CEREBROVASCULAR IMPEDANCE MEASUREMENTS WITH US DOPPLER TECHNIQUE.

The authors present different experimental models performed in the attempt to determine whether the alterations of brain circulation following an increase in the intracranial impedance can be estimated by systolic and diastolic common carotid artery (CCA) velocity Doppler signals recorded at 15-minute intervals until 60 minutes and 10 hours. Statistically significant results confirming the well-known theoretical relationship between increased encephalic impedance and flow velocity Doppler signals were obtained. The results demonstrated that a sudden increase in the encephalic impedance can affect both systolic and diastolic flow velocities in afferent vessels.