgery)
4. Age ≥ 65 years
5. ASA classification II-III
6. Informed consent was obtained from patients or their guardians

Exclusion Criteria:

1. History of allergy to opioids, propofol, or ciprofol components.

2. Anticipated difficult airway (limited mouth opening, restricted neck movement, or modified Mallampati grade III-IV) or difficult mask ventilation.

   Body mass index ≤18 or ≥35 kg/m².

3. Severe hepatic dysfunction (total bilirubin ≥3.0 mg/dL or AST/ALT ≥2 times the upper limit of normal).

4. Severe renal impairment (creatinine clearance ≤30 mL/min).

5. Cardiac diseases (AV block higher than first-degree, heart rate <50 bpm, severe arrhythmias, severe valvular heart disease, heart failure, or unstable angina on the day of surgery).

6. Preoperative cognitive impairment, cerebrovascular disease, or history of psychiatric illness.

7. Abnormal thyroid-stimulating hormone levels or history of thyroid replacement therapy.

8. Unstable asthma or history of asthma.

9. Alcohol abuse, drug abuse, chronic opioid dependence, or analgesic use exceeding 3 months.

10. Lactating or pregnant women.