INTRAINDIVIDUAL VARIABILITY OF CEREBRAL BLOOD-FLOW VELOCITIES IN CHILDREN WHILE AWAKE AND ASLEEP

A considerable intraindividual variability of blood flow velocities in the middle and posterior cerebral artery was found in 74 children by continuous transcranial Doppler recording during EEG registration. The coefficient of variation of the mean flow velocities in the posterior cerebral artery was higher than in the middle cerebral artery, and higher in restless children than in calm children. During hyperventilation the mean flow velocities decreased to about 50 per cent of the baseline values. They increased to 130-140 per cent of the baseline values after hyperventilation. Repeated variations of the velocities of more than 30 per cent of the baseline values were observed during non-REM sleep in the majority of the children. They may be caused by a lower damping of the cerebral autoregulatory response. The intraindividual variability of cerebral blood flow velocities in children has to be kept in mind in pathological conditions and during Doppler monitoring.