The evaluation of cerebral blood flow velocities in normal newborns and infants.

The cerebral blood flow velocities of 80 normal newborn babies and 117 normal infants were evaluated by pulsed-Doppler investigation of anterior cerebral arteries through the open anterior fontanel. Peak systolic blood flow velocity (PSFV), end-diastolic blood flow velocity (EDFV), mean blood flow velocity (MFV), and the pulsatility index (PI) values were measured for all subjects. In the neonate group, all flow velocities increased in the first 20 days after birth, with rapid increase from one to two months of age. After that, velocities increased steadily within the first year of age. The increasing flow velocities probably reflect the changes in cerebral blood flow and arterial blood pressure during the first year of life. On the contrary, the pulsatility indices (PI) slightly decreased during this first year. The result supports the hypothesis of a decrease in cerebrovascular resistance during infancy. This study may have value as reference for normal cerebral blood flow velocities and pulsatility indices as determined during infancy for different age groups.