Cerebral blood flow velocities in postasphyxial term neonates

Blood flow velocities of the anterior cerebral artery and right radial artery were studied in 15 postasphyxial term neonates using a continuous waveform bidirectional Doppler Pulsatility index (PI) values of most mild asphyxic infants were within the normal range. However, the infants with anoxic encephalopathy showed high or low PI values. The minimal flow velocities of the right radial artery (RRA) showed markedly retrograde flow velocity shortly after birth in comparison with those of the controls. The high PI values may be mainly due to a marked decrease of diastolic flow velocity representing retrograde flow in RRA. The low PI values indicated the poor prognosis in the postasphyxial infants. In low PI cases the cerebrovascular autoregulation may be presumed to be impaired, and arterioles to be markedly dilated.