Transcranial Doppler (TCD/TCCS) and Cerebral Blood Flow Velocities: Parameters of Normality

Abstract

The interpretation of the values obtained by TCD/TCCS examination is dependent on the clinical context and the systemic circulatory status, with reference to the normal values expected for a patient. 2. The identification of the insonated vessel depends on the window, the direction of the probe points, the depth of insonation and the direction of flow in the vessel; therefore, after appropriate training an examiner can accurately identify the vessels. 3. Studies discovered that cerebral blood flow velocity is not the same in women as in men. It found that females usually have higher velocity than contemporary males without differences in pulsatility or resistance indexes. 4. Cerebral blood flow is auto-regulated, and its distribution throughout the brain depends partially on the metabolic activity of the tissue. Therefore, in actively working brains, we can expect to find higher CBF, hence higher cerebral blood flow velocities (CBFV) in the side with higher metabolic activity. 5. Cerebral blood flow velocities (CBFVs) are higher in younger persons. The decline in velocities is found in most series after the fifth decade, and thereafter there is a steady decrease in mean velocity in most series.

The effect of various types of COVID-19 vaccines on the retinal microvasculature

“…One of the main limitations of our study was the mismatch between male and female numbers in the study might affect the results. It is well known that females have a faster blood flow than males [ 24 , 25 ].…”