Comparative effects of ciprofol, propofol, and etomidate on cerebral blood flow velocity during anesthetic induction: a prospective comparative study

Background Maintenance of cerebral perfusion during anesthetic induction is essential, particularly in patients vulnerable to hemodynamic instability. Transcranial Doppler (TCD) ultrasonography enables bedside assessment of cerebral blood flow (CBF) velocity and provides insight into cerebral hemodynamic changes during anesthesia. This study evaluated changes in CBF velocity during induction with Ciprofol and compared them with those of propofol and etomidate. Methods This prospective quasi-experimental observational study included 72 adult patients (American Society of Anesthesiologists I–II) undergoing elective surgery with tracheal intubation. Patients received propofol (Group P), ciprofol (Group C), or etomidate (Group E) through non-randomized allocation based on routine clinical practice. Mean arterial pressure was maintained within ±20% of each patient’s baseline value using a standardized blood-pressure-guided management strategy. Bilateral middle cerebral artery (MCA) flow velocities were continuously monitored using TCD from baseline to 15 min after induction. Primary outcomes were mean flow velocities of the left and right MCA. Secondary outcomes included systolic velocity, diastolic velocity, pulsatility index, and resistance index. Between-group comparisons, area under the curve (AUC) analysis, and linear mixed-effects modeling were performed. Results Although conventional hypothesis testing showed no significant differences in baseline characteristics (all P > 0.05), standardized mean difference analysis indicated potential baseline imbalances (Max standardized mean difference >0.2). AUC analysis of CBF parameters during the first 15 min after induction showed no significant differences among the three groups. Short-term fluctuation analysis revealed similar changes during the immediate and overall induction phases. During the stable phase, a significant difference was observed only in the right-sided resistance index. Linear mixed-effects models demonstrated significant group-by-time interactions for diastolic velocity, pulsatility index, and resistance index, indicating distinct temporal patterns among agents. Conclusions In this prospective observational study, under a strict blood-pressure-guided management strategy, propofol, ciprofol, and etomidate were associated with broadly similar cerebral hemodynamic profiles during anesthetic induction, although subtle, parameter-specific differences in time-dependent cerebrovascular responses were observed. Given the non-randomized exploratory design, potential baseline imbalances, differences in phenylephrine requirements among groups, and the fact that the study was not designed or powered to establish equivalence, these findings should be interpreted cautiously as associative rather than causal and within the context of the standardized hemodynamic protocol. Confirmation in larger randomized controlled studies is warranted. Clinical trial number This prospective observational study was registered and filed prior to participant enrollment in the Medical Research Registration and Filing Information System of the National Healthcare Security Information Platform (China) under registration number MR-44-23-036912. The registration information is provided for transparency.