Cerebral blood flow velocimetry in infants with polycythemia: effects of partial exchange transfusion

The aim of this study was to evaluate changes in cerebral blood flow velocity in newborns with polycythemia. Twenty infants were examined, ten before and after partial exchange transfusion with 5% albumin, and ten controls. Blood flow velocity and resistance index of the anterior cerebral, medium cerebral and internal carotid arteries were performed using color and pulsed Doppler systems. A decrease in cerebral blood flow velocities in the polycythemic infants was observed when compared with the control group. The reduction in hematocrit produced a significant increase in maximal systolic velocity, average velocity or both, respectively, in the anterior cerebral, medium cerebral and internal carotid arteries, but no significant decrease in resistance index. After partial exchange transfusion, cerebral blood flow velocities in polycythemic newborn infants were similar to those of the control group. These results indicate that infants with polycythemia have a decreased cerebral blood flow velocity that normalizes after partial exchange trans fusion. Whether or not these hemodynamic changes can cause cerebral damage still remains a matter of controversy.