Remimazolam Versus Propofol for Maintenance of Anaesthesia During Major Hepatectomy Under Low Central Venous Pressure

The goal of this clinical trial is to learn whether remimazolam helps prevent low blood pressure better than propofol during major liver surgery in adults. All participants will have planned surgery to remove at least three liver segments. The main question is whether participants who receive remimazolam have less low blood pressure while the surgeon removes liver tissue. Researchers will measure both how low the blood pressure falls and how long it stays low. Researchers will randomly assign 224 participants to receive remimazolam or propofol to maintain general anesthesia. Participants will not know which drug they receive until their postoperative assessments are complete. The anesthesiologist giving the drug will know the assignment for safety reasons. Participants will: * Receive one of the two study drugs during surgery * Have their blood pressure monitored continuously * Receive standard treatment if their blood pressure becomes low * Complete follow-up through 30 days after surgery Researchers will also compare the use of medicines to support blood pressure, bleeding, blood transfusion, recovery after anesthesia, organ complications, heart injury, and adverse events.

Inclusion Criteria: * Age 18 to 85 years * Scheduled for elective liver resection * Preoperative surgical plan includes resection of at least three Couinaud liver segments * Planned use of low central venous pressure management, general anesthesia, invasive arterial pressure monitoring, and central venous pressure monitoring * American Society of Anesthesiologists physical status II or III * Both study anesthesia strategies are considered clinically appropriate * Able to understand the study information and provide written informed consent Exclusion Criteria: * Emergency surgery or inability to complete written informed consent before surgery * Known contraindication or serious hypersensitivity to remimazolam, another benzodiazepine, propofol, or a relevant excipient * Preoperative shock, ongoing vasoactive drug support, or another hemodynamically unstable condition that makes either study anesthesia strategy unsafe * Child-Pugh class C, Model for End-Stage Liver Disease score of 20 or higher, or end-stage liver disease in the investigator's judgment * Massive ascites, recent variceal bleeding, clinically important hypersplenism with severe thrombocytopenia, or portal hypertension sufficient to substantially alter circulatory management * Regular long-term benzodiazepine use, drug dependence, or alcohol misuse expected to affect the pharmacological evaluation * Clinical requirement for an inhalational anesthetic or another maintenance anesthesia strategy incompatible with randomized assignment * Pregnant or breastfeeding * Concurrent participation in another interventional study that may affect the primary outcome * Any other condition that, in the investigator's judgment, makes participation unsafe or prevents completion of the study procedures