The Effects of Remimazolam on Cerebral Blood Flow Following General Anesthesia Induction

This study will enroll 40 subjects aged 18 years or older scheduled for elective surgery under general anesthesia with endotracheal intubation. Basic medical history information will be collected. Subjects will be divided into two groups of 20 each: a remimazolam group and a propofol group. The study period will span from one day before surgery to one day after surgery. The study will assess middle cerebral artery cerebral blood flow following general anesthesia induction and postoperative anesthesia recovery.

A significant reduction in cerebral blood flow (CBF) frequently occurs following general anesthesia induction. This decrease in CBF can lead to a reduction in the delivery of oxygen and glucose to brain tissue. If the magnitude or duration of this reduction exceeds the compensatory capacity of cerebral autoregulation, it can result in an imbalance between cerebral oxygen supply and demand, thereby increasing the risk of cerebral ischemia and neurological injury. Patients who are elderly, have hypertension, a history of cerebrovascular disease (e.g., stroke, intracranial arterial stenosis), or pre-existing brain injury are at higher risk for pronounced CBF reduction after induction, making them more susceptible to postoperative cognitive dysfunction, exacerbation of existing deficits, or new ischemic events. This underscores the urgent need to identify effective and safe therapeutic strategies to mitigate this risk. Remimazolam is a novel benzodiazepine agent, structurally derived from midazolam with the introduction of a metabolically labile methyl propionate side chain. It similarly acts on the GABAA receptor, promoting chloride ion influx and inhibiting neuronal electrical activity. Administered intravenously for sedation and hypnosis, it is characterized by rapid onset, short duration of action, rapid recovery, minimal accumulation, and metabolism independent of hepatic or renal pathways. Previous studies indicate that benzodiazepines generally lack significant cardiovascular depressant effects and are associated with a lower incidence of hemodynamic instability during anesthesia induction. However, the specific impact of remimazolam on CBF following general anesthesia induction remains unclear. Therefore, to further elucidate the effects of this novel benzodiazepine, remimazolam-which reportedly lacks significant cardiovascular depression-on CBF post-induction, we propose the following strategies for our clinical study: (1) compare remimazolam with the commonly used agent propofol for anesthesia induction; (2) administer remimazolam as an intravenous bolus of 0.3 mg/kg and propofol at 2 mg/kg for induction; (3) implement goal-directed fluid management during the peri-induction period; (4) utilize ultrasound to monitor blood flow in the middle cerebral artery; and (5) assess postoperative recovery parameters. Through this comprehensive approach, we aim to determine whether remimazolam offers a protective or optimizing effect on CBF during general anesthesia induction, thereby providing an empirical foundation for its routine clinical use in this context.