[Dynamic changes and physiological regulation of common carotid artery blood flow during general anesthesia in elderly patients: a prospective study].

OBJECTIVES

To explore the dynamic pattern and physiological regulation of common carotid artery (CCA) blood flow during general anesthesia in elderly patients.

METHODS

A total of 193 elderly patients undergoing abdominal surgery were prospectively enrolled. Respiratory and hemodynamic variables and anesthetic depth of the patients were recorded throughout the perioperative period. CCA blood flow was measured at predefined time points using vector flow imaging. Heart rate, mean arterial pressure, end-tidal carbon dioxide, and bispectral index were included in a linear mixed-effects model, with patient ID as a random effect, to explore the physiological determinants of intraoperative CCA blood flow.

RESULTS

CCA blood flow showed clear stage-related changes during general anesthesia. The mixed-effects model explained 52.0% of the variation in CCA blood flow (adjusted R²=0.520, P<0.001). Heart rate, mean arterial pressure, end-tidal carbon dioxide, and bispectral index were all significantly associated with CCA blood flow (all P<0.001). The standardized model further showed that the strength of these associations differed, with flow-related factors showing a stronger effect than blood pressure or heart rate alone. Surgical approach and patient position had no significant effect on CCA blood flow.

CONCLUSIONS

Intraoperative cerebral perfusion is not maintained by blood pressure alone but influenced jointly by ventilation, hemodynamic status, and anesthetic depth. Recognizing and managing these factors may help optimize cerebral perfusion during surgery.