[Transcranial Doppler sonography in childhood. 1. Study technic and biological effect magnitudes].

The blood flow velocities in the basal cerebral arteries can be recorded at any age by transcranial Doppler sonography. Using a standardised examination technique the vessel identification is reliable even without visual control. A stable state of vigilance is necessary to obtain constant recordings. Age has a definite influence on the flow velocities. Velocities increase linearily during the first weeks and later on more slowly until they reach their maximum around the 6th year of life. The influence of CO2 partial pressure, gestational age, birth weight and haematocrit on the flow velocities must be taken into consideration. Heart rate and arterial blood pressure are relevant only in case of extreme values.