observational study The purpose of this observational study is to clarify the consistency, accuracy, and reproducibility of portable patch carotid ultrasound (CADFlow) compared to desktop ultrasound machines in detecting cardiac output (CO), peak velocity (Vmax), and minimum velocity (Vmin) in healthy volunteers.

Parameters including cardiac output (CO), peak carotid artery velocity (Vmax), and minimum velocity (Vmin) were monitored in healthy subjects using a portable patch-type carotid ultrasound device (CADFlow). The subjects were placed in a supine position with the head rotated 30° to the contralateral side and the neck slightly extended. The dual-patch probe was then attached to the sites of the most prominent bilateral carotid artery pulsations. The automatic measurement mode was initiated to record blood flow waveforms for 60 seconds. After 30 minutes, the same subjects underwent reassessment of the aforementioned parameters using a conventional ultrasound system. The distal internal diameters of the bilateral common carotid arteries were measured in two-dimensional mode (mean of three measurements). Using pulsed-wave Doppler with an insonation angle ≤60°, Vmax and Vmin were recorded over three consecutive cardiac cycles. The probe was subsequently switched to a transthoracic cardiac probe for CO measurement at the left ventricular outflow tract (LVOT) (mean of three consecutive measurements). The order in which the subjects were monitored with the two devices was randomized.

Inclusion Criteria:

• Age between 18 and 79 years; No abnormalities found in physical examination; Signed informed consent form.

Exclusion Criteria:

• Previous or current cardiovascular or cerebrovascular diseases; Carotid intima-media thickness (IMT) ≥ 1.0 mm or plaque; Arrhythmia; ④ BMI > 35 kg/m²; Pregnancy.

Include healthy individuals aged 18 to 79