What are the transfusion parameters for Sickle Cell Disease (SCD)?

From the Guidelines

Transfusion parameters for sickle cell disease (SCD) should aim to maintain hemoglobin levels between 9-10 g/dL and hemoglobin S (HbS) levels below 30% for most patients, as recommended by the American Society of Hematology 2020 guidelines for SCD: transfusion support 1.

Key Considerations

• Red blood cell transfusions are indicated for acute complications like stroke, acute chest syndrome, or multi-organ failure, and for prevention of complications in high-risk scenarios such as pregnancy or major surgery.
• Simple transfusions are used for moderate anemia, while exchange transfusions are preferred for severe complications to rapidly reduce HbS levels without increasing blood viscosity.
• Phenotypically matched blood is recommended to reduce alloimmunization risk, with leukocyte-reduced units being standard, as alloimmunization incidence in patients with SCD is high due to factors such as relatively large transfusion burdens and RH genetic diversity 1.
• Extended antigen matching (particularly for C, E, and Kell antigens) is important for patients receiving chronic transfusions to minimize the risk of alloantibody formation.
• Iron chelation therapy should be considered for patients receiving regular transfusions to prevent iron overload, a common complication of chronic transfusion therapy.

Transfusion Methods

• Automated red cell exchange (RCE) is a preferred method for chronic transfusion therapy, as it allows for precise programming of target HbS%, hematocrit, and overall fluid balance, and minimizes acute blood volume shifts 1.
• Manual RCE and simple transfusion are also used, but may have limitations such as requiring more time, trained personnel, and red cell units.
• The choice of transfusion method depends on institutional resources, expertise, and patient-specific factors.

Monitoring and Prevention

• Regular monitoring of hemoglobin levels, HbS levels, and iron stores is essential to adjust transfusion parameters and prevent complications.
• Preventing red cell alloimmunization is a desirable goal, and extended antigen matching can help minimize the risk of alloantibody formation 1.
• Iron chelation therapy should be considered for patients receiving regular transfusions to prevent iron overload and its associated complications.

From the Research

Transfusion Parameters for Sickle Cell Disease (SCD)

The transfusion parameters for Sickle Cell Disease (SCD) are as follows:

• Transfusions are used to improve blood flow by reducing the proportion of red cells capable of forming sickle hemoglobin polymer, limiting hemolysis and endothelial damage 2
• Transfusions are used to increase blood oxygen carrying capacity in sickle cell patients with severe chronic anemia or with severe anemic episodes 2
• Transfusion is well-defined as prophylaxis (stroke) and as therapy (acute chest syndrome and stroke) for major complications of sickle cell disease 2
• The major and unavoidable complication of transfusions in sickle cell disease is iron overload 2
• Transfusion, simple or exchange, is a mainstay of therapy, since it reduces the amount of Hgb S in circulation and suppresses erythropoiesis 3
• Transfusion is indicated for symptomatic anemia and specifically to prevent stroke (first or recurrent), during acute stroke, and for acute chest syndrome 3
• For patients with SCD who may be chronically transfused, iron overload occurs frequently, and due to differences in RBC antigens between donors and recipients, these patients are at increased risk for development of RBC alloantibodies 3
• It is important to prevent alloimmunization by transfusing leukoreduced RBCs that match the patient for the C, E, and K1 antigens 3
• Blood transfusion should be aimed to increase tissue delivery of oxygen, and the transfused blood should be Hb S negative, Rh and Kell antigen matched 4
• Chronic transfusion protocols are implemented in cases of strokes or high cerebral blood flow ultrasonic studies as a prophylactic measure 4
• Exchange blood transfusion is used in some complications of the disease such as acute chest syndrome (ACS), priapism or peri operatively 4
• Red cell exchange transfusions remain an effective but possibly underutilized therapy in the acute and chronic treatment of sickle cell disease, providing needed oxygen carrying capacity while reducing the overall viscosity of blood 5
• Acute red cell exchange is useful in acute infarctive stroke, in acute chest and the multi-organ failure syndromes, the right upper quadrant syndrome, and possibly priapism 5
• A double-volume red cell exchange transfusion decreases the percentage of hemoglobin S (Hgb S) containing red blood cells to less than 20%, improving vascular perfusion 6
• Red cell exchange transfusion lowers WBC, ANC, platelets, and sVCAM-1 levels, but the effect is short-lived 6