Carotid Artery Corrected Flow Time as a Predictor of Hypotension After Induction of General Anesthesia in Elderly Patients

Ultrasonic measurement of carotid corrected blood flow time: 1. Patient's head turned to the left 30°. Firstly, the 6.0 \~ 13.0MHz linear probe was placed longitudinally on the maternal neck, and the probe marker was oriented towards the maternal head. Real-time B-ultrasound images of the long axis of the right common carotid artery were obtained from the lower margin of the thyroid cartilage. Then, the probe was placed in the center of the carotid lumen, about 2cm from the bifurcation of the carotid artery, to obtain the arterial pulse Doppler flow spectrum and store the carotid flow waveform. 2. Using the caliper function of the ultrasonic instrument, carotid flow time (FT) was obtained by measuring the interval between the systolic ascending stage and the restroke notch. Wodey (W) formula to calculate FTc. FTc= FT+\[1.29× (HR-60)