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 veloci ty in newborns with polycythemia. Twenty infants were examined, ten before and after partial exchange transfusion with 5% albumin, and ten controls. B lood flow velocity and resistance index of the anterior cerebral, medium ce rebral and internal carotid arteries were performed using color and pulsed Doppler systems. A decrease in cerebral blood flow velocities in the polycy themic infants was observed when compared with the control group. The reduc tion in hematocrit produced a significant increase in maximal systolic velo city, average velocity or both, respectively, in the anterior cerebral, med ium cerebral and internal carotid arteries, but no significant decrease in resistance index. After partial exchange transfusion, cerebral blood flow v elocities in polycythemic newborn infants were similar to those of the cont rol group. These results indicate that infants with polycythemia have a dec reased cerebral blood flow velocity that normalizes after partial exchange trans fusion. Whether or not these hemodynamic changes can cause cerebral d amage still remains a matter of controversy.