 Common chronic transfusion modalities include ST or RMPET. The goal of therapy is to reduce the hemoglobin S level either by diluting the blood ST or by removing and replacing the blood with non-sickle hemoglobin RMPET. To prevent further brain injury, the goal of transfusion therapy is to lower the hemoglobin S quantification to less than 30 on a routine basis, usually monthly transfusion procedure. There are many large centers that utilize erythrocytapheresis which is considered the preferable method if available. 