Simultaneous ultrasonic measurement of carotid blood flow and intracerebral haemodynamics in man

AbstractCommon carotid blood flow and middle cerebral artery velocities were determined simultaneously by using a range gated Doppler velocimeter and transcranial apparatus in ten subjects. Middle cerebral artery velocities were used as an index of cerebral resistance. Different gas mixture concentratrions were breathed in order to change cerebral haemodynamic conditions. In each condition there was a simultaneous modification of blood gases and cervicocerebral haemodynamics in common carotid blood flow and cerebral vascular resistance index. Carotid blood flow and the resistance index in middle cerebral artery changed also on opposite side. Acute hypercapnia in normoxia increases common carotid blood flow by 33% and simultaneously decreases cerebral resistance index by 11%. Normocapnic hyperoxia was associated with a fall in common carotid blood flow by 13% and with an increase in cerebral resistance index by 7%. There was a inter-subject statistically significant relation between common carotid blood fl...