[Doppler ultrasonography for evaluation of the reactivity of cerebral vessels].

Using ultrasonographic measurements based on Doppler's phenomenon the author determined in 86 subjects the velocity of blood flow in the common carotid arteries before and after breathing 6% CO2. Acceleration of blood flow resulting from dilation of cerebral blood vessels was observed in all healthy subjects up to the age of 45 years. In older subjects the vasomotor reaction was sometimes absent, significantly more frequently in cases of past cerebrovascular accidents. These results indicate absence of vasomotor reserve in most patients with disturbances of cerebral circulation. The used method of investigation makes possible, in view of its simplicity and non-invasiveness, a more widespread determination of cerebral vascular reactions in clinical studies.