Red blood cell (RBC) transfusion has been shown to be beneficial as part of the treatment and management of sickle cell disease (SCD), whether as episodic treatment for an occurrence of acute anemia or as chronic transfusion for prevention of stroke recurrence. RBCs transfused to patients with SCD should, at minimum, be from donors negative for hemoglobin S (HbS), but patients may also benefit from leukoreduction of these blood components. As with any transfusion, RBC transfusion should only be used when the benefit to the patient outweighs the risks, which in this instance include transfusion-transmitted infectious diseases, transfusion reactions, RBC alloimmunization, and iron overload. However, because SCD patients have one of the highest incidences of RBC alloimmunization among transfused patients, strategies focused on prophylactic Rh and Kell antigen matching and the increased use of automated RBC exchange appear to mitigate the risks of RBC alloimmunization and transfusion-related iron overload, respectively. In the event of complex alloimmunization or hyperhemolysis, transfusion indications may be limited and transfusion may require preventative immunomodulatory therapies.
Indications for RBC Transfusion in SCD
When the hemoglobin decreases below the patient’s baseline value and symptoms occur, transfusion of RBCs can be considered by administering the fewest units necessary to alleviate symptoms. RBC transfusion increases hemoglobin, reduces the proportion of HbS in the circulation, and improves oxygen delivery. The underlying cause of the acute anemia, defined as a decrease in hemoglobin by ≥2 g/dL below the baseline value, should be investigated.1 Acute anemia may be caused by aplastic crisis, splenic or hepatic sequestration, or delayed hemolytic transfusion reactions (if the patient has been transfused in the past 3-4 weeks), or it may be a harbinger of acute chest syndrome in a patient with a vaso-occlusive crisis (VOC).
Stroke and Stroke Prevention
Without preventative measures, 8% of children with SCD in high-income countries will have strokes by the age of 14 years.2 In children with SCD, strokes are usually due to occlusion of the internal carotid or middle cerebral artery; however, adults may have hemorrhagic or ischemic strokes.1 In sub-Saharan African countries and in India, before the age of 18 years, 50% of children with SCD will have either a stroke or a silent cerebral infarction.3 Among the risk factors for cerebral ischemia in SCD are the existence of cerebral vasculopathy, anemia with a compensatory increase in cerebral blood flow and increased HbS percentage (HbS%) with decreasing cerebrovascular reserve, and a rapid increase in hemoglobin levels to >12 g/dL.3 Thus, the primary goal of RBC transfusion in the treatment of acute stroke, prevention of primary stroke in those with abnormal transcranial Doppler ultrasound, and prevention of stroke recurrence is to reduce the HbS% to ≤30% and to maintain the hemoglobin close to 10 g/dL. In acute stroke, it is particularly important to rapidly reduce ...