Acute change with transfusion and groupwise comparisons are shown for TR jet velocity and FMD. There was no significant change in TR jet velocity from pre- to posttransfusion. The distribution between control subjects, nontransfused SCD, pretransfusion SCD, and posttransfusion SCD is shown next to the acute change with transfusion. The TR jet velocity in the nontransfused subjects was significantly higher than the control and posttransfusion subjects, but not different than the pretransfusion subjects (*P < .05). There was a wide distribution of FMD among SCD patients, similar to TR jet velocity. However, there was a significant increase in FMD acutely after transfusion (P < .05), and FMD was significantly higher in control subjects vs nontransfused SCD patients (P < .05).