Cerebral blood flow velocity in infants with polycythemia and hyperviscosity: effects of partial exchange transfusion with Plasmanate.

To determine if there are significant changes in cerebral blood flow velocity and vascular resistance in neonates with polycythemia and hyperviscosity, 11 such infants were studied before and after partial exchange transfusion with Plasmanate. Seven matched control infants were also studied. Blood flow velocity of the anterior cerebral artery was measured with a bidirectional continuous waveform Doppler velocimeter. Blood flow and vascular resistance were calculated from the velocity tracings, using the area under the velocity curve and the Pulsatility Index. Reduction in hematocrit and viscosity produced significant increases in blood flow velocity and a reduction in vascular resistance. The postexchange values were similar to those of the control group. These results indicate that infants with polycythemia and hyperviscosity have decreased cerebral blood flow velocity and increased vascular resistance which normalize after partial Plasmanate exchange transfusion.