[Significance of pCO2 for cerebral blood flow in neonatology. A Doppler sonographic study].

Range-gated pulsed Doppler-ultrasonographic blood flow measurements of 3 cerebral arteries (a. cerebri anterior, a. carotis interna, a. basilaris) were performed during acute pCO2-changes in 16 neonates treated in an intensive care unit. Pulsatility index, peak systolic and end diastolic flow velocity, and mean velocity were evaluated. Mean velocity in the a. carotis interna and the a. basilaris depends on the pCO2, and increases resp. decreases by 5.6% per mm Hg of rise resp. fall of the pCO2. Assuming no pCO2-dependent diameter changes of the large cerebral arteries volume flow would increase resp. decrease by a proportional amount. When obtaining qualitative or semiquantitative informations about volume flow by Doppler-ultrasonography anatomic conditions must be considered carefully.